European Journal of Phycology

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Keynote and Oral Papers

To cite this article: (2019) Keynote and Oral Papers, European Journal of Phycology, 54:sup1, 31-117, DOI: 10.1080/09670262.2019.1626627 To link to this article: https://doi.org/10.1080/09670262.2019.1626627

Published online: 20 Aug 2019.

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Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tejp20 EUROPEAN JOURNAL OF PHYCOLOGY 2019, VOL. 54, NO. S1, 31–117 https://doi.org/10.1080/09670262.2019.1626627

Keynote and Oral Papers 1. Phylogeny in the ‘omics’ era: new approaches for the study of the evolution of algae and their organelles

1KN.1 those, CASH lineages have plastids related to red algae, but the mechanisms by which they were DIVERSIFICATION TRENDS IN THE ARCHAEPLASTIDA INFERRED FROM acquired remain unclear. Contrary to expectations CHLOROPLAST GENOME DATA of secondary endosymbiotic models, a sizable part of their plastid-targeted genes is not from the same Heroen Verbruggen ([email protected]) origin as the plastid itself. Scenarios as the ancestral cryptic serial endosymbioses or the shopping bag model University of Melbourne, Parkville, Victoria 3010, Australia provide a substantial interpretation of this gene mosaicism but are exclusively focusing on an endo- Thanks to high-throughput sequencing, it has symbiotic mechanism. Similarly, while the Rhodoplex become easier and cheaper than ever to generate hypothesis fits the single phylogenetic origin of com- genome-scale data for a broad array of non-model plex red plastids, it does not explain gene mosaicism. species. This offers great perspectives to improve our Moreover, it implies multiple tertiary (or quaternary) understanding of algal classification and evolutionary endosymbiotic events, whereas most complex algae biology. We inferred phylogeny of the Archaeplastida do not bear nucleomorphs and only have 3 or 4 using >460 chloroplast genomes and calibrated in membranes surrounding their plastids. To overcome time using 19 fossil occurrences, providing a mostly the inconsistencies of those models, we propose klep- resolved picture of the phylogenetic history of the toplasty as an additional mechanism for explaining group. We used the time-calibrated phylogeny to plastid spread in CASH lineages. In line with the investigate patterns of diversification through time shopping bag model, our hypothesis posits multiple and across lineages, showing an increase of lineage transient interactions with preys of diverse origins accumulation during the Paleozoic, with stark differ- but also proposes a rationale for the selective force ences between the contributions of different func- driving the progressive accumulation of plastid- tional form-groups to overall diversification. targeted genes: to maintain functional kleptoplastids for increasingly longer periods of time, before ulti- 1KN.2 mately reducing them into fully integrated plastids. In such a scenario, the phylogenetic diversity of plastid- AUTOMATED BIOINFORMATICS targeted genes would be higher than predicted with APPROACHES TO EVALUATE THE RELATIVE endosymbiotic models, where genes originate mostly CONTRIBUTION OF ENDOSYMBIOSIS AND from a single source, the algal symbiont. To test our KLEPTOPLASTY IN THE EVOLUTION OF hypothesis, we designed and implemented an auto- COMPLEX RED ALGAE mated pipeline for building and parsing gene trees in Mick Van Vlierberghe (mvanvlierberghe@doct. a discovery-driven and taxonomy-aware fashion. This uliege.be) and Denis Baurain (denis.baurain@u- approach allows us to infer whether any given CASH liege.be) alga rather arose through endosymbiosis or klepto- plasty by reading its position on an alpha-diversity – InBioS PhytoSYSTEMS, Eukaryotic Phylogenomics, University ladder, ranging from (theoretically) single-source of Liège, Liège, Belgium nucleomorph-bearing organisms (e.g., Guillardia Complex algae form a network of photosynthetic theta) to multiple-source kleptoplastic organisms organisms spread across the eukaryotic tree. Among (e.g., Dinophysis acuminata).

© 2019 British Phycological Society

Published online 20 Aug 2019 32 KEYNOTE AND ORAL PAPERS

1OR.1 The red algal order Ceramiales was previously arranged on the basis of morphological studies into five families: FACILITATED MITOCHONDRIAL EVOLUTION Ceramiaceae, Dasyaceae, Delesseriaceae, Rhodomelaceae OF AN EXTREMOPHILIC RED ALGAE and Sarcomeniaceae. The first phylogenies based on one 1 Chung Hyun Cho ([email protected]), Seung In or two molecular markers failed to produce well-resolved Park1 ([email protected]), Claudia Ciniglia2 phylogenies or to resolve the first three families as mono- ([email protected]) and Hwan Su phyletic. At present, nine families are recognized in the Yoon1 ([email protected]) Ceramiales after the split of the Ceramiaceae into five families. Moreover, the Delesseriaceae and Dasyaceae 1 Department of Biological Sciences, Sungkyunkwan University, include three and two subfamilies, respectively. 2066 Seobu-ro, Jangan-gu, 16419 Suwon, Korea and 2Department of Environmental, Biological and Pharmaceutical However, relationships among families and subfamilies Science and Technology, University of Campania “L. are poorly understood. Recent advances in High Vanvitelli”, Viale Abramo Lincoln, 5, 81100 Caserta, Italy Throughput Sequencing techniques facilitate the sequen- cing of plastid genomes, which have been used for resol- It is generally fatal in harsh conditions to the most of ving challenging phylogenies in the red algae. In this species, but some species can thrive in extreme environ- study, we attempted to produce a well-resolved ments including high temperature, acidic, and heavy- phylogeny for the order Ceramiales using 80 (27 newly metal rich conditions. Compare to many prokaryotic sequenced) plastid genomes representative of the major extremophiles, only a few eukaryotic species are reported lineages. We aligned and concatenated 208 plastid from this environment. The Cyanidiophyceae coding sequences (CDSs) that we used to construct (Rhodophyta) are the best eukaryotic example that thrive a maximum likelihood tree. The resulting phylogeny in acidic (pH 0-2), and high-temperature habitats (35- resolved most of the nodes with full support and showed 50°C). Study on this interesting organism, however, is that a family-level reclassification is required. The poorly conducted. To fill the gap of our understanding of Rhodomelaceae, Ceramiaceae and Wrangeliaceae were the cyanidiophycean biology, we have completely resolved as monophyletic and we propose to maintain sequenced and annotated five new mitogenomes from their current circumscription. By contrast, the families the representative clades of Cyanidiophyceae. In this Callithamniaceae, Dasyaceae, Delesseriaceae, Sarcome- study, we addressed two different issues; i) resolving the niaceae, Spyridiaceae and Inkyuleeaceae require revision. phylogenetic relationship and ii) the classification of mitochondria type in Cyanidiophyceae. To this end, we compared trees based on a concatenated gene set and 1OR.3 sub-sampled datasets. The relationship between the “ ” major lineages of Cyanidiophyceae has been resolved RAPPEMONADS IS THE THIRD LINEAGE OF from our analysis. We also distinguished two mitochon- HAPTOPHYTA drial types, Cyanidium-type and Galdieria-type, based on Ryoma Kamikawa1 ([email protected]. their distinctive features of mitogenomes. The result jp), Azusa Itoh1 ([email protected]), represents that a strong selective pressure affected mito- Motoki Kayama1 ([email protected]. chondria of Galidieria-type, which are altered the protein jp), Mami Nomura1 ([email protected]), Takuro properties of mitochondrial genes. Based on comprehen- Nakayama2 ([email protected]), Hideaki sive genomic analyses, we will provide insights into the Miyashita1 ([email protected])and evolutionary history of Cyanidiophyceae. Masanobu Kawachi3 ([email protected])

1Graduate School of Human and Environmental Studies, Kyoto 1OR.2 University, Kyoto, Kyoto 606-8501, Japan; 2Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, PHYLOGENOMICS OF THE RED ALGAL Japan and 3The National Institute for Environmental Studies, ORDER CERAMIALES: IMPLICATIONS FOR Tsukuba, Ibaraki 305-8506, Japan FAMILY LEVEL CLASSIFICATION “Rappemonads” is a monophyletic plastid-bearing 1,2 2 Pilar Díaz-Tapia ([email protected]), Marisa M. Pasella lineage that is comprised of only environmental 2 ([email protected]), Heroen Verbruggen (heroen. DNA sequences in the plastid 16S rRNA tree. [email protected]) and Christine A. Maggs3 “Rappemonads” is not nested in any of algal clades ([email protected]) in the phylogenetic tree, and therefore “Rappemonads” is thought to be a novel lineage independent from any 1 Coastal Biology Research Group, University of A Coruña, of known major algal groups. However, because no A Coruña, Spain; 2School of BioSciences, University of Melbourne, Melbourne, Australia and 3Portaferry Marine one could have succeeded in the observation of living Laboratory, Queen’s University Belfast, Northern Ireland cells of “Rappemonads,” identity of this eukaryotic EUROPEAN JOURNAL OF PHYCOLOGY 33 group has been unknown. In this study, we found Many non-photosynthetic chrysophytes lost their “Rappemonads” as a novel haptophyte lineage. The red-algal derived plastid and evolved several times haptophyte strain NIES-3900 was isolated in and had through independent parallel evolution within the been maintained from 1990. Cells of the haptophyte Chrysophyceae. The Spumella-like flagellates were strain NIES-3900 have a haptonema between two fla- characterized by a naked cell surface, non-colonial, gella, and four or more plastids. HPLC analysis and heterokont flagella. Recently, the genera unveiled that the haptophyte strain NIES-3900 pos- Pedospumella and Poteriospumella were erected as sessed two unidentified pigments in addition to pig- an independent lineage from Spumella-like flagellates ments known to be detectable in other haptophyte based on molecular phylogeny. Although the member species, such as chlorophyll a, chlorophyll c2, chloro- of Spumella-like flagellates lost their photosynthetic phyll c3, and fucoxanthin. The number of plastids and ability, they still possess a leucoplast and retain the pigment composition indicate that NIES-3900 is a plastid genome. Here, we report a comparative distinguishable from the two classes of haptophytes, analysis of plastid genomes sequenced from the non- Prymnesiophyceae and Pavlovophyceae, and thus this photosynthetic chrysophyceae: Spumella, haptophyte strain is to be recognized as a novel species Pedospumella and Poteriospumella. We carried out belonging to a novel, third class of haptophytes. a detailed analysis of their genome structures and Phylogenetic analyses of 18S rRNA gene sequences, coding capacities relative to a published photosyn- mitochondrial genomes, and plastid genomes strongly thetic chrysophycean plastid genome sequences of suggest that the haptophyte strain NIES-3900 is the Ochromonas species CCMP1393 and synurophycean sister lineage of Prymnesiophyceae and that algae. The plastid genome of Spumella-like flagellates Pavlovophyceae is the deepest lineage of haptophytes. is strongly related with other photosynthetic chryso- To explore environmental DNA sequences that corre- phycean lineages in genome structure and gene con- spond to the lineage to which NIES-3900 belong, we tents. Not surprisingly, most of the gene loss was also performed phylogenetic analyses of plastid 16S related with photosynthesis and carbon fixation, rRNA gene sequences and environmental DNA except petF encoding Ferredoxin. The three non- sequences. Most importantly, NIES-3900 was recon- photosynthetic chrysophycean plastid genomes are structed as monophyletic with environmental highly conserved with respect to genome structure sequences previously identified as “Rappemonads.” and coding capacity, with the exception of gene re- Given these findings, we conclude here that arrangements and partial duplications at the bound- “Rappemonads” is the third class of haptophytes. ary of the inverted repeat and single-copy regions. The plastid genome of Spumella-like flagellates ran- 1OR.4 ged from ~55.7 Kbp (Spumella species) to ~62.9 Kbp COMPARATIVE PLASTID GENOMICS OF (Poteriospumella species) and shared a core set of 60 NON-PHOTOSYNTHETIC CHRYSOPHYTES: functional protein-coding genes, 3 rRNAs, and 32~34 GENOME REDUCTION AND COMPACTION tRNAs. Several lineage-specific gene loss/gain events were detected. We also uncovered a few examples of Jong Im Kim ([email protected]), Minseok Jung gene loss/gain, duplication and gene rearrangement ([email protected]) and Woongghi Shin in an inverted repeat region. Our results provide new ([email protected]) insights into the evolutionary history of organelle Department of Biology, Chungnam National University, genomes via genome reduction and gene loss related Daejeon 34134, Korea to photosynthesis in chrysophycean evolution. 34 KEYNOTE AND ORAL PAPERS

2. Ecology and evolution of algal symbiosis

2KN.1 2OR.1 FROM WATER TO LAND: EVOLUTION OF THE A ‘MISSING LINK’ DINOFLAGELLATE ARBUSCULAR MYCORRHIZAL SYMBIOSIS DURINSKIA KWAZULUNATALENSIS EXHIBITS 1 THE CONVERSION PROCESS OF THE Melanie Rich ([email protected]), Jean KLEPTOPLASTIDS TO PERMANENT Keller1 ([email protected]), Tatiana Vernié1 ENDOSYMBIONTS ([email protected]), Nicolas Vigneron1 1 ([email protected]), Guru Radhakris- Norico Yamada ([email protected]), 2 hnan2 ([email protected]), Giles Oldroyd3 John J. Bolton ([email protected]), Rosa 3 3,4 ([email protected]), Guillaume Bécard1 Trobajo ([email protected]), David G. Mann ł ą 5 ([email protected]) and Pierre-Marc Delaux1 ([email protected]), Przemys aw D bek (pdabe- 5 ([email protected]) [email protected]), Andrzej Witkowski (witkowsk@univ. szczecin.pl), Ryo Onuma6 ([email protected]), Takeo 1 Laboratoire de Recherche en Sciences Végétales, UMR5546, Horiguchi7 ([email protected]) and Peter Université de Toulouse, UPS, CNRS, 31326 Castanet-Tolosan 1 CEDEX, France and 2John Innes Centre, Norwich NR4 7UH, G. Kroth ([email protected]) UK and 3 Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK 1Department of Biology, University of Konstanz, Universitaet str. 10, 78467 Konstanz, Germany; 2Department of Biological Sciences, University of Cape Town, Rondebasch, 7701 Cape The plant lineage faced two major transitions over Town, South Africa; 3Marine and Continental Waters the last 450 million years: the colonization of land Program, Institute for Food and Agricultural Research and and the transition from a gametophyte- to Technology, Crta. Poble Nou km. 5.5, 43540 Sant Carles de la Rapita, Spain; 4Royal Botanic Garden Edinburgh, 20A a sporophyte-dominant lifestyle, resulting in the Inverleith Row, EH5 3LR Edinburgh, United Kingdom; divergence of vascular plants. These two events 5Natural Sciences Education and Research Centre, University required the evolution of new mechanisms and the of Szczecin, Mickiewicza 16a, 70383 Szczecin, Poland; 6 recruitment of existing pathways in a new develop- Department of Cell Genetics, National Institute of Genetics, Yata 1111, 4118540 Mishima, Japan and 7Department of mental context. The fossil record and its broad host Biological Sciences, Hokkaido University, North 10 West 8, range suggest that the Arbuscular Mycorrhizal sym- 0600810 Sapporo, Japan biosis evolved in first land plants and was one of the critical innovations that allowed plants to successfully ‘Dinotoms’ are dinoflagellates possessing endosym- colonize lands. Studying the evolution of AM sym- biotic diatoms (ESDs) as tertiary plastids. The ESDs biosis in land plants thus offers a unique opportunity are evolutionary intermediate plastids: they still retain to understand how key innovations evolve and are nuclei, mitochondria, ribosomes, ER, as well as the recruited during plant evolution. We use combina- plastids, and the ESD nuclei remain mostly function- tions of phylogenomics, genetics in multiple land ally intact. However, although the ESDs in dinotoms plants and biochemistry to understand how this com- are genetically and structurally independent from plex trait evolved. Using a comprehensive phyloge- their host cells, it has been reported that the host netic analysis on more than 200 transcriptomes and dinoflagellates maintain their ESDs permanently by newly sequenced genomes of land plants and green controlling the ESD karyokinesis. Recently, we found algae, we identified the evolutionary path leading to that the ESDs of the dinotom Durinskia capensis and the emergence of symbiotic gene networks in land its close relative D. kwazulunatalensis show atypical plants and we have validated the importance of these evolutionary stages when compared to other dino- pathways in vascular and non-vascular plants. We toms. The former species is a kleptoplastic dinotom, predict that AM symbiosis evolved in land plants by which can keep the ESD only for two months, due to the recruitment of pre-existing pathways, neo- the inability of the ESD nucleus replication. functionalization of recently diverged paralogs and D. kwazulunatalensis, on the other hand, can main- gene fusion. The development of algal models will tain the ESDs permanently similarly to other dino- in the future allow us to further test this prediction. toms, while possessing three to six multiple ESD EUROPEAN JOURNAL OF PHYCOLOGY 35 nuclei in the single cells. Because all other dinotoms (Germany, France, Virginia and California) and con- possess an ESD nucleus in each cell, and the ducted high-throughput sequencing of partial 16S and D. capensis is still in kleptoplastic stage, we suggest 18S rDNA to characterize pro- and eukaryotic com- the ESDs of D. kwazulunatalensis have evolved only munities. Our data show that both the algal surface recently from kleptoplastids to permanent endosym- (epiphytes) and tissue (endophytes) host a set of ‘core bionts. Interestingly, the ESD nuclei of taxa’ that are continuously associated across all collec- D. kwazulunatalensis show unique morphological tion sites. Aside this conserved subset of microbes, we dynamics: the ESD nuclei change their morphology found that communities are differently structured from round to string shaped, then disperse alongside between the algal surface and tissue. Further, there the plastids during the host interphase, while chan- was a strong spatial pattern, where individuals within ging back to a round shape to replicate, prior to host the same population harboured similar communities cell division. We further noticed that such whereas those were more different between popula- a morphological change has been observed in perma- tions. Our results indicate that the microbiome of nent ESD nuclei of two other dinotoms, while never A. vermiculophyllum contains a set of core taxa, in any other eukaryotic nuclei, including the ESD of which has been maintained across the native and non- D. capensis. It is possible that the establishment of native ranges. At the same time, site-specific differ- this novel nuclear dynamics might be a critical step ences across the ranges exist which require further for converting kleptoplastids to permanent investigation, as they could reflect adaptations during endosymbionts. the invasion process.

2OR.2 2OR.3 MICROBIAL COMMUNITIES ASSOCIATED TO AN INVASIVE SEAWEED AND HOW THEY PHOTOSYNTHETIC C & N UPTAKE OF VARY ACROSS ECOLOGICAL SCALES SYMBIOTIC RADIOLARIA ASSESSED BY STABLE ISOTOPE ANALYSIS Guido Bonthond1 ([email protected]), Stacy Joost Mansour1 ([email protected]), A. Krueger-Hadfield2 ([email protected]), Francisco Fabrice Not1 ([email protected]); Andreas Norlin2 R. Barboza1 ([email protected]), Massa Nakaoka3 ([email protected]) and Johan Decelle3 ([email protected]), Myriam Valero4 (valer- ([email protected]) [email protected]), Gaoge Wang5,6 ([email protected]), 1 1 Till Bayer ([email protected]) and Florian Weinberger 1UPMC Université Paris 06, CNRS, Laboratoire Adaptation et ([email protected]) Diversité en Milieu Marin UMR7144, Sorbonne Université, Station Biologique de Roscoff, 29688 Roscoff, France; 2 3 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Biosciences, Swansea University, Swansea SA2 8PP, UK and Düsternbrooker Weg 20, 24105, Kiel, Germany; 2Department Cell & Plant Physiology Laboratory, University of Grenoble of Biology, University of Alabama at Birmingham, 1300 Alpes, CNRS, CEA, INRA, 38054 Grenoble Cedex 9, France University Blvd, CH464, Birmingham, AL, USA, 35294; 3Akkeshi Marine Station, Field Science Center for Northern Acantharia and Collodaria, (Radiolaria, Rhizaria), are Biosphere, Hokkaido University, Aikappu 1, Akkeshi, heterotrophic protists that can be found in the planktic Hokkaido 088-1113, Japan; 4UMI EBEA 3614, CNRS, Sorbonne Universités, UPMC, UCCh, UACH, Station realm across all oceans. All Collodaria and a large frac- Biologique de Roscoff, Roscoff, France; 5College of Marine Life tion of Acantharia live in symbiosis with microalgae Sciences, Ocean University of China, 5 Yushan Road, Qingdao belonging to the dinoflagellates and haptophytes, 266003, China and 6Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, respectively, therefore exhibiting a mixotrophic beha- China viour. These radiolarians are abundant and ubiquitous in surface waters of oligotrophic oceans where they Over the course of the invasion process, the red alga could account for up to 4% of the total primary pro- Agarophyton vermiculophyllum (synonym: Gracilaria duction and as much as 20% of the surface production. vermiculophylla) has developed tolerance to several Despite the key ecological roles of these protists in stressors, including epiphytic overgrowth. Therefore, energy transfer, carbon flux and the biological carbon the interaction between the seaweed host and the pump, physiological research focusing on this photo- epiphytic community might have contributed impor- symbiosis has been lagging behind in comparison to tantly to the invasion success. However, little is known our understanding of the similar relationship of benthic about the composition of these communities and how invertebrates, like corals. Likely, because of their deli- they vary across the wide distribution range of this cateness and that the host-symbiont complex cannot be invasive species. We collected A. vermiculophyllum maintained in culture, the biochemical link and nutrient from 6 populations in the native range (Japan, fluxes between symbionts and their hosts remains lar- China) and 8 populations in the non-native range gely unexplored. In this study, we performed bulk 36 KEYNOTE AND ORAL PAPERS

Carbon and Nitrogen stable isotope enrichment experi- nitrogen source. Both Radiolaria seem to be better ments, showing the uptake of carbon and nitrogen by adapted in the uptake of ammonium, which in turn symbiont photosynthesis for both Collodaria and stimulates the carbon assimilation. Along with follow Acantharia. Though nitrogen measurements for up bulk CN analysis in order to shed light on CN Acantharia were impeded by sample quantity, we can uptake rates and content for these Radiolaria, this show the first measurements of carbon content for the study is a critical step to understanding and ultimately Acantharian holobiont. Furthermore, we see a variation modeling of planktic photosymbiosis relationships and of photosynthetic carbon uptake depending on the their roles in oceanic ecosystems functioning. EUROPEAN JOURNAL OF PHYCOLOGY 37

3. Biodiversity and biogeography of algae

3KN.1 3KN.2 UNFOLDING THE GLOBAL BIODIVERSITY PATTERNS AND DRIVERS OF SEAWEED PATTERNS AND STRUCTURE OF MARINE BIODIVERSITY: SPECIATION AND DISPERSAL PLANKTONIC DIATOM COMMUNITIES IN OF THE RED ALGAL GENUS PORTIERIA AND THE WORLD OCEAN BROWN ALGAL ORDER DICTYOTALES Shruti Malviya ([email protected]) Frederik Leliaert1,2 (frederik.leliaert@meisebotanic- garden.be), Christophe Vieira2 ([email protected]), Simons Centre for the Study of Living Machines, National 2 Centre for Biological Sciences, Tata Institute of Fundamental Frédérique Steen ([email protected]) and Olivier 2 Research, UAS-GKVK Campus, Bellary Road, Bangalore De Clerck ([email protected]) 560065, India 1Meise Botanic Garden, Nieuwelaan 38, 1860 Meise, Belgium 2 Plankton forms the base of the marine food web and and Phycology Research Group, Biology Department, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium plays an essential role in the global climate and bio- geochemical cycles. The vast majority of ocean bio- Understanding the biogeographical processes under- mass and biodiversity is composed of these tiny lying current biodiversity patterns is a central goal in creatures. Despite their global importance, very little ecology and evolutionary biology. We gain important is known about these biological entities. The advent insights in the evolutionary processes generating sea- of high-throughput omics approaches has revolutio- weed biodiversity patterns in two widespread clades, nized molecular biodiversity studies facilitating the the red algal genus Portieria and the brown algal understanding of biogeography, community assembly order Dictyotales, by applying DNA-based species and ecological processes. Diatoms are one of the most delimitation methods, phylogenetic analyses, and diverse and ecologically prominent groups of phyto- probabilistic modeling of geographic range evolution. plankton. Although widely studied, their diversity A first striking outcome of was that species diversity and biogeographic distribution patterns are not well in the two clades is far greater than assumed based on known. The metabarcoding data set generated from formally described taxa. Although cryptic diversity is the biological samples collected during the Tara no exception in the marine environment, the degree Oceans (2009-2013) global circumnavigation was of cryptic diversity found in Portieria and some gen- used to elucidate diatom global biodiversity patterns era of Dictyotales (e.g. Lobophora) is remarkable. and structure across the world oceans. Notably, this Although a wide variation in species ranges was community-level molecular survey reveals a new esti- found, many species have restricted distributions, mate of the total number of planktonic diatom spe- indicating overall low dispersal capacity. A clear pat- cies, a considerable unknown and exceptionally high tern of high diversity was found in the tropical cen- diversity in the Open Ocean, and complex diversity tral Indo-Pacific, with declining diversity when patterns across oceanic provinces. This work provides moving away longitudinally as well as latitudinally a comprehensive perspective on diatom distribution from this region. Time-calibrated phylogenetic ana- and diversity in the world oceans and elaborates lyses indicate that the two clades are ancient (late interconnections between associated theories and Cretaceous to middle Jurassic) and likely originated underlying drivers. It demonstrates how metabarcod- in the region that is now the central Indo-Pacific. We ing approaches can provide a framework to investi- find general support for a higher diversification rate gate environmental diversity at a global scale, which in tropical regions, in particular, the central Indo- is deemed as an essential step in answering various Pacific, and repeated dispersal events to peripheral ecological research questions. Consequently, this regions. In the Dictyotales, two large clades, approach also provides a reference point to explore Dictyota and Lobophora, experienced a major burst how microbial communities will respond to environ- of diversification in the central Indo-Pacific in the mental conditions. Paleocene, followed by dispersal outward. While 38 KEYNOTE AND ORAL PAPERS

Lobophora diversified strictly in tropical regions, geographic distances, effective dispersal has not Dictyota also expanded towards temperate regions. been sufficiently frequent to prevent speciation, Our analyses show that given the old age of the clades resulting in the accumulation of numerous genetically involved, and the large diversity of organisms with distinct lineages with restricted geographical distribu- different traits, different mechanisms produced bio- tions. The importance of dispersal limitation and geographical patterns in seaweeds. Finally, our study historical factors in shaping P. borealis communities shows once more that accurate delimitation of species was further confirmed by diversity differences is important for the understanding of distributions between the Polar Regions: whereas lineage-level and diversification of tropical seaweeds. diversity of P. borealis is higher in the Arctic, the degree of intra-specific differentiation is higher in Antarctica. Altogether, our findings highlight that 3OR.1 even relatively mobile micro-organisms can be sub- GLOBAL COLONISATION AND ject to extreme lineage-diversification and that bio- DIVERSIFICATION IN THE TERRESTRIAL geographical patterns may vary widely even among DIATOM SPECIES COMPLEX PINNULARIA closely related taxa. BOREALIS

1,2 Eveline Pinseel ([email protected]), Steven 3OR.2 B. Janssens2 ([email protected]), Pieter Vanormelingen3 (pieter.vanormelingen@na- METABARCODING DIVERSITY AND SEASONALITY IN THE MARINE PLANKTONIC tuurpunt.be), TERDIA consortium, Bart Van de DIATOM FAMILY CHAETOCEROTACEAE Vijver2,4 ([email protected]) and 1 Wim Vyverman ([email protected])1 Wiebe HCF Kooistra ([email protected]), Chetan C Gaonkar2 ([email protected]), Marina 1 Laboratory of Protistology & Aquatic Ecology, Department of Montresor1 ([email protected]), Roberta Piredda1 Biology, Faculty of Sciences, Ghent University, Krijgslaan 281, 1 9000 Gent, Belgium; 2Research Department, Meise Botanic ([email protected]), Diana Sarno (diana.sar- Garden, Nieuwelaan 38, 1860 Meise, Belgium; 3Natuurpunt, [email protected]) and Adriana Zingone1 ([email protected]) Michiel Coxiestraat 11, 2800 Mechelen, Belgium and 4 Ecosystem Management Research Group, Department of 1Department of Integrative Marine Ecology, Stazione Zoologica Biology, Faculty of Sciences, University of Antwerp, Anton Dohrn, Villa Comunale, 80121 Napoli, Italy and 2Texas Universiteitsplein 1, 2610 Wilrijk, Belgium A&M University O&M Building, Room 911C MS 3146 College Station, Texas 77843, USA Due to their immense diversity, the systematics of diatoms is complex and challenging. In particular, Environmental DNA metabarcoding constitutes the biogeography and ecology of (pseudo)cryptic dia- a powerful approach to assess planktonic diatom tom species are highly understudied and there are diversity. We examined the performance of 18S only a few data available on species limits, diversity rDNA V4-metabarcoding in revealing the species and the timing of lineage splitting within species diversity in the diatom family Chaetocerotaceae at complexes. To address these issues, we used the ter- the LTER-MC station in the Gulf of Naples. To this restrial diatom species complex Pinnularia borealis as aim, we analyzed chaetocerotacean metabarcodes a case study, employing phylogenetic analysis and obtained from plankton samples collected on 48 environmental metabarcoding to study its diversity dates over three years. Phylogenetic results resolved and biogeography. Sampling on multiple continents, the metabarcodes into solitary haplotypes, each com- including Antarctica, allowed for the development of prising a modest number of metabarcodes, and term- an extensive reference database, comprising over 800 inal polytomies composed of multiple haplotypes, cultures. Phylogenetic analyses of the cultured mate- each with usually one haplotype containing the bulk rial revealed an unprecedented high molecular diver- of the metabarcodes. Solitary haplotypes and poly- sity implying the existence of hundreds of previously tomies were considered molecular operational taxo- undetected (pseudo)cryptic, presumably species-level, nomic units (MOTUs). A total of 53 out of the 73 lineages which started diversifying between 25 and 36 MOTUs included a reference, usually matching the Ma. Although several lineages seem restricted in their solitary or dominant haplotype, and could thus be geographic distributions, others are present on multi- identified. Distribution of the metabarcodes over the ple continents in both northern and southern hemi- sampling dates revealed clear seasonal patterning. sphere. Intra-lineage phylogeographic patterns were Species in cryptic species complexes generally were present in at least one widely-distributed lineage, and found in different or offset periods. A comparison were estimated to have originated in the late with contextual LM data showed that the species Pleistocene. Although several lineages within the commonly recognized in the LM data were also pre- complex have the ability to disperse over vast sent in the contemporary metabarcode data. EUROPEAN JOURNAL OF PHYCOLOGY 39

Comparison of the phylogenetic results with those of from Kamchatka and the lectotype of U. stipitata commonly applied clustering revealed the following: Areschoug 1850 from the Swedish west coast are the number of MOTUs recovered using clustering conspecific. Thus, U. fenestrata is the correct name depended on the similarity cut-off threshold. Set the for the common boreal species previously known in clustering threshold too close to 100% and numerous Europe as U. lactuca. We hypothesize that Linnaeus’ fringe haplotypes within phylogenetically delineated U. lactuca type was collected in the Indo-Pacific by MOTUs dropped over it into “rare MOTUs.” Set it at one of his ‘apostles’. rbcL sequences obtained from a lower % and phylogenetically closely related the type material of U. pertusa Kjellman 1897 from MOTUs collapsed into single MOTUs. No magic cut- Japan are nearly identical to the types of U. australis off exists for clustering at which results are anywhere and U. laetevirens, both described by Areschoug in comparable with those of phylogenetic assignation. 1854 from South Australia. The data indicate that these three names all belong to the same taxon. DNA sequences from historic specimens have 3OR.3 allowed us to look back in time at distributions of STABILIZING THE SEA LETTUCES: DNA Ulva species prior to modern global introductions, SEQUENCES FROM TYPE SPECIMENS OF ULVA and address historic, taxonomic and biogeographic (CHLOROPHYTA) ILLUMINATE questions. NOMENCLATURE AND BIOGEOGRAPHY Jeffery R. Hughey1 ([email protected]), Christine 3OR.4 A. Maggs2 ([email protected]), Frédéric SPECIATION IN THE ENDEMIC LAKE BAIKAL Mineur2 ([email protected]), Charlie Jarvis3 (c.jar- CLADOPHORALES SPECIES FLOCK [email protected]), Kathy Ann Miller4 (kathyannmil- [email protected]), Soha Hamdy Shabaka5 Giuseppe C. Zuccarello ([email protected]), ([email protected]) and Paul W. Gabrielson6 Sergio Diaz-Martinez ([email protected]. ([email protected]) mx) and Christian Boedeker ([email protected])

1Division of Mathematics, Science, and Engineering, Hartnell School of Biological Sciences, Victoria University of Wellington, College, 411 Central Ave., Salinas, California, 93901, USA; PO Box 600, Wellington, 6012, New Zealand 2School of Biological Sciences, Queen’s University Belfast, 97 Lisburn Rd., Belfast BT9 7BL, UK; 3Department of Botany, Ancient Lake Baikal in eastern Russia is a known Natural History Museum, Cromwell Road, London SW7 5DB, center of freshwater diversity and many radiations. UK University; 4Herbarium, 1001 Valley Life Sciences Building #2465, University of California, Berkeley, CA 94720, USA; Lake Baikal also contains several endemic 5National Institute of Oceanography and Fisheries, Cladophorales species and genera. While there is Mediterranean Sea Branch: Qayet-Bay, Alexandria, Egypt and a great morphological range in the endemic 6Herbarium and Biology Department, Coker Hall, CB 3280, University of North Carolina - Chapel Hill, Chapel Hill, NC Cladophorales (15 taxa, in 4 genera), recent studies 27599-3280, USA have shown that all these taxa represent a monophyletic group nested within the genetically The type species of Ulva is the well-known sea lettuce variable, but morphological simple, genus Ulva lactuca Linnaeus, but the genus also includes the Rhizoclonium. The Baikal clade shows remarkably tubular Enteromorpha gut weeds. Morphological low genetic variation (2.8% in the ITS rDNA marker), development in the genus is so plastic and variable considering its wide morphological variation, indicat- that species identification now relies largely on DNA ing both recent radiation but also making species sequences such as ITS, rbcL and tufA. Nomenclature delimitation problematic. We wanted to determine nevertheless requires the correct application of typi- if these morphological taxa were distinct species and fied names. To answer longstanding systematic ques- possibly a case of in situ speciation. Eleven microsa- tions in Ulva we analyzed the DNA of many type tellites, plus different genetic clustering methods, specimens. Partial rbcL sequences obtained from the were used to address these questions. Microsatellite Linnaean type of U. lactuca showed that it was not amplification revealed that most loci had more than the most common northern European sea lettuce, as two alleles, suggesting polyploidy, and needing differ- had been assumed for over 200 years, but instead was ent coding approaches. Two genetic clustering meth- identifiable as the warm-water species known since ods showed that some morphotaxa (e.g., 1813 as Ulva fasciata Delile (type locality: Alexandria, Chaetomorpha baicalensis, Chaetomorpha monilifor- Egypt). Kützing’s Phycoseris lobata 1847 from Chile mis, Cladophora compacta) were clearly distinct and (= U. lobata (Kützing) Harvey) also is the same suggest reproductive isolation of these species. Other species. DNA sequences, obtained by Sanger sequen- taxa were probably conspecific or were ambiguously cing and more recently using NGS, showed that the assigned, confirming some taxonomic hypotheses holotype of U. fenestrata Postels & Ruprecht 1840 obtained with rDNA. Our data shows that speciation 40 KEYNOTE AND ORAL PAPERS has probably occurred sympatrically in Lake Baikal, lineages equivalent to the estimated times of specia- possibly through the mechanism of polyploidization. tion in plants and animals. Further studies should address the mechanisms of polyploidization and its effects on the life cycle of 3OR.6 these species and whether it has led to the morphol- ogy diversity of these algae. EVOLUTIONARY HISTORY OF CORALLINE RED ALGAE (CORALLINOPHYCIDAE, RHODOPHYTA) INFERRED FROM 3OR.5 A MULTILOCUS TIME-CALIBRATED SPECIATION IN PROTISTS: SPATIAL AND PHYLOGENY ECOLOGICAL DIVERGENCE PROCESSES Viviana Peña1 ([email protected]), Christophe Vieira2 CAUSE RAPID SPECIES DIVERSIFICATION IN ([email protected]), Juan C. Braga3 (jbraga@ugr. A FRESHWATER CHRYSOPHYTE es), Julio Aguirre3 ([email protected]), Guy Baele4 Š 1 Pavel kaloud ([email protected]), Magda ([email protected]), Anja Rösler3 (roeslanja@g- Š 1 kaloudová ([email protected]), Pavla mail.com), Olivier De Clerck2 (Olivier. č 1 Dosko ilová ([email protected]), Jong Im [email protected]) and Line Le Gall5 (line.le-gall 2 2 Kim ([email protected]), Woongghi Shin (woong- @mnhn.fr) [email protected]) and Petr Dvořák3 (dvorikus@sez- 1 nam.cz) BioCost Research Group & CICA, Department of Biology, Faculty of Science, University of A Coruña, Campus de A Zapateira s/n, 15071, A Coruña, Spain; 2Phycology 1Department of Botany, Charles University, 12800 Praha, Czech Research Group, Ghent University, Krijgslaan 281, Building Republic; 2Department of Biology, Chungnam National S8, 9000, Ghent, Belgium; 3Departamento de Estratigrafía University, 305764 Daejeon, Korea and 3Department of y Paleontología, Universidad de Granada, Campus Fuente Botany, Palacký University, 78371 Olomouc, Czech Republic Nueva, 18002 Granada, Spain; 4Department of Microbiology and Immunology, Rega Institute, KU Leuven - University of Though eukaryotic microorganisms are extremely Leuven, Herestraat 49, 3000 Leuven, Belgium and 5Institut numerous, diverse, and essential to global ecosystem Systématique Evolution Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, functioning, they are largely understudied by evolu- EPHE, Université des Antilles, 57 rue Cuvier, CP 39, 75005 tionary biologists compared to multicellular macro- Paris, France scopic organisms. In particular, very little is known about the speciation mechanisms which may give rise The subclass Corallinophycidae encompasses four to the diversity of microscopic eukaryotes. It was orders of benthic red seaweeds unique by the pre- postulated that enormous population sizes and ubi- sence of calcite. Except for the order quitous distribution of these organisms could lead to Rhodogorgonales, a tropical group of gelatinous a lack of population differentiation and therefore very algae with calcification limited to calcite husks, the low speciation rates. However, such assumptions remaining orders are diverse and widely distributed, have traditionally been based on morphospecies characterized by having calcified cell walls and highly which may not accurately reflect the true diversity, variable morphology. Recent application of molecular missing cryptic taxa. In this study, we aim to articu- phylogenies fostered our understanding of their affi- late the major diversification mechanisms leading to nities within the Florideophyceae; nevertheless, the the contemporary molecular diversity by employing origin and evolution of this group are still controver- a colonial freshwater flagellate, Synura sphagnicola,as sial. Unequivocal coralline fossils date back to the an example. Phylogenetic analysis of five sequenced early Cretaceous (140 Mya), however, a series of loci showed that S. sphagnicola differentiated into two fossils with some coralline algal resemblance would morphologically distinct lineages approximately 15.4 push back the origin of the group to the Mya, which further diverged into several evolutiona- Neoproterozoic (Ediacaran, ca. 600 Mya). The taxo- rily recent haplotypes during the late Pleistocene. The nomic affinities of these fossil taxa however is not most recent haplotypes are ecologically and biogeo- without discussion. In the present study, we provide graphically much more differentiated than the old a comprehensive phylogenetic framework, enabling lineages, presumably because of their persistent dif- the reconstruction of the evolutionary history of the ferentiation after the allopatric speciation events. Our subclass Corallinophycidae. This approach involved study shows that in microbial eukaryotes, species phylogenetic analyses of molecular data obtained for diversification by colonizing new geographic regions seven genes (cox1, psbA, rbcL, 23S rRNA, SSU rRNA, or ecological resources occurs much more readily LSU rRNA and EF2), and the revision of available than was previously thought. Consequently, diver- literature on taxonomy, phylogeny and systematics gence times of microorganisms may be in some for all the genera currently accepted taxonomically. EUROPEAN JOURNAL OF PHYCOLOGY 41

An exhaustive list of fossil records (>2000) encom- Antarctic Realm. A strong biogeographic structuring passing different genera was compiled in order to at multiple spatial scales was observed with distinct, obtain the most accurate timeline for calibrating the differently sized diatom floras characterizing Corallinophycidae phylogeny. Our main results sup- Continental Antarctica, Maritime Antarctica and the port an origin of the subclass Corallinophycidae in Sub-Antarctic islands. Additional biogeographic pro- the Lower Jurassic (Toarcian, ca.180 Mya), followed vincialism emerged in all three regions. These pat- by the separation of two main lineages, terns were underlain by species turnover rather than Rhodogorgonales and Sporolithales, in the Upper nestedness; explained predominantly by historical Jurassic and the split of the orders Hapalidiales and and spatial factors, such as distance between regions Corallinales in the lower Cretaceous together with the and differences in the deglaciation history. A total of emergence of the monotypic Corallinapetra. 59% of the recorded species are currently only known from the Antarctic Realm. The proportion of region- ally restricted species was particularly high in predo- 3OR.7 minantly terrestrial genera and, in contrast to the PRONOUNCED GEOGRAPHIC STRUCTURING local and regional richness, significantly increased AND ENDEMISM IN FRESHWATER DIATOMS with increasing latitude. This strong biogeographical OF THE ANTARCTIC REALM structuring suggests that effective dispersal between 1,2 the biogeographical regions has been limited, foster- Bart Van de Vijver (bart.vandevijver@plantentuin- ing the evolution of highly endemic diatom floras, 3 meise.be), Elie Verleyen ([email protected]), making a compelling case for the important role of 3 Bjorn Tytgat ([email protected]), Dominic historical events in the evolution of lacustrine dia- 4 1,3 A. Hodgson ([email protected]), Eveline Pinseel toms, which is similar to macroscopic organisms ([email protected]), Kateřina Kopalová5 (k. from the Antarctic Realm based on morphological [email protected]), Steven L. Chown6 (steven. and genetic data. [email protected]), Eric Van Ranst7 (Eric. [email protected]), Koen Sabbe3 (koen.sabbe@g- mail.com) and Wim Vyverman3 (wim.vyverman@u- 3OR.8 gent.be) BRIDGING FUNCTIONAL AND 1Meise Botanic Garden, Research Department, Nieuwelaan 38, PHYLOGENETIC DIVERSITY OF MARINE B–1860 Meise, Belgium; 2University of Antwerp, Department of HETEROTROPHIC PROTISTS VIA – Biology - ECOBE, Universiteitsplein 1, B 2610 Wilrijk, Belgium SINGLE-CELL TRANSCRIPTOMICS 3Ghent University, Protistology and Aquatic Ecology, Campus de Sterre, Krijgslaan 281 S8, 9000 Gent, Belgium; 4British Sabrina N. Kalita1 ([email protected]), Bente Edvardsen2 Antarctic Survey, Natural Environment Research Council, 1 High Cross Madingley Road, CB3 0ET, Cambridge, UK; ([email protected]), Gurjeet Singh Kohli 5Monash University, Faculty of Science, School of Biological ([email protected]), Jan Janouškovec3 (janjan.cz@gmail. Sciences, Melbourne, Australia, 6Charles University in Prague, Š 2 č com), Luka upraha ([email protected]), Per Department of Ecology, Vini ná 7, 128 44 Prague 2, Czech 4 1 Republic and 7Department of Geology and Soil Science, Ghent Juel Hansen ([email protected]) and Uwe John University, Campus de Sterre, Krijgslaan 281 S8, B 9000 Ghent, ([email protected]) Belgium 1Alfred Wegener Institute, Helmholtz Centre for Polar and Microorganisms are crucial players in all global bio- Marine Research (AWI), Research Division of Biosciences, geochemical cycles and ecosystem functioning in ter- Section for Ecological Chemistry, Am Handelshafen 12, 27570 Bremerhaven, Germany; 2University of Oslo, Department of restrial and aquatic habitats. Despite this, information Biosciences, Section for Aquatic Biology and Toxicology, P.O. on their large-scale biogeographic structuring is lar- Box 1066 Blindern, 0316 Oslo, Norway; 3University College gely lacking, mainly due to a lack of taxonomic reso- London, Department of Genetics, Evolution & Environment, Gower Street, London, WC1E 6BT, United Kingdom and lution and consistency in the available datasets. 4University of Copenhagen, Department of Biology, Despite a growing number of morphology- and Strandpromenaden 5, DK-3000 Helsingør, Denmark DNA-based studies on microbial biodiversity, our understanding of large-scale microbial biogeographi- The comprehensive description of unicellular hetero- cal patterns remains a contentious issue, mainly trophic protists is essential for understanding the because of the lack of taxonomic resolution and con- functioning of marine ecosystems and defining evo- sistency in the available datasets. In this lecture, an lutionary relationships within marine microbial com- analysis will be presented of biogeographic patterns munities. For that reason, new insights into the in freshwater diatoms based on a high-resolution and functional genes of key protists, such as ciliates and internally fully consistent species-level taxonomic dinoflagellates, are needed to complement the data set from > 400 lakes covering the entire increasing taxonomic complexity and bridge the gap 42 KEYNOTE AND ORAL PAPERS between various eco-functional processes in the morphological approaches to create a taxonomic fra- ocean. In this study, single-cell transcriptomic mework for studying Arctic protist diversity and dis- sequencing proved to be an efficient method to create tribution. In recent years, we have conducted a snapshot of expressed genes of unicellular hetero- a number of sampling surveys in the Atlantic section trophs. We sequenced 65 single-cell transcriptomes of the Arctic focusing on Svalbard, the Barents Sea, from 20 fresh field samples collected from Sub-Arctic and the Arctic Ocean, with an aim to comprehen- and North Sea waters. These 13 ciliate and 52 dino- sively describe the protist diversity. In these surveys, flagellate transcriptomes will generally contribute to the metabarcoding of protist communities was a greater understanding of functional and evolution- coupled with detailed morphological analysis using ary processes of these marine protists. Further, we light and electron microscopy, thus linking morpho- generated multi-gene phylogenies of several dozen logical traits with molecular diversity. Moreover, an genes to unravel the relationships of these hetero- intensive culturing effort which included highly trophic taxa to other dinoflagellates and ciliates, understudied sea-ice taxa led to the morphological respectively. These approaches also helped to eluci- and genetic characterization of over 200 new micro- date the evolution of functional genes and traits for algal cultures, mostly diatoms and dinoflagellates. these understudied essential groups. Additionally, the This allowed for the expansion of rRNA gene refer- datasets were incorporated into our metatranscrip- ence databases, descriptions of new species and tomic reference database to fill the gap (of approx. advances in phylogenetic placements of these taxa. 50%) of genomic information of heterotrophic organ- Subsequently, single-cell PCR of mostly heterotrophic isms and their functional processes. Overall, identify- dinoflagellates and ciliates generated almost 100 new ing the phylogenetic relationships and functional and morphologically verified 28S and 18S rRNA diversity of heterotrophic and mixotrophic protists reference sequences from the Barents Sea and the will clarify paramount marine microbial food web Arctic Ocean, which will greatly improve the ability processes and provide clues to the system’s sensitivity to detect these taxa in metabarcoding datasets. In to climate change. conclusion, our work will lay the foundation for future metabarcoding and microscopy surveys of pro- tist diversity and distribution in the Arctic and at the 3OR.9 same time advance the knowledge on phylogeny and STUDIES ON THE BIODIVERSITY OF ARCTIC taxonomy of modern protists. PROTISTS – BRIDGING THE GAP BETWEEN MORPHOLOGICAL AND MOLECULAR APPROACHES 3OR.10 Luka Šupraha1 ([email protected]), Wenche ARE SEAWEEDS FROM THE MEDITERRANEAN Eikrem1,2 ([email protected]), Uwe John3 SEA AND ATLANTIC OCEAN SISTER? ([email protected]), Sabrina N. Kalita3 (sabrina.kali- Line Le Gall1 ([email protected]), Delphine Gey2 [email protected]) and Bente Edvardsen1 (bente.edvardse- ([email protected]) and Florence Rousseau2 [email protected]) ([email protected])

1University of Oslo, Department of Biosciences, P.O. Box 1066 Institut Systématique Evolution Biodiversité (ISYEB), Muséum Blindern, 0316 Oslo, Norway; 2University of Oslo, Natural National d’Histoire Naturelle, CNRS, Sorbonne Université, History Museum, P.O. Box 1172 Blindern, 0318 Oslo, Norway EPHE, Université des Antilles, 57 rue Cuvier, CP 39, 75005 and 3Alfred Wegener Institute, Helmholtz Centre for Polar and Paris, France and 2Service de Systématique Moléculaire, UMS Marine Research (AWI), Research Division of Biosciences, 2700, Acquisition et Analyse de Données pour l’Histoire natur- Section for Ecological Chemistry, Am Handelshafen 12, 27570 elle (2AD)), Muséum National d’Histoire Naturelle, 57 rue Bremerhaven, Germany Cuvier, CP 39, 75005 Paris, France

To understand the functioning of the Arctic ecosys- The Mediterranean Sea is the cradle of a wide diver- tem and predict its response to the ongoing climate sity of marine organisms. Among them, c.a. 1,200 warming, it is essential to map the diversity and species of seaweeds are currently recognized belong- distribution patterns of Arctic protists. Recent meta- ing to the three phylogenetically distinct lineages of barcoding surveys in the Arctic Ocean have revealed seaweeds (green, red and brown algae). In compar- a remarkable diversity of protist OTUs. However, ison with other marine organisms, the endemicity these OTUs could not always be assigned to the rate of algae is rather low. On the basis of our exten- taxonomically verified morphospecies due to inade- sive recent collections form both the Atlantic and the quate representation of morphologically described Mediterranean European coasts We used the tools of Arctic protists in current reference DNA sequence molecular systematics (5’end of CO1) to examine the databases. The TaxMArc project aims to bridge this relationship between Atlantic and Mediterranean spe- gap by applying state-of-the-art molecular and cies of brown and red algae. The phylogeographical EUROPEAN JOURNAL OF PHYCOLOGY 43 patterns of Mediterranean marine flora revealed by spatial diversity of the diatom assemblages and their molecular systematics tools suggest a significant flow relation to substrate have been tested with multivariate of Atlantic ocean species into the Mediterranean Sea analysis and multimetric ordination analysis (nonpara- through the Gibraltar opening. Nonetheless, a few metric multidimensional scaling – MDS). This grouped lineages without close allied detected anywhere in the diatom assemblages according to the sampling the world have been highlighted. The implications location. Sampling sites from the West and East coasts of these results will be discussed in terms of conser- formed two distinct clusters with the warm temperate vation and biodiversity dynamics in the context of South coast in an intermediate position between the global change. Last but not least, we will examine the cold west and warm east coast. The Langebaan Lagoon possible causes of the underestimation of the algal site was firmly nested within the East coast cluster. We diversity of the Mediterranean Sea in light of the hope that the current result will serve as a baseline for history of the phycology of this region. the future assessment of the impact of ongoing climate change along the South African coast.

3OR.11 3OR.12 SPECIES COMPOSITION OF EPIPHYTIC HIDDEN GENERA WITHIN THE DIATOMS CONFIRM MARINE OSCILLATORIALES IN POLAR REGIONS BIOGEOGRAPHICAL PROVINCES IN SOUTH 1 AFRICA Lenka Raabová ([email protected]) and Otakar Strunecký2,3 ([email protected]) Andrzej Witkowski1 ([email protected]), 1 Przemysław Dąbek ([email protected]), Thomas 1Department of Biology, Faculty of Natural Sciences, University 2 of Ss. Cyril and Methodius in Trnava, Nám. J. Herdu 2, 917 01 G. Bornman ([email protected]), Phumlile 2 2 Trnava, Slovakia; Faculty of Science, University of South Cotiyane ([email protected]), Brygida Wawrzyniak- Bohemia, Branišovská 135, 370 05 České Budějovice, Czech Wydrowska1 ([email protected]), Ewa Republic and 3Institute of Aquaculture, CENAKVA, Faculty of 1 Fisheries and Protection of Waters, University of South Górecka ([email protected]), Marta ř Č ě 1 Bohemia, Husova t . 458, 370 05 eské Bud jovice, Czech Krzywda ([email protected])andJong- Republic Gyu Park3 ([email protected]) Recently, the very thin filamentous cyanobacteria have 1 Palaeoceanology Unit, Institute of Marine and Coastal undertaken a significant taxonomical evaluation. These Sciences, Faculty of Geosciences, University of Szczecin, Mickiewicza 16a, 70-383 Szczecin, Poland; 2 Elwandle Coastal species are usually ubiquitous in a wide range of envir- Node, South African Environmental Observation Network, onments. They were traditionally studied according to Ocean Sciences Campus, Nelson Mandela University, Port their morphological properties only. With the intro- Elizabeth 6001, South Africa and 3 Faculty of Marine Applied Biosciences, College of Ocean Science & Technology, Kunsan duction of additional taxonomic methods (cytomor- National University, Republic of Korea phological analyses, molecular sequencing, exact ecological studies, etc.) traditional genera such as Regularly sampling since 2012 of diatom assemblages Leptolyngbya, Pseudanabaena, Limnothrix and along the entire coast of South Africa from Sodwana Phormidium were found to be polyphyletic. Bay (Indian Ocean) to Porth Nolloth (Atlantic Ocean) Nowadays, the new genera are described worldwide, and sporadically to Terrace Bay in Namibia provided including the Polar Regions. These taxonomical a valuable spatial and temporal dataset. The sampling changes greatly influence biogeographical studies. was accompanied with measurements of basic environ- Recent studies show, that some species previously mental variables that included salinity, temperature, described as endemic, could have a worldwide or cir- pH, oxygen and, in the last two years, also nutrients. cumpolar distribution. Presented research collected Various substrates and environments were sampled data about microbial phototrophs from Petuniabukta, including sand, mud, rock scrapes, plankton, seaweeds Svalbard and North Slope, Alaska during a summer and seagrass. From 31 sites we sampled and analyzed research expeditions in the period of 2011-2017. They diatom assemblages from Corallina sp. and Porphyra are focused on filamentous cyanobacterial genera from sp. (10 sites), Ulva sp., Codium sp., Halimeda sp. (13 terrestrial and water biotopes, where they represent sites), unidentified Phaeophyta (7) and Zostera sp. (1). a dominant species of phototrophs. The results bring Dominant epiphytic diatoms in our counts were: descriptions of new species and genera specific for Amphora helenensis, Cocconeis scutellum, these biotopes, but they also bring evidence about the C. californica, Nitzschia frustulum, N. peridistincta, worldwide distribution of some species, which were Rhoicosphenia flexa and Tabularia fasciculata.The previously considered an endemic. 44 KEYNOTE AND ORAL PAPERS

3OR.13 3OR.14 BIOGEOGRAPHY AND ECOLOGY OF THE EVOLUTION OF SULFUR METABOLISM IN CHLOROMONADINIA PHYLOGROUP PHYTOPLANKTON (CHLOROPHYCEAE) Daniel Pousa Kurpan Nogueira (danielkurpan@g- Dovilė Barcytė1 ([email protected]), Ladislav mail.com), Caterina Gerotto (caterina.gerotto@g- Hodač2 ([email protected]) and Linda mail.com), Alessandra Norici ([email protected]) Nedbalová1 ([email protected]) and Mario Giordano ([email protected])

1Department of Ecology, Faculty of Science, Charles University, Dipartimento di Scienze della Vita e dell’Ambiente, Università Viničná 7, Prague 2, 128 44, Czechia and 2Department of Politecnica delle Marche, Via Brecce Biance, Ancona 60121, Systematics, Biodiversity and Evolution of Plants (with Italy. Herbarium), Georg-August-University of Göttingen, Untere Karspüle 2, 37073, Göttingen, Germany The concentration and chemical state of sulfur (S) in oceans has varied substantially during Earth’shis- The phylogroup Chloromonadinia encompasses a high tory and may have played a central role in the diversity of unicellular green flagellates reported evolution of phytoplankton communities. Diatoms, mainly from freshwaters and snow. However, very coccolithophorids and dinoflagellates arose during little is known about (aero)-terrestrial members of an interval particularly marked by increased sulfate the Chloromonadinia. We have recognized four validly concentration in seawater and became major pri- described genera and numerous species incertae sedis mary producers in oceans, whereas abundance of within the phylogroup. The most widespread and green algae and cyanobacteria diminished in the diversified genus is Chloromonas, occurring in both same period. The physiological mechanisms leading freshwater and terrestrial environments. Ixipapillifera to this transition are still unclear. Although sulfate also inhabits both environments, whereas Gloeomonas assimilation is assumed to be highly conserved in all occurs only in freshwaters and Chlainomonas repre- photosynthetic organisms, some recently published sents snow algae. The phylogroup Chloromonadinia is particularities, especially among algae groups, may known for its extremophilic and extremotolerant help understanding differential growth and compe- members and our aim was to contribute to the knowl- titiveness under varying sulfate concentrations. The edge of their distribution and phylogeny. We have first committed step of sulfate assimilation seems to studied several new and authentic Chloromonas-like host most of these peculiarities on such parameters strains, isolated from polar and temperate habitats. as regulation, activity and localization. This step Our results have shown that ecologically similar spe- consists in the activation of sulfate, producing ade- cies cluster close to each other within the nosine-5’-phosphosulfate (APS) and is catalysed by Chloromonadinia phylogeny. As an example, the theenzymeATPsulfurylase(ATP-S),which,for genus Chloromonas consists of three monophyletic instance, appears to be subject to redox regulation lineages supported by morphological as well as ecolo- in oceanic cyanobacteria and eukaryotic algae gical differences. Chloromonas clade 1 (with the type (except dinoflagellates), but not in plants, freshwater species Cr. reticulata) encompasses mesophilic and and coastal cyanobacteria and dinoflagellates. Also, psychrotolerant species that likely do not form snow this enzyme’s activity and localization have been blooms. In contrast, Chloromonas clade 2 includes described as fairly heterogenous among clades. Our psychrophilic snow species and clade 3 covers meso- study aims to raise comprehension about the transi- philes. Other lineages of the phylogroup can be found tional period when red lineage algae (chlorophyll a also in acidic environments and we have reported such +c) overcame green lineage algae (chlorophyll a+b) species for the first time in a terrestrial habitat. From concomitantly to a considerable increase of sulfate the biogeographic point of view, the phylogroup in seawater. We hypothesize that ATP-S heteroge- encompasses several species with a widespread distri- neity could be the major physiological factor affect- bution. On the other hand, numerous species are ing phytoplankton composition in this case. To known only from a single locality, especially the major- investigate it, microalgae belonging to different ity of psychrophilic snow species. However, the latter groups will be S starved and assessed in terms of pattern can be biased by limited and unevenly distrib- growth rate, final cell yield, C, N and S quotas and uted sampling efforts. ATP-S activity and regulation. EUROPEAN JOURNAL OF PHYCOLOGY 45

3OR.15 Yang2 ([email protected]), and Daisuke Fujita3 ([email protected]) SEAWEED PHYLOGEOGRAPHY IN THE NORTHWEST PACIFIC 1Department of Biology, Jeju National University, 102 2 Zi-Min Hu1 ([email protected]), Jie Zhang1 (zhang- Jejudaehakno, 63243 Jeju, Korea; Marine Ecosystem Research 2 Center, Korea Institute of Ocean Science and Technology, 49111 [email protected]), Ang Jr. Put ([email protected]) Busan, Korea and 3Laboratory of Applied Phycology, Graduate and De-Lin Duan1 ([email protected]) School of Tokyo University of Marine Science and Technology, Tokyo, Japan 1Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China and 2Marine Science Laboratory, The genus Gloiopeltis is known as commercial uses Chinese University of Hong Kong, Shatin, N.T. Hong Kong because it is an edible red alga used as a thickening SAR, China agent, agarose named funoran. Since the economic value of seaweeds is species-dependent, it is essential Coastal tectonic configurations during the to obtain accurate species-level identification in the Quaternary ice ages combined with substantive ocea- genus Gloiopeltis which is absent an obvious morpho- nographic processes (e.g. surface current systems) in logical differences between species. In this study, we the Northwest Pacific enable it to be an important aimed at characterizing the molecular diversity of the centre of seaweed species diversity on the earth. widespread intertidal red algae, Gloiopeltis furcata, However, phylogeographic patterns and processes of from Korea and Japan using the mitochondrial COI seaweed diversity in this area just have received lim- barcoding region to investigate the phylogeographic ited research attention since 2010s, relative to the patterns based on haplotype networks. The phyloge- continuous and intensive research effort in the netic analyses provided the evidence of 10 cryptic North Atlantic in the past few decades. Here, we lineages within G. furcata, highly divergent clades. summarized the main research advances of molecular Distribution map of haplotypes revealed that phylogeography and biodiversity conservation of sea- G. furcata populations along the Nagasaki in Japan weeds in the Northwest Pacific during the past a few and Jeju Island in Korea exhibited the highest genetic years, including results from other research units in diversity and the areas might be the diversification East Asia. We focused on the brown seaweeds center of G. furcata. Lineage A was found only in the Sargassum, the red seaweed Chondrus and the green cold temperate region (eastern Korea and Hokkaido seaweed Ulva. We concluded that: i) sea level fluctua- in Japan), whereas lineage C was mostly distributed tions induced by the Quaternary ice ages imposed in the warm temperate region from the southern part significant signatures in contemporary seaweed of Japan and Jeju in Korea. This study highlights that populations, leading to diverged genetic lineages; ii) G. furcata shows strong genetic heterogeneity at the ocean surface circulations drove population genetic cryptic species level and extensive geographical over- homogeneity and proximity of distant populations lap. We will provide descriptions of several new and/or lineages; iii) some late-Pleistocene glacial refu- Gloiopeltis species in the near future. gia identified, including the Japanese Islands from Kyushu and Shikoku to the Kanto district, the south- west of Hainan Island, China; iv) phylogeographic 3OR.17 diversity provided important insights for conserving SPECIES DIVERSITY, ENDEMISM AND commercially cultivating seaweeds species. We also GENETIC STRUCTURE IN THE BANGIALES discuss the main problems existed in seaweed phylo- (RHODOPHYTA) ALONG THE SOUTH geography in this area and possible resolutions to AFRICAN COAST better understand diversity and evolution of seaweeds Maggie M. Reddy1 ([email protected]), in the Northwest Pacific. Olivier De Clerck3 ([email protected]), Frederik Leliaert3,4 ([email protected]), Robert J. Anderson1,2 ([email protected]) and John 3OR.16 J. Bolton1 ([email protected])

CRYPTIC DIVERSITY IN THE WIDESPREAD 1 Department of Biological Sciences, University of Cape Town, GLOIOPELTIS 2 INTERTIDAL RED ALGAE, Private Bag X3, Rondebosch 7701, South Africa; Branch: FURCATA (GIGARTINALES, RHODOPHYTA) Fisheries, Department of Agriculture, Forestry and Fisheries, 3 FROM THE NORTHWESTERN PACIFIC Private Bag X2, Rogge Bay, 8012, South Africa; Phycology Research Group, Biology Department, Ghent University, 9000, 4 Myung Sook Kim1 ([email protected]), Mi Ghent, Belgium and Meise Botanic Garden, Nieuwelaan 38, Yeon Yang1 ([email protected]), Eun Chan Meise, Belgium 46 KEYNOTE AND ORAL PAPERS

The taxonomy of the Bangiales has seen a major species in three genera (11 Porphyra, four Pyropia paradigm shift over the past two decades. The and one Bangia) are present in South Africa. Two order, which previously consisted of two genera afro-temperate species were described, Pyropia mer- based on morphology, now comprises sixteen genera idionalis sp. nov. and Porphyra agulhensis sp. nov. based on DNA sequence data. The present study and two species with uncertain taxonomic status are explored the biodiversity of the Bangiales in South yet to be confirmed using a molecular approach. Africa, where six species, belonging to three genera, Species boundaries were affirmed for two endemic have been recorded. Based on a comprehensive col- species, Py. saldanhae and Py. aeodis, but not for lection of the Bangiales from the region, 241 Porphyra capensis which was shown to comprise mul- sequences were generated from three unlinked loci tiple cryptic species. High genetic diversity and geo- (nSSU, rbcL&cox1). Species were identified or graphic structure was apparent within and among delimited using an integrative taxonomic approach species of Porphyra in the region. Globally, South based on molecular, morpho-anatomical and ecolo- African Bangiales shared close phylogenetic affinities gical data. A multigene phylogeny (nSSU, rbcL& to species from the Southern Hemisphere and pro- cox1) was reconstructed and three DNA-based spe- vide support for historic connectivity in the Southern cies delimitation methods (ABGD, GMYC, PTP) Ocean. The extensive genetic diversity and endemism were applied to the mitochondrial, cox1 and the plas- found along this coastline compares well with other tid, rbcL genes. Results indicate that 16 Bangialean Southern Hemisphere countries. EUROPEAN JOURNAL OF PHYCOLOGY 47

4. Algal cell biology: making sense of cell structure

4KN.1 4KN.2 TERRESTRIALIZATION IN THE NEW STUDIES ON THE WARNOWIACEAE STREPTOPHYTE ZYGNEMA: INVOLVEMENT (DINOPHYCEAE), SOME OF THE MOST OF CELL WALL COMPONENTS AND EXTRAORDINARY MARINE FLAGELLATES TRANSCRIPTOMIC CHANGES KNOWN 1 Andreas Holzinger1 ([email protected]), Øjvind Moestrup ([email protected]), Sandra 2 2 Klaus Herburger1,2 ([email protected]), C. Craveiro ([email protected]) , António J. Calado 3 David Domozych3 ([email protected])3, ([email protected]), Andreas Altenburger (aaltenbur- 3 Martin Rippin1,4 ([email protected]) and [email protected]) and Nina Lundholm (nlund- Burkhard Becker4 ([email protected])4 [email protected])

1 1Department of Botany, University of Innsbruck, Sternwartestr. Marine Biological Section, Department of Biology, University of 2 Copenhagen, Universitetsparken 4, DK-2100 Copenhagen Ø, 15, 6020 Innsbruck, Austria; Department of Plant and 2 Environmental Sciences, University of Copenhagen, Denmark; Department of Biology and GeoBioTec Research 3 Unit, University of Aveiro, P-3810-193 Aveiro, Portugal and Copenhagen, Denmark; Department of Biology, Skidmore 3 College, Saratoga Springs, NY, United States and 4University Natural History Museum of Denmark, University of of Cologne, Botanical Institute, Zülpicher Str. 47B, 50674 Copenhagen, Gothersgade 128 DK-1123 Copenhagen K, Denmark Cologne, Germany The warnowiaceans constitute a family of unicellular, The conjugating green alga Zygnema sp. thrives in gymnodinioid flagellates characterized by a unique and extreme habitats such as alpine and polar freshwater complex eye-like photoreceptor in the cell, the ocelloid, springs, where it develops large mats by vegetative cell which includes both a lens-like structure and division in early spring. These mats change during the a photoreceptor lined by a cup-shaped shield of caro- season and pre-akinetes develop from vegetative cells, tenoids. Among the ca. 6 genera, species of which strongly increases their resistance against differ- Nematodinium are unique by possessing also normal- ent abiotic stresses. We investigated the role of homo- looking chloroplasts and so-called nematocysts, each galacturonan (HG, major pectic domain) as a key agent nematocyst resembling a rocket battery. Species of of resistance against water scarcity and the involvement Proterythropsis differ by lacking chloroplasts, while of arabionogalactan proteins (AGPs) in cell adhesion the remaining 4 genera are thought to lack both chlor- phenomena. Older akinete-rich filaments produced oplasts and nematocysts. Description of the first species more homogalacturonan, resulting in a higher desicca- of ocelloid-bearing dinoflagellates, in Germany in 1884, tion resistance as monitored by measurements of the was received with disbelief, and it was argued that such effective quantum yield of photosystem II. AGPs are a creature did not exist: it was claimed to be most likely key adhesion molecules, allowing algae to a protozoan that had been eating part of a medusa at interact with their substrates and neighboring fila- the time it was fixed in osmium tetroxide. However, ments. For transcriptomic analysis, field samples of some 50 species of the family have now been described, Zygnema sp. were collected in the high arctic although the taxonomy is in a state of chaos, mostly (Longyearbyen, Svalbard). The bottom layer of the because cells are very fragile and prone to change when extracted mats contained dark green algal filaments handled. I will report on our ongoing studies on mem- and a top layer contained pale filaments. This layer bers of the Warnowiaceae from Denmark and was directly exposed to high levels of irradiation. In Greenland, which include serial sectioning of whole the top layer, 6,569 genes were significantly up- cells (as many as 600 sections through each cell), regulated, 149 down-regulated. Up-regulated genes from which we aim to elucidate the detailed structure include compounds of PS I and II, light-harvesting of the ocelloid, the nematocysts, the flagellar apparatus, complexes and chlorophyll synthesis, and early light- etc. If progress permits, I may also be able to report on inducible proteins (ELIPs), carbohydrate metabolism studies on eyespot function, presently underway by an including starch degrading enzymes and cell wall meta- associated group at the universities of Copenhagen and bolism proteins. These observations show an active Lund. At the end of the project we hope to understand adaptation process in this sister group to land plants more about the function of the cell’s organelles and also that likely contributes to terrestrialization. to use a modern approach to evaluate how to create 48 KEYNOTE AND ORAL PAPERS a reliable taxonomy of at least some of the family’s (>20) of MIPs forming several subfamilies often loca- species. lized to specific compartments (e.g. PIPs localized to the PM; TIPs found in the tonoplast, or SIPs present in the ER membrane). In contrast, the sequenced 4OR.1 green algal genomes contain only a small number NANO X-RAY FLUORESCENCE TOMOGRAPHY (<6) of MIP protein family members. In this presen- (SR-NXRF) FOR IMAGING ELEMENT tation, we will present a phylogeny of the MIP pro- DISTRIBUTION AT THE SUBCELLULAR LEVEL tein family in the Viridiplantae showing several gains IN ALGAE and losses of complete subfamilies. Driving forces for the complex evolution pattern within the Frithjof C. Küpper ([email protected]) Viridiplantae and the importance of this protein family for the evolution of land plants from strepto- School of Biological Sciences, University of Aberdeen, Cruickshank Building, St. Machar Drive AB24 3UU, phyte algae will be discussed. Scotland, UK

For understanding many aspects of metabolism – espe- 4OR.3 cially involving inorganic element such as metals and DIFFERENTIAL INVOLVEMENT OF CELLULAR – halogens accurate information about the localization MACHINERY IN PHOTOMOVEMENT OF of transport and storage is essential. Many conven- SPIROGYRA VARIANS tional techniques are prone to artefacts during sample preparation: (1) Chemical – chemical speciation has Ji Woong Lee ([email protected]) and Gwang changed due to sample treatment (disruption of orga- Hoon Kim ([email protected]) nelles, impact of fixatives, etc.). (2) Dislocation – the Department of Biological Sciences, Kongju National University, localization observed is not the original/natural one. In 32588, Korea this context, synchrotron-based nano X-ray fluores- cence tomography (SR-nXRF) offers significant new Freshwater algae living in shallow waters have opportunities. By eliminating the need for chemical evolved various photomovement to optimize their fixation and freeze-drying of biological samples, all photosynthetic efficiency. The filaments of Spirogyra the liquid and dissolved content of cells as well as varians exhibit complex photomovement and form membranes are preserved intact in their original loca- a compact mat which enables them to adjust their tion. A well-known phycological model, the accumula- light exposure. Different patterns of movement were tion of iodine in Laminaria digitata, is used to observed in response to monochromatic lights. The demonstrate the usefulness of this approach for the filaments of S. varians showed positive phototropism first time ever in an algal model, and to provide under blue light. Under red light, the filaments bent groundbreaking new insight into the mechanism of to the irregular shape, but rapidly became unbent by the storage mode of iodine in seaweeds, with implica- exposure to far-red light. To decipher the genetic tions for the understanding of innate immunity and the control of photomovement, phototropin homologues role of seaweeds in atmospheric and marine chemistry. (SvPHOTA, SvPHOTB) and phytochrome homolo- gues (SvPHY1, SvPHY2, SvPHYX2) were character- ized in S. varians. Photomovement of filaments was 4OR.2 analyzed using cytoskeleton inhibitors under mono- EVOLUTION OF THE MIP (AQUAPORIN) chromatic lights. The movement of filaments under PROTEIN FAMILY WITHIN THE red light was inhibited by the treatment of the micro- VIRIDIPLANTAE: A STORY OF GAINS AND tubule inhibitor, oryzalin. The actin inhibitor, cyto- LOSSES chalasin D did not show any inhibitory effect. The blue light responsive movement, however, was Burkhard Becker ([email protected]) and Birger blocked only when the filaments were treated with Marin ([email protected]) the combinations of cytochalasin D and oryzalin. In Botanical Institute, University of Cologne, Zuelpicher Str. 47b, immunofluorescence staining, the formation of actin 50674 Cologne, Germany filaments in S. varians differently induced by mono- chromatic lights. Mannitol and sorbitol treatment Aquaporins are water channels facilitating the water significantly inhibited far-red light movement sug- flow through biological membranes. They are part of gesting that turgor pressure is the driving force of a large protein family called “Major Intrinsic this movement. Our results suggested that the com- Proteins” which facilitates membrane transport of plicated photomovement of S. varians is the result of water and other non-charged molecules such as gly- photoresponse driven by different combinations of cerol. Embryophyte genomes encode a large number cellular machinery. EUROPEAN JOURNAL OF PHYCOLOGY 49

4OR.4 ([email protected]) and Taizo Motomura2 ([email protected]) REACTIVE OXYGEN SPECIES (ROS) SIGNAL TRIGGERS FERTILIZATION IN A RED ALGA 1Department of Biology, Kongju Naltional University, Gongju, BOSTRYCHIA MORITZIANA Korea and 2Hokkaido University, Field Science Center for Northern Biosphere, Muroran Marine Station, Muroran, Eun Young Shim ([email protected]) and Gwang Hokkaido, 051–0013, Japan Hoon Kim ([email protected]) Cell repair needs help from adjacent cells and trans- Department of Biology, Kongju Naltional Unveristy, Gongju, portation of nutrients and signals among cells is essen- Korea tial to maximize benefit for being multicellular. It has The fertilization of red algae offers a good model for long been believed that red algal intercellular transport “ ” the studies on cell-cell recognition, signal transduction is plugged by the pit connection which is the only and the relocation of cellular organelles. The fertiliza- physical connection between adjacent cells. We tion process of Bostrychia moritziana composed of five hypothesized that pit connection is a specialized junc- distinctive stages; 1) binding between male spermatia tion for intercellular transport analogous to plasmodes- and female trichogyne, 2) spermatial nuclear division, mata of other plant and algae. The intercellular 3) hydrolysis of trichogyne wall, 4) formation of ferti- transport was examined by using microinjection of lization channel between spermatia and trichogyne, 5) fluorescent tracers to various cell types of two filamen- migration of spermatial nuclei in the trichogyne and tous red algae, Griffithsia monilis and Heterosiphonia gamete nuclear fusion. Gamete binding in red algae is japonica. Fluorescein isothiocyanate-dextran (FD) with mediated by a lectin-carbohydrate complementary sys- different molecular sizes and a recombinant green tem, and female lectins have been isolated and mole- fluorescent protein were used as tracers. The limit cular characterized. However, little is known for the size of molecules which can be transported to the signal transduction after the gamete binding. Our his- next cells was in between 20 kDa to 40 kDa. The time tochemical studies using 3,3-Diaminobenzidine (DAB) necessary for the transport to the next cell was depen- staining showed that the accumulation of hydrogen dent on the molecular size and the direction of the peroxide occurs successively after gamete binding; transport. The fluorescent dextran of 3-10 kDa was first at the binding area between spermatia and tricho- transported to next cell in 1-2 h, but that of 20 kDa gyne, then at the cytoplasm of trichogyne and carpo- took 24 to 48 hours. Often, the low molecular weight gonial branches. When male gametophyte was tracers were transported to whole cells in a filament in pretreated with diphenylene iodonium (DPI), a day. The fluorescent tracer over 40 kDa was not a suicidal inhibitor of NADPH oxidase for 30 min, transported to the next cell, but was strongly accumu- the released spermatia could still bind to the tricho- lated in the pit-connection area. The transportation gyne, but no ROS accumulation was observed at the occurred faster to adjacent reproductive cells and to binding area as well as the carpogonial cells. the apical direction than to the vegetative basal cells. Quantitative PCR and RNA in situ hybridization Our results showed that pit-connection plays a key role results showed that significant upregulation of as a transfer junction in red algal cells and macromo- NADPH oxidase occurred in the spermatia and female lecules can travel across the cells by leaking through the gametophyte after the gamete binding. The develop- gap between the pit-plug and cell wall. ment of carposporophyte was significantly inhibited when the spermatia were pretreated with DPI. These 4OR.6 results indicate that successive ROS signal transduction occurs from spermatia to trichogyne and then to car- BIOVOLUME CALCULATION FOR pogonial cells, and this signal is essential for the suc- PLANKTONIC ALGAE BY USING 3 cessful fertilization and successive development of DIMENSIONAL MODELS carposporophyte in Bostrychia moritziana. Gábor Borics1,2 ([email protected]),, Viktoria Béres1,2 ([email protected]),, 1 4OR.5 Ágnes Bolgovics ([email protected]), Gábor Várbíró1,2 ([email protected]), CELL REPAIR AND INTERCELLULAR Igor Stanković3 ([email protected]), Levente NUTRIENT TRANSFER IN FILAMENTOUS RED Pickó4 ([email protected]), and Verona Lerf1 ALGAE, GRIFFITHSIA MONILIS AND HETEROSIPHONIA JAPONICA ([email protected]) Gwang Hoon Kim1 ([email protected]), Chikako 1MTA Centre for Ecological Research, Danube Research 2 Institute, Department of Tisza Research, Bem square 18/c., Nagasato ([email protected]), Tatyana 4026 Debrecen, Hungary;2MTA Centre for Ecological A. Klochkova ([email protected]), Minseok Kwak1 Research, GINOP Sustainable Ecosystems Group, Klebelsberg 50 KEYNOTE AND ORAL PAPERS

Kuno str. 3., 8237 Tihany, Hungary and 3Hrvatske vode, thecaseofcomplicatedforms.Herewepropose Central Water Management Laboratory, Ulica grada a new approach which uses 3D models to visualize Vukovara 220, 10000 Zagreb, Croatia and 4MEDIAKREATOR Ltd, Holló str. 22, 7635 Pécs, Hungary algae, and calculates the volume and the surface of these virtual models. On the bases of these models, Biovolume is one of the most important character- specific shape and surface area constants could be istics of planktic organisms which basically influ- calculated. These species-specific constants can be ences their functional properties like sinking stored in a database, and enable a quick and accurate velocity or tolerance to grazing. Biovolume calcula- surfaceareaandvolumecomputationevenforthe tion of microalgae is based on the determination of most complicated algal forms. Precise estimation of the geometrical shapes that approximate best the these metrics could help in the calculation of size- shape of the algal cells. After measuring the necessary related metrics and traits like surface area/volume dimensions of the cells and using the formulas for the ratio or diameter of spherical equivalent, which geometric shapes cell biovolumes can be calculated. allows more accurate data analysis and interpretation However, this approach may have uncertainties in of the results in phytoplankton ecology. EUROPEAN JOURNAL OF PHYCOLOGY 51

5. Life cycles and life strategies of micro- and macroalgae

5KN.1 5KN.2 EVOLUTION OF LIFE-CYCLE-RELATED LIFE CYCLE COMPLEXITIES OF THE DEVELOPMENTAL PROCESSES IN THE BLOOM-FORMING COCCOLITHOPHORE BROWN ALGAE EMILIANIA HUXLEYI J. Mark Cock1 ([email protected]), Alok Miguel Frada1,2 ([email protected]) ([email protected]), Olivier Godfroy1 1 1 The Interuniversity Institute for Marine Sciences of Eilat, ([email protected]), Delphine Scornet (scor- Israel and 2Ecology, Evolution and Behavior -Alexander 1 [email protected]), Simon Bourdareau (bourdar- Silberman Institute of Life Sciences, The Hebrew University [email protected]), Akira F. Peters2 ([email protected]) Jerusalem and Susana M. Coelho1 ([email protected]) Emiliania huxleyi is a prevalent microalga that 1Algal Genetics Group, UMR 8227 CNRS-UPMC, Station forms extensive blooms in high latitude regions of Biologique de Roscoff, Place Georges Teissier, CS 90074, the oceans with major ecological and biogeochem- 2 29688 Roscoff, France and Bezhin Rosko, 29250, Santec, ical implications. E. huxleyi has been shown to France alternate between the bloom-forming calcified The molecular processes that regulate life cycle pro- diploid phase, and a less known biflagellate non- gression provide an essential foundation for the cor- calcified haploid phase as part of a haplodiplontic rect initiation of diverse biological processes, sexual life cycle. Recently we have additionally including multicellular development and sexual shown that under infection by specific lytic viruses reproduction1. The life cycle of the model brown (EhV) that are responsible for the termination of – alga Ectocarpus2 4 involves an alternation between blooms, a subpopulation of diploid-calcified cells two independent multicellular organisms, the sporo- that are sensitive to EhV can produce viral- phyte and the gametophyte. We have shown that the resistant cells that display a biflagellate phenotype identities of the two generations are not determined like haploid cells, but retain a diploid level. These by ploidy, but rather are determined genetically. new phenotype-ploidy uncoupled cells may be pro- Mutations affecting either the OUROBOROS (ORO) duced as a mechanism to escape EhV and enhance or the SAMASARA (SAM) locus result in complete survival rates during blooms at sea. In order to conversion of the sporophyte generation into a - advance our understanding of the degree of differ- gametophyte5. Both ORO and SAM encode three entiation between calcified-diploid, haploid and amino acid loop extension homeodomain transcrip- uncoupled cells as well as the potential drivers of tion factors (TALE HD TFs). Similarities between phenotype switch during EhV infection, we com- ORO/SAM and HD-TF-based life cycle regulation pared the transcriptome profiles of the 3 cell types. systems in other eukaryotic supergroups indicate We found that at the gene expression level, haploid not only that these systems have an extremely ancient and decoupled cells are more similar relative to the origin but also that TALE HD TFs have been inde- calcified cells, and we were able to unveil part of pendently recruited to regulate sporophyte develop- the genetic foundation underlying the observed mental programs in at least two different complex phenotypic variability. Moreover, we developed of multicellular eukaryotic supergroups, Archaeplastida life-phase specific gene-markers that we can now and Chromalveolata. The presentation will discuss use to probe different life cycle phases of E. huxleyi genetic regulation of life cycle progression and will at sea. Overall our study emphasises the complexity also look at some of the genetic and epigenetic events ofthelifecycleofE. huxleyi and the adaptive that occur downstream of the switch to either the significance of morpho-physiological plasticity in sporophyte or gametophyte developmental programs. eukaryotic microbes. 52 KEYNOTE AND ORAL PAPERS

5OR.1 S. nigripes, Laminaria digitata), their survival capa- city, gametogenesis and sporophyte recruitment and DIFFERENCES IN ACID-BASE REGULATION hypothesized that warming scenarios will negatively BETWEEN THE HEAVILY CALCIFYING affect winter survival. Under autumn conditions, DIPLOID AND THE WEAKLY CALCIFYING spores preferably developed into multi-cellular game- HAPLOID LIFE CYCLE STAGE OF THE tophytes, irrespective of the species and only rarely COCCOLITHOPHORE COCCOLITHUS BRAARUDII formed microscopic sporophytes within a 3-week period. In contrast to our hypothesis, uni- and multi- Dorothee Kottmeier ([email protected]), Gerald cellular gametophytes of all three kelp species had Langer ([email protected]), Glen Wheeler (glw@mba. a high ability to survive 4 months of darkness irre- ac.uk) and Colin Brownlee ([email protected]) spective of temperature. Dark survival capacity of microscopic sporophytes, however, was considerably Marine Biological Association, The Laboratory, Citadel Hill, reduced at 8 °C compared to 4 and 0°C. Post- Plymouth, PL1 2PB, United Kingdom cultivation simulating spring conditions after Polar night conditions resulted in highest sporophyte Coccolithophores are calcifying microalgae that carry recruitment when multicellular gametophytes had characteristic calcite platelets (coccoliths) on their entered the dark period. There were species-specific surfaces. Most coccolithophore species exhibit diploid differences in recruitment capacity dependent on and haploid life cycle stages, each adjusted to differ- temperature. While cold-temperate to Arctic ent environmental conditions. The diploid life cycle S. latissima recruited best at 8°C, Arctic S. nigripes stage of the coccolithophore C. braarudii is heavily recruited best at 0°C. In situ sporophyte recruitment calcifying with calcification rates that exceed the rates of the three kelp species was followed in parallel on of photosynthesis. During calcification, it produces + seeded field tiles but was extremely slow, and macro- excess amounts of H that have to be continuously scopically visible juvenile sporophytes became only disposed by voltage-gated proton channels in order to apparent in August 2017 - 10 months after seeding. keep the intracellular pH constant (Taylor et al. The overall results suggest that formation of multi- 2011). The haploid life-cycle of C. braarudii is weakly cellular gametophytes is a natural mean of enhancing calcifying and therefore generates significantly less recruitment success and that there is a very good H+. This life-cycle stage may therefore use substan- adaptation of Arctic kelp gametophyte stages to the tially different physiological strategies to regulate seasonal day-length regime and Polar darkness, but their intracellular pH under varying environmental future elevated winter temperatures may change the conditions. The aim of this work is to identify the spring recruitment potential of kelps. differences in the cellular mechanisms involved in pH regulation between both life-cycle stages. We com- bine physiological measurements with molecular and 5OR.3 pharmacological approaches, allowing to identify and ULVA – characterize membrane proteins involved in pH SEXUAL REPRODUCTION IN HOW homeostasis. DOES IT LOOK? Ante Žuljević ([email protected]), Boris Antolić (anto- [email protected]) and Petra Lučić ([email protected]) 5OR.2 Institute of Oceanography and Fisheries, Laboratory for WINTER SURVIVAL CAPACITY OF Benthos, I. Meštrovića 63, 21000 Split, Croatia MICROSCOPIC POLAR KELP STAGES The green algae of genus Ulva are among the most Inka Bartsch ([email protected]) and Katharina common algal group of the shallow marine bottom. Zacher ([email protected]) Plentiful of publications cover their life history and Alfred-Wegener-Institute for Polar and Marine Research, Am demonstrate a wide range of variation in their sexual Handelshafen 12, 27570 Bremerhaven, Germany and asexual reproduction. Those studies were mostly made in laboratory conditions while just a few In October 2016, we initiated an experiment simulat- included field observation that mainly investigated ing the seasonal sequence of autumn (short day- the connection between lunar phases and the devel- lengths, low light), Polar winter (no light) and opment of fertile plants. Based on in situ observation, spring conditions (short daylengths, low light) at we discovered how sexual reproduction in several Kongsfjorden/Spitzbergen under current and elevated Ulva species is highly synchronized events. Each of winter temperature scenarios (0, 4 and 8°C) in the the species releases gametes at a species-specific laboratory. We compared the development of spores intensity of light around sunrise. In the semi-field of three sympatric kelp species (Saccharina latissima, experiment, made in parallel with in situ observation, EUROPEAN JOURNAL OF PHYCOLOGY 53 we determined the exact time the gametes were RITMO1 is not directly dependent on light inputs. released, in each of the observed thalli. Every fertile We also describe strong diurnal rhythms of cellular gametophyte releases gametes within a few minutes fluorescence in wild-type cells, which persist in and contributes to develop the visible green gamete continuous light conditions, indicating the existence cloud. Depending on the algal density and sea state of an endogenous circadian clock in diatoms. The condition, gamete cloud can reduce visibility in the altered rhythmicity observed in RITMO1 over- sea to zero and can last even over an hour. In such expression lines in continuous light supports the long-lasting reproduction event, gamete cloud is involvement of this protein in circadian rhythm usually a result of reproduction in several taxa that regulation. Phylogenetic analysis reveals a wide dis- occurred successively around sunrise. Synchronized tribution of RITMO1-like proteins in the genomes release of gametes in sessile species is essential to of diatoms as well as in other marine algae, which ensure successful fertilization. Although synchronized may indicate a common function in these photo- reproduction was predicted in Ulva species, the level trophs. This study adds new elements to our under- of their synchronization, the quantity and visibility of standing of diatom biology and offers new the gamete cloud is much greater than expected. perspectives to elucidate timekeeping mechanisms in marine organisms belonging to a major, but under-investigated, branch of the tree of life. 5OR.4 THE BHLH-PAS PROTEIN RITMO1 REGULATES DIEL BIOLOGICAL RHYTHMS IN 5OR.5 THE MARINE DIATOM PHAEODACTYLUM TRICORNUTUM EVOLUTION OF MATING TYPES IN MAMIELLOPHYCEAN GREEN ALGAE 1 Rossella Annunziata ([email protected]), GENOMES Andres ([email protected]), Antonio L. Felipe Benites1 ([email protected]), François Emidio Fortunato1 ([email protected]), Bucchini2 ([email protected]), Nigel Grimsley1 Alessandro Manzotti1,2 (alessandro.manzotti@upmc. ([email protected]), Sophie Sanchez- fr), Soizic Cheminant-Navarro1,2 (soizic.cheminant_- Brosseau1 ([email protected]), [email protected]), Marie J. J. Huysman1,3 Klaas Vandepoele2 ([email protected]. ([email protected]), Per Winge4 (per.win- be)2 and Gwenael Piganeau2 (gwenael.piganeau@obs- [email protected]), Atle Bones4 ([email protected]), banyuls.fr) Jean Pierre Bouly1,2 ([email protected]) and Angela Falciatore1,2 ([email protected]) 1Observatoire Océanologique de Banyuls-sur-Mer - Laboratoire Arago - Integrative Marine Biology Laboratory (BIOM), CNRS 1Sorbonne Université, CNRS, Laboratory of Computational and UMR7232, Sorbonne University, Avenue Pierre Fabre, Banyuls- 2 Quantitative Biology, Paris, France; 2Institut de Biologie sur-Mer 66650, France, Ghent University, Department of Plant Physico-Chimique, Laboratory of Chloroplast Biology and Biotechnology and Bioinformatics; VIB Center for Plant Systems Light Sensing in Microalgae, UMR7141 CNRS Sorbonne Biology, 9052 Ghent, Belgium Université, 13 rue Pierre et Marie Curie, Paris, France; 3Ghent University, Department of Plant Biotechnology and Sex is a ubiquitous and ancestral feature of eukaryotes Bioinformatics, Ghent, Belgium and 4Department of Biology, NTNU Norwegian University of Science and Technology, that is well documented or predicted to occur in many Trondheim, Norway protists lineages. Nevertheless, direct observation of sexual interactions is lacking for many unicellular Periodic light-dark cycles govern the timing of basic eukaryotic species, as is the case for biological processes in organisms inhabiting land as Mamiellophyceae, a class of planktonic green algae. well as the sea, where life evolved. Although pro- These worldwide spread algae contain the smallest minent marine phytoplanktonic organisms such as photosynthetic eukaryotes and form the basis of the diatoms show robust diel rhythms, the mechanisms food chain in coastal marine ecosystems. In natural regulating these processes are still obscure. By char- populations of Ostreococcus tauri from the order acterizing a Phaeodactylum tricornutum bHLH-PAS Mamiellales, indirect genetic evidence of recombina- nuclear protein, hereby named RITMO1, we shed tion suggests that a cryptic sexual stage for this genus light on the regulation of the daily life of diatoms. exists. In many protists, sexual interactions are deter- Alteration of RITMO1 expression timing and level mined by mating types (MTs), sex chromosome-like results in lines with deregulated diurnal gene regions that may have evolved before the development expression profiles compared to the wild-type of morphologically different gametes. Recently, our cells. Reduced gene expression oscillations are also group described a candidate MT locus in O. tauri observed in these lines in continuous darkness, located in a 500 kb long region on the Big Outlier showing that the regulation of rhythmicity by Chromosome (BOC) with low GC (guanine-cytosine) 54 KEYNOTE AND ORAL PAPERS content, accumulation of transposons and recombina- without tetrasporangia. In this context, we have stu- tion suppression, that taken together suggest that this died sex phenotypes in some populations of the is a sex chromosome. Here, we use eight available Gracilaria gracilis/Gracilaria dura species complex. Mamiellophyceae genomes, 33 transcriptomes from First results using population genetic approaches the “Marine Microbial Eukaryote Transcriptome suggest that some taxa have abandoned classical Sequencing Project” (MMETSP) and the “1000 plants sexual reproduction, reproducing asexually by sup- project” (1KP), to address two main questions regard- pressing or modifying meiosis and producing ing these genomic regions: what is the evolutionary diploid spores that can develop without fertilization. history of candidate MT loci in the Mamiellophyceae, and is there evidence for MTs in other species of this group? Phylogenomic and compositional analysis of 5OR.7 specific, shared and core gene families located in MT loci and low GC regions of Ostreococcus, Bathycoccus COCCOLITHOPHORE LIFE CYCLES: and Micromonas suggest an ancient divergence of two UNDERSTANDING PHYSIOLOGICAL AND MTs in the genus Ostreococcus, while transcriptomic ECOLOGICAL DIFFERENCES BETWEEN LIFE data moreover indicates the presence of candidate CYCLE PHASES MTs in O. lucimarinus, O. mediterraneus and Joost de Vries1,2 ([email protected]), Fanny possibly M. commoda. Monteiro1 ([email protected]), Glen Wheeler2 ([email protected]) and Colin Brownlee2 (cbr@MBA. 5OR.6 ac.uk)

SEXUAL AND ASEXUAL REPRODUCTION IN 1School of Geographical Sciences, University of Bristol, RHODOPHYTA: THE EXAMPLE OF University Road, Bristol BS8 1SS, UK and 2Marine Biological GRACILARIA GRACILIS AND G. DURA SIBLING Association, The Laboratory, Citadel Hill, Plymouth PL1 SPECIES 2PB, UK Christophe Destombe ([email protected]), Coccolithophores are most recognizable for their pro- Stéphane Mauger1 ([email protected]), Begoña duction of intricate calcium carbonate platelets, called Ramirez2 ([email protected]) and ‘coccoliths’, which lead them to play an important Myriam Valero1 ([email protected]) role in the carbon cycle. The production of coccoliths is however not their only unique trait. As haplo- 1 UMR 3614 CNRS, Station Biologique de Roscoff, Sorbonne diplotonic organisms, coccolithophores are able to Université, 29682 Roscoff, France and 2UMR 3614, CNRS Departamento de Ecologıa, Facultad de Ciencias Biologicas, reproduce asexually in two different life phases (the Pontificia Universidad Catolica de Chile, Santiago, Chile ‘haploid’ and ‘diploid’ phase). This is in contrast to most phytoplankton, which can reproduce asexually In most populations of Gracilaria,thelifehistoryis in only the haploid or diploid phase. The haploid and of the Polysiphonia type,i.e.havingmorphologically diploid phases of the same coccolithophore species identical diploid tetrasporophyte and haploid game- can differ significantly in size, calcification status, and tophytephases,thelatterconsistingofequalnum- abundance. The two cell forms may furthermore bers of male and female plants. The female gamete is inhabit different niches, which has proposed to pro- fertilized in situ andthezygotedevelopsasathird vide a competitive advantage in variable ecosystems. phase, the diploid carposporophyte, a spore- To date research has however primarily focused on producing structure entirely dependent on the the diploid life phases, and relatively little is known in female gametophyte. The resulting carpospores, the regards to the biogeography of the haploid life phase, product of a single fusion of gametes, are numerous and how this correlates to the biogeography of and genetically identical. Each spore can develop diploid life phases. Recent research suggests that hap- into a diploid tetrasporophyte in which reproduc- loids are preferably found in shallower, oligotrophic tion involves meiosis, resulting in haploid geneti- waters relative to diploid life phases of the same cally variable tetraspores. From in vitro species, and that haploid distribution is highly seaso- demonstrations one would expect only male and nal. Through a synthesis of coccolithophore abun- female gametophytic and tetrasporophytic indivi- dance data and literature review, we have duals in natural populations but in many cases in investigated these trends further and identified excep- nature this is not so, indicating variations to this tions and key gaps in our knowledge. The findings clear-cut sequence. For example, in some cases small will pave the way for further studies examining the gametophytic thalli develop as epiphytes on parental physiology and ecology of coccolithophore life phases tetrasporophytes or in other cases male and/or using both laboratory and ecological modeling female organs occur on the same thallus with or approaches. EUROPEAN JOURNAL OF PHYCOLOGY 55

5OR.8 suggest the presence of chemical cues that induce the formation of spores and also suggest that biological HIGH CELL DENSITY AND VIRAL INFECTION interactions, both between cells of the same species TRIGGER FORMATION OF RESTING STAGES and between diatom cells and the virus, can play an IN THE MARINE DIATOM CHAETOCEROS SOCIALIS important role in this process. Angela Pelusi1 ([email protected]), Anna Godhe2 ([email protected]) Maria Immacolata 5OR.9 Ferrante1 ([email protected]), Maurizio Ribera SEX IN ASTERIONELLA FORMOSA? d’Alcalà1 ([email protected])1,Kimberlee 1 2 Thamatrakoln3 ([email protected]), Kay Stephen Maberly ([email protected]), Carine Puppo 2 Bidle3 ([email protected]) and Marina ([email protected]) and Brigitte Gontero (bmeu- Montresor1 ([email protected]) [email protected])

1 1Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Lake Ecosystems Group, Centre for Ecology & Hydrology, 2 Villa comunale, 80121 Napoli, Italy; 2Department of Marine Lancaster LA1 4AP, UK and Aix Marseille Univ CNRS, BIP, Science, University of Goteborg, SE 40530 Gotemborg, Sweden UMR 7281, 31 Chemin Joseph Aiguier, 13009 Marseille, France and 3Department of Marine and Costal Sciences, Rutgers University, 08901 New Brunswick, New Jersey Asterionella formosa is a widely-distributed and well- studied freshwater pennate diatom but, unlike many Many diatoms have heteromorphic life cycles that other diatoms, sexual stages have never been include the formation of resting stages. These stages observed. Sexual reproduction is presumed to occur can increase the range of conditions in which species in nature in A. formosa because mean cell length does can survive, thus ensuring their persistence in time not decline monotonically over time in lakes. The with important ecological implications for population enigmatic lack of observed sex in A. formosa dynamics. Although common to many species, cues famously led David Mann to write a chapter in and modality of resting stage formation remain a Festschrift for J.W.G. Lund with the title ‘Why unclear. Nitrogen starvation is reported as the most didn’t Lund see sex in Asterionella?’ We grew clones effective one in the laboratory; however, the link of A. formosa, isolated from one of the lakes in the between spore formation and nitrogen depletion in English Lake District that Lund studied, Esthwaite the natural environment remains elusive. Using the Water, under different conditions of light, tempera- widespread marine diatom Chaetoceros socialis as ture and medium composition. Using light- and epi- model species, we tested additional factors that may fluorescence microscopy and videos we observed play a role in inducing spore formation. Even though what appears to be auxosporulation in A. formosa. nitrogen depletion was confirmed to be the most Isogametes were produced and fused leading to the effective trigger in laboratory conditions, resting formation of auxospores with biovolumes equivalent stages were formed also when cell density was high to that of a full-sized cell. Auxospores were observed but nutrients were not limiting and when cultures in mixed clones but also in monoclonal cultures. were grown in culture medium conditioned by high These observations of sexual reproduction help to cell density. Chaetoceros socialis can be infected by explain how cell length is maintained in nature. The a small RNA virus and we also tested if the viral lack of observed gametes and auxospores in open attack can induce a life cycle shift from vegetative water samples might be because they were not recog- cells to resting spores. Indeed, significantly higher nized or were destroyed by the fixation procedure, numbers of spores were produced in infected cultures but alternatively sexual reproduction might not occur as compared to the non-infected control. Our results in the pelagic zone. 56 KEYNOTE AND ORAL PAPERS

6. Biofilms and microphytobenthos: community composition, physiology, functional aspects, interactions with bacteria

6KN.1 6KN.2 A STICKY SITUATION: UNDERSTANDING THE NEAR-INFRARED LIGHT DRIVEN OXYGENIC MOLECULAR MECHANISM OF DIATOM PHOTOSYNTHESIS IN BIOFILMS - NOVEL UNDERWATER ADHESION INSIGHT TO THE ECOLOGY OF CYANOBACTERIA WITH FAR-RED Nicole Poulsen ([email protected]), Jirina ABSORBING CHLOROPHYLLS Zackova Suchanova (Jirina.Zackova.Suchanova@tu- Michael Kühl ([email protected]) dresden.de), Valeria Sabatino (valeria.sabatino@tu- dresden.de), Beata Wilgan ([email protected]) Marine Biology Section, Department of Biology, University of and Nils Kröger ([email protected]) Copenhagen and Climate Change Cluster, University of Technology Sydney Center for Molecular and Cellular Bioengineering, B CUBE, Technische Universität Dresden, Tatzberg 41, 01307 Dresden, Far-red absorbing chlorophylls are constitutively pre- Germany sent as Chl d in the cyanobacterium Acaryochloris marina, or dynamically expressed by the synthesis Diatoms are unicellular microalgae that together with of Chl f and red-shifted phycobilins via far-red light bacteria dominate marine biofilms in sunlit marine photoacclimation in a range of cyanobacteria, which environments. The underwater adhesion of diatoms enables the use of near-infrared radiation (NIR) for is accomplished through the secretion of carbohy- oxygenic photosynthesis. While the biochemistry and drate-rich extracellular polymeric substances (EPS). molecular physiology of cyanobacteria with far-red In motile pennate diatoms, the adhesive EPS are chlorophylls has been unraveled in culture studies, secreted through a specialized slit in the cell wall the actual habitats and ecological significance of (termed raphe) and are deposited as trails on the such cyanobacteria remain largely unexplored as no substratum thus providing the traction required for data on their in situ activity exist. However, an cell motility. So far, the molecular composition of the increasing amount of reports demonstrate that cya- diatom adhesive trails has remained poorly character- nobacteria with far-red absorbing chlorophylls are ized. Recently, we have developed a method for isolat- linked to shaded biofilm habitats. With a novel com- ing cell-free diatom adhesive trails and demonstrated bination of hyperspectral imaging, confocal laser that they contain a complex mixture of carbohydrates scanning microscopy, and nanoparticle-based O2 and proteins. Unlike the well-characterized adhesion imaging, we have demonstrated substantial NIR- mechanism of marine mussels, diatom adhesion does driven oxygenic photosynthesis within a natural bea- not appear to be mediated by proteins contains dihy- chrock biofilm habitat by endolithic, Chl f-containing droxyphenylalanine (Dopa). To gain a deeper under- cyanobacteria. In this keynote, I present a detailed standing of the role of proteins in diatom adhesion we account of the spatial organization and in situ activity have performed proteomics analysis of the adhesive of Chl d and f-containing cyanobacteria in trails isolated from the fouling diatom a widespread ecological niche, which indicates an Craspedostauros australis. A number of novel proteins important role of NIR-driven oxygenic phototrophs were identified that contain sequence features that are in endolithic biofilm habitats. reminiscent of those found in extracellular and bacter- ial cell-wall anchored proteins (Choice-of-Anchor A domain, von Willebrand factor type A domain, PTS-rich). GFP-tagging and immunolocalization stu- 6OR.1 dies confirmed the presence of some of the identified INTERACTIONS BETWEEN DIATOMS AND proteins within the adhesive trails and biofilms. This BACTERIA IN FRESHWATER work provides insight into the biomacromolecular PHOTOAUTOTROPHIC BIOFILMS structure of diatom EPS trails and lays the foundation 1 for unraveling the molecular mechanism for diatom Adrien Lapointe ([email protected]), underwater adhesion. Lachlan Dow1 ([email protected]), Dieter EUROPEAN JOURNAL OF PHYCOLOGY 57

Spiteller2 ([email protected]) and Peter France; 2UPRES EA 2160 MMS ‘Mer, Molécules, Santé’, G. Kroth1 ([email protected]) Université de Nantes, Faculté des Sciences et Techniques, 2 rue de la Houssinière, BP 92208, 44322 Nantes cedex 3, France and 3UMI3376 Takuvik, CNRS/ULaval, Département 1Plant Ecophysiology, University of Konstanz, Universitätstr. 10, 2 de Biologie, Université Laval, Pavillon Alexandre-Vachon, 78464 Konstanz, Germany and Chemical Ecology/Chemical 1045 avenue de la Médecine, Québec (Qc) G1V0A6, Canada Biology, University of Konstanz, Universitätstr. 10, 78464 Konstanz, Germany Estuarine intertidal flats strong productivity is mainly Epilithic photoautotrophic biofilms represent com- based on the biological activity of benthic microalgae plex communities of algae and bacteria, allowing communities, or microphytobenthos (MPB), mostly cooperative nutrient utilization, production of extra- dominated by diatoms. Epipelon is a major MPB cellular polymeric substances, and intercellular com- growth form comprising motile species which undergo ‘ ’ munication. The freshwater biofilm-forming diatom vertical so-called migration patterns in the upper Achnanthidium minutissimum and its naturally asso- sediment layers. Typically, at the beginning of daylight ciated bacteria were isolated from biofilms of Lake emersion (but not during nighttime), epipelic diatoms Constance. In the presence of its associated bacteria, move upward and form dense and transient photo- the xenic diatom produces insoluble carbohydrates synthetic biofilms at the surface of the sediment, while forming stalks and capsules, which facilitate attach- usually before and/or when immersion and/or night ment to surfaces. After removal of bacteria, axenified start, they move downward in the deeper sediment diatoms no longer form biofilms and grow in layers. While this well-known behavior has been a suspended mode, not adhering to surfaces. The extensively studied for more than a century, it remains diatom satellite bacterium Bacteroidetes sp. 32 was an enigma. Indeed, this unique motility pattern repeats isolated from the same location as A. minutissimum. according to tidal and diurnal cycles and periods, This bacterium is known to induce the stalks, cap- continuously resetting to fit the everyday tides and sules, and thus biofilm formation by excreting the seasonal changes in day length. Because of such unknown bioactive molecules, while the bacterium pattern, it is believed that epipelon migratory rhythms can feed on the carbohydrates excreted by the dia- are driven by a mix of endogenous internal clock of tom. This transition to a benthic lifestyle is evidently unknown nature, and by diverse environmental sti- accompanied by changes to the photophysiology of muli, the later probably entraining/resetting at least the diatom, typified by changes in pigment concen- part of the clock system. Among the environmental trations and electron transport rates. This tight inter- stimuli impacting on epipelon vertical migration, light dependence of this diatom and the bacteria in is probably the most important. The present work biofilms also raises questions about the benefits of intended to further decipher its role. Rhythmic such communities with regard to responses to envir- changes in surficial abundance of natural MPB assem- onmental changes. For this purpose, we have studied blages were continuously assessed by Imaging-PAM the generation of such mixed-species photoauto- fluorimetry over several days in sediment sampled at trophic biofilms under controlled conditions in different seasons (85 migration profiles from 40 sedi- a sterile incubator system for biofilms. Taken ment samplings over 2 years), and exposed to differ- together, our study demonstrates the impact of nutri- ential light conditions. In particular, we manipulated i) ent limitation and associated physiological acclima- the natural photoperiod MPB was acclimated to in tion of diatoms during biofilm formation. order to disentangle the tight link between the diurnal and tidal rhythmicity of epipelon migration, and ii) the light spectrum in order to potentially impact on MPB 6OR.2 accumulation at the surface of sediment: we found a specific and positive effect of blue wavelengths that THE WAY YOU MOVE: THE VERTICAL was diatom species-dependent. MIGRATORY RHYTHM OF INTERTIDAL MICROPHYTOBENTHOS IN SEDIMENT DEPENDS ON THE PHOTOPERIOD, THE LIGHT INTENSITY AND SPECTRUM 6OR.3 Alexandre Barnett1,2 (alexandre.barnett@univ-nantes. THE ECOLOGICAL CONSEQUENCES OF fr), Vona Méléder2 ([email protected]), SPECIFICITY IN DIATOM BACTERIA Christine Dupuy1 ([email protected]) and Johann ASSOCIATIONS Lavaud1,3 ([email protected]) Willem Stock1 ([email protected]), Coco Koedooder1 ([email protected]), Anne 1UMRi7266 LIENSs ‘Littoral, Environnement et Sociétés’, CNRS/Université de La Rochelle, Institut du Littoral et de Willems² ([email protected]), Sven l’Environnement, 2 rue Olympe de Gouges, 17000 La Rochelle, Mangelinckx³ ([email protected]), Wim 58 KEYNOTE AND ORAL PAPERS

Vyverman1 ([email protected]) 1 and Koen (CONICET), Florida 4750, Bahía Blanca, B8000FWB, Sabbe ([email protected]) Argentina

1Laboratory of Protistology and Aquatic Ecology, Biology Eutrophication is one of the main drivers affecting Department, Ghent University Krijgslaan 281 – S8, B-9000 phytobenthic communities in coastal habitats. ² Ghent, Belgium; Laboratory of Microbiology, Department of Tropical seagrass ecosystems are particularly vulner- Biochemistry and Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium and ³SynBioC, able to increasing nutrient pollution and seagrass loss Department of Green Chemistry and Technology, Faculty of can be exacerbated under global warming scenarios, Bioscience Engineering, Ghent University, Coupure Links 653, as levels exceed temperature tolerance limits, provid- B-9000 Ghent, Belgium ing a competitive advantage to different phytobenthic bloomers. To examine the phytobenthic community Benthic diatoms and heterotrophic bacteria live in dynamics and study their responses to nutrients and close association in marine intertidal mudflats. While temperature alterations, a multifactorial mesocosm it has been shown that diatom species tend to differ in experiment mimicking an Indo-pacific seagrass com- their associated bacterial taxa, the implications of this munity was set up. The single and potential syner- specificity for the algal host and more broadly, the getic effect of nutrients (low and high doses of N+P) functioning of microphytobenthos, are currently not and temperature (25° and 31°C) were tested on the known. To test if this specificity results in the composition and physiology of phytobenthic algae improved fitness of the host, we exposed diatoms to and biofilms. Changes in the phytobenthic commu- microbiomes initiated from the same natural bacterial nity pattern were followed by sequencing photo- community but selected by different hosts. The assem- graphs and micro phytobenthic compositions were bly process was accompanied by a reduction in com- confirmed by microscopic and molecular investiga- petition between host and bacteria and indeed led to tions. Preliminary data showed, bloom formation of species-specific algal microbiomes. We further show different phytobenthic taxa along the benthic algal that when these microbiomes were confronted with succession trajectory. As blooms of dinophyceae another diatom host, competition increased as (e.g. Prorocentrum cf. lima) and chrysophyceae a function of phylogenetic distance to the original peaked over a rather short time, the abundances of host diatom species. By challenging a synthetic diatom the cyanobacterial Oscillatoriales (e.g. Oscillatoria community, consisting of Cylindrotheca closterium, spp.) seem to be linked to the trajectory of either Navicula phyllepta and Seminavis robusta, with a green (Cladophoropsis sp.) or red macroalgal a natural bacterial inoculum, we verified if these spe- (Laurencia sp.)-dominated state within the nutrient- cies-specific effects on diatom fitness would also have enriched treatments. In contrast, the brown tide implications for the outcome of competitive interac- forming pelagophyceae (e.g. Aureococcus sp.) domi- tions between diatom species. The bacteria differen- nated the phytobenthic communities under nutrient- tially impacted the growth of the different diatom depleted conditions. Phytobenthic alterations were species, resulting in compositional shifts in this com- also reflected in photosynthetic performances (e.g. munity. Together, our results suggest that the specific measured as rETR and biological oxygen demand, interactions between bacteria and diatoms are a key measured in sediment and water column). factor in determining community composition and growth of benthic diatoms in intertidal flats. 6OR.5 COUPLING PAM FLUOROMETRY, C-FLUXES 6OR.4 AND REFLECTANCE TO ESTIMATE PHYTOBENTHIC BLOOM DYNAMICS WITHIN MICROPHYTOBENTHOS PRIMARY A TROPICAL MESOCOSM SEAGRASS PRODUCTION BY HYPERSPECTRAL COMMUNITY REMOTE-SENSING 1 Anna Fricke 1,2 ([email protected]), Germán Meng Zhang ([email protected]), Bruno 2 2 Kopprio1,2 ([email protected]), Fay Belshe1 (eliza- Jesus ([email protected]), Manuel Giraud 2 [email protected]), Agustin Moreira Saporiti1 ([email protected]), Patrick Launeau 3 ([email protected]), Kim Anderle1 patrick.launeau@univ-nantes), Johann Lavaud 4 ([email protected]) and Mirta Teichberg1 (mirta. ([email protected]), Pierre Polsenaere 1 [email protected]) ([email protected])andVonaMéléder ([email protected]) 1Leibniz Centre for Tropical Marine Research (ZMT), WG Algae and Seagrass Ecology, Fahrenheitstrasse 6, 28359 1Université de Nantes, Laboratoire Mer Molécules Santé, EA 21 2 Bremen and Instituto Argentino de Oceanografía (IADO), 60, BP 92208, 44322 Nantes, France; 2Université de Nantes, Consejo Nacional de Investigaciones Científicas y Técnicas LPGN, UMR CNRS-6112, BP 92208, 44322 Nantes,France; EUROPEAN JOURNAL OF PHYCOLOGY 59

3UMI3376 Takuvik, CNRS/ULaval, Département de Biologie, [email protected]), Adriana Trotta2 (adriana.trot- Université Laval, Pavillon Alexandre-Vachon, 1045 avenue de 3 4 [email protected]), Aliki Panagopolou ([email protected]), la Médecine, Québec (Qc) G1V0A6, Canada and IFREMER, 4 French research institute for exploitation of the sea, Resources Maja Lukač ([email protected]), Marialaura and Environment Laboratory, BP 7, 17137 L’Houmeau, France Corrente2 ([email protected]), Antonio Di Bello2 ([email protected]), Romana Tidal flats are amongst the most productive marine Gračan1 ([email protected]) and Sunčica ecosystems on the Earth mainly due to the presence of Bosak1 ([email protected]) microscopic algae colonizing sediments (i.e. microphy- tobenthos). These ecosystems provide important services 1Department of Biology, Faculty of Science University of Zagreb, such as biodiversity depositories, storm protection, Rooseveltov trg 6, 10000 Zagreb, Croatia; 2Department of shoreline stabilization, food production and contribute Veterinary Medicine, University of Bari “Aldo Moro”, s.p. per Casamassima km.3, 70010 Valenzano, BA, Italy; 3ARCHELON, totheBlueCarbon.Theyareoneofthemostextensive the Sea Turtle Protection Society of Greece, Solomou 57, 104 32 coastal ecosystems, with an estimated global area of Athens, Greece and 4Department of Poultry Diseases with ~130.000 km2. With a global annual Gross Primary Clinic, Faculty of Veterinary Medicine, University of Zagreb, Production (GPP) estimated to be in the order of Heinzelova 55, 10000 Zagreb, Croatia 500 million tons of carbon, these ecosystems can be The external surfaces of marine vertebrates provide responsible for up to 20% of the ocean GPP although suitable hard substrata for the growth of rich micro- occupying only 0.03% of their surface. In spite of their bial biofilms. Many aspects of turtle ecology and potentially high contribution to the Global Carbon behavior are still unknown and the micro-epibionts Budget, their actual contribution remains unknown. may be used as an indicator of the animal behavioral The only way to fill this gap is the use of remote sensing pattern or as a proxy of the anthropogenic impact to imagery calibrated with C-flux measurements, especially coastal marine habitats of this species. However, the with the use of hyperspectral technology. With several composition of these surface micro-communities is dozens of narrow spectral bands, this technology is the largely unknown. In recent years, numerous studies only one able to detect and map changes in relation to apply DNA metabarcoding approach using 16S and biological and physiological processes involved in GPP. 18S amplicons to analyze different types of commu- The objective of this study is to couple hyperspectral nities in various environments such as the surface reflectance (400-900 nm), PAM-fluorometry and layer of the ocean, sediments, and animal biofilms. C-fluxes measured on sediment cores colonized by In our study, we analyzed carapace and skin biofilm natural biofilms under a range of light (50 to 2300 − − samples of ten loggerhead turtles (Carreta carreta) μmol m 2 s 1) and temperature (15, 25 and 40 °C) collected from distinct habitats in the Mediterranean conditions. First, light curves from C-fluxes, expressed − − Sea, along the Croatian and Italian coast of the in mgC m 2 h 1, and from PAM fluorometry, expressed Adriatic Sea and Amvraikos Gulf in Greece. The in rETR (Electron Transfer Rate) and photosynthetic composition of OTUs representing bacterial commu- parameters (alpha, Ek and Pmax) for each temperature nities living on the carapace and the skin were highly were compared. Second, reflectance data were used to similar among both the Greek and Adriatic turtles retrieve the absorption cross-section (a*) using the bio- reflecting taxa that are most abundant in the marine film optical model (i.e the MPBOM). Third, radiometric ecosystems such as proteobacteria (alpha, beta, indices, as the MBPLUE, were tested to estimate primary − − gamma and delta), cyanobacteria, actinobacteria and production expressed in rETR and mgC m 2 h 1.Finally, bacteroidetes. The results of 18S amplicon analysis GPP at the cores scale was mapped using hyperspectral showed more variation between the Greek and reflectance in the function of light and temperature. Adriatic turtles, including different ratios of taxa which occupied the skin and the carapace. 6OR.6 Eukaryotic OTUs that mostly dominated across sam- ples were those of green, brown and red algae, crus- METAGENOMIC CHARACTERIZATION OF taceans, ciliates and diatoms. This study provides THE SURFACE BIOFILM ON MEDITERRANEAN valuable insights into how microbial taxa associated LOGGERHEAD SEA TURTLES with animal surface biofilm vary among surface types Hrvoje Višić1 ([email protected]), Klara Filek1 and habitats which loggerheads utilize in the ([email protected]), Maja Mucko1 (maja. Mediterranean Sea. 60 KEYNOTE AND ORAL PAPERS

7. Algae in a changing environment: perception of environmental signals, physiological changes, changes in community composition

2 7KN.1 Department of Biology, Faculty of Sciences, University of Balear Islands, Ctra. de Valldemossa, km 7,5. Campus UIB, 07122 STATISTIC MODELING OF AQUATIC Palma, Spain PRIMARY PRODUCTION AND WATER MONITORING The Polar ecosystems are among those more threa- tened by the changing climate. The increase in tem- Heiko Wagner ([email protected]), Andrea perature in the Arctic is being particularly alarming. Fanesi ([email protected]) and Christian Hardbottom polar coastal areas are densely populated Wilhelm ([email protected]) by macroalgae, many of which are present even during the long winter period. A number of campaigns have University of Leipzig, Department Life Science, Plant been carried out in Kongsfjorden (Svalbard), and com- Physiology, Permoserstrasse 15, 04318 Leipzig, Germany mon macroalgae species have been tested for their Different phytoplankton groups acclimate to certain ability to perform in an increased atmospheric CO2 growth conditions with respect to their physiological and/or increased temperature scenario. We have features. Mechanisms to cope with high light, alter- shown that increased CO2 can modify the carbon bal- native electron pathways and biomass composition ance of different species in different ways, affecting are of special interest. These physiological features, both their ability to cope with summer excess light however, alter the metabolic fluxes within the cell and their internal composition, in a manner different (carbon allocation) as well as the energy partitioning to their cold-temperate ecotypes (North Atlantic). But (usage of absorbed energy within different pathways). the new weather conditions are also threatening their To analyze the quantum efficiency of each subprocess ability to overcome long dark winter periods, compro- a variety of methods have been established: e.g. O2/ mising the interannual survival. An increase in winter CO2 gas exchange, chlorophyll fluorescence measure- temperature of 4 °C doubles the speed of thallus degra- ments and Fourier transformed infra-red spectro- dation and suppress the ability to generate new scopy. Our setup is used to develop an overall view photosynthetic tissue. Taking into account that in wes- of energy fluxes within phytoplankton cells with tern Svalbard the increase in winter temperature is respect to abiotic factors (light climate, nutrient con- about 3.6 °C per decade, we might be close to see centration, temperature, pH). Our recent results a drastic change in the community. Primary produc- showed high plasticity, but also species-specific tion has been measured by three different methods (O2 14 responses. These will be used for the interpretation evolution, C fixation and PAM fluorometry), so of different growth strategies depending on the abio- uncoupling of photosynthetic processes have been tic factors and therefore to model aquatic primary revealed as part of the acclimation mechanisms. production as well as to optimize growth conditions These adjustments allowed for the internal composi- in biotechnological applications. tion (carbohydrates, lipids and proteins) and growth being more resilient to the changing environment, so that acclimation is mainly taking part in the photosyn- 7KN.2 thetic machinery. Photoinhibitory conditions occur- ring during the 24 h illumination during summer PERFORMANCE OF POLAR MACROALGAE IN may explain some seasonal traits in these species. A CHANGING ENVIRONMENT: A SEASONAL PERSPECTIVE AND IMPLICATIONS FOR THE FUTURE 7OR.1 Francisco JL Gordillo1 ([email protected]), Concepción Iñiguez2 ([email protected]), Raquel Carmona1 (rcar- EFFECTS OF POLLUTION ON POPULATIONS CYSTOSEIRA CRINITA [email protected]), and Carlos Jiménez1 ([email protected]) OF 1 1 Sònia de Caralt ([email protected]), Jana Department of Ecology, Faculty of Sciences, Universidad 1 1 de Málaga, Bulevard Louis Pasteur, 29010 Malaga, Spain and Verdura ([email protected]), Alba Vergés (alba. EUROPEAN JOURNAL OF PHYCOLOGY 61 [email protected]), Enric Ballesteros2 ([email protected]) 7OR.2 and Emma Cebrian1 ([email protected]) CRUSTOSE CORALLINE ALGAE AND OCEAN 1Institute of Aquatic Ecology, Faculty of Science, University of ACIDIFICATION: THE ROLE OF Girona, c/M. Aurèlia Capmany 69, 17003 Girona, Catalonia, EVOLUTIONARY HISTORY 2 Spain and Center for Advanced Studiesof Blanes (CEAB), 1 Spanish Research Council (CSIC), c/d’Accés a la Cala St Guillermo Diaz-Pulido ([email protected]), Francesc 14, 17300 Blanes, Catalonia, Spain Alexandra Ordoñez1 (alexandra.ordonezalvarez@grif- fithuni.edu.au), Ellie Bergstrom1 (ellie.bergstrom@grif- In the Mediterranean Sea, species of the genus fithuni.edu.au), Maureen Ho1 (maureen.ho@griffithuni. Cystoseira (Order Fucales) are amongst the most 2 edu.au), Catriona Hurd ([email protected]) important canopy-forming seaweeds on photophilic and Tessa Page1 ([email protected]) rocky bottoms. They provide high stand structure, biomass, food and habitat for many other associated 1School of Environment & Science, Griffith University, 170 organisms creating very productive, complex and Kessels Road, Brisbane, Nathan, Queensland 4111, Australia 2 diverse assemblages. Nevertheless, Cystoseira species and Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, 20 Castray Esplanade, Battery Point, are highly vulnerable to anthropogenic disturbances. Hobart, Tasmania, 7004, Australia Cystoseira crinita is a Mediterranean endemic spe- cies that develops a complex assemblage in shallow Crustose coralline algae (CCA) are fundamental to the rocky habitats. During the last decades, C. crinita is functioning of tropical and temperate marine ecosys- facing severe declines and even local extinctions in tems. In coral reefs, CCA are important for reef cemen- different areas from Spain, France, Italy, Croatia, tation, substrate stabilization and reef resilience. Montenegro and Greek coasts being extremely vul- However, CCA are sensitive to the impacts of global nerable. Some of these losses have been direct con- climate change. Our knowledge of the effects of ocean sequences of habitat destruction and overgrazing by acidification and warming on CCA has increased sub- sea-urchins, but frequently have been attributed to stantially in the last 10 years, however, little is known sea surface pollution and eutrophication. However, about the variability in responses among coralline algal up to now, there is no experimental evidence of the species to climate change, and particularly on the role of impacts of pollution on C. crinita populations. evolutionary history as drivers of the CCA responses. To Therefore, this study aims to evaluate for the first fill in this knowledge gap, we tested the effects of variable time the impacts that real conditions of pollution pCO2 and temperature scenarios on a range of CCA can cause to populations of C. crinita through species from the Great Barrier Reef, Australia. The selec- laboratory experiments. Different sources of com- tion of species included representatives of different evo- mon pollutants such as nitrates, heavy metals (cop- lutionary lineages, including basal (Sporolithales) and per and lead), and herbicides (glyphosate) were more derived groups [Hapalidiaceae, Lithophylloideae, applied to adults and juveniles of C. crinita during and Mastophoroideae]. We assessed a range of physio- 6 months. Early and adult stages were monitored to logical (photosynthetic oxygen evolution, maximum determine the possible effects of pollutants at the quantum yield, carbon stable isotope values), mineralo- biological and physiological level. For adult speci- gical (mineral composition) and individual (growth, cal- mens, survival, growth, fertility level and photosyn- cification, survival) responses across species to gain thetic activity were monitored once a month. For insights into potential processes and mechanisms early stages, density and size were measured in explaining the observed variability among lineages. We months 3 and 6. After 6 months of treatment, found considerable variability in the metrics across spe- adult specimens were tolerant to moderate levels of cies, but there are trends of declining growth with pollution. However, the survival and growth of early increased pCO2. Basal taxa seem more robust to the stages were compromised already after 3 months of impacts of ocean acidification than those from the treatment being glyphosate and nitrates the pollu- more derived groups. We also found some flexibility in tants with the most severe effects. This higher sen- the carbon uptake mechanisms in response to elevated sitivity of early stages in front of pollutants could CO2 and the strength on this response varied across taxa. compromise the long-term viability of these popula- Our study provides insights into the biological traits that tions. Ascertain the effects of current levels of pollu- may have facilitated the survival and success of some tion in both adults and early stages and identify the CCA to past ocean acidification and warming events. most harmful contaminant will help to get a full This information is important to predict taxa that may understanding of the biological and ecological con- be more sensitive to rapid climate change, and under- sequences and can contribute to develop effective stand ecosystem functions that are at risk due to conservation plans and recovery strategies. increased CO2 emissions to the atmosphere. 62 KEYNOTE AND ORAL PAPERS

7OR.3 7OR.4 DRIVERS OF THERMAL TOLERANCE OF THE BOOM-BUST INVASION BY A COSMOPOLITAN KELP SPECIES: HABITAT LOPHOCLADIA LALLEMANDII HAS A LOWER SUITABILITY, POPULATION QUALITY OR IMPACT THAN EXPECTED ON NATIVE LOCAL ADAPTATION? ECOSYSTEMS Sylvain Faugeron ([email protected])1,2 and Raul Golo1 ([email protected]), Enric Ballesteros2 Ronan Becheler ([email protected])1,2 ([email protected]), Jana Verdura1 (jana.verdur- 3,4 1 [email protected]), Fiona Tomàs ([email protected]. Departamento de Ecología, Facultad de Ciencias Biologicas, 1 Pontificia Universidad Catolica de Chile, Av. Bernardo es), Alba Vergés ([email protected]) and Emma O’Higgins 340, Santiago, Chile and 2CNRS Sorbonne Cebrian1 ([email protected]) Université Pontificia Universidad Catolica de Chile Universidad Austral de Chile, UMI Evolutionary Biology and 1Universitat de Girona, Departament de Ciències Ambientals, Ecology of Algae, Station Biologique, Roscoff, France Institut d’Ecologia Aquàtica, C Maria Aurèlia Capmany, 17003, Girona, Spain; 2Centre d’Estudis Avançats de Blanes (CEAB- 3 The giant kelp Macrocystis pyrifera is a cosmopolitan CSIC), Departament d’Ecologia Marina, Spain; Institut Mediterrani d’Estudis Avançats (IMEDEA), Ecologia marina, species of cold-temperate coasts, yet encompassing Spain and 4Department of Fisheries and Wildlife, Oregon State a considerable temperature gradient across its distribu- University, Corvallis, OR, USA tion range, from 3 to 20°C. Its large distribution may strongly rely on a great dispersal capacity to (re)colonize Invasions of marine habitats by exotic algae are of distant habitats and maintain the species cohesion major ecological concern since long-lasting negative through gene flow. Yet, dispersal is expected to counter- effects have been reported on the diversity and the balance diversifying selection on thermal tolerance. This functioning of invaded ecosystems. Almost all stu- study aimed at testing for the existence of local adaptation dies on the impacts of invasive algae rely on observa- among regions separated by up to 4000km and strong tional comparisons of native diversity in invaded and thermal divergence. Common garden experiments un-invaded locations only a few years after the start mimicking reciprocal transplants were performed, each of the invasion. However, many times, the invasion habitat being assimilated by a given temperature corre- shows a boom-bust dynamics, with a progression sponding to the regional average of the sampled popula- from a transient “harmful” stage to a more persistent tions. Several proxies of fitness were measured in the “harmless” phase. Here we show a first example on haploid stage of the kelp, and sympatric versus allopatric the effects of an invasive alga with a boom and bust conditions were compared. Additionally, a heat wave at dynamics on different native communities during 24°C was applied to measure the tolerance limits of these a medium-term (15 years) invasion process. We gametophytes. Significant differences among regions monitored Lophocladia lallemandii abundance and were observed in the responses to thermal variability, native species composition from its introduction to yet local adaptation sensus stricto was not detected. 15 years later in two different MPAs. Initially, Fertility was more influenced by the geographic origin Lophocladia lallemandii exponentially increased in than by temperature per se, with possible effects of mar- abundance, reaching coverage values > 70% in only ginal conditions at the extremes of the distribution range. 5 years; however, after some years when coverage The effect of deme quality was also strongly determinant, values were maintained, Lophocladia steeply suggesting that local stochasticity (i.e. genetic drift) may declined to much lower abundances (<15%). actually restrict the process of local adaptation. Small Changes in native species composition were detected effective population sizes and low gene flow were con- during the boom phase, but native communities firmed by a population genetic survey, which also tended to return to its original state in the bust revealed a slight correlation between genetic diversity phase, showing a great capacity for recovery. We and average fitness of the populations. Even though all conclude that the final impacts of Lophocladia on the gametophytes were able to survive at 24°C, native communities will strongly depend on whether a temperature rarely met at the northern limit of the this bust phase remains or it returns to a boom distribution range (i.e. during major heat waves), the phase. Our results question the long-lasting effects capacity to evolve adaptations to local or regional tem- of macroalgae invasions on native species, which is perature regimes seems hampered by the effects of local of critical importance for predicting ecosystem stochasticity. change and for managing the invasion. EUROPEAN JOURNAL OF PHYCOLOGY 63

7OR.5 7OR.6 CAN THERMAL HISTORY SHAPE THE ECOPHYSIOLOGICAL RESPONSES OF SIX THERMOTOLERANCE RESPONSE OF INTERTIDAL SEAWEEDS THAT FOLLOWED MEDITERRANEAN MARINE CONTRASTING ABUNDANCE SHIFTS IN THE HABITAT-FORMING MACROALGAES? LAST DECADES UNDER THE INFLUENCE OF Jana Verdura1 ([email protected]), Sónia de Caralt1 MULTIPLE STRESSORS ([email protected]), Jorge Santamaria1 (jorge.san- Cristina Piñeiro-Corbeira1 ([email protected]), [email protected]), Alba Vergés ([email protected]), Rodolfo Barreiro1 ([email protected]), João Maria-Elena Cefalí2 ([email protected]), Luisa Franco2 ([email protected]), Sara Barrientos1 Mangialajo3 ([email protected]), Ljiljana Ivesa4 ([email protected]), Javier Cremades1 (javier.cre- ([email protected]), Simone Farina5 (s.farina@fondazio- [email protected]) and Francisco Arenas2 (farenas@ciimar. neimc.it), Simonetta Fraschetti6 (simona.fraschetti@uni- up.pt) 7 salento.it), Enric Ballesteros ([email protected])and 1 1 Área de Ecología, Facultad de Ciencias, Campus A Zapateira, Emma Cebrian ([email protected]) Universidad de A Coruña, 15008 A Coruña, Spain and 2CIIMAR-Centro Interdisciplinar de Investigação Marinha 1Universitat de Girona, Departament de Ciències Ambientals, e Ambiental, Terminal de Cruzeiros do Porto de Leixões, Av. Institut d’Ecologia Aquàtica, Spain; 2Estació d’Investigació General Norton de Matos s/n, 4450-208, Matosinhos, Portugal Jaume Ferrer, Instituto Español de Oceanografía (IEO), Spain; 3Nice Sophia Antipolis University, France; 4Ruđer Bošković Institute, Center for Marine Research, Rovinj, Croatia; Temperature and nutrients are major drivers of the 5International Marine Centre (IMC), Italy; 6Laboratorio di distribution of seaweeds. Recent local losses of sea- Biologia Marina Dipartimento di Scienze e Tecnologie per weeds have been linked to climatic stressors like ’ 7 ’ l Ambiente, Università del Salento, Italy; Centre d Estudis temperature or changes in upwelling intensity. Avançats de Blanes (CEAB-CSIC), Departament d’Ecologia Marina, Spain A better assessment of these field observations requires disentangling the potential interaction Macroalgae of the genus Cystoseira (Order Fucales), between warming and nutrient supply on the ecophy- are the main marine canopy-forming species on siological performance of seaweeds. Using a factorial photophilic Mediterranean rocky bottoms. During design, we investigated the effects of temperature and the last decades, several populations from different nutrient on growth, photosynthesis and respiration of areas of the Mediterranean Sea have gone missing six intertidal seaweeds that recently followed con- mainly due to habitat destruction, pollution and over- trasting upward and downward abundance shifts in grazing although no evidence of warming impact has NW Iberia. For six weeks, seaweeds were exposed to yet been published. After observing for the first time conditions that simulated present (14 and 18 °C) and a negative impact of high temperatures on warmed (22 and 26 °C) thermal scenarios, combined a Cystoseira crinita population, we experimentally with nutrient concentrations that emulated nutrient tested how thermal stress affects the growth, eco- supply with (high) and without (low) the influence of physiology and survival of this species. We aimed to the upwelling system. Nutrient supply modulated the acquire basic information about the thermotolerance effects of warming on the growth rate of some sea- features of C. crinita and to evaluate the role of weeds only. Growth markedly slowed down in history acclimation (particular thermal regimes) on a warmed scenario in two of the downward group thermal stress responses. To do so, we compared the (Mastocarpus stellatus and Fucus vesiculosus), but thermal tolerance of populations dwelling in the cold- only if nutrients were available in large quantity. est and warmest areas of the Mediterranean Sea by Otherwise, growth was largely insensitive to tempera- means of aquaria cultures at different temperature ture in the third representative of the downward treatments (from 26ºC up to 29 ºC). We show that group (Chondrus crispus) as well as in the upward C. crinita populations from warmer areas like those group, regardless of nutrient supply. The temperature thriving in the Eastern Mediterranean showed dependence of photosynthesis, showed consistent dif- a temperature tolerance threshold 2ºC higher than ferences between trend groups. Regardless of the those living in colder areas. Moreover, we demon- nutrient regimen, photosynthesis was insensitive to strate a strong correlation between the observed dif- temperature in the upward group while water warm- ferential responses and the local temperature regimes ing accelerated the photosynthetic rate in the down- experienced by each population. These results are one ward group when nutrients were in great supply. of the first evidence for the role of thermal history in Altogether, our results suggest that physiology and shaping the thermotolerance responses of habitat- performance are more sensitive to warming in down- forming macroalgae under contrasting temperature ward seaweeds, but only if nutrients are available in environments. large quantity. From the perspective of future 64 KEYNOTE AND ORAL PAPERS scenarios, the differential effects of water warming on plasticity among and within the phylogenetically upward and downward seaweeds might greatly dis- diverse groups and seems to be related to the diver- appear if nutrient decrease in the region because of sity of carbon concentrating mechanisms and the a weakening of the upwelling system. thermal environment. This information will be espe- cially useful for understanding the effects in the pro- ductivity and ecological success of the different 7OR.7 aquatic organisms in future scenarios of Global Change. ENVIRONMENTAL FACTORS SHAPING RUBISCO AND CARBON CONCENTRATING MECHANISM CO-EVOLUTION ACROSS 7OR.8 AQUATIC ORGANISMS Concepción Iñiguez1 ([email protected]), Ülo THE ROLE OF VOLTAGE-GATED ION Niinemets2,3 ([email protected]), Kristiina CHANNELS IN DIATOMS Mark2 ([email protected]), Lauri Laanisto2 Friedrich Kleiner1,2 ([email protected]), Katherine ([email protected]) and Jeroni Galmés1 (jeroni.gal- Helliwell1 ([email protected]), Glen [email protected]) Wheeler1 ([email protected]) and Colin Brownlee1,2 ([email protected]) 1Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears–INAGEA, Palma, 1 2 Marine Biological Association of the United Kingdom, The Balearic Islands, Spain; Institute of Agricultural and Laboratory, Citadel Hill, Plymouth PL1 2PB, UK and Environmental Sciences, Estonian University of Life Sciences, 2 3 National Oceanography Centre Southampton, Department Kreutzwaldi 1, Tartu 51006, Estonia and Estonian Academy of Ocean and Earth Science, University of Southampton, Sciences, Kohte 6, 10130 Tallinn, Estonia Waterfront Campus, European Way, Southampton SO14 3ZH, UK Despite the unquestionable importance of the main CO2-fixing enzyme in the biosphere, Rubisco, its Calcium signaling is employed ubiquitously in eukar- natural catalytic diversity, especially in aquatic organ- yotes, as well as bacteria, to mediate their response to isms, still remains poorly understood. Aquatic photo- a range of abiotic and biotic stimuli. Upon sensing synthesis not only forms the basis of marine and a stimulus, Ca2+ channels located in cell-membranes freshwater food webs, representing half of the global open and allow Ca2+ to quickly enter the cytosol. primary productivity but also exerts an important These changes in Ca2+ are detected by diverse Ca2+ control on the global carbon cycle through regulation binding proteins, triggering a range of downstream of the ocean’s biological pump. Although Rubisco responses. Within the Ca2+ signaling toolkit, voltage- kinetics is currently an area of active study, there is gated channel calcium channels are known for their also a lack of an integrative and complete meta- fast opening and closing kinetics, making them a vital analysis of all the Rubisco catalytic data even part of rapid signaling events such as muscle contrac- reported. This analysis becomes an essential requisite tion or neuronal action potentials in vertebrates. We to succeed in providing new relevant information on are examining calcium signaling mechanisms in uni- Rubisco phylogenetic evolution and environmental cellular algae in order to better understand their adaptation in aquatic ecosystems. Whit this aim, we cellular functions. In particular, we are interested in undertook an exhaustive compilation of all the data the role of voltage-gated calcium channels in marine published so far on the in vitro Rubisco catalytic diatoms. The genomes of Thalassiosira pseudonana parameters of aquatic macro and microorganisms, and Phaeodactylum tricornutum possess from bacteria to plants. Original data were corrected a surprisingly sophisticated array of voltage-gated using a novel formulation to eliminate study-to-study ion channels. Little is known in what context these effects. Rubisco evolution in aquatic organisms was algal voltage-gated Ca2+-channels are used, but their re-evaluated in the context of environmental tem- diversity suggests that different signaling mechanisms perature, CO2 and O2 concentrations, and in the from those found in land plants or animals might be appearance and strength of carbon concentrating present. We are currently investigating the role of the mechanisms. The analysis of these data revealed evo- voltage-gated Ca2+ channels in marine diatoms using lutionary trends in Rubisco kinetics among the dif- a range of molecular and physiological techniques. ferent phylogenetic groups. Importantly, this analysis These include live cell imaging to examine the sub- questioned the canonical trade-off between Rubisco cellular dynamics of Ca2+ in response to a range of affinity for CO2 and velocity of carboxylation pre- environmental stressors such as osmotic stress. In viously described for Spermatophyta. The existence of addition, gene knockout technologies are being contrasting relationships between the catalytic traits employed to examine the roles of specific ion chan- across aquatic organisms is indicative of catalytic nels in these signaling processes. The results indicate EUROPEAN JOURNAL OF PHYCOLOGY 65 that diatoms possess unique mechanisms for sensing F. cylindrus from an alternance of light:dark photo- and responding to their environment and more period (18:6) to either complete darkness (0:24) or widely provide insight into the evolution of calcium- continuous light (24:0). Results suggest that the dependent signaling processes in eukaryotes. observed photophysiological rhythmicity might depend on an endogenous circadian regulation based on the regular alternation of light and dark 7OR.9 phases. F. cylindrus shows extraordinary light- response abilities allowing it to grow under the EFFECTS OF CHANGING PHOTOPERIOD ON extreme Arctic seasonal light conditions and transi- THE REGULATION OF PHOTOPHYSIOLOGY tions, mainly through a finely tuned photoprotection IN THE POLAR DIATOM FRAGILARIOPSIS CYLINDRUS ability. Sébastien Guérin1 ([email protected]. ca), Flavienne Bruyant1 (flavienne.bruyant@takuvik. 7OR.10 ulaval.ca), Joannie Ferland1 (joannie.ferland@takuvik. ulaval.ca), Michel Gosselin2 (Michel_Gosselin@uqar. WHY IS THE PLASTID BLUEGREEN IN THE CHROOTHECE MOBILIS ca), Marcel Babin1 ([email protected]) RED ALGA PASCHER and Johann Lavaud1 ([email protected] & PETROVÁ (STYLONEMATOPHYCEAE, RHODOPHYTA)? val.ca) Marina Aboal1 ([email protected]), Pilar Díaz-Tapia2 1 Takuvik Joint International Laboratory, Laval University ([email protected]), Mónica Roldán3 (mroldanm@sjdhos- (Canada) - CNRS (France), UMI3376, Département de biologie, 4 Université Laval, Québec, Québec G1V 0A6, Canada and pitalbarcelona.org), John West ([email protected]. 2Institut des Sciences de la Mer de Rimouski, Université du au) and Heroen Verbruggen4 (heroen@unimelb. Québec à Rimouski, 310, allée des Ursulines, Rimouski, Québec G5L 3A1, Canada edu.au)

1Laboratorio de Algología, Universidad de Murcia, E-30100 In the Arctic Ocean, the availability of light is mainly Murcia, Spain; 2Coastal Biology Research Group, Faculty of controlled by the seasonal dynamic of sea-ice and Sciences and Centre for Advanced Scientific Research (CICA), 3 snow cover. The on-going impact of climate change University of A Coruña, 15071, A Coruña, Spain; Hospital San Juan de Dios, Barcelona, E-08950, Barcelona, Spain and 4 results in an early melting of the snow-ice cover in School of BioSciences, University of Melbourne, Parkville, VIC spring leading to a general increase in the available 3010, Australia light intensity. The light dose that is sufficient to allow algal growth is now reached earlier in spring Chroothece mobilis is a red alga from salt-rich flooded thus extending the productive period. However, in terrains. It is seldom reported and always in very these conditions, Arctic diatoms experience larger shallow water bodies or in marshes. A distinct char- seasonal light dose changes due to the extreme nat- acter of this species is its bluish colour, turning into ural photoperiod (i.e. from potentially complete dark- yellow-orange with high light intensity, that contrasts ness in winter to continuous light in summer). The with the red colour typical of its phylum. Confocal impact of photoperiod on the regulation of photo- Laser Microscopy (CLMS) showed the complexity of physiological processes of arctic algae is largely its 3-D stellate chloroplast and failed to detect phy- unknown. The aim of this study was to characterize coerythrin in any of the strains and species of the the phenological and rhythmic response of the cold- genus studied. For the examination of the underlying adapted diatom species Fragilariopsis cylindrus to genetic causes of the particular colour of Chroothece representative seasonal photoperiods observed at 67° mobilis its plastid genome was sequenced using N. Cells were acclimated for three weeks in bioreac- Illumina Hiseq technology. We assembled and anno- tors with light:dark photoperiods of 0 h:24 h (middle/ tated a draft plastid genome (186,153 bp) that con- end of December), 6:18 (early February), 12:12 (end tained 179 CDSs. In the plastid genome of C. mobilis, of March), 18:6 (early May) and 24:0 (end of May). the gene cpeB that encodes for the β subunit of Experiments were conducted at 0°C and with an phycoerythrin was present but the gene cpeA gene − − illumination of 30 μmol photons m 2 s 1, the optimal that encodes for the α subunit was absent. These irradiance for growth. Our results suggest that some genes form a single operon in all other red algal aspects of the photophysiology of F. cylindrus, espe- plastid genomes that have been analyzed. This find- cially photoprotection (non-photochemical quench- ing provides the molecular basis to understand the ing and xanthophyll pigments content), have strong absence of phycoerythrin in this red algal genus and photoperiodic rhythmicity. We further exposed its particular colour. 66 KEYNOTE AND ORAL PAPERS

7OR.11 7OR.12 GLOBAL WARMING AND GHOST OF THE PAST: EVIDENCE OF OLIGOTROPHICATION SYNERGY LEADS TO ECOLOGICAL MEMORY IN PHYTOPLANKTON GREATER PHYTOPLANKTON LIPID COMMUNITIES EXPOSED TO LONG-TERM PRODUCTION HERBICIDE APPLICATION Tihana Novak1 ([email protected]), Jelena Godrijan1,2 Didier Baho1 ([email protected]), Luca Nizzetto1 ([email protected])DanielaMarić Pfannkuchen3 ([email protected]), Simone Rizzuto2 (s.rizzu- ([email protected]), Tamara Djakovac3 (tamara.dja- [email protected]), Dag Hessen3 (d.o.hessen@mn. [email protected]), Nikola Medić4 ([email protected]. uio.no), and Eva Leu4 ([email protected]) č ć3 dk), Ingrid Ivan i ([email protected]), Marina 1 1 ž Norwegian Institute for Water Research (NIVA), 0349 Oslo, Mlakar ([email protected])andBlaenka Norway; 2Lancaster Environment Centre, Lancaster University, Gašparović1 ([email protected]) LA1 4YQ, Lancaster, United Kingdom; 3Department of Biosciences, University of Oslo, 0316 Oslo, Norway and 4 1Division of Marine and Environmental Research, Ruđer Akvaplan-NIVA AS, 0349 Oslo, Norway Bošković Institute, POB 108, HR-10002 Zagreb, Croatia, 2Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive Long-term exposure to stressors can induce physio- East Boothbay, ME 04544, USA; 3Center for Marine Research, Ruđer Bošković Institute, G. Paliaga 5, HR-52210 Rovinj, logical and evolutionary changes in individuals that Croatia,4Marine Biological Section, Department of Biology, tend to persist over multiple generations. This University of Copenhagen, DK-3000, Helsingør, Denmark recollection of information from antecedent events that helps ecosystems to recover and prevent cata- Earth temperature is rising and oligotrophication is strophic failures from recurring stressors has been becoming apparent even in coastal seas. In a highly term ecological memory. However, this concept still changing environment, phytoplankton use carbon lacks validation. We addressed this knowledge gap and nutrients to form important biomolecules, by using a two-phase lab controlled experimental including lipids. However, the link between lipid approach with the aim of differentiating between production and changing environment is still unex- long-term adaptation vs short-term acclimation of plored. In order to investigate phytoplankton lipid natural phytoplankton communities originating production under different temperature, salinity and from different historical contamination back- nutrient regimes we conducted batch cultures and grounds. Sediments containing seedbanks were col- in situ experiments. The diatom Chaetoceros pseu- lected from two Swedish lakes: a near-pristine lake docurvisetus cultures were grown under controlled (Finnsjön) in a forested catchment and an impacted temperatures ranging from 10 to 30 °C and nutrient lake (Tåkern) located in an extensive agricultural regimes mimicking oligotrophic and eutrophic con- catchment with long-term contamination by herbi- ditions. Results were compared to plankton commu- cides. During phase I, phytoplankton communities ’ nity s lipid production in the northern Adriatic at fromthetwolakesweregerminatedinthepresence two stations considered as oligotrophic and meso- and absence of an herbicide isoproturon (12 μg/L). trophic during an annual monthly sampling. In In phase 2, the communities from phase I was order to gain detailed information on the investi- exposed to four concentrations of isoproturon (7, gated system, we supplemented lipid data with 12, 61, 92 μg/L). The biomass development, photo- chlorophyll a concentrations, phytoplankton taxon- synthetic efficiency (maximum quantum yield of omy, cell abundances and nutrient concentration photosystem II) and community composition were along with hydrographic parameters. We found tracked. The presence of the herbicide in phase enhanced particulate lipid production at higher tem- I had negligible effects on germination. In phase peratures, and substantially higher lipid production II, the two highest exposure levels significantly in oligotrophic conditions. Lipid remodeling, reduced the total biomass production, with Tåkern including change in the ratio of phospholipids and generally performing better. However, the presence/ glycolipids, is more affected by the nutrient status, absence of herbicide during the germination phase than the temperature increase. Triacylglycerol accu- had contrasting consequences for the communities’ mulation was observed under the nitrogen performances in phase II. Herbicide exposure dur- starvation. ing germination had a stronger detrimental effect EUROPEAN JOURNAL OF PHYCOLOGY 67 on the recovery of photosynthetic yield and while in the 1970s distinct seasonal community increased the dissimilarities in communities’ struc- types were present, a striking seasonal homogeniza- tures for the two highest exposure levels in tion had occurred by the 2000s. Finally, we observed Finnsjön. In contrast, Tåkern became more resis- a pronounced increase in harmful diatom and dino- tant, which might be the result of selecting species/ flagellate genera. The observed changes are most ecotypes from a genetic pool that are already accus- likely due to an increase in sea surface temperature, tomed to herbicides. These results show that posi- water transparency and changing nutrient loads and tive effects of short-term acclimation only occurred ratios. when communities had previous repeated encoun- ters with the stressor. 7OR.14 THE ICELANDIC MARINE ECOSYSTEM: 7OR.13 MAPPING PHYTOPLANKTON IN A COMPLEX LONG-TERM PHYTOPLANKTON CHANGE IN HYDROGRAPHIC ENVIRONMENT A HEAVILY IMPACTED COASTAL AREA IN Mia Cerfonteyn1,2 ([email protected]), René Groben1 THE NORTH SEA BETWEEN THE 1970S AND ([email protected]), Kristinn Guðmundsson3 (kristinn. 2000S [email protected]), Pauline Vannier1 (pau- Koen Sabbe1 ([email protected]), Anja Nohe1 [email protected]) and Viggó Þór Marteinsson1 (viggo@- ([email protected]), Lennart Tyberghein2 matis.is) ([email protected]), Ruth Lagring³ 1 2 ([email protected]), Karien De Cauwer³ Matís, Vinlandsleið 12, 113 Reykjavik, Iceland, Faculty of Food Science and Nutrition, University of Iceland, ([email protected]) and Wim Læknagarður, Vatnsmyrarvegur 16, 101 Reykjavik, Iceland 3 Vyverman1 ([email protected]) and Marine and Freshwater Research Institute, Skúlagata 4, 101 Reykjavík, Iceland 1Ghent University, Department of Biology, Laboratory of Protistology & Aquatic Ecology, Krijgslaan 281 (S8), 9000 Iceland, located at a high latitude and economically 2 Gent, Belgium; Flanders Marine Institute, Wandelaarkaai 7, reliant on local fish spawning grounds, is particularly 8400 Oostende, Belgium and 3Operational Directorate Natural Environment, Royal Belgian Institute of Natural Sciences, vulnerable to climate change. The island is surrounded Vautierstraat 29, 1000 Brussels, Belgium by four different water masses which create a very dynamic and complex hydrographic environment. In the last 50 years, the North Sea has undergone Marine micro-organisms play a crucial role in the important environmental changes which have food web and geochemical cycles, yet many questions affected all trophic levels. Since the 1970s, both regarding the dynamics of phytoplankton in Icelandic increases and decreases in phytoplankton biomass waters remain. Novel molecular methods can contri- and production have been reported from different bute to existing knowledge by increasing sample parts of the North Sea. These conflicting observations throughput and a better characterization of small and may be caused by methodological differences but may morphologically similar taxa. The aim of the “Microbes also reflect actual regional differences related to in the Icelandic Marine Environment (MIME)” project hydrodynamics, climate and riverine and Atlantic is to give a better understanding of the underlying influence. We compared biomass, community struc- mechanisms that control the marine food web sur- ture and seasonality of diatom and dinoflagellate rounding Iceland. Seawater samples were collected communities between the 1970s and 2000s, based annually from 19 coastal and oceanic stations around on a newly compiled dataset from the Belgian part Iceland in May 2011-2018 and seasonally for one year of the North Sea. This hydrodynamically and bath- (August 2017, February 2018 and May 2018). At the ymetrically complex area is under strong human stations, seawater was sampled at several fixed depths influence, and has been characterized by eutrophica- from surface to bottom (n = 348) and metadata were tion (up to the 1980s) and de-eutrophication (1990s collected for each sampling event (temperature, salinity onwards), and pronounced long-term changes in tur- and nutrients). High-throughput amplicon sequencing bidity and water temperature. Distinct changes were of the May 2018 samples (n = 165) shows observed between the two periods. Diatoms showed a considerably higher abundance and diversity of a pronounced increase from late winter to summer, Chlorophyta than previously estimated for this region resulting in a more intense and extended growing by microscopy. Preliminary data also show that certain season in the 2000s. Dinoflagellates increased year- areas around Iceland are dominated by different phy- round but especially in summer. The onset of both toplankton taxa, confirming the impact of contrasting diatom and dinoflagellate blooms showed a marked water masses on phytoplankton diversity. Sequencing shift towards an earlier bloom start. In addition, of the May 2012, August 2017 and February 2018 68 KEYNOTE AND ORAL PAPERS sample sets is in process, and the addition of these monitoring with punctual light stress experiments dur- datasets could clarify these patterns. This presentation ing the ice microalgal bloom period. In addition, we will show the diversity and relative abundance of the performed similar experiments on two typical sea- ice phytoplankton in waters around Iceland including taxa diatom strains, Nitzschia frigida found to be dominant not previously identified in this region by traditional at our study site, and Fragilariopsis cylindrus which microscopic methods, such as Mamiellophyceae and genome has been recently sequenced. Our results different Phaeocystis species. Phytoplankton dynamics show that the bottom-ice microalgal community is will be presented in the context of time and physical able to cope with changing irradiance conditions oceanography. including a sudden light increase of relatively high irradiance. Its response appears well supported by strong photoprotective regulation, including 7OR.15 a combination of processes such as non- A BRIGHTER FUTURE? THE photochemical quenching-NPQ, damaged- PHOTOPHYSIOLOGICAL RESPONSE OF Photosystem II repair and modulation of the Rubisco BOTTOM-ICE MICROALGAL COMMUNITY content. Under alike experimental conditions, the DURING SPRING TO SUMMER TRANSITION response of N. frigida and F. cylindrus was generally IN THE ARCTIC similar to the one of the community, paving the path for further ecophysiological investigations at the finest 1 Johann Lavaud ([email protected]), molecular level under lab-controlled conditions. Virginie Galindo2,4 ([email protected]), Aurélie Delaforge2 ([email protected]), Dany Croteau1 ([email protected]), Nathalie 7OR.16 Donaher3 ([email protected]), Doug Campbell3 TALES FROM A MELTING ARCTIC: ([email protected]), Soren Rysgaard2 (rysgaard@cc. MICROALGAL BLOOM PHENOLOGY IN AN umanitoba.ca) and Marcel Babin1 (marcel.babin@ta- ERA OF CLIMATE CHANGE kuvik.ulaval.ca) Eva Leu1 ([email protected]), Clara J.M. 2 3 1 Hoppe ([email protected]), Ane Cecilie Kvernvik UMI3376 Takuvik, CNRS/ULaval, Département de Biologie, 4 Université Laval, Pavillon Alexandre-Vachon, Québec G1V 0A6, ([email protected]), Zofia T. Smoła (zosiasmola@iopan. 2 Canada; Centre for Earth Observation Science, Faculty of gda.pl), Jozef M. Wiktor4 ([email protected]), Environment, Earth and Resources, University of Manitoba, 5,6 Winnipeg, Manitoba R3T 2N2, Canada; 3Department of Finlo Cottier ([email protected]) Biology, Mount Allison University, Sackville, New Brunswick E4L 3G7, Canada and 4Institut des Sciences de la Mer de 1Akvaplan-niva, CIENS, Gaustadalleen 21, 0349 Oslo, Norway; Rimouski, Université du Québec à Rimouski, Rimouski, Québec 2Alfred-Wegener-Institute Helmholtz Centre for Polar and G5L 3A1, Canada Marine Research, Bremerhaven, Germany; 3UNIS- The University Centre in Svalbard, Longyearbyen, Norway; 4Institute of Oceanology, Polish Academy of Science, Sopot, Poland; The diatom-dominated microalgal community inhabit- 5Scottish Association for Marine Science, Oban, PA37 1QA, UK ing the bottom centimeters of first-year sea-ice sup- and 6UiT – The Arctic University of Norway, Tromsø, Norway ports a large fraction of the annual primary productivity in the Arctic Ocean. During the most Climate change is impacting the Arctic most severely productive early spring to summer transition, sea-ice already today and leads to profound changes in the diatoms have to cope with a changing light environ- physical and chemical environment with complex (and ment due to a complex combination of increasing day partly contradicting) implications for ecosystems. Ice length and solar irradiance, coupled with snow cover (and snow) cover does not only control light availability and ice melting. During the last decades, this ancestral but functions also as a barrier against wind-induced seasonal scheme has been disturbed by the impact of deep mixing. Melting will increase light availability, but climate change. As light transmittance through ice also stratification which controls nutrient availability. In increases, it is foreseen that the average irradiance to order to improve our projections of future Arctic pro- which sea-ice diatoms will be exposed will increase, and ductivity, we have studied intensively how algal bloom subsequently the future pan-Arctic Ocean primary pro- phenology in Arctic sea ice and water is controlled by its ductivity. Nevertheless, the Arctic diatom physiological environment. In the FAABulous project (Future Arctic and metabolic bases for such prediction remains AlgaeBlooms-andtheirroleonthecontextofclimate unclear: this is mainly due to our poor assessment of change) we combined extensive field studies in several their photophysiology. In order to fill this gap, we have fjord systems in Svalbard with experiments and model- monitored the photosynthetic activity of bottom-ice ing. Our results indicate that distinct physiological and microalgal community over an unpreceded long period ecological responses of different algae groups determine from early May to mid-July during the Green Edge the climate change ‘winners’ and ‘losers’–and need international field campaign. We paralleled our therefore to be considered correspondingly. Sea ice EUROPEAN JOURNAL OF PHYCOLOGY 69 algae appear less capable of handling high irradiances, an algal bloom. We, therefore, conclude that ice algae and more vulnerable to ocean acidification than their will have competitive disadvantages in the transition pelagic counterparts. Shorter (and thinner) sea ice cover- from a light-limited to a nutrient-limited production age affects the timing of blooms with cascading effects regime in the Arctic, and alterations in species composi- on higher trophic levels, while nutrient availability deter- tion and bloom timing will potentially affect grazers and mines the overall biomass production and duration of higher trophic level production. 70 KEYNOTE AND ORAL PAPERS

8. Omics and genetic tools for algal model organisms_ understanding the biology of algae using metabolomic, proteomic, and genomic approaches

8KN.1 ([email protected]), Wim Vyverman2 (Wim. [email protected]), Remo Sanges3 ([email protected]) ULVA, A MODEL SYSTEM FOR GREEN and Marina Montresor1 ([email protected]) SEAWEEDS Olivier De Clerck ([email protected]) 1Stazione Zoologica Anton Dohrn, Villa Comunale 80121, Napoli, Italy and 2Protistology and Aquatic Ecology, Department of Biology, Ghent University, 9000 Gent, Belgium Phycology Research Group and Center for Molecular 3 Phylogenetics and Evolution, Ghent University, Krijgslaan 281 and Scuola Internazionale Superiore di Studi Avanzati (SISSA) S8, 9000 Ghent B-9000, Belgium - via Bonomea 265, 34136 Trieste, Italy

Seaweeds evolved several times independently. The Pseudo-nitzschia is an important genus of marine degree of commonality in the genetics underlying diatoms responsible for blooms in coastal and ocea- the transitions from simple unicellular to (relatively) nic waters. We selected Pseudo-nitzschia multistriata complex macroscopic and mostly multicellular thalli, as a model system to explore the process of sexual however, remains to be determined. Several whole reproduction, which in diatoms is linked to the for- genome sequences of brown and red seaweeds mation of large-sized F1 cells within the cell size resulted in interesting insights in the biology of reduction/restitution cycle. P. multistriata is these respective organisms. So far, however, no a heterothallic species in which sex is induced when whole genome sequence was available for a green cells of the opposite mating type (MT) get in contact. seaweed. The publication of the Ulva mutabilis gen- We sequenced the P. multistriata genome, defined its ome (~100 MB) is possibly a game changer. I will meiotic toolkit and elucidated the gene expression discuss observations resulting from comparative changes occurring in the opposite mating types genomics, highlighting gene family expansions asso- when they are exchanging signals that will trigger ciated with multicellularity, bacterial to eukaryote sexual reproduction. To further refine our knowledge lateral gene transfer and the endogenous production of this process, we are studying the gene expression of plant hormones in green seaweed development. changes occurring at later stages, when gametes and Last, I will give an update on the progress to develop F1 cells appear. Although only ~20% of cells engage a toolbox for functional genomics in green seaweeds in meiosis, all cells arrest their growth during the (promotor screening, transformation protocols, gen- sexual phase. Transcriptional changes involve genes ome editing and protoplast regeneration). related to photosynthesis and nutrient uptake, strongly down-regulated, and genes related to DNA repair and epigenetic modifications, up-regulated compared to control conditions. A transcriptomic- 8KN.2 based approach comparing groups of strains of oppo- MOLECULAR MECHANISMS REGULATING site mating type has also been instrumental in identi- SEXUAL REPRODUCTION AND MATING TYPE fying a set of genes that are preferentially expressed in DETERMINATION IN THE DIATOM one or the other of the two mating types. These PSEUDO-NITZSCHIA MULTISTRIATA mating type-related genes play a role in defining the mating type and in governing cell behaviour during Maria Immacolata Ferrante1 ([email protected]), 1 sexual reproduction. For one of these genes, we Monia Teresa Russo ([email protected]), Rossella hypothesize a function in the pheromone system of 1 Annunziata ([email protected]), Camilla the species, and the heterologous expression of its 1 Borgonuovo ([email protected]), Francesco protein product is underway. Finally, we identified Manfellotto1 ([email protected]), Pina structural differences in the genomic region for Marotta1 ([email protected]), Laura Vitale1 another mating type-related gene and demonstrated ([email protected]), Massimiliano Volpe1 that it acts as a sex determinant in P. multistriata. EUROPEAN JOURNAL OF PHYCOLOGY 71

8OR.1 8OR.2 V FOR SEX CHROMOSOME AUREOCHROMES: THE BLUE BOX OF Agnieszka P. Lipinska1 ([email protected]), DIATOMS Nicholas Toda1 ([email protected]), Olivier Shvaita Madhuri1 (shvaita.madhuri@uni-konstanz. Godfroy1 ([email protected]), Lyam Baudry2 de), Soo Hyun Im1 ([email protected]), ([email protected]), Martial Marbouty2 (mar- Carolina Rio Bartulos1 (carolina-rio.bartulos@uni- [email protected]), Romain Koszu2 (romain. konstanz.de), Manuel Serif2 ([email protected]), [email protected]), Svenja Heesch1 (sheesch@sb- Bernard Lepetit1 ([email protected]) roscoff.fr), Zofia Nehr1 ([email protected]), Olivier and Peter G Kroth1 ([email protected]) 3 4 Panaud ([email protected]), Akira F. Peters 1 1 Plant Ecophysiology, University of Konstanz, Universitätstrasse ([email protected]), Mark J. Cock (cock@sb- 10, 78464 Konstanz, Germany and 2Department of Biology, roscoff.fr) and Susana M. Coelho1 (coelho@sb- Norwegian University of Science and Technology, N-7491, roscoff.fr) Trondheim, Norway

1CNRS, Algal Genetics Group, Integrative Biology of Marine Aureochromes are blue light-dependent transcription Models, Sorbonne Université, UPMC Univ Paris 06, Station factors so far only found in Stramenopiles. They are Biologique de Roscoff, CS 90074, F-29688, Roscoff, France; unique in their inversed effector-sensor (bZIP-LOV) 2Institut Pasteur, Département Génomes et Génétique, Groupe Régulation Spatiale des Génomes, Paris Cedex 15, France; topology. Four paralogues of Aureochromes have CNRS, UMR 3525, Paris Cedex 15, France; Institut Pasteur, been identified in the model diatom, Phaeodactylum Center of Bioinformatics, Biostatistics and Integrative Biology tricornutum, named Aureo1a, 1b, 1c, and 2. We (C3BI), Paris, France; 3Laboratoire Génome et Développement des Plantes, UMR CNRS/UPVD 5096, Université de Perpignan investigated the role and regulation of the Via Domitia, 52 Avenue Paul Alduy., 66860, Perpignan Cedex, Aureochromes by a combined molecular and physio- France and 4Bezhin Rosko, 29250, Santec, France. logical approach. Accordingly, PtAureo1a expression follows a light-independent circadian rhythm, while Brown algae (Phaeophyceae) represent a unique PtAureo1b expression is light-dependent. Expression group to study aspects of sexual reproduction due of PtAureo2 is time and light independent. PtAureo1a to the rich variation of life cycles, fertilization was suggested to be involved in high light photoac- modes and sex determination systems found in this climation in P. tricornutum. To verify this phenotype, class. Particularly interesting are the aspects of the we complemented PtAureo1a knockout lines gener- evolution of sex determination during the haploid life ated via TALEN technique with its wild type stage (UV sex chromosomes) and the various degrees PtAureo1a gene. We demonstrated a new methodo- of sexual dimorphism between gametes of closely logical approach for complementing knockout strains related species, ranging from isogamy to oogamy. in diatoms. Strengths and pitfalls of this method will With the advent of -omics techniques we now have be presented here. Furthermore, we created and access to the whole genome sequences and transcrip- investigated PtAureo1a overexpression lines. While tomic data for males and females of several brown Aureochrome knockout and overexpression had algal species, which allows us to investigate the geno- important consequences on the photoacclimation mic architecture and evolutionary history of the sex phenotype of P. tricornutum, it also influenced the chromosomes across Phaeophyceae and correlate it expression of the other Aureochromes, pointing with the different life history traits. In this study, we towards a tight regulatory feedback mechanism applied specific bioinformatic pipelines to identify between Aureochromes. We are now just beginning and analyze the structural and evolutionary features to understand the detailed molecular mechanisms for of the male (V) sex chromosomes across two major light regulation via blue light receptors in diatoms. brown algal orders, the Ectocarpales and the Laminariales. We used high-quality genomic, tran- 8OR.3 scriptomic and genetic marker data to construct genetic maps, annotate genic regions and determine HOW HAPTOPHYTE MICROALGAE MANAGE the sex-chromosomes containing the sex-determining VITAMIN B12 LIMITATION regions (SDRs) in S. japonica and D. herbacea. Charlotte Nef ([email protected]), Francis Comparative genomic analysis with the model Mairet ([email protected]), Raymond Kaas brown alga Ectocarpus suggests that a core set of sex- ([email protected]), and Matthieu Garnier linked genes is conserved across all the investigated species, however, the sex-chromosome regions are ([email protected]) highly dynamic with modifications occurring in IFREMER, Physiology and Biotechnology of Algae Laboratory, a lineage-specific fashion. rue de l‘Ile d’Yeu, 44311, Nantes, France. 72 KEYNOTE AND ORAL PAPERS

Vitamin B (cobalamin) participates to the control of 1LISBP, Université de Toulouse, 135 Avenue de Rangueil, 12 2 phytoplankton development and community compo- F-31077, Toulouse, France and Department of Biology, Norwegian University of Science and Technology, N-7491, sition in oceans. B12-dependency is common among Trondheim, Norway microalgae and seems unrelated across lineages, with an estimate half of species requiring this co-factor for Development of targeted nucleases for precise gen- growth. Cobalamin auxotrophy is characterized by ome editing, like TALEN and CRISPR/Cas9, has the presence of B12-dependent methionine synthase, strongly enriched the available molecular toolbox a key enzyme involved in methionine biosynthesis, for the model diatom Phaeodactylum tricornutum. and the lack of a B12-independent isoform. Despite Stable knockout can now be achieved, allowing for their important role in carbon and sulphur biogeo- a more stringent characterization of target gene func- chemistry, little is known about how haptophytes use tion compared to classical RNAi-mediated knock- cobalamin and cope with the effects of B12 limitation down approaches. However, the nuclease-encoding in the environment. Therefore, deciphering B12 genes are most commonly transformed into dependency and associated metabolism of this taxa P. tricornutum via particle bombardment or electro- is relevant for elucidating primary production and poration, two methods that have several drawbacks: nutrient cycling processes in the ocean. Here we The exogenous DNA is stably integrated into the report an evaluation of cobalamin auxotrophy genome at random loci, resulting in a highly variable among Haptophyta lineage based on publicly- transgene expression among transformants and available molecular data for 19 species. We found potentially unintended disruption of additional that none of the species encode the B12-independent genes. Furthermore, the integrated nuclease is con- methionine synthase, suggesting ubiquitous B12 aux- tinuously expressed, increasing the risk for off-target otrophy in this phylum. Considering actual literature, effects. Therefore, we aimed to reduce nuclease expo- Haptophyta would be the only microalgae phylum sure time to a minimum by establishing a protocol gathering exclusively cobalamin-dependent species. based on biolistic delivery of Cas9 and gRNA as We then addressed the effect of different levels and a ribonucleoprotein (RNP) complex. For selection of dynamics of B12 on the molecular physiology of the positive transformants without co-delivery of model haptophyte Tisochrysis lutea by coupling a plasmid encoding for an antibiotic resistance gene, growth assays in batch and chemostat, cobalamin the use of two endogenous marker genes was estab- quantification and gene expression analyses. We lished: Knockout of PtApt (adenine phosphoribosyl- focused on genes encoding either B12-dependent transferase) conferring resistance to 2-fluoroadenine enzymes, methionine cycle proteins or intracellular and knockout of PtUmps (Uridine-5’-monophosphate cobalamin transporters. Our results suggest that hap- synthase) resulting in resistance to 5-fluoroorotidic tophytes may use different strategies to counterba- acid as well as an uracil auxotrophy. We then vali- lance cobalamin deprivation. They can uptake dated this approach by generating double knockout dissolved methionine from seawater. They finely strains by simultaneously using RNPs targeting one and quickly up-regulate methionine cycle genes when of these endogenous markers and PtAureo1a, a gene B12 becomes rare and down-regulate genes involved encoding for a blue-light dependent transcription in B12 transport to the mitochondrion, presumably factor. About 30% of the clones obtained were bial- facilitating B12 allocation for methionine synthase lelic PtAureo1a knockout strains, which showed activity. Taken together, these results point out the a decreased capacity for photoprotection via non- importance of cobalamin in haptophytes cellular pro- photochemical quenching, confirming the phenotype cesses and give new insights for understanding how previously observed in PtAureo1a knockout strains B12-producing bacteria could shape the dynamics of generated via plasmid-based delivery of TALENs. this important phytoplankton community.

8OR.4 8OR.5 DNA-FREE GENOME EDITING USING CRISPR/ CAS9 IN THE DIATOM PHAEODACTYLUM NEW INSIGHTS INTO ALGAL MANNITOL TRICORNUTUM BIOSYNTHETIC PATHWAYS 1 Manuel Serif1,2 ([email protected]), Gwendoline Thierry Tonon ([email protected]), Mary Ann 2 Dubois1 ([email protected]), Anne- Madsen ([email protected]), Ludi 1 1 Laure Finoux1 ([email protected]), Wang ([email protected]), Muhiadin Omar 1 Marie-Ange Teste1 (marie-ange.teste@insa-toulouse. ([email protected]), Fay Wainwright 1 fr), Denis Jallet1 ([email protected]) and Fayza ([email protected]), Thomas Wells (twaw500@york. 2 Daboussi1 ([email protected]) ac.uk), Stefan Semerdzhiev ([email protected]. EUROPEAN JOURNAL OF PHYCOLOGY 73 uk), Anna Amtmann2 ([email protected]. photosynthetic production of mannitol in industrially uk), and Simon McQueen-Mason1 (simon.mcqueenma- relevant organisms. [email protected])

1Centre for Novel Agricultural Products, Department of Biology, University of York, Wentworth Way, Heslington, York YO10 8OR.6 5DD, United Kingdom and 2Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life TOXIN BIOSYNTHESIS IN PRYMNESIUM Sciences, University of Glasgow, Glasgow G12 8QQ, United PARVUM: FROM STRUCTURE TO GENES Kingdom Konstantinos Anestis1 ([email protected]), Gurjeet 1 1,2 Photosynthetic Eukaryotes produce mannitol, sugar Singh Kohli ([email protected]), Sylke Wohlrab alcohol, for carbon storage and in response to envir- ([email protected]), Per Juel Hansen3 (pjhansen@- onmental stress. In algae, mannitol biosynthesis is bio.ku.dk), Elisabeth Varga4 (elisabeth.varga@univie. a two-step process: (1) fructose-6-phosphate is ac.at), Thomas Ostenfeld Larsen5 ([email protected]) reduced into mannitol-1-phosphate (M1P) by and Uwe John1 ([email protected]) a reversible M1P dehydrogenase (M1PDH); (2) a M1P phosphatase (M1Pase) hydrolyzes the phos- 1Ecological Chemistry, Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, phate group to produce mannitol. A recent analysis 2 Germany, Helmholtz Institute for Functional Marine of algal genomic and transcriptomic resources Biodiversity, Ammerländer Heerstraße 231, 26129 Oldenburg, showed that potential genes coding for M1PDHs 3Marine Biology Section, University of Copenhagen, 4 and M1Pases are prevalent across algal lineages with Strandpromenaden 5, 3000 Helsingør, Denmark, Department of Food Chemistry and Toxicology, Faculty of Chemistry, different evolutionary history. Two distinct types of University of Vienna, Währinger Straße 40, 1090 Vienna, M1Pases are currently known, histidine phosphatases Austria and 5Department of Biotechnology and Biomedicine, (His-M1Pase), and haloacid dehalogenase phospha- Technical University of Denmark, Søltofts Plads 221, 2800 Kongens Lyngby, Denmark tases (HAD-M1Pase). M1PDHs and M1Pases occur as separate standalone enzymes, and as fusion pro- The haptophyte Prymnesium parvum is known to teins containing one M1PDH module fused with one cause massive fish kills during its blooms. The toxi- M1Pase module. Both standalone and fusion proteins city of P. parvum is attributed to its ability to produce co-exist in some algae. In this context, mannitol prymnesins, a group of supersized ladder-frame poly- biosynthetic genes from selected algae were expressed ether compounds. This group of toxins can be further heterologously to assess corresponding enzymatic divided into three different types (A-, B- and C- activity and further biochemical characterization. type), which present further diversity in terms of Among green algae, Micromonas pusilla potential number and chemical structure of derivatives. In the standalone HAD-M1Pase and M1PDH/HAD- present study, we used nine P. parvum strains repre- M1Pase fusion confer mannitol production to senting all three types of prymnesins to elucidate the Escherichia coli. Subsequent characterization of the molecular mechanisms involved in prymnesin bio- purified recombinant fusion protein revealed inter- synthesis. Due to the polyketide nature of prymne- esting biochemical properties. Another green alga, sins, particular attention was paid to polyketide Pterosperma sp., harbours a unique fusion formed synthase genes (PKSs). The transcriptomes of all by an M1PDH module and a His-M1Pase module, nine P. parvum strains were screened for the presence and this protein is functional in E. coli. The hapto- of PKS genes. A mean of 25 contigs containing multi- phyte Emiliania huxleyi exhibits one standalone modular type I PKS ketosythase (KS) domains were HAD-M1Pase and one standalone His-M1Pase, and found per strain, which were subsequently used to both are active in E. coli. Among brown algae, ana- assess the evolutionary history of prymnesin produc- lysis of the Ectocarpus sp. and Saccharina japonica tion. The phylogenetic analysis of the KS domains genomes revealed the presence of several genes cod- showed that, compared to KS transcripts from other ing for M1PDHs and HAD-M1Pases. Corresponding organisms, they form distinct clades as well as clades recombinant enzymes have been characterized, and corresponding to each prymnesin type. In addition, Ectocarpus HAD-M1Pases exhibit different substrate a comparative transcriptomic analysis of all strains specificity compared to Saccharina orthologs. To revealed the presence of candidate genes involved in complete this overview, M. pusilla fusion protein the biosynthesis of specific prymnesin derivatives. was considered for mannitol production in the indus- The current study will contribute to a better under- trial biotechnology chassis Synechococcus. While pro- standing of the mechanisms of toxin production in duction rates were low in engineered cyanobacteria, P. parvum in order to develop efficient tools for results obtained lay the ground for optimization of monitoring purposes. 74 KEYNOTE AND ORAL PAPERS

9. Algae in their ecosystems: novel approaches to study algal ecology

9KN.1 holobiont (“total organism”) with its co-occurring prokaryotic component. Rhodoliths are marine bio- DNA METABARCODING DEMONSTRATES diversity hotspots that may function as seedbanks, THE IMPORTANCE OF RHODOLITHS FOR temporary reservoirs for life history stages of eco- MACROALGAL ECOLOGY AND BIODIVERSITY logically important eukaryotic microalgae, or as IN GULF OF MEXICO DEEP-WATER refugia for ecosystem resilience following environ- MESOPHOTIC HABITATS mental stress. Suzanne Fredericq1 ([email protected]), Sherry Krayesky-Self1 ([email protected]), Thomas 2 1 9KN.2 Sauvage ([email protected]), Joe Richards ([email protected]), Ronald Kittle1 (ronaldkittle- APPLICATION OF HIGH-THROUGHPUT [email protected]), C. Frederico Gurgel3 (f.gurgel@ufsc. METABARCODING IN LIMNOLOGY AND br), Daniela Gabriel4 danielalgabriel), and William PALEOLIMNOLOGY TO CHARACTERIZE E. Schmidt1 ([email protected]) CHANGES IN MICRO-EUKARYOTIC DIVERSITY FACING ENVIRONMENTAL 1Department of Biology, University of Louisiana at Lafayette, PRESSURES 411 East St. Mary Blvd, Lafayette, Louisiana 70504-3604, USA; 1 2Smithsonian Marine Station, 701 Seaway Drive, Fort Pierce, Isabelle Domaizon ([email protected]), 3 FL 34949, USA, Departamento de Botânica, Universidade François Keck1 ([email protected]) Eric Federal de Santa Catarina, Florianópolis, SC 88040-900, 1,2 3 Brazil and 4Research Center in Biodiversity and Genetic Capo ([email protected]), Didier Debroas Resources (CIBIO), University of the Azores Rua da Mãe de ([email protected]), Cécile Chardon1 (cecile. Deus, 9501-801 Ponta Delgada, Portugal [email protected]), Marie-Elodie Perga1 (marie-elodie. [email protected]), Fabien Arnaud5 (fabien.arnau- Understanding the ecology and biodiversity of 1 deep-water communities is a major challenge. In [email protected]), David Etienne (david.etienne@u- 6 the NW Gulf of Mexico, unique deep bank habitats niv-savoie.fr) and Laurent Millet (laurent. associated with salt domes occur at ~50-90m on the [email protected]) continental shelf offshore Louisiana and Texas. In 1 INRA, Université de Savoie Mont Blanc- CARRTEL, 74 - these mesophotic rubble habitats rhodoliths, Thonon les bains, France; 2 Umea University, Dept Ecology accreted by calcified crustose coralline red algae, and Environmental Science Umeå University, Umeå, Sweden; 3 are the main hard substrata for the attachment of Université Clermont, UMR 6023, LMGE, 63 - Aubière, France; 4 CNRS Université de Savoie Mont Blanc- EDYTEM, 73 - Le benthic macroalgae. Metabarcoding of environmen- Bourget du Lac, France, 5CNRS, Université Besançon, 25 - tal DNA using molecular markers (including 16S Besançon, France gene V4 region and tufA gene) for endolithic por- tions of rhodoliths has revealed hidden cryptic algal The application of high-throughput sequencing for diversity including spores, propagules, and unsus- the analysis of environmental DNA (eDNA) offers pected life history stages (e.g., dinoflagellates, hap- many new areas of inquiry in limnology and paleo- tophytes, unicellular red algae). We explored cryo- limnology, allowing to study the spatial and temporal SEM as a potentially more informative method than dynamics of biological assemblages and their regular SEM to minimize artifacts of sample pre- responses to anthropogenic and climatic pressure. paration in the study of endolithic cell inclusions Here, we illustrate recent applications aiming at char- which brought to light a suite of microalgal stages. acterizing the diversity of planktonic micro- We were able to differentiate floridean starch from eukaryotes and their turn-over at various time- cellular inclusions. Analyses of combined 16S V4 scales. A large diversity of taxa is considered from metabarcodes and 16S Sanger sequences of several phytoplankton (chlorophyta, bacillariophyta, …)to macroalgal orders increased the established record micro-heterotrophs (ciliophora, fungi, cercozoa, …). of diversity in the region. Progress is underway to Diverse metrics as richness, composition, community link the eukaryotic component of the rhodolith structure and patterns of co-occurrence are taken EUROPEAN JOURNAL OF PHYCOLOGY 75 into account to study the responses of these biological using the traditional microscopy methods. assemblages to local anthropogenic disturbances Compared to traditional approaches, for most of the (eutrophication) or more global pressures (tempera- algal groups (e.g. Zygnemophyceae, Dinophyceae) ture conditions). Multi-scale temporal rearrange- HTS allowed to discover a wider number of taxa ments occurring within micro-eukaryotic never detected until then in the large lakes south of communities are studied from both “modern” and the Alps. Nevertheless, while HTS approaches enable “ancient” DNA. Retro-observation (analysis of sedi- increasing the knowledge of protists diversity, their ment archives) provides an opportunity to place use in the evaluation of target groups is not free of recent changes in a broader temporal context and difficulties due, among the others, to the short length better decipher the relative importance of environ- of 18S rDNA sequences obtained with present tech- mental drivers affecting planktonic communities. The nologies. Further, the presence of varying copy num- potential and challenges associated with the study of ber of 18S rDNA still represents a source of eDNA to address critical research questions in lacus- uncertainty in assessing community structure and trine ecology are discussed. seasonal dynamics in protists.

9OR.1 9OR.2 UNVEILING THE HIDDEN DIVERSITY OF SURVEY OF PHYTOPLANKTONIC PHOTOSYNTHETIC AND MIXOTROPHIC ALLELOPATHIC INTERACTIONS PROTISTS IN A LARGE AND DEEP SUBALPINE 1 LAKE USING A HIGH THROUGHPUT Lydia A. Papanikolopoulou (lydia.papanikolopou- SEQUENCING APPROACH [email protected]), Remington X. Poulin1 (rxpou- 1 Nico Salmaso ([email protected]), Adriano [email protected]), Franziska Speck (franziska. [email protected]), Colomban de Vargas2 (var- Boscaini ([email protected]) and Massimo 2 Pindo ([email protected]) [email protected]), Ian Probert (probert@sb-roscoff. fr) and Georg Pohnert1 ([email protected]) Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38010, San Michele all’Adige, Italy 1Institute of Inorganic and Analytical Chemistry, Faculty of Chemistry and Earth Sciences, Friedrich Schiller University Jena, Lessingstrasse 8, 07743, Jena, Germany and 2Station The structure and abundance of aquatic microbial Biologique de Roscoff, CNRS, Sorbonne Université, Place communities, microalgae, protozoans and fungi con- Georges Teissier 29680, Roscoff, France tribute to characterize trophic webs and productivity. Nevertheless, in freshwater environments, the major- The plethora of coexisting phytoplankton species uti- ity of the investigations were historically addressed lizing the same finite number of nutrients in the same towards the study of microalgae, either pelagic (“phy- ecological niche contradicts the competitive exclusion toplankton”) or periphytic. These two broad func- principle which states that the number of coexisting tional groups are composed of a wide variety of species cannot exceed the number of the limiting photosynthetic and mixotrophic organisms that resources (Gause, 1932). This violation of the princi- show specific adaptations to different lake typologies ple, known as the “paradox of the plankton” and trophic status. Traditionally, in addition to the (Hutchinson 1961) has been studied extensively. protist fraction, microalgae also include photosyn- However, our knowledge of the mechanisms respon- thetic cyanobacteria. Based on high throughput sible for this paradox and to what extent each of them sequencing approaches (HTS) (16S rDNA), previous contribute to that is still limited. Amongst the many studies carried out in Lake Garda and in the other hypothesized mechanisms, phytoplankton’s biochem- large lakes south of the Alps allowed identifying ical interactions, have been examined only scarcely a higher number of cyanobacterial taxa compared to and few relevant chemicals have been identified. those previously characterized by light microscopy. In Those interactions, that can be either beneficial of this contribution, we will characterize and critically inhibitory, are known as allelopathy. Hitherto, in discuss the composition, alpha diversity, and seasonal phytoplankton allelopathy studies, attention has dynamics of planktic photosynthetic and mixotrophic been paid to toxic species and usually, the studies protists through a two-year study carried out in Lake are restricted to a few highly studied systems. In Garda using HTS analyses (18S rDNA). The planktic order to determine at what extent biochemical inter- community showed a higher diversity during late actions affect phytoplankton communities, we estab- spring and summer, caused by a greater development lished a systematic and representative survey of of many algal groups (mostly Ochrophyta, allelopathic interactions involving 18 species from Chlorophyceae, Dinophyceae). The main pattern of 14 different taxonomic groups, including both toxic seasonal change was comparable to that obtained and non-toxic species. With these 59 co-culture 76 KEYNOTE AND ORAL PAPERS combinations, we aimed to determine the prevalence usually performed on short barcodes due to technical of and magnitude of allelopathy in natural phyto- issues. We then matched the short barcodes of the plankton assemblages. Allelopathy accounted for the different taxa(-groups) to three sets of environmental majority of all observations amongst surveyed phyto- samples with available ecological data: from France, plankton. This surprising finding suggests that phy- the Disunited Kingdom, and Sweden. This was done toplankton utilizes exuded chemistry to a greater by 1) processing all runs with the bioinformatics degree than previously hypothesized and that phyto- pipeline DADA2, 2) merging all the amplicon plankton likely have the ability to influence commu- sequence variants (ASVs) tables, 3) extracting the nity structure significantly by tailoring their chemical Fragilaria sequences, and finally 4) linking them to environment. We also found that some species exhi- the environmental data. We assume that the better bit global patterns of resistance or susceptibility to taxonomic discrimination obtained using DNA meta- multiple competitor species surveyed or patterns of barcoding translates into better ecological under- negative interference or stimulation towards compe- standing, or at least clearly shows the limits of using titor growth. This survey supports that allelopathy barcoding for environmental analysis and assessment. could be an important driver of phytoplankton spe- cies’ diversity in the open ocean. 9OR.4 ON THE SHOULDERS OF GIANTS: WHAT 9OR.3 EPIZOIC DIATOMS ARE TEACHING US CONNECTING THE MOLECULAR SPECIES ABOUT DIATOM EVOLUTION FRAGILARIA CONCEPT OF THE GENUS Matt P Ashworth1 ([email protected]), Thomas (BACILLARIOPHYTA) TO ECOLOGY A Frankovich2 ([email protected]), Michael Maria Kahlert1 ([email protected]), Martyn J. Sullivan3 ([email protected]), Roksana G. Kelly2,3 ([email protected]), Majewska4,5 ([email protected]), Sunčica Bosak6 David G. Mann ([email protected])4; Frédéric ([email protected]), Bart Van de Vijver7,8 Rimet5 ([email protected]); Shinya Sato6 (ssa- ([email protected]), Mike [email protected]); Agnès Bouchez5 (agnes.bouchez@inra. Arendt9 ([email protected]), Jeff Schwenter9 fr); Bonnie Bailet1 ([email protected]); Stephen ([email protected]), Nicole I Stacy1°(stacy- Juggins7 ([email protected]); Francois [email protected]) and Schonna R Manning1 (schonna.man- Keck5 ([email protected]) and Valentin [email protected]) Vasselon5 ([email protected]) 1UTEX Culture Collection of Algae, Department of Molecular 1Swedish University of Agricultural Sciences, Department of Biosciences, University of Texas, Austin, Austin, Texas, USA; 2Florida Bay Interagency Science Center, Florida International Aquatic Sciences and Assessment, PO Box 7050, SE-750 07 3 2 University, Key Largo, Florida, USA; Madison, Mississippi, Uppsala, Sweden; Bowburn Consultancy, Bowburn, Durham 4 3 USA; School of Biological Sciences, North-West University, DH6 5QB, UK; Department of Geography, University of 5 4 Potchefstroom, South Africa; South African Institute for Nottingham, Nottingham NG7 2RD, UK; Royal Botanic 6 Garden Edinburgh, Edinburgh EH3 5LR, Scotland, UK, and Aquatic Biodiversity (SAIAB), Grahamstown, South Africa; Department of Biology, University of Zagreb, Zagreb, Croatia; IRTA, Sant Carles de La Ràpita, Catalonia, E-43540, Spain; 7 5 Botanic Garden Meise, Research Department, B-2610 Meise, INRA, UMR CARRTEL, 75bis avenue de Corzent, F-74200 8 Thonon-les-Bains, France; 6Fukui Prefectural University, Belgium; Department of Biology, University of Antwerp, Wilrijk, Belgium; 9Department of Natural Resources, South Department of Marine Science and Technology, 917-0003 1 Fukui, Japan and 7School of Geography, Politics and Carolina, USA and °Large Animal Clinical Sciences, Sociology, University of Newcastle, Newcastle upon Tyne, NE1 University of Florida, Gainesville, Florida, USA 7RU, UK Our knowledge and understanding of diatom diver- After a recent examination of diversity within the sity, diversification and evolution increase with every genus Fragilaria (Bacillariophyta), connecting mor- collection made from benthic marine habitats. In phological and molecular data to produce harmo- recent years, one such habitat has been the body nized species concepts for part of the genus (Kahlert surfaces of sea turtles and manatees. This habitat et al., in press), we now need to revisit the ecological has yielded many new data, particularly on taxa his- preferences of the curated taxa, including three new torically associated with the Rhoicospheniaceae, For described species, to be able to use this knowledge for example, we have found both photosynthetic and research and environmental assessment. We first non-photosynthetic species of the genus Tursiocola tested whether the Fragilaria taxa in the curated and Holmes, Nagasawa & Takano. This is the first updated open-access barcoding library Diat.barcode reported non-photosynthetic diatom which does not (Rimet et al. 2016, 2018a) can be separated by a short appear to be associated with the order Bacillariales. part (312bp) of the rbcL gene at all, because routine The morphology of Tursiocola suggests no affinity to DNA metabarcoding of environmental samples is the Bacillariales, and DNA evidence, collected by EUROPEAN JOURNAL OF PHYCOLOGY 77 single-cell DNA amplification techniques, confirmed genomics, -transcriptomics, -metabolomics) over sev- that the loss of photosynthesis in Tursiocola was eral time scales, validated with in-vitro and in-silico novel and unrelated to losses in the Bacillariales. investigations and processed by advanced computa- The DNA sequence data also question the placement tional approaches, such as niche and network model- of Tursiocola and the epizoic diatoms Poulinea ling, as well as artificial intelligence algorithms. Being Majewska et al. and Chelonicola Majewska et al.in aware that the integration of all the approaches above the Rhoicospheniaceae, suggesting that these genera it is still in its infancy, we set up, based on this vision, are quite distant genetically from other marine “gom- a pilot-project for the NEREA Augmented Marine phonemoid” (transapically asymmetrical) raphid dia- Observatory in the Gulf of Naples (Italy), toms. We are also exploring the potential of the a multidisciplinary effort started on the Darwin Day epizoic habitat as a model system for benthic diatom 2019 (12th February), in synergy with the Long Term diversification. Thus far, the ease and ubiquity of Ecological Research MareChiara, and in the frame- obtaining cultures of the monoraphid diatom genus work of the international program BioGeoSCAPES. Achnanthes Bory from manatees and multiple sea Periodic, question-driven process studies within turtle species in the southeastern US suggest that NEREA will reveal present limitations in our strate- this genus may be an ideal model to study not only gies to study plankton and will eventually lead to the diversification of diatoms in the epizoic habit but a new understanding of aquatic communities and to also across hosts. the provision of knowledge-based directions to stakeholders.

9OR.5 9OR.6 EXPLOITING OMICS POTENTIAL TO FACE SARPA SALPA THE COMPLEXITY OF PLANKTON LEARNING TAKES TIME. ´S COMMUNITIES: FROM PRESENT CHALLENGES PREFERENTIAL FEEDING ON THE INVASIVE CAULERPA CYLINDRACEA AND LIMITATIONS TO AN INTEGRATIVE ALGA SHIFTS PIPELINE THROUGHOUT THE INVASION PROCESS Domenico D’Alelio1 ([email protected]), Jorge Santamaría ([email protected]), Raül Damien Eveillard2 (damien.eveillard@univ-nantes. Golo ([email protected]), Jana Verdura (jana. fr), Victoria J. Coles3 ([email protected]), Luigi [email protected]) and Emma Cebrian (emma.cebria- Caputi1 ([email protected]), Maurizio Ribera d’Alcalà1 [email protected]) ([email protected]), Daniele Iudicone1 (daniele. GRMAR, Institute of Aquatic Ecology, University of Girona, [email protected]) and the NEREA Augmented Marine Campus Montilivi, Faculty of Sciences, E-17003 Girona, Observatory1 ([email protected]) Catalonia, Spain

1Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 The green alga Caulerpa cylindracea is one of the 2 Napoli, Italy; LS2N UMR 6004 CNRS, Université de Nantes, most invasive algae species in the Mediterranean France and 3University of Maryland Center for Environmental Science, Horn Point Laboratory, PO Box 775 Cambridge, MD Sea. However, a recent study has highlighted the 21613, USA role of the native fish Sarpa salpa as a possible control mechanism of this alga in well-preserved systems, Plankton drive global biogeochemical cycles and give limiting its abundance mainly at intermediate depths the primary boost to aquatic food webs. The huge (between 5 and 25 m). In fact, this mechanism might biological complexity characterizing this community be responsible for the local regressions observed in makes the development of well-resolved, and ecolo- many populations some years after Caulerpa´s intro- gically robust models, particularly challenging. In this duction. In this study, we tested whether the prefer- respect, systems ecology and evolutionary investiga- ence of S. salpa towards C. cylindracea changes i) tions focused on plankton might strongly profit from throughout the invasion process, which might explain omics-based biological analyses, which would add the observed delay on the grazing effect (Caulerpa another dimension to traditional modeling. regressions happening some years after the invasion); Plankton span over several order of magnitude in or ii) throughout Caulerpa abundances (whether size and include all kingdoms of life, including micro- Salpa only feeds on Caulerpa when this alga is algae. Approaching their complexity requires a major component of the community). Feeding a deeper and adaptive integration between data- experiments were performed in places with high acquisition and data-analysis, covering traditional and low abundances of Caulerpa, both in areas that observations (i.e., physical, chemical and biological) have been invaded long time ago (well-established and information from omics (meta-barcoding, - invasion) and in places where C. cylindracea is 78 KEYNOTE AND ORAL PAPERS a recent component of the benthic community (initial to get used to C. cylindracea before feeding on it, invasion). Our results show that in places where which might explain why Caulerpa population C. cylindracea is ancient, S. salpa prefers the invasive regressions always happen with some delay. alga to the native ones, even when Caulerpa abun- Furthermore, it seems that once S. salpa is used to dances are low; however, in areas where the invasion C. cylindracea, the preference for this alga is main- is recent, S. salpa does not show any preference tained even when its abundance is low, which means towards C. cylindracea, even when it is very abun- that the control mechanism is maintained through dant. This study shows that S. salpa needs some time time. EUROPEAN JOURNAL OF PHYCOLOGY 79

10. Microbial friends and enemies of algae

10KN.1 competition between planktonic species but also their control by parasites. COEXISTENCE OF GENERALIST AND SPECIALIST PARASITES IN THE PLANKTON: INTERPLAY BETWEEN DIFFERENT INFECTIVE STRATEGIES AND ENVIRONMENTAL 10KN.2 CONSTRAINTS BACTERIAL EFFECTS ON ALGAL LIFE, DEATH, Catharina Alves-de-Souza ([email protected]) AND GEOLOGY Einat Segev ([email protected]) Algal Resources Collection, MARBIONC, Center for Marine Sciences, University of North Carolina Wilmington, 5600 Weizmann Institute of Science, Department of Plant and Marvin Moss K. Lane, Wilmington, NC 28409, USA Environmental Sciences, Rehovot 7610001 Israel

The astonishing diversity of parasites in marine Micro-algae greatly influence present and past plankton assemblages detected in the last decades oceans. Recently we have come to realize that bacteria has greatly increased interest in the ecological roles interact with micro-algae in various ways, ranging played by these organisms. Analysis of metabarcod- from pathogenicity to mutualism. My research inves- ing data obtained at a global geographic scale tigates physical and chemical interactions between revealed that parasites figure among the most abun- micro-algae and bacteria across multiple scales; dant organisms and a high incidence of parasitic links from the chemical crosstalk to the influence these appear in interaction networks. A single plankton interactions have on the marine environment. In my assemblage can contain multiple active parasites talk, I will introduce Emiliania huxleyi, the most infecting the same hosts. Understanding how these prevalent micro-alga in modern oceans. I will discuss parasitic species coexist is key to explaining their high the role of bacteria as hidden farmers that control the diversity and quantifying the relevance of parasitic life cycle of algae; determining how fast algae will ’ interactions to the control of hosts populations and grow and how fast they will die. I will link laboratory the flow of matter and energy through plankton food findings to work conducted at sea and demonstrate webs. Here, I present results from combined experi- the importance of these findings in the study of mental and modeling approaches assessing how dif- climate reconstructions. ferences in intrinsic characteristics exhibited by sympatric generalist and specialist parasites can account for their co-existence. Infection parameters, 10OR.1 generation times, and host ranges were compared over different temperatures to understand the effect MULTI-LAYERED AND CONSERVED DEFENCE of environmental constraints. Results indicate that MECHANISMS OF PHAEOPHYCEAE AGAINST specialist parasites compensate for the competitive PHYLOGENETICALLY UNRELATED disadvantage imposed by the dependence upon PATHOGENS a sole host species by showing infective strategies Pedro Murúa1,2 ([email protected]), that allow them to explore more efficiently the host Dieter G. Müller3 (dieter.gerhard.mueller@uni- population when compared to generalists (e.g., konstanz.de), Yacine Badis2 ([email protected]. shorter generation, more resistant infective stages). 1 Specialists also showed higher tolerance to extreme uk), Pieter van West ([email protected]) and 2 temperatures, allowing them to explore marginal con- Claire M. M. Gachon ([email protected]) ditions of their realized environmental niches, con- 1Aberdeen Oomycete Laboratory, International Centre for ferring an additional compensatory advantage. Aquaculture Research and Development, University of Interestingly, the infectivity of generalist parasites Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, United 2 responded to temperature depended on the host. Kingdom; The Scottish Association for Marine Science, Scottish Marine Institute, Culture Collection for Algae and These results are particularly relevant under the cur- Protozoa, Oban, Argyll, PA37 1QA, Scotland, United rent scenario of climate change, with shifts in tem- Kingdom and 3Fachbereich Biologie der Universität Konstanz, perature conditions potentially affecting not only the D-78457 Konstanz, Germany 80 KEYNOTE AND ORAL PAPERS

Anisolpidium ectocarpii (Oomycota) and Maullinia Avanzadas (CICA), Universidade da Coruña, 15071 A Coruña, 3 ectocarpii (Phytomyxea) are two pathogens that can Galicia, Spain and Institute for Inorganic and Analytical Chemistry, Jena School for Microbial Communication, parasite several different orders of brown algae. In Friedrich Schiller University Jena, Lessingstr. 8, 07743 Jena, this study, the phenotypic changes of 43 different Germany brown algal strains from different Phaeophycean clades were characterized against both parasites Ulva spp. cultures are being used in Integrated using different microscopy techniques. We found Multitrophic Aquaculture as biofiltration systems in that the host ranges of A. ectocarpii (Asterocladales, fish farms, both in open and recirculating systems Desmarestiales, Ectocarpales, Laminariales, (IMTA-RAS). The laminar thallus of Ulva spp. provides Sporochnales, Scytothamnales and Tilopteridales) a niche for biofilm-forming bacteria, including those and M. ectocarpii (Desmarestiales, Ectocarpales, from the Phaeobacter genus that can reduce growth Laminariales, Scytothamnales) are even broader than and kill fish pathogens, such as Vibrio anguillarum,by previously reported, and encompass one additional producing tropodithietic acid. The possibility of experi- order (Syringodermatales) for A. ectocarpii and four mental colonization of Ulva spp. with Phaeobacter additional orders for M. ectocarpii (Asterocladales, strains – previously isolated from Ulva species – has Syringodermatales, Sporochnales and Tilopteridales). been proposed to control harmful bacteria in fish-algae Additionally, we report four defense hallmarks that IMTA-RAS. This would not only improve fish health are conserved in Phaeophyceae and strongly relate but may also decrease algae fouling by detrimental with resistance: i) cell wall reinforcements, namely bacteria, enhancing algae production. The experimental local papilla formation beneath the infection site, colonization of U. ohnoi with P. gallaeciensis was sometimes accompanied of systemic cell wall thicken- demonstrated and small-scale trials showed a probiotic ing across the entire challenged thallus; ii) cell death effect of P. gallaeciensis-colonised Ulva,decreasingthe particularly in challenged host cells, which after TEM mortality of V. anguillarum-infected turbot larvae. evidence of swollen mitochondria, nuclear lysis and However, the environmental conditions for Ulva culture plasmodesmata obstruction suggest its relation to (e.g. agitation and high light intensity) could have a hypersensitive response; iii) phlorotannin metabo- a determinant influence on the maintenance of the lism upregulation, which may suggest a defensive role Phaeobacter biofilms. Small-scale cultures under differ- as much important as against grazers and iv) ent light intensities demonstrated a negative influence Inducibility of pathogen autophagy, where pathogens of light on the maintenance of P. gallaeciensis biofilms turn systematically autophagic in a suicidal manner, on U. ohnoi. This fact was not observed when and would correspond as a last line of defense. P. gallaeciensis biofilms were formed on a glass surface Additionally, most of the investigated brown algal submitted to the same light regimes, indicating that species show v) a strong hydrogen peroxide produc- light influences the algae physiology inducing chemical tion after being co-incubated with both pathogens, changes that affect P. gallaeciensis maintenance. Exo- confirming an oxidative stress pathway participation Metabolomic profiling was performed by disruption- in these algal-pathogen interactions. From our study, free solid phase extraction of surface metabolites and we conclude that these responses are widely con- UHPLC-HR-ESI-MS analysis. Significant different fea- served across Phaeophyceae, and altogether account tures (m/z) were obtained from the 24 samples ana- to algal defenses. However, we observed that in sev- lyzed. Principal component analysis (PCA) showed eral strains these responses were not strong, yet they a different behaviour of the two treatments (Presence were still resistant, suggesting that more undescribed of Phaeobacter or non-presence) based on the light mechanisms are contributing to the overall immunity intensity. High light intensity promoted a clear group- in brown algae. ing of Phaeobacter-present samples that was not observed under low illumination. This fact indicates a potential effect of light on bacteria-mediated or bac- 10OR.2 teria-induced changes of the compound constituents on THE EFFECT OF LIGHT ON PHAEOBACTER Ulva´s surface. GALLAECIENSIS BIOFILMS ON ULVA OHNOI (ULVALES, CHLOROPHYTA) 10OR.3 José Pintado1 ([email protected]), Patricia Ruiz1 DETECTION AND CHARACTERIZATION OF ([email protected]), Javier Cremades2 (javier. MIXOTROPHY IN COCCOLITHOPHORES [email protected]) and Thomas Wichard3 (thomas. 1,2 [email protected]) Yoav Avrahami ([email protected]) and Miguel J. Frada1,2 ([email protected]) 1Instituto de Investigaciones Marinas (IIM-CSIC), Eduardo Cabello 6, 36208 Vigo, Galicia, Spain); 2Coastal Biology 1The Interuniversity Institute for Marine Sciences of Eilat, Israel Research Group (BioCost), Centro deInvestigacións Científicas and 2Department of Ecology, Evolution and Behavior - EUROPEAN JOURNAL OF PHYCOLOGY 81

Alexander Silberman Institute of Life Sciences, Hebrew Dressler-Allame1 ([email protected])1, University of Jerusalem, Edmond J. Safra Campus at Givat Raffaele Siano3 ([email protected]), Eileen Ram, Jerusalem 91904, Israel Bresnan4 ([email protected]) and 1 The current view of the marine microbial food web Claire M.M. Gachon ([email protected]) assumes a dichotomy between autotrophs represented 1The Scottish Association for Marine Science, Scottish Marine by phytoplankton that drive about 45% of the global Institute, PA37 1QA, Oban, UK;2 IFREMER, ODE/UL/LER/BO, primary productivity and heterotrophic microzoo- Station de Biologie Marine de Concarneau, Quai de la Croix, plankton that consume phytoplankton. However, 29900, Concarneau, France, 3 IFREMER – Centre de Brest, DYNECO PELAGOS, 1625 Route de Sainte-Anne, 29280, growing evidence indicates that an important fraction 4 Plouzané, France and Marine Scotland Science, Marine of phytoplankton are mixotrophic combining both the Laboratory, 375 Victoria Road, AB11 9DB, Aberdeen, UK ability of perform photosynthesis but also to ingest by phagotrophy living prey. The functional role of marine Photoautotrophs underpin most food webs and para- phytoplankton is therefore more complex than pre- sites affecting them have potential cascading effects at viously thought. Coccolithophores (henceforth every level in the ecosystem. In aquatic environments, cocco), a group of important calcifying, unicellular diatoms are one of the dominant groups of photo- algae belonging to the phylum Haptophyta, represent trophs and are known to be infected by oomycetes an important component of marine phytoplankton. traditionally assigned to the genus Ectrogella. Yet the Early evidence indicates that they may be able to act assessment of the genetic diversity, evolutionary rela- mixotrophically and ingest bacterial prey. In this study, tionships and ecological importance of this oomycete we quantitatively assessed cocco mixotrophy. Three genus has been seriously hindered by the limited cocco species and the respectively different life cycle amount of molecular information available. Here we phases were examined, Calyptrosphaera sp. (haploid), present results from the application of single-cell (SC) Emiliania huxleyi (both haploid and diploid life forms) molecular analyses on marine oomycete parasites of and Calcidiscus leptoporus (both haploid and diploid diatoms isolated from field material. SC-PCRs, SC- life forms), all representing important members of the whole genome sequencing and in silico analyses have cocco group. Cells were grown under nutrient-replete been used to retrieve marker genes and subsequently (k/5 medium) and phosphate depletes (k/5-P medium) investigate the phylogeny, distribution and parasitic media, in the presence of fluorescently labeled bacteria dynamics of these organisms. Our findings suggest (FLB) used as prey item at the ratio of 1:20. Cells and that parasitic oomycetes infecting diatoms are wide- FLB were monitored by flow cytometry and light spread in the global ocean and highlight local swift microscopy at time points 0, 1h, 2h, 4h, 24hr and parasitic dynamics, likely to be one of the causes of 48hr. Our results showed the active ingestion of FLB the underappreciation of their presence by molecular by Calyptrophaera sp. and C. leptoporus haploid life ecology methods. Furthermore, metabarcoding data phase, in both mediums. In contrast, E. huxleyi (both analysis and SC approaches alike, suggested a broad life forms) and the diploid phase of C. leptoporus did host range within diatoms, even for closely related not ingest FLB. These results suggest the existence of parasite species. Finally, by strengthening the link wide variability in mixotrophic abilities across cocco between morphological and molecular data, SC taxa and a higher prevalence in haploid cells. We plan approaches granted the possibility to reassess the to expand our survey to natural populations in order classical taxonomy of Ectrogella. Our results highlight to unveil the prevalence of cocco mixotrophy at sea. a high genetic diversity underlying the rather homo- geneous thallus morphology observed, demonstrating the polyphyly of Ectrogella, and demand for the reas- 10OR.4 sessment of its taxonomic treatment and for the clar- ification of its relationships with the genera of marine SINGLE-CELL MOLECULAR ANALYSES oomycetes Anisolpidium and Olpidiopsis. DEMONSTRATE THE POLYPHYLY OF THE GENUS ECTROGELLA AND SHED LIGHT ON 10OR.5 THE DISTRIBUTION AND ECOLOGY OF OOMYCETE PARASITES OF MARINE DIATOMS HOW BACTERIA CAN DRIVE HAPTOPHYTES Andrea Garvetto1 ([email protected])1, THROUGH VITAMIN B12 METABOLISM Yacine Badis1 ([email protected]), Elisabeth Charlotte Nef1 ([email protected]), Francis Nézan2 ([email protected]), Gwenael Mairet1 ([email protected]), Céline Henry2 Bilien2 ([email protected]), Paola Arce1 ([email protected]), Raymond Kaas1 (raymond. ([email protected]), Marie-Mathilde Perrineau1 [email protected]), and Matthieu Garnier1 (matthieu. ([email protected]), Melina [email protected]) 82 KEYNOTE AND ORAL PAPERS

1IFREMER, Physiology and Biotechnology of Algae Laboratory, and on the influences of these interactions on the ‘ ’ 2 rue de l Ile d Yeu, 44311, Nantes, France and Micalis Institute, metabolism of haptophytes. PAPPSO, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France 10OR.6 Recent results (Nef et al, 2019) suggest that all hapto- phytes lineages including species of great ecological WHY THE RED ALGAL HOST PYROPIA YEZOENSIS importance are auxotrophic for vitamin B12.B12 is RESPOND DIFFERENTIALLY TO produced only by some prokaryotes acting as THREE OLPIDIOPSIS SPECIES? a transmission belt between bacteria and microalgae Je Jin Jeon ([email protected]) and Gwang Hoon metabolisms, and driving growth of haptophytes. Kim ([email protected]) Whereas synthesis of B12 is well described, very few information are available on how much B12 are pro- Department of Biology Graduate School of Kongju National duced by marine bacteria, in what way it becomes University, Gongju-si singwandong 182, Gongju-si, Korea available to microalgae, and how a B12 limitation impacts the metabolism of haptophytes. In this con- Olpidiopsis blight caused by Oomycete pathogens is one of the most serious threats for Pyropia farming in East text, we first studied the B12 production in 16 marine halomonas and phaeobacter strains. High variability Asia. Four closely related Olpidiopsis species which was recorded between strains and comparative geno- infect Pyropia blade have been identified so far; mic analysis was used to highlight potential molecular O. porphyrae in Japan, O. pyropiae and O. porphyrae var. koreanae in Korea, and O. porphyrae var. scotiae in mechanisms. How the bacterial B12 becomes available for microalgae is now under study (excretion or lysis). Scotland. We compared infection pattern of three Olpidiopsis species which showed different infectivity We then studied the impact of a B12 limitation on the metabolism of the model haptophyte Tisochrysis lutea. towards Korea Pyropia yezoensis. O. pyropiae showed Axenic continuous cultures in chemostat were used the strongest infectivity from the initial stage of infec- and a full analysis of cellular carbon allocation was tion and spread to the whole blade much faster than the other two. Apoptosis of host cell was inversely related to done. Deep comparative proteomics showed that B12 limitation, compared to other nutrient limitation the infectivity of infection. The apoptosis was most (nitrogen), involves a down accumulation of some prominent in the host infected with var. scotieae, enzymes of the central carbon metabolism that induces which showed the weakest infectivity. The color of a metabolic orientation of carbon from carbohydrates infected host cell changed differently when it was towards lipids. Based on our experimental results on infected by O. pyropiae (yellow), O. porphyreae (green) and var. scotiae (green) suggesting that the chloroplasts the minimal B12 quota in T. lutea and B12 production in the most productive bacteria, approximately one respond differently to each pathogen. The infection of bacteria per algal cell is required to sustain microalgae Olpidiopsis pathogen was mediated by the lipid-raft of the host cell membrane. When the PI3K inhibitor, growth, with the hypothesis that bacterial B12 is fully available for algae. On the other hand, the carbon LY294002, and Wortmannin, was treated prior to infec- tion the infection rate decreased in all pathogens. These excreted by T. lutea under B12 limitation would be enough to sustain such bacterial load. These results results suggest that three species of Olpidiopsis infect the give new insight into how the interaction between host cell using similar lipid-raft mediated process, but the apoptosis of the host cell after the initial infection haptophytes and B12 producing bacteria can be shaped affects the spread of disease in the infected blade. EUROPEAN JOURNAL OF PHYCOLOGY 83

11. Biotechnological applications of algae: algae as a source of food, drugs, energy

2018-2020), we have developed various biofilm culti- 11KN.1 vation strategies in response to light, salinity, carbon RECENT ADVANCES IN MICROALGAL sources, shape configuration, rotating speed and har- BIOTECHNOLOGY WITH AN EMPHASIS ON vesting frequency using rotating algal biofilm (RAB) BIOFILM CULTIVATION systems. The RAB systems in use have been run 1,2 during a full year keeping contamination to a very Freddy Guihéneuf ([email protected]), 2 Margaux Caïa2 ([email protected]), Antoine low level, achieving ground productivity of 18 g/m / day when the biomass was collected every 10-12 days. Sciandra2 ([email protected]), Olivier Bernard3 ([email protected]) and Hubert Bonnefond1,2 ([email protected]) 11KN.2 1 SAS inalve, 181 chemin du lazaret, 06230 Villefranche/Mer, TRANSITION FROM AQUATIC TO France; 2Sorbonne Universités, Laboratoire d’Océanographie de Villefranche, CNRS, UMR 7093, 06230 Villefranche/Mer, TERRESTRIAL SYSTEMS: A PARADIGM France and 3Université Côte d’Azur, Inria, BIOCORE, BP 93, CHANGE IN ALGAE BIOTECHNOLOGY? 06902 Sophia Antipolis Cedex, France Michael Lakatos1 ([email protected]), Peter 1 1 Microalgae are at the center of a very dynamic activ- Groß ([email protected]), Daniel Zabicki 2 ity both in terms of research and industry. Current ([email protected]), Roland Ulber (ulber@mv. 3 production systems are mainly based on suspension uni-kl.de), Michael Wahl (m.wahl@umwelt-campus. culture units using large volumes of water such as in de) and Timo Schmidt4 (timo.schmidt@hs-augsburg. raceway ponds or photobioreactors. The relatively de) low biomass concentration observed within these 1 planktonic-based cultures leads to high water require- Faculty of Polymers, University of Applied Sciences Kaiserslautern, Carl-Schurz-Str. 10-16, D-66953 Pirmasens, ments and expensive harvesting costs, alone covering Germany; 2Bioprocess Engineering, University of for 30% of the energy cost of production. The recent Kaiserslautern, Gottlieb-Daimler-Straße 49, D-67663 3 technological breakthrough of biofilm-based algal Kaiserslautern, Germany; Development and Construction; University of Applied Sciences Trier, post box 13 80, D-55761 cultivation systems offers an alternative that could Birkenfeld, Germany and 4Facade technology and energy effi- solve some of these problems. Indeed, extracellular cient design; University of Applied Sciences Augsburg, An der polymeric substances (EPS) secreted by microalgae Hochschule 1,D- 86161 Augsburg, Germany bind cells and allow them to adhere to solid materials. Biofilms usually consist of autotrophic microalgae In the field of algae biotechnology, pressing chal- associated with other heterotrophic microorganisms lenges are the optimization of algae production, the such as bacteria that play a crucial role in their corresponding process engineering and the scale-up initiation and development. Well-developed microal- of photobioreactors. The main focal points are the gal biofilms may vary from a few to several hundred reduction of fermentation limitations in terms of micrometers and can be harvested by simple scrap- mass transfer (in particular CO2 &O2 gas), thermal ing, thus providing a considerable energy gain of stability, photoinhibition and the efficiency of energy approximately 50% in comparison with suspension- and resource investments. So far, almost all cultiva- based cultivation. The other advantage, which lies in tion technologies are realized under submerged con- better access to light, allows productivities 300% ditions with aquatic microalgae. The biotechnological higher than conventional production systems. In implementation of terrestrial microalgae, however, this context, this presentation will describe recent shows several physiological and procedural advan- advances on microalgal biofilm cultivation systems, tages for efficient production in biofilm- their main uses to date, and their process optimiza- photobioreactors (Lakatos & Strieth 2017, Strieth tion and modeling for better growth performance and et al., 2017). Their outstanding performance and sig- controlled biochemical composition. As part of the nificant benefits for biotechnology may remove some Phyto’Recolt project (GRAINE-ADEME, France, of the current limitations and provide new concepts in biotechnological fermentation. How terrestrial 84 KEYNOTE AND ORAL PAPERS microalgae can contribute to the technological and Copenhagen Plant Science Centre, Section for Plant Molecular economic improvement of microalgae biotechnology Biology, Department for Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 is discussed in terms of biodiversity and physiological Frederiksberg C, Denmark range of new concepts and applications. The focus is on important key processes of emerse photo- Cyanobacteria are versatile photosynthetic microor- fermentation with terrestrial microalgae: thermo- ganisms with great potential as sustainable cell fac- stability, light adaptation and desiccation tolerance. tories. However, there are several major limitations that will have to be overcome to make cyanobacteria a competitive alternative to existing biotechnological 11OR.1 chassis. The Cynthetica project, funded by the CHLAMYDOMONAS CAN BE CONVERTED Horizon 2020 research and innovation programme INTO AN EFFICIENT AND CONTINUOUSLY of the European Union, uses a synthetic biology WORKING GLYCOLATE-PRODUCTION approach to tackle one of the principal limitations MACHINE WITHOUT FORMING BIOMASS in cyanobacteria: low product yields. Our goal is to engineer designated locations and compartments for Anja Taubert ([email protected]), Jakob product synthesis within the cell. To achieve this, we Torsten ([email protected]), Anja Schramm, and are engineering cytoplasmic protein-based structures Christian Wilhelm ([email protected]) serving as a scaffold for enzymes of a biosynthetic pathway. We have expressed a structural scaffold Department of Plant Physiology, Faculty of Life Science University of Leipzig, Johannisallee 23, D-04103 Leipzig, protein in two different cyanobacterial species, the Germany widely used model organism Synechocystis sp. PCC 6803 and a recently described, fast-growing cyano- Glycolate can be synthesized in autotrophic cells bacterium Synechococcus elongatus UTEX 2973. Our under high temperatures and Ci-limitation via oxyge- preliminary results are promising to show intracellu- nation of ribulose-1,5-bisphosphate by photorespira- lar, de novo structures formed in vivo. Here, we will tion. In unicellular algae, photorespiration consumes discuss the implications of this technology for the reductants, ATP and emits CO2 and is, therefore, an next generation of cyanobacterial cell factories. inhibitory process for biomass production. However, if the cells are manipulated in a way that they per- form carboxylation/oxygenation in a ratio of 2, they 11OR.3 become glycolate producing “cell factories”. However, MARINE MACROALGAE AS FUNCTIONAL the efficiency of this pathway is high only when the FOOD TOWARDS GENOME PROTECTION – C2 cycle is blocked, glycolate excretion becomes the FROM AQUACULTURE TO HUMAN HEALTH only pathway of photosynthetic carbon flow. Here we Ana Marques1, 2 ([email protected]), Raquel show that it is possible to run a culture of 1 1 Chlamydomonas under specific cultivation conditions Marçal ([email protected]), Vitória Pereira (vitoria. 1 to establish a constant and long-term stable glycolate [email protected]), Sofia Guilherme (sofia.g.guilher- 2 excretion during the light phase. The results demon- [email protected]), João Ferreira (joaommf93@hotmail. strate a constant high C-assimilation and an extremely com), Ana Cerqueda-Pacheco3 (anaccpacheco@hot- high rate (82%) of assimilated carbon transferred into mail.com), Rui Pereira4 ([email protected]), glycolate biosynthesis without losses of function in Helena Abreu4 ([email protected]), Paula cell vitality for weeks. Moreover, the glycolate accu- Oliveira3 ([email protected]), Isabel Gaivão2 (igai- mulation in the medium is high enough to be directly [email protected]) and Mário Pacheco1 ([email protected]) used for microbial fermentation without any changes in the composition of the medium allowing complete 1Department of Biology & CESAM, University of Aveiro, recycling after glycolate consumption by the fermen- Campus Universitário de Santiago, 3810-193, Aveiro, Portugal; 2Department of Genetics and Biotechnology & tation process. CECAV, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5000-801, Vila Real, Portugal; 3Department of Veterinary Sciences & CITAB, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5000-801, Vila Real, 11OR.2 Portugal and 4ALGAplus, Lda., Travessa Alexandre da PROTEIN SCAFFOLDING FOR Conceição s/n 3830-196, Ílhavo, Portugal NEXT-GENERATION CYANOBACTERIAL CELL Marine macroalgae are considered a source of bioactive FACTORIES compounds, highlighting them as a functional food. Julie A. Z. Zedler ([email protected]) and Poul Their genoprotection ability is raising interest, but Erik Jensen ([email protected]) they are underexplored regarding nutraceutical and EUROPEAN JOURNAL OF PHYCOLOGY 85 biotechnological applications, namely as food or feed 3Necton SA, 8700-152 Olhão, Portugal and 4Faculty of (e.g. aquafeeds) items. Hence, our goals concerned the Biosciences and Aquaculture, Nord University, 8049, Bodø, Norway evaluation of the antigenotoxic potential of Ulva rigida, Fucus vesiculosus and Gracilaria gracilis (i) on fish Since night biomass losses can have a significant (Sparus aurata), through a diet supplementation, and impact upon the productivity of microalgal cultures, (ii) on mice (Mus musculus,FVBnstrain),bothdirectly the introduction of artificial lighting during the night and indirectly (using fish as a vehicle of algae phyto- cycle is considered as a promising solution to enhance components), complemented by basic haematological biomass productivity. Moreover, artificial light is able parameters. For that purpose, two trials were designed. to supply a higher photon flux in shaded areas of The first concerned fish diet supplementation with culture systems, which is a key limiting factor for a mix of the three algae (5%) for 2 months, after algal growth. Our goal was to prevent a bioenergetic which fish were injected with the genotoxicant cyclo- shift of the cells from photosynthesis to a respiration- – −1 phosphamide (CP 20 mg kg b.w.). Four days later, only stage by using LEDs to artificially extend the light blood was collected to perform erythrocytic nuclear period.Tothisend,weusedNannochloropsis oceanica abnormalities (ENA) and erythrocytic maturation cultures grown in 300-L outdoor pilot-scale raceway index (EMI) assays. The second trial concerned mice ponds operated in batch under a controlled circadian diet supplementation with the algae mix (5%) (A), cycle using three conditions: 1) LEDs turned on for 24 muscle of S. aurata (10%) fed with an aquafeed supple- hours; 2) LEDs turned on during the night; 3) Without mented with the same algae mix (FA), or muscle of LEDs (control). Sampling was performed daily, before S. aurata (10%) fed with standard aquafeed (F). After 1 the light period and again at the end of the day to month, mice were injected with the genotoxicant monitor the growth performance and nightly biomass – −1 methyl methanesulfonate (MMS 40 mg kg b.w.). loss due to respiration. Cell fitness (chlorophyll fluor- Two days later, blood was collected, and comet and escence) and biosynthesis of pigments (chlorophyll and micronuclei assays were performed, alongside micro- carotenoids), lipids, proteins, carbohydrates, and fatty hematocrit. Algae supplementation barred the CP- acids were also monitored. Higher growth perfor- induced chromosomal damage and enhanced the ery- mance was observed when cells were LED-lit for 24 thropoiesis rate in fish. Regarding mice, the different hours, followed by cultures LED-lit at night, as com- diets (F, FA and A) prevented MMS-induced genetic pared to control cells (no LEDs). Conversely, control damage (comet assay) while the A diet was the most cells showed the lowest values of non-photochemical effective considering chromosomal damage (micronu- quenching. Daily variations in biochemical composi- clei assay) (A

11OR.4 11OR.5 THE EFFECT OF LED LIGHTING ON NIGHT FRESHWATER MACROALGAE AS BIOMASS LOSSES OF NANNOCHLOROPSIS A SUSTAINABLE RAW MATERIAL FOR THE OCEANICA GROWN IN OUTDOOR PILOT PRODUCTION OF AGROCHEMICALS SCALE RACEWAYS Izabela Michalak ([email protected]) Mariana Carneiro1 ([email protected]), Inês Beatriz Maia2 ([email protected]), Hugo Pereira3 Department of Advanced Material Technologies, Faculty of 2 Chemistry, Wroclaw University of Science and Technology, ([email protected]), Tamára Santos (tfsantos@ualg. Smoluchowskiego 25, 50-372 Wroclaw, Poland pt), Tânia Magina3 ([email protected]), Peter Schulze4 ([email protected]), João Navalho3 Freshwater macroalgae, being the result of eutro- ([email protected]), Francisco Xavier Malcata1 phication of water reservoirs, constitute an unused fmalcatafe.up.pt) and João Varela2 ([email protected]) source of the biomass in many regions around the world. Due to their unique chemical composition 1LEPABE: Laboratory of Process Engineering, Environment, (micro- and macroelements, amino acids, vitamins, – Biotechnology and Energy Department of Chemical polysaccharides, antioxidants etc.) and properties Engineering, Faculty of Engineering of the University of Porto, 4200-465 Porto, Portugal; 2 Centre of Marine Sciences, they can be used as a raw material for the produc- University of Algarve, Gambelas, 8005-139 Faro, Portugal; tion of agrochemicals. In the research, different 86 KEYNOTE AND ORAL PAPERS methods were applied in order to obtain valuable diatoms. It is also responsible for the greening of products from the freshwater alga – Cladophora oysters in refining ponds in Western France, however, glomerata. Biosorption process was used to produce the greening of bivalves or other invertebrates’ gills biological feed additives or components of fertili- occur naturally elsewhere in the world (e.g., USA, zers with microelements. Enriched algae can have Australia). For decades, any record worldwide of beneficial effects on the growth and health para- a blue diatom or green-gill bivalves was assigned to meters of animals and plants. Ultrasound-assisted H. ostrearia. However, recent works on the blue extraction enabled the production of algal extracts Haslea using scanning electron microscopy and mole- that can be used as biostimulants of plant growth cular approaches have enlightened unexpected biodi- that are known to enhance the nutrition efficiency, versity of this taxon, with the description of new tolerance to the biotic and abiotic stress and the species, H. karadagensis collected in the Black Sea, crop yield and quality. Additionally, in the research, H. provincialis in the Mediterranean Sea, and the effect of algal extracts applied individually or in H. nusantara in the Java Sea. Some progress has been the combination with different physical factors made regarding our knowledge about the formation of (e.g., static and alternating magnetic field; near- blue Haslea blooms in natural environments, the pos- infrared radiation) on the germination of seeds sible consequences of the amount of marennine-like (soybean, carrot) was examined. Pyrolysis of fresh- pigments produced and released in seawater, and the water macroalgae resulted in the production of chemical nature of these pigments. NMR spectroscopy biochar which when applied to the soil can influ- has revealed that the scaffold of marennine is a complex ence its properties, increase plant productivity and polysaccharide, probably with an aromatic aglycon as has a positive impact on the environment. These chromophore. The composition of the carbohydrate studies indicate the importance of algae for agricul- has been determined quantitatively after hydrolysis. ture and the multitude of applications for this biomass. 11OR.7 SCREENING OF ANTIOXIDANT AND 11OR.6 ANTI-INFLAMMATORY ACTIVITY OF CYSTOSEIRA AMENTACEA STRICTA HASLEA OSTREARIA-LIKE DIATOMS OR ‘LA VAR. VIE EN BLEU’ EXTRACTS Jean-Luc Mouget1 ([email protected]), Gina De La Fuente ([email protected]), Nellie Francezon1,2 ([email protected]), Valentina Asnaghi ([email protected]), Lila Zebiri3 ([email protected]), Jens Mariachiara Chiantore (mariachiara.chiantore@u- Dittmer2 ([email protected]), Boris nige.it), Marina Pozzolini (marina.pozzolini@unige. Jacquette2 ([email protected]) and it) and Sonia Scarfì ([email protected]) 2 Pamela Pasetto ([email protected]) DiSTAV – Dipartimento di Scienze della Terra, dell’Ambiente e della Vita, Università degli Studi di Genova, Corso Europa 26, 1MMS (Mer-Molécules-Santé), Le Mans Université, Ave 16132 Genova, Italy O. Messiaen, 72085 Le Mans, France; 2IMMM, Le Mans Université, Ave O. Messiaen, 72085 Le Mans, France and 3Greenpharma S.A.S., 3, allée du Titane 45072 Orléans Cedex Marine macroalgae represent a valuable resource in 2, Orléans, France pharmaceuticals, cosmetics and food industry. Brown macroalgae are rich in phenolic compounds that The genus Haslea is a taxonomic unit of marine pen- exert several promising bioactivities, particularly, nate diatoms defined by R. Simonsen in 1974, which phlorotannin compounds are involved in antioxidant refers to fusiform or lanceolate cells, the frustule of and anti-inflammatory processes. In the present which is made of two valves, each presenting two layers study, the in vitro antioxidant and anti- assembled in a typical bi-layered structure. Haslea frus- inflammatory activities of Cystoseira amentacea var. tule valves present characteristically a totally different stricta were evaluated using water/ethanol (CaEt) and aspect when comparing their external and internal dimethyl sulfoxide (CaD) extraction methods. The surfaces. The former presents continuous longitudinal antioxidant capacity was measured by the 2,2-diphe- fissures, the latter is perforated by areolae, square to nyl-1-picrylhydrazyl (DPPH), hydroxyl (OH·) and rectangular openings, forming grate-like bars. The nitrite (NO·) radical scavenging activities, as well as genus Haslea type species is Haslea ostrearia, the Ferric reducing antioxidant power (FRAP) by a tychopelagic/benthic/epiphyte organism that pro- spectrophotometric tests. The antioxidant and anti- duces marennine, a water-soluble blue pigment. inflammatory potential was also evaluated using two Marennine is a bioactive compound with antioxidant, different cell lines: RAW 264.7 murine leukemia cells antimicrobial, and allelopathic effect against other and L929 murine fibroblasts. Additionally, the total EUROPEAN JOURNAL OF PHYCOLOGY 87 phenolic and flavonoid content of both extracts was majority of the TorA-TfAA10A was found unpro- quantified. Both extracts revealed significant antiox- cessed in the plasma membrane with only a small idant activity in all spectrophotometric tests, espe- fraction of the mature protein ultimately translo- cially, for DPPH test and NO· radical with a 100% cated to the periplasm. The native, Sec-targeted, and > 80 % of scavenging activity, respectively. In the TfAA10A was recognized by the cyanobacteria two cell lines tested, the two extracts were able to secretion machinery and virtually all the protein quench completely intracellular ROS production sti- was directed to the culture medium with μ −1 mulated by incubation with 200 MH2O2 for 2 a secretion yield estimated at 779 ± 40 μg L . h. Regarding the anti-inflammatory activity, both Additionally, TfAA10A was shown to be correctly extracts were able to inhibit the production of typical folded and active on the model LPMO substrate pro-inflammatory mediators in RAW 264.7 macro- phosphoric acid swollen cellulose. This proof-of- phage cell line stimulated with 100 ng/ml LPS for concept study constitutes the first demonstration of 24h. qPCR analysis revealed inhibition of 83% of the full secretion of an industrially relevant enzyme Cyclooxygenase-2 gene over-expression and a 73% in S. elongatus UTEX 29731. Cyanobacterial secre- inhibition of Interleukin-1β over-expression caused tion may have applications in whole cell biocatalysis, by CaD extract. In the same cells, stimulated by bioremediation and carbon capture. LPS, over-expression of the NO synthase enzyme was significantly inhibited by > 90% using both 11OR.9 extracts. Finally, the total phenolic and flavonoid content was higher for CaD extract (75.42 and INCREASING BIOMASS AND LIPID 603.93 g/mg extract), which, overall, reported PRODUCTIVITY BY ENGINEERED a slightly higher antioxidant and anti-inflammatory PHAEODACTYLUM TRICORNUTUM capacities. In conclusion, these data demonstrate Seungbeom Seo ([email protected]), Joon Kim a valuable and exploitable pharmacological potential ([email protected]), Kwang Suk Chang of Cystoseira amentacea var. stricta extracts to be ([email protected]) and EonSeon Jin (esjin@- further pursued. hanyang.ac.kr)

Department of Life Science and Research Institute for Natural 11OR.8 Sciences, Hanyang University, Seoul, 04763, Republic of Korea EFFICIENT SECRETION OF A LYTIC POLYSACCHARIDE MONOOXYGENASE IN A Diatom Phaeodactylum tricornutum is one of the best FAST-GROWING CYANOBACTERIUM organism to study bio-resources. Its biomass and lipid are representative bio-resources. Generally, the David A. Russo ([email protected]) and Poul culture conditions for the accumulation of lipids in E. Jensen ([email protected]) the cells inhibits cell growth and biomass, but normal growth conditions for algae do not trigger lipid accu- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, mulation. So we attempted to find the strategy that Denmark could produce both high biomass and lipid simulta- neously. Pyruvate is a precursor of various amino Cyanobacteria have great biotechnological potential acids, fatty acids, and so on. Cells have certain trans- due to their ability to use water as an electron porters which transport pyruvate sodium- donor, CO2 as a carbon source and light as dependently or proton-dependently. Pyruvate trans- a primary energy source to express heterologous porter, especially plastid-localized type, is known to enzymes. In particular, Synechococcus elongatus be involved in lipid synthesis, transporting pyruvate UTEX 2973 is a novel fast-growing cyanobacterium into plastid and providing a precursor for fatty acid that has gained attention as a new biotechnological synthesis. BILE ACID:SODIUM SYMPORTER chassis. To establish this strain as a host for hetero- FAMILY PROTEIN 2 (BASS2) is a plastid-localized logous protein production we demonstrate the pyruvate transporter recently has been identified in expression and secretion of industrially relevant plants. So we searched BASS2 homolog from TfAA10A, a lytic polysaccharide monooxygenase P. tricornutum. Then, we cloned full-length cDNA (LPMO) from the gram-positive bacterium sequences of pyruvate transporter (PtPTP) from Thermobifida fusca. We generated two cyanobacter- P. tricornutum by 5’/3’- RACE (rapid amplification ial transformants expressing the TfAA10A – one of cDNA ends), and sub-cloned into an expression with the native, Sec-targeted, signal peptide vector, pPhat-EF2, which contains an endogenous (TfAA10A) and a second with a heterologous, Tat- constitutive promoter. To determine the localization targeted, signal peptide (TorA-TfAA10A) replacing of PtPTP, transformants expressing pyruvate trans- the native signal peptide. Results showed that the porter tagged with EYFP were generated. 88 KEYNOTE AND ORAL PAPERS

Fluorescence microscopy showed pyruvate transpor- increased salt concentration up to some limit may ter localized to the plastid. Next, we obtained two suppress contamination without substantial growth transformants highly overexpressing pyruvate trans- reduction. porter. To examine the effects of overexpressed PtPTP, we analyzed their growth rate, biomass and lipid contents. As a result, we confirmed that the 11OR.11 transformants not only have shown better growth rates than that of wild type, but also biomass EFFECT OF CULTURE MEDIUM ON THE increased as much as 13% to 22%, lipid contents BIOMASS PRODUCTION AND BIOCHEMICAL increased as much as 11% to 30%. These results COMPOSITION OF SELECTED MALAYSIAN suggest that the overexpressing plastid-localized pyr- THRAUSTOCHYTRIDS uvate transporter increases biomass production and Hui-Yin Yeong1 ([email protected]), Siew-Moi lipid contents. Phang1,2 ([email protected]), Mei-Cing Ou1,2 (mei- [email protected]), Shin-Jing Lim1,2 ([email protected]), Kai-Lai Pang3 (klpang@n- 11OR.10 tou.edu.tw) RAPID SCREENING TEST TO ESTIMATE 1Institute of Ocean and Earth Sciences (IOES), University of MICROALGAE VIABILITY USING Malaya, 50603 Kuala Lumpur, Malaysia; 2Institute of PHOTOSYNTHESIS MEASUREMENTS Biological Sciences, Faculty of Science, University of Malaya, 3 1 50603 Kuala Lumpur, Malaysia and Institute of Marine Gergely E. Lakatos ([email protected]), Karolína Biology, National Taiwan Ocean University, Keelung 20224, Ranglová1,2 ([email protected]), Tomáš Grivalský1 Taiwan ([email protected]), João A. Câmara Manoel1,3 (man- [email protected]) and Jiří Masojídek1 ([email protected]) Thraustochytrids are a diverse group of non- photosynthetic marine protists that are commonly 1Centre Algatech, Laboratory of Algal Biotechnology, Institute found in marine and estuarine habitats including 2 of Microbiology, Třeboň, Czech Republic; Faculty of mangroves. They produce large amounts of lipids, Agriculture, University of South Bohemia, České Budějovice, Czech Republic and 3Faculty of Science, University of South have a fast growth rate and high biomass production. Bohemia, České Budějovice, Czech Republic More recent studies have shown that in addition to being an important feedstock for biofuel production, Microalgae viability is influenced by several environ- thraustochytrids also produce other high-value bio- mental variables, such as temperature, irradiance, products such as omega-3 long-chain polyunsatu- nutrient availability, salt concentration, etc. Various rated fatty acids (PUFAs) particularly microalgae tolerate a different range of these vari- docosahexaenoic acid (DHA) and eicosapentaenoic ables; thus fast pre-screening method is of interest acid (EPA); carotenoids like astaxanthin, squalene, to control pilot or large scale cultivation. Some and sterol, which further contribute to the commer- microalgae grow between 15 and 40 °C (e.g. some cialization value of thraustochytrids. This study Chlorella strains) while the other, namely marine aimed to determine the biomass and lipid productiv- strains require more accurate temperature regulation. ity of Aurantiochytrium UMACC-T023 under differ- We aimed to work out a rapid procedure for fast pre- ent culture media (carbon and nitrogen sources and screening of growth regime based on photosynthesis concentrations). Aurantiochytrium UMACC-T023 measurements. Three techniques were employed to was isolated from the Port Dickson mangrove, west monitor photosynthetic activity: measurement of coast Peninsular Malaysia. The biomass productivity photosynthetic oxygen evolution as well as two chlor- of UMACC-T023 increased from 0.54 ±0.09 to 1.39 ophyll fluorescence techniques – saturating pulse ±0.26 g/L/D and lipid productivity increased from analysis of fluorescence quenching and fast fluores- 19.93 ±9.34 to 31.27 ±2.45 mg/L/D, when the glycerol cence induction kinetics. To verify this procedure concentration was increased from 1% v/v to 8% v/v in several microalgae strains were used, e.g. Chlorella, the medium. The biomass productivity of UMACC- Scenedesmus, Synechocystis, Nostoc etc. Such pre- T023 increased from 0.13 ±0.05 to 0.43 ±0.09 g/L/D screening tests taking about one day make it possible and lipid productivity increased significantly (P< to estimate suitable growth regime (temperature, light 0.05) from 10.91 ±4.93 to 45.47 ±8.17 mg/L/D in demand) of microalgae strains. Then, more precious the polypeptone concentration was increased from growth trials can be carried out to verify strain suit- 0.1% w/v to 2% v/v in the medium. DHA was pro- ability for biomass production. On the other hand, duce in highest abundance. Highest total carotenoid activity-controlled nutrient deprivation may induce content of UMACCT-023 (1.1837 μg/ml) was accumulation of valuable compounds, although over- reported in culture medium contain 2% w/v yeast stressed culture can be lost rapidly. For example, extract, 1% w/v glucose, 0.1% polypeptone, pH7.0 EUROPEAN JOURNAL OF PHYCOLOGY 89 and 30ppt. Aurantiochytrium UMACC-T023 had contaminants. Thus, it is challenging to reproduce potential as a source of biochemical for the neutra- the CO2 mitigation values obtained at smaller scales ceutical and cosmeceutical industry. and prove its feasibility at an industrial scale. To solve this problem, a two-stage scale-up process was devel- oped: heterotrophically Chlorella vulgaris cells grown 11OR.12 in fermenters (1st stage) were used to directly inocu- HETEROTROPHY AS A TOOL TO ENABLE late an outdoor industrial autotrophic microalgal pro- LARGE SCALE MICROALGAE CULTIVATION duction unit with multiple flat panel photobioreactors (2nd stage). Cells were grown het- FOR CO2 MITIGATION erotrophically adapted readily to autotrophic growth 1 Ana I. Barros ([email protected]), Hugo conditions without any measurable difference as 2 1 Pereira ([email protected]), Joana Campos (joana. compared to autotrophic inocula. Biomass concentra- − [email protected]), Pedro Quelhas1 (pedro. tions of 174.5 g L 1 were achieved in a 5-L fermenter [email protected]), Ana Marques1 (ana. during the scale-up process using the novel hetero- [email protected]), João Varela2 (jvare- trophic route. Inocula grew in 0.2- and 5-m3 fermen- 3 [email protected]) and Joana Silva1 (joana.g.silva@allmi- ters were later used to seed several outdoor 100-m croalgae.com) tubular flow-through photobioreactors. The biomass originated from the heterotrophic pathway reached − 1ALLMICROALGAE, Natural Products S.A., Avenida Engº 23.98 ± 1.57 mg g 1 DW of chlorophyll and 52.18 ± – 2 Duarte Pacheco, 19 9º, 1070-100 Lisboa, Portugal and 1.30 % of DW of protein within 5 days of autotrophic CCMAR - Centre of Marine Sciences, University of Algarve, Gambelas, 8005-139 Faro, Portugal growth. These values are in accordance with the reported range for exclusive autotrophic Chlorella Mass culture of microalgae is a promising strategy for vulgaris. In addition to providing reproducible, high- CO2 sequestration. However, its autotrophic scale-up quality inocula, this two-stage approach led to process is slow, requires a large occupancy area, and a 4-fold and 12-fold decrease in scale-up time and depends on weather conditions, being also prone to occupancy area of the facilities used for microalgal culture collapse and to the appearance of unwanted culture scale-up. 90 KEYNOTE AND ORAL PAPERS

12. Planktonic and benthic Harmful Algal Blooms: a threat for human health and resources

12KN.1 several environmental stressors (which, however, are not necessarily the same that stimulate cell prolifera- ROLE OF ENVIRONMENTAL FACTORS ON tion). This fact could represent an additional diffi- DYNAMICS AND TOXIN PRODUCTION OF culty in the management of bHAB phenomena. BENTHIC HARMFUL ALGAL BLOOMS Stefano Accoroni ([email protected]) 12KN.2 Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, CYANOBACTERIAL BLOOMS IN LAKES: Italy ECOLOGY, PREVENTION AND CONTROL Coastal waters are widely exploited by human activ- Petra M. Visser ([email protected]), Tim Piel (t.f. ities and, in tropical regions, are traditionally threa- [email protected]), Erik Weenink ([email protected]), tened by outbreaks of toxic benthic dinoflagellates Giovanni Sandrini ([email protected]), J. Merijn (Gambierdiscus, Ostreopsis, Coolia and Schuurmans ([email protected]), Maria van Prorocentrum). Some species are responsible for Herk ([email protected]), Pieter Slot (P.C. severe illnesses, caused by consumption of contami- [email protected]), Senna Kuijt ([email protected]), Michiel nated seafood or the formation of toxic bio-aerosols. Kraak ([email protected]) and Jef Huisman (j.huis- In the last decades, benthic Harmful Algal Blooms [email protected]) (bHABs) have increased in frequency, intensity and geographic distribution in temperate areas as well, Department of Freshwater and Marine Ecology, Institute for probably due to a combination of natural and Biodiversity and Ecosystem Dynamics, University of human-driven effects, including climate change. Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands Environmental factors, both abiotic and biotic, are known to influence several aspects of bHABs, from In this overview presentation, the ecology and eco- their formation, toxin production and accumulation physiological traits of different cyanobacterial groups to their effects on the environment and human will be discussed. Many cyanobacteria produce toxins health. While in tropical regions benthic dinoflagel- which can harm aquatic animals, but also dogs, cattle lates are common members of microphytobenthos and humans. Cyanobacterial blooms often cause pro- communities throughout the year, in temperate blems in lakes and reservoirs for the use of the water areas their maximum abundances are associated for drinking water and recreation purposes. with the high water temperatures typical of the sum- Prevention of blooms requires that external and mer-autumn period. However, many studies have internal sources of nutrients are managed to levels recently highlighted that other environmental factors where development of cyanobacterial blooms is besides temperature affect growth and toxin produc- restricted. A system analysis of the lake, in particular tion of benthic dinoflagellates, such as hydrody- its morphometry, water and nutrient balance are namics, depth, nutrient concentrations, substrate needed. Preventing toxic cyanobacterial blooms by availability and allelochemical interactions, with dif- reducing internal and external nutrient loads is ferent effects depending on the phases of the bloom. a preferable method in lakes and reservoirs that The availability of both inorganic and organic phos- cope with these blooms, yet it is usually a long-term phorus seems to play a key role in triggering and process. Control of blooms, in which their presence is maintaining blooms of benthic dinoflagellates, parti- reduced to a level where they no longer pose a risk cularly in P-limited areas. Interactions with benthic through additional measures such as biomanipulation diatoms and macroalgae, detected both in laboratory or artificial mixing, demands an understanding of the and field studies, suggest that the production of some key ecological traits of the dominant cyanobacteria allelochemicals, such as Polyunsaturated Aldehydes taxa, and adequate design and execution of the man- (PUAs), could affect bloom dynamics. Toxin produc- agement methods of choice. Cyanocides like hydro- tion is modulated by cellular physiological status, gen peroxide can be used to reduce the cyanobacterial which is affected by a wide range of factors, including biomass since cyanobacteria typically show a higher EUROPEAN JOURNAL OF PHYCOLOGY 91 sensitivity to hydrogen peroxide than other groups of PSU, +13 PSU) under two conditions of temperature aquatic biota and this control agent does not leave (25°C and 18°C the control condition). During the any harmful residuals due to its breakdown into 48-hour experiment, monitoring of photosynthetic oxygen and water. Treatment with H2O2 can be activity, cell density, biovolume, toxins and DMSP a rapid, highly effective and low-cost method to were recorded. The conditions leading to significant combat cyanobacterial blooms, but the duration of variability in DMSP and PSTs will be tested by RNA- the post-treatment period with no or low numbers of seq analysis to identify genes likely involved in DMSP cyanobacteria varies among lakes. The choice of and PSTs biosynthesis in A. minutum and a method for prevention or control of cyanobacterial A. catenella. This study provides an important first blooms for a specific lake is dependent on its lake step towards the understanding of the influence of morphology, water and nutrient balance, dominant two abiotic factors on the DMSP and toxin produc- cyanobacterial species, and economical aspects. tion and gives new insights on the potential contribu- tion of these molecules in a changing ocean.

12OR.1 EFFECT OF SALINITY AND TEMPERATURE 12OR.2 STRESSES ON DMSP AND PSTS CONTENT IN A. MINUTUM AND A. CATENELLA SEASONAL MONITORING OF CYANOBACTERIA AND CYANOTOXINS BY 1 1 Solène Geffroy ([email protected]) , Tanguy FLOW CYTOMETRY AND LIQUID 1 1 Sergent ([email protected]), Fabienne Hervé CHROMATOGRAPHY COUPLED TO TANDEM ([email protected]), Georges-Augustin MASS SPECTROMETRY, IN TWO LOWLAND Rovillon1 ([email protected]), FRESHWATER RESERVOIRS SITUATED IN Laure Guillou2 ([email protected]), Zouher SOUTHERN BRITAIN 1 Amzil ([email protected]) and Amandine David M Hartnell1,2 ([email protected]), 1 Caruana ([email protected]) Genoveva F Esteban2 ([email protected]. 1 1 uk), Andrew D Turner ([email protected]) Ifremer, Laboratoire Phycotoxines, Rue de l’Ile d’Yeu, 44311 2 Nantes, France and 2 CNRS, UMR 7144, Station Biologique de and Daniel J Franklin (dfrankin@bournemouth. Roscoff, Université Pierre et Marie Curie – Paris 6, Sorbonne ac.uk) Universités, Roscoff Cedex, France 1The Centre for Environment, Fisheries and Aquaculture Microalgae of the genus Alexandrium are able to Science (Cefas) The Nothe, Barrack Road, Weymouth, Dorset 2 form blooms and may have health and climate DT4 8UB, United Kingdom and Centre for Ecology, Environment and Sustainability, Faculty of Science & impacts because they produce two molecules of key- Technology, Bournemouth University, Fern Barrow, Poole, stone significance: saxitoxin and analogues known as Dorset, BH12 5BB, United Kingdom paralytic shellfish toxins (PSTs) and the dimethylsul- fonioproprionate (DMSP), an organosulfur com- Cyanobacteria blooms can adversely affect freshwater pound. The production of DMSP and PSTs may be resources by cell super abundance and the release of influenced by various environmental conditions such potent toxins. Microcystis is a genus of unicellular as salinity, temperature, light, turbulence and nutri- and colony-forming coccoid cyanobacteria, which ent concentrations. Interestingly, under certain tur- are ubiquitous in freshwaters across the globe. bulence conditions, it was observed that the Microcystins are a group of toxic cyclic heptapeptides biosynthetic pathway of DMSP was favored and that produced by Microcystis and other genera, which can PSTs metabolic pathways were not, suggesting impede mammalian liver function and have been a possible link between the metabolic pathways of associated with tumor promotion. An increase in DMSP and PSTs. In a context of climate change the occurrence and severity of blooms has been that predicts an increase in the frequency and inten- linked to anthropogenic climate change and eutro- sity of Alexandrium blooms, it appears important to phication. The prediction of cyanobacterial blooms is better understand the impact of temperature and an important objective of monitoring regimes and salinity variations on the production of DMSP and paramount in freshwater resource management. PSTs, and potential interactions between both meta- Longham Lakes are two connecting reservoirs, vary- bolites. The effect of changing salinity and tempera- ing in age and management strategies, situated on the ture conditions on DMSP and PSTs were investigated south coast of Britain. Water samples were taken in batch cultures of two French strains of A. minutum approximately every 10 days over a 13-month study (AM1231 and AM1232) and two strains of period (05/2016 to 05/2017), simultaneously biologi- A. catenella (IFR-ACA-15 and H8-4). The strains cal and chemical water measurements were recorded were subjected to three salinity shocks (-15 PSU, +8 by the multi-parameter probe. Cyanobacterial cells 92 KEYNOTE AND ORAL PAPERS were differentiated and enumerated by established at assessing the potential impact of global change key light microscopy and newly developed flow cytome- factors on growth, distribution and toxicity of toxic spe- try methods. Microcystin variants were qualified and cies of the genus Dinophysis. It is also important to quantified by a novel UHPLC-MS/MS, which was understand the ecology of prey organisms of this obligate suited to high throughput regulatory testing. mixotroph since Teleaulax amphioxeia and Mesodinium Cyanobacterial cell counts exceeding UK threshold rubrum have been shown to be sources of plastids for levels of >20,000 cells mL-1 were recorded on four Dinophysis. Optimal growth and physiology of occasions. Toxins were detected in both reservoirs, T. amphioxeia as a prey model were determined without but concentrations were significantly higher in one acclimation using a factorial design for temperature, and did not correspond with the highest levels of irradiance and pH in an experimental set-up with 15 Microcystis cells. Microcystin levels did not exceed combinations. The model predicted a higher growth the WHO medium health threshold of 20 μgL-1 rate of T. amphioxeia at high light intensity (400 μmol − − although low threshold values (1.0 μgL-1) were photons m 2 s 1), and in more acidic pH (7.6) and detected. Monitoring data indicated complex bottom- warmer temperature (17.6 °C) than current conditions up and top-down control mechanisms in the mod- in French Atlantic waters. Subsequently, M. rubrum was eration of cyanobacterial taxa abundance and popula- fed with T. amphioxeia acclimated at different conditions tion structure, the latter potentially mediated by the to investigate potential impacts of prey quality and quan- presence of omnivorous fishes. Application of basic tity on the physiology of the predator. M. rubrum growth general linear modeling to the dataset indicated that appeared to be more constrained by the quantity of prey approximately 60-65% of the variability could be provided than by the pigment content of the prey. explained by combined independent abiotic and bio- Monitoring over a 20 year monitoring period of tic variables indicating the future applicability of this Dinophysis and its toxins along French Atlantic coasts approach. did not show a clear time trend. While no significant increase in the occurrence of Dinophysis was observed over this period, the experimental studies indicate 12OR.3 a potential for a significant increase of T. amphioxeia CULTURE OF PREY ORGANISMS OF and M. rubrum occurrences in future climate conditions, DINOPHYSIS HELPS EXPLAIN WHY ITS which in turn may lead to increased occurrence of OCCURRENCE ALONG THE FRENCH Dinophysis spp., already significantly impacting the ATLANTIC COAST DOES NOT SHOW TRENDS European shellfish industry. OVER A 20-YEAR PERIOD Sylvain Gaillard1 ([email protected]), Liliane 12OR.4 Carpentier1 ([email protected]), Aurelie 2 STUDY OF GROWTH AND TOXIN Charrier ([email protected]), Florent PRODUCTION OF CULTURED 1 2 Malo ([email protected]), Gaël Bougaran GAMBIERDISCUS SPP. STRAINS FROM 3 ([email protected]), Jean-Olivier Irisson MACARONESIA ([email protected]), Marc Sourisseau4 (marc. Francesco Pisapia1 ([email protected]), Carlos [email protected]), Hélène Hégaret5 (helene. Marrero Aléman1 ([email protected]), Emilio [email protected]), Véronique Séchet1 (veroni- Soler Onis2 ([email protected]), Juan [email protected]), and Philipp Hess1 (philipp. Fernández-Zabala2 (jfernandez@marinebiotechnol- [email protected]) ogy.org), Félix Acosta3 ([email protected]), 3 1 Ifremer, Laboratoire Phycotoxines (PHYC), Rue de l’Ile d’Yeu, Jimena Bravo ([email protected]), Eduardo 44331 Nantes, France; 2 Ifremer, Laboratoire Physiologie et 1 ’ ’ Portillo Hahnefeld ([email protected]) and Biotechnologies des Algues (PBA), Rue de l Ile d Yeu, 44331 1 Nantes, France, 3 Sorbonne Université, CNRS, Laboratoire Patricia Assunção ([email protected]) d’Océanographie de Villefranche (LOV), Chemin du Lazaret, 06230 Villefranche-sur-Mer, France, 4 Ifremer, Dyneco Pelagos, 1Department of Biotechnology, Technological Institute of the Route de Sainte-Anne, 29280 Plouzané, France and 5 IUEM- Canary Islands (ITC), Playa de Pozo Izquierdo, s/n, 35119 - UBO, Laboratoire des sciences de l’environnement marin Pozo Izquierdo, Gran Canaria, Spain; 2Banco Español de Algas (LEMAR), Technopôle Brest Iroise, 29280 Plouzané, France (BEA), FPCT, University of Las Palmas, Muelle de Taliarte, s/n, 35215 - Telde, Gran Canaria, Spain and 3University Institute of Aquaculture and Sustainable Marine Ecosystems (IU- Several species of the genus Dinophysis are known to ECOAQUA), University of Las Palmas, 35200 - Telde, Gran produce lipophilic toxins and form harmful algal blooms Canaria, Spain (HABs) globally. Such toxins can be accumulated in suspension feeding bivalves and may intoxicate consu- Ciguatera poisoning is a food-borne illness mostly mers of contaminated shellfish. This study is part of the caused by consumption of fish contaminated with European project CoCliME which, among others, aims polyether toxins known as ciguatoxins (CTXs). EUROPEAN JOURNAL OF PHYCOLOGY 93

Originally known as a tropical disease, Ciguatera is Oceanography and Geography, University of Gdansk, being increasingly reported from areas previously not Marszałka J. Piłsudskiego 46, PL-81-378 Gdynia, Poland considered endemic, namely in the North-Eastern Atlantic. The epi-benthic dinoflagellates The development of cyanobacteria communities in Gambierdiscus and Fukuyoa are considered to be the freshwaters is substantially related to the number of causative agents of Ciguatera. Furthermore, these gen- simultaneously acting environmental conditions. era have recently been shown to have an increasing Nutrient enrichment plays an important role in causing number of species, also discovered in areas where it toxic blooms of cyanobacteria and also may modify had not been observed before, namely the Canary dominant species composition. Experimental Islands. The study presented here is part of the approaches are a very helpful tool to understand the MIMAR project (MAC/4.6D/066) aiming at the char- response and role of a particular species in an ecosys- acterization of hitherto unidentified CTXs from the tem. Therefore, eight strains of native (Planktothrix Macaronesian region. A total of 54 strains of the agardhii, Aphanizomenon gracile) and alien genus Gambierdiscus were recently isolated from field (Chrysosporum bergii, Sphaerospermopsis aphanizome- samples collected from Macaronesia (species identifica- noides) cyanobacteria were selected to test their growth tion is ongoing). Five strains from the Canary Islands rate, production of cyanotoxins and oligopeptides, and (G45, G85, G92, G100 and G141) were used in this to assess interspecies competition in response to the study for evaluation of cell growth and toxin produc- increased availability of nutrients and temperature tion. Cell growth was performed in 75 cm2 culture changes. The general linear model showed that con- flasks under the same culture conditions, using both centrations of inorganic phosphorus (IP), inorganic semi-continuous and batch cultures. Two brands of the nitrogen (IN) and their ratio significantly positively culture flasks (VWR® and Corning®) and four different affected the growth of all tested cyanobacteria. The treatments of the bottom surface (non-treated, treated, growth rate depended on the particular strain, species – – and species origin also. The highest growth rates were cell bind treated and ultra-low attachment treated) − found for A. gracile (0.43±0.08 day 1)and were evaluated for their influence on the growth of − S. aphanizomenoides (0.40±0.12 day 1), the lowest – the strains. All the conditions tested were suitable for −1 culturing Gambierdiscus spp., although some slight for P. agardhii (0.14±0.25 day ) at all tested nutrient differences were observed in growth rates and cell concentrations. Low IP concentrations and IN:IP ratio behavior. Triplicate samples obtained by semi- inhibited the growth of non-diazotrophic P. agardhii continuous cultures of the five strains (exponential cyanobacteria. The highest amount of prevailing toxins growth phase) were used for screening their CTX- dmMC-RRm, dmMC-LR variants and other oligopep- activity using the neuroblastoma neuro-2a assay. tides (anabaenopeptins, aeruginosins, cyanopeptolins) Preliminary results suggest that G45 and G92 are the in P. agardhii were detected at the lowest IP concentra- most CTX-producing strains. Further studies will focus tion. A clear relationship between STX production by on culture scale-up and bioguided fractionation of the A. gracile and nutrients was not revealed. Nutrients most toxic strains in combination with high-resolution concentration had a greater effect on species competi- mass spectrometry to pinpoint known and/or pre- tion than temperature and species origin. Native viously undescribed toxins. P. agardhii and A. gracile competed mainly for nutri- ents whereas co-cultured native and alien species acted differently. P. agardhii growth was suppressed by alien S. aphanizomenoides. Nutrients and temperature rather 12OR.5 than interspecies competition were important for EFFECT OF NUTRIENTS ON NATIVE AND P. agardhii and C. bergii growth. A. gracile suppressed ALIEN NUISANCE CYANOBACTERIA STRAINS the growth of native and both alien species. FROM TEMPERATE LAKES AND THEIR INTERSPECIES COMPETITION Judita Koreivienė1 ([email protected]), Ksenija 12OR.6 1 Savadova ([email protected]), Hanna Mazur- PSEUDO-NITZSCHIA: THE PHYSIOLOGY OF 2 Marzec ([email protected]), Jurate SUCCESS IN A HIGHLY STRUCTURED AND Karosienė1 ([email protected]), Jurate DYNAMIC PHYTOPLANKTON ECOSYSTEM č ė1 Kasperovi ien ([email protected]), Irma Daniela Marić Pfannkuchen1 ([email protected]), Mirta ė1 Vitonyt ([email protected]) and Anna Smodlaka Tanković1 (mirta.smodlaka.tankovic@irb. ń 2 Toru ska-Sitarz ([email protected]) hr), Ana Baričević1 ([email protected]), Nataša ž 1 ž š ć1 1Nature Research Centre, Akademijos Str., LT-08412 Vilnius, Ku at ([email protected]), Bla enka Ga parovi Lithuania and 2Division of Marine Biotechnology, Faculty of ([email protected]), Emina Pustijanac3 94 KEYNOTE AND ORAL PAPERS

([email protected]) and Martin earlier studies, we found that alkaline phosphatase Pfannkuchen1 ([email protected]) extracellular activity as well as membrane lipidremo- deling are major reactions of phytoplankton to phos- 1 Center for marine research, Rudjer Boskovic Institute, phate limitations. However, each species is using those G. Paliaga 5, 52210 Rovinj, Croatia; 2Division of Marine and Environmental Research, Ruđer Bošković Institute, POB 108, functions in its own way to ensure survival and success HR-10002 Zagreb, Croatia and 3Department for Natural and within the phytoplankton community. Having identi- Health Sciences, Juraj Dobrila University of Pula, Zagrebačka fied phosphate limitation as a major shaping factor, we 30, HR-52100 Pula, Croatia here present how harmful algae species of the genera Pseudo-nitzschia ensure successful competition within The northern Adriatic is a very convenient ecosystem the phytoplankton community. Here we report data on to observe phytoplankton under a variety of different species-specific growth rates under different nutrient conditions. Steep gradients of nutrient concentration/ regimes, phosphate uptake rates, alkaline phosphatase availability in this shallow basin allow the observation activity, localization and activation patterns and char- of the very same species under changing nutrient acteristics of alkaline phosphatase activity in four regimes on small temporal and spatial scales. The Pseudo-nitzschia species regularly occurring in the genus Pseudo-nitschia is among the most abundant basin. Our results demonstrate a high interspecific and most frequent diatoms in the northern Adriatic variation in metabolic responses to phosphate limita- phytoplankton community over the last four decades. tion in sympatric congeneric species. The ecological After studying in situ behaviour of this genus along the significance and function appears hence to be defined aforementioned gradients, we set out and isolated key on the species level and appears far from homogeneous species for in vitro experiments, where we analyzed within genera. their reactions to contrasting nutrient regimes. In EUROPEAN JOURNAL OF PHYCOLOGY 95

13. Lessons from local experiences: the Adriatic Sea

13KN.1 cervicornis (19.3%) are the most abundant species (89.7%). However, these NIS are not a concern for MACROALGAE IN THE LAGOON OF VENICE: the environment. Some of them are rare species of LONG-TERM CHANGES, ALIEN TAXA AND high ecological value that increase biodiversity. Other ENVIRONMENTAL IMPACT NIS like G. vermiculophylla have a positive impact on Adriano Sfriso1 ([email protected]), Alessandro the environment. This species grows under prohibi- Buosi1 ([email protected]), Yari Tomio1 tive conditions for the other macroalgae: high nutri- ([email protected]), Marion Adelheid Wolf1 (mar- ent concentrations and very turbid waters, replacing [email protected]), Abdul-Salam Juhmani1 Ulvaceae and avoiding anoxic crises. ([email protected]) and Andrea Augusto Sfriso2 ([email protected]) 13KN.2 1Department of Environmental Sciences, Informatics & Statistics, University of Ca’ Foscari Venice,Via Torino 155, LONG TERM IMPACT OF RIVERINE 30172 Mestre-Venezia, Italy and 2Department of Chemical DISCHARGES AND NUTRIENTS LOADS IN THE and Pharmaceutical Sciences, University of Ferrara, Via NORTHERN ADRIATIC SEA Fossato di Mortara 17, 44121 Ferrara, Italy Michele Giani1 ([email protected]) and Tamara The first macroalgal studies in the lagoon of Venice Djakovac2 ([email protected]) date back to the end of the eighteenth century. They 1 show only taxonomic data but without mentioning Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, via A. Piccard 54 34151, Trieste, Italy and 2Center for Marine either the quantitative distribution of the species or Research (CMR), Ruđer Bošković Institute, G. Paliaga 5, Rovinj, any environmental relationship. Maps of the macro- 52210 Croatia algal distribution and density have been drawn since 1980 and studies on their relationship with the envir- The freshwaters discharged in the Adriatic Sea onment started a few years later. Over the past 40 account for about 38% of the total freshwaters dis- years over three hundreds of papers have been pro- charged in the Mediterranean. The northern Adriatic duced deepening the close relationship between (NAd) rivers contribute 54% of the total freshwater macroalgae, trophic status and ecological status. discharged in the Adriatic. The Po River and other This knowledge was the basis for the development NE rivers carry relevant loads of particulate matter, of the Macrophyte Quality Index (MaQI), dissolved organic matter and nutrients which a categorical index for the evaluation of the ecological strongly affect the trophic status of the NAd waters. status of the Mediterranean transitional water sys- Strong oscillations in the discharges occurred during tems. MaQI is not based on the structure and mor- the last decades which determined variations in the phology of macroalgae but on the correlations of phytoplankton biomass abundance. The long-term macroalgae with numerous environmental para- discharge of Po freshwaters (1917-2017) is positively meters, nutrients and pollutants. This index can also correlated with the meteorological variations at large be applied in the presence of negligible biomass or scale (Western Mediterranean Oscillation Index) dur- microscopic epiphytes, according to their ecological ing the late spring-summer. The drought occurred in value. In the lagoon ca. 310 taxa are present and over the mid 2000s determined a drastic reduction of 80 are sensitive species that colonize only environ- chlorophyll concentrations in the NAd which recov- ments of good-high ecological status. Furthermore, ered in the years 2010, 2013 and 2014. A load of the Venice lagoon is a hotspot of non-indigenous P after the peak in the late 1980s revealed species (NIS). At present ca. 30 NIS colonize the a decreasing trend due to the ban of P in detergents lagoon accounting for ca. 32% of the total macroalgal and lower use in agriculture, whereas the NO3 load biomass. Among them 6 species account for 98.8% of remained elevated. Accordingly, nutrient concentra- the total NIS biomass and Gracilaria vermiculophylla tions in seawater (1972-2017) monitored along the (45.3%), Agardhiella subulata (25.1%) and Hypnea transect Rovinj-Po River mouth, the NAd evidenced 96 KEYNOTE AND ORAL PAPERS

PO4 decreasing and NO3 increasing trends at most 13OR.2 stations as well as an elevated NO /PO ratio. Overall 3 4 EFFECTS OF INCREASED SEAWATER notwithstanding the recent increase of the discharges TEMPERATURE AND BENTHIC MUCILAGE the chlorophyll a shows a long-term decreasing trend. FORMATION ON SHALLOW CYSTOSEIRA FORESTS OF THE WEST ISTRIAN COAST (NORTHERN ADRIATIC SEA) 13OR.1 Ljiljana Iveša([email protected]) PSEUDO-NITZSCHIA SPP. IN THE NW ADRIATIC SEA: MORPHOLOGICAL AND Ruđer Bošković Institute, Center forMarine Research, MOLECULAR CHARACTERIZATION, G. Paliaga 5, 52210 Rovinj, Croatia SEASONAL DISTRIBUTION AND TOXIN CONTENT The northern Adriatic represents the northernmost biogeographic sector of the Mediterranean Sea. The Sonia Giulietti1 ([email protected]), Stefano 1 1 sea bottom along the west Istrian Coast is mainly Accoroni ([email protected]), Tiziana Romagnoli rocky and therefore particularly suitable for the growth 2 ([email protected]), Simone Bacchiocchi (s.bac- of canopy-forming brown macroalgae of the genus 1 [email protected]) and Cecilia Totti ([email protected]) Cystoseira. Comparison with historical data revealed long-term changes of Cystoseira species abundance. 1Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, A phase of regression, occurring during the last decades Italy and 2Istituto Zooprofilattico Umbria e Marche, Via Cupa of the past century, was followed by a phase of recovery. di Posatora, 3, 60100 Ancona, Italy The composition of Cystoseira forests in the period from 2009-2013 might be considered similar to that Pseudo-nitzschia species are common representatives assessed during the 1950s. Starting from 2015, of the northern Adriatic diatom communities occur- aregressionofCystoseira forests was observed at some ring throughout the year often causing intense sites located in the central part of the west Istrian Coast. 6 blooms (abundances up to 10 cells/l). Some species These sites were not directly threatened by anthropo- of the genus Pseudo-nitzschia are well known to pro- genic pressure. The die-off chronology of Cystoseira duce domoic acid (DA) involved in Amnesic Shellfish forests was followed from spring 2015 to spring 2019. Poisoning (ASP). The existence of cryptic and/or Before 2015, mixed stands of Cystoseira compressa, pseudo-cryptic species (e.g. P. delicatissima complex) Cystoseira barbata, Cystoseira crinita, Cystoseira foeni- makes identification at the species level problematic. culacea and Cystoseira humilis formed flourishing for- The aim of this study is to characterize Pseudo- ests, which predominantly covered the rocky bottom. nitzschia species, during an annual cycle, in the NW From February to April 2016, i.e. during the period of Adriatic Sea. Sampling was carried out with monthly intensive vegetative growth of Cystoseira thalli at inves- frequency in a LTER site, i.e. the coastal station of the tigated sites, all deciduous branches fell off leaving Senigallia-Susak transect. Niskin samples were ana- perennial cauloids entirely barren. In May 2016, sparse lyzed under an inverted microscope for the abun- adventitious branches developed on cauloids. However, dance estimation. Net samples were collected at the vegetative apices were degraded impeding the regenera- surface to set up cultures for molecular, ultrastruc- tion of primary branches and the formation of repro- tural (TEM) and toxin analyses. Seventy-five strains ductive parts. During this period epiphytes heavily were established throughout the sampling period. overgrew the cauloids and the sites experienced The analysis of abundances revealed that species of a transitory sea urchin invasion. During summer 2018, both P. delicatissima and P. pseudodelicatissima com- surviving thalli gradually detached from the rocks initi- plexes co-occurred during the entire investigation ating the final phase of the forest die-off. Unusually 6 period with the highest abundances in May (2.8*10 high temperatures during summer and the impact of −1 6 −1 cells l ) and June (1.9*10 cells l ), respectively. benthic mucilage forming microalgal and macroalgal Among the P. seriata group, P pungens and blooms could play a pivotal role in the decline of P. fraudulenta have been recorded mainly in winter − Cystoseira forests along the west Istrian Coast. (6*103 and 1.4*104 cells l 1, respectively). The allochthonous species P. multistriata has been found − only in winter and autumn (6*103 cells l 1). The 13OR.3 molecular (LSU marker) and electron microscopy HIDDEN DIATOM DIVERSITY OF THE (TEM) analyses confirmed the presence of NORTHERN ADRIATIC THROUGH P. pungens, P. fraudulenta, P. delicatissima, METABARCODING P. calliantha and P. mannii. To date, no toxins were detected in 20 tested strains of P. calliantha, Ana Baričević1 ([email protected]), Cécile P. mannii and P. delicatissima. Chardon2 ([email protected]), Daniela Marić EUROPEAN JOURNAL OF PHYCOLOGY 97

Pfannkuchen1 ([email protected]. 1Ruđer Bošković Institute, Center for Marine Research, 2 hr), NatašaKužat1 ([email protected]), Valentin Vasselon2 Giordano Paliaga 5, 52210 Rovinj, Croatia and Marine Biology, Department of Biology, University of Copenhagen, 1 ([email protected]), Mirta Smodlaka Tanković Strandpromenaden 5, 3000 Helsingør, Denmark ([email protected]), Maja Levak Zorinc1 (maja.leva- [email protected]), Frédéric Rimet2 ([email protected]), As a shallow basin and under the strong influence Agnès Bouchez2 ([email protected]) and Martin of freshwater input (Po river), Northern Adriatic Pfannkuchen1 ([email protected]) (NA) is characterized by pronounced spatiotem- poral changes of nutrient concentrations over 1Ruđer Bošković Institute, Center for Marine Research, the year with unbalanced N/P ratios and also it is 2 G. Paliaga 5, 52210 Rovinj, Croatia and INRA, UMR- phosphate-limited. This represents a challenge for Carrtel, 75 avenue de Corzent, 74200 Thonon-les-Bains, France the phytoplankton survival and imposes adaptation of individual life strategies which results in highly The northern Adriatic (NA), a shallow sub-basin of structured phytoplankton community through the the Adriatic Sea, is under significant influence of basin. In situ measurements showed that activation various environmental factors that shape and deter- of enzyme alkaline phosphatase helps phytoplank- mine (phytoplankton) community structures in this ton species to overcome nutrient-limited conditions. distinctive marine ecosystem (region). The phyto- Based on the long-term data (45-year monitoring plankton community represents the base of the mar- programme) on diatom diversity and related nutri- ine food chain and a good sensing tool of the changes ent measurements, several diatom species were cho- in the environment. Hence, diversity of the phyto- sen. We isolated them from the environment, plankton has a long-term monitoring implementation cultured in opposite nutrient conditions (phos- in the NA. Even though, extensive knowledge of the phorus enriched and phosphorus depleted) and NA phytoplankton community exists, still, some observed their behavior and physiological adapta- groups and species remain undetected by traditional tions. In this paper, we focused on centric diatoms microscopy approaches. To overcome these limita- as a very important class of diatoms in NA and tions, we implemented metabarcoding to describe showed data on growth rates, localization and acti- diatom diversity of the NA. Sampling stations cov- vation patterns of alkaline phosphatase in laboratory ered the entire NA region and the marine protected conditions and also showed long term in situ data. area Lim bay. Usage of two barcodes (18S and rbcL) The combination of laboratory experiment and and strict taxonomy assessment (99% similarity in situ data play a key role in understanding species threshold) enabled detailed and reliable insights into behavior under different environmental conditions. the diatom diversity of the area studied. Common Our results imply species level adaptation to nutri- and/or abundant taxa, detected also with microscopy, ent-limited conditions. Each diatom species devel- were confirmed, and taxa not known so far for the oped different life strategy in order to compete for area studied or taxa difficult to identify with light nutrients and find its’ own niche where it can microscopy (pico and nano-size classes) were suc- thrive. This is of great importance to better under- cessfully detected through metabarcoding. stand and predict phytoplankton community struc- A number of reads, also with high sequence similarity ture in the ever-changing marine environment. to reference sequences, were assigned to freshwater genera, opening further questions about their DNAs origin or species persistence in the marine environ- 13OR.5 ment of the NA. CHANGES IN MACROALGAL RICHNESS AND ABUNDANCE IN THE INFRALITTORAL BELT OF NORTHERN ADRIATIC SEA 13OR.4 Martina Orlando-Bonaca1 ([email protected]), CENTRIC DIATOMS RESPONSE TO NUTRIENT Ana Rotter1 ([email protected]) and Lovrenc Lipej1 LIMITATION IN NORTHERN ADRIATIC ([email protected]) Natasa Kužat1 ([email protected]), Ana Baričević1 (Ana. [email protected]), Ingrid Ivančić1 (Ingrid.Ivancic@irb. Marine Biology Station, National Institute of Biology, Fornace 41, SI – 6330 Piran, Slovenia hr), Maja Levak Zorinc1 ([email protected]), ć 1 Daniela Mari Pfannkuchen (Daniela.Maric. Benthic macroalgae are regularly sampled along the ć1, 2 [email protected]), Nikola Medi (nikola.medic@- Slovenian coastline starting from 2006, since, in 1 bio.ku.dk), Mirta Smodlaka Tanković (Mirta.Smodlaka. accordance with the Water Framework Directive [email protected]) and Martin Pfannkuchen1 (Martin. (WFD, 2000/60/EC) requirements, they are used as [email protected]) a relevant biological element for the assessment of the 98 KEYNOTE AND ORAL PAPERS

Ecological Status. Among macroalgae, Cystoseira spp. Italy; 2 Dipartimento di Scienze della Vita, Università di 3 (also called canopy-forming species) are known to Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy; Dipartimento di Biologia, Università di Padova, Via U. Bassi, play an important role as ecosystems-engineers, espe- 58/B, 35131 Padova, Italy; 4 Ruđer Bošković Institute, Center cially in the upper-infralittoral belt. Since such long- for Marine Research, G. Paliaga 5, 52210 Rovinj, Croatia and 5 living species follow long-term periodicity, their dis- Department of Environmental Sciences, Informatics & Statistics, University Ca’ Foscari Venice, Via Torino 155, 30172 Mestre- appearance or even just a decrease in their abundance Venezia, Italy along the coastal rocky bottom should be considered as indicative of environmental degradation. Under The northern Adriatic Sea is a shallow, semi- key anthropogenic stressors, these species are enclosed basin characterized by oceanographic fea- replaced by persistent and smaller taxa, defined as tures considerably different from the rest of the turf-forming algae. These low-lying algae then form Mediterranean. The northern Adriatic was recolo- an alternative stable state that is able to inhibit reco- nized by marine biota in the last 20,000 years, after lonization by canopy-forming species. The goal of its emersion at the time of the Last Glacial this research was an in-depth investigation of the Maximum. Despite of such recent hydrogeological infralittoral macroalgal cover, to search for: trends origin, it hosts a relatively diverse seaweed flora in macroalgal abundance and richness, shifts from consisting of approximately 500 species (with the canopy-forming to turf-forming taxa, and changes highest diversity recorded for the Lagoon of in macroalgal spatial and seasonal diversity on the Venice, over 310 species). Literature information infralittoral rocky bottom of the northern Adriatic and surveys carried out in the last two decades Sea. At many sampling sites, significant changes in allow to highlight some changes in the composition the abundance of the macroalgal cover were detected, of its seaweed vegetation. The most evident change together with fluctuations in the proportion of is a remarkable loss of fucoid brown algae, which canopy-forming species and in the macroalgal diver- have decreased in distribution and abundance sity. In many Slovenian coastal areas, the resuspen- throughout the basin in the last 50-60 years. Fucus sion of sediments along major navigation routes and virsoides, the only endemic Mediterranean species of due to localized dredging and construction works Fucus, has suffered the most dramatic decline and is reach the rocky upper-infralittoral belt and, therefore, now relegated to a few sites in the Lagoon of Venice, negatively affects macroalgal communities. During Slovenia and northern Croatia; unfortunately, this the 12 year-long sampling period, the sites with the species appears now a strong candidate for extinc- highest abundance of canopy-forming taxa remained tion. Concurrently, a substantial increase in the mainly those located along the Slovenian coastal belt number of introduced species took place in the last that is still in its natural state and, thus, is very few decades, particularly in the Lagoon of Venice; important from a nature-conservation point of view, many alien species are now well-established and comprising also three MPAs. some (Caulerpa cylindracea, Gracilaria vermiculo- phylla, Agardhiella subulata, Hypnea cervicornis, 13OR.6 Sargassum muticum)havebecomelocallyveryabun- dant. At the same time, recent surveys discovered DIVERSITY PATTERNS AND LONG-TERM a previously unappreciated diversity in some habi- CHANGES IN THE BENTHIC MACROALGAL tats, namely the offshore reefs scattered in the VEGETATION OF THE NORTHERN ADRIATIC northernmost part of the basin (Tegnue and SEA Trezze). At least 173 species have been reported Fabio Rindi1 ([email protected]), Annalisa Falace2 from these biogenic concretions and molecular ([email protected]), Isabella Moro3 (isabella.moro@u- investigations are now unraveling a great diversity in the number of encrusting coralline algae. We nipd.it), Ljiljana Iveša4 ([email protected]), Analisa suggest that future investigations on the northern Caragnano1 ([email protected]) and Adriano Adriatic seaweed vegetation should focus on detailed Sfriso5 ([email protected]) assessments of species diversity in poorly-studied 1Dipartimento di Scienze della Vita e dell’Ambiente, Università areas and continued monitoring of ecologically Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, important/floristically interesting species. EUROPEAN JOURNAL OF PHYCOLOGY 99

14. Public outreach and citizen science

14KN.1 The Mediterranean Sea, considered as a true hotspot of biodiversity, is currently experiencing a decline in THE BIG SEAWEED SEARCH: SCIENCE, the number of species and deterioration of habitats, LESSONS AND INSPIRING THE CITIZENS as a consequence of different anthropogenic pres- Juliet Brodie1 ([email protected]), Justine Millard2 sures, which are predicted to increase in the future. ([email protected]) and Lucy Robinson1 (l. Among these pressures, the increase of human popu- [email protected]) lation, habitat modification and loss, pollution, coastal urbanization, overexploitation, the intentional 1 Natural History Museum, Department of Life Sciences, or indirect introduction of Non-Indigenous Species Cromwell Road, London, SW7 5BD, UK and 2Marine Conservation Society, Overross House, Ross Park, Ross-on- (NIS, i.e. organisms introduced outside of their nat- Wye, Herefordshire, HR9 7US, UK ural range) and climate changes (i.e. acidification and warming) have been pointed out as the major threats One of the critical underpinning aspects of a citizen to biodiversity. Therefore, biodiversity monitoring science project is a sense of purpose such as a robust and surveillance plans are strongly required in order scientific framework for generating reliable and to improve information on the distribution and meaningful data that will contribute to real scientific change of biodiversity and/or to find and track NIS research. At the same time, the project needs to be and detect early outbreaks of invasive species. In this engaging and easily achievable by anyone who wants respect, the creation of early-warning systems could to join in. The Big Seaweed Search serves as an be crucial. Since intensive monitoring programs are excellent case study to examine these objectives. The very expensive, Citizen Science, actively involving rationale behind this project is based on three key volunteers (e.g. citizen, students, fishermen, divers), environmental changes in the marine environment: could be a useful tool for gathering data, that would sea temperature rise, ocean acidification and the rise otherwise be impossible to collect because of limita- of non-native species. People are invited to search the tions on time and resources. Citizen Science has seashore around the British Isles for fourteen con- grown rapidly in recent years, also thanks to mobile spicuous and easily identifiable seaweeds whose dis- technologies, websites and social networks that enable tribution and abundance may be affected by these an easy and cheap way to communicate, share and changes. The original project was conceived in 2006, interchange data. Of course, in order to be used for launched in 2009 and ran until 2015. This taught us scientific purposes and management decisions, the a lot about what worked well and what was less collected data need appropriate quality assurance successful, notably ensuring the data can contribute measures such as validation and verification by taxo- to scientific research, the challenges of being able to nomic experts. We report on the experience of four identify seaweeds and the relatively low return rate Citizen Science activities: the Project “Caulerpa cylin- compared to the levels of activity. This enabled us to dracea – Egadi Islands”, the Project “Aliens in the review, revise and relaunch the project in 2016. In sea”, the Project “Invasive Algae”, included within the this talk, we will review the results of the Big Seaweed “Seawatchers” platform and the Marine Forests plat- Search and explore possible ways forward for the form. These Projects highlight how important Citizen development of citizen science projects. Science is for collecting data on marine biodiversity and marine NIS and to significantly improve the 14OR.1 efficacy of monitoring and surveillance plans. CITIZEN SCIENCE: A SUCCESSFUL TOOL FOR 14OR.2 MONITORING MARINE BIODIVERSITY FOOD FOR FISH, OXYGEN FOR ALL: Anna Maria Mannino1 (annamaria.mannino@unipa. BOTTOM-UP COMMUNICATION OF it) and Paolo Balistreri2 ([email protected]) PHYTOPLANKTON RELEVANCE 1 Department of Biological, Chemical and Pharmaceutical Luca Russo ([email protected]), Emanuela Sciences and Technologies, University of Palermo, Via Archirafi 38, 90123 Palermo, Italy and 2 Vicolo Giotto 6, Dattolo ([email protected]) and Domenico 91023 Favignana, Italy D’Alelio ([email protected]) 100 KEYNOTE AND ORAL PAPERS

Department of Integrative Marine Ecology, Stazione Zoologica numerous negative effects on natural resources, Anton Dohrn, Villa Comunale, 80121 Napoli, Italy being the second cause (after habitat destruction) of global biodiversity loss. In addition, biological inva- Despite the fundamental role they play in the aquatic sions pose a great threat to human beings because environments and, as a cascade, in the provision of they can also have important negative effects on primary resources to human beings, the majority of society as they impact economic, social and public the general public ignores phytoplankton existence, health resources (e.g. fisheries, water quality, tourism, in our country. This communication gap stems from etc.). In Europe the impact of aquatic invasive species multiple causes, from the overall inadequacy of has been estimated in at least 2.2 billion euros school programmes to the extremely weak, top- per year, although a thorough knowledge and full of down, media-coverage gathered by aquatic ecology, the impacts of marine invasive species is still very especially micro-biology, in public and private broad- limited. The Mediterranean Sea is a hotspot of mar- casts. To counteract this apparent lack of literacy, we ine invasions, with more than 700 multicellular alien run a series of outreach actions during the last five species detected, as a result of a long history of ship- years. These actions included (i) public engagement ping, the opening of the Suez Canal and other activ- ‘ with science initiatives using so-called guerrilla mar- ities. Of particular concern is the invasion of ’ keting techniques, such as improvised microscopic macrophytes (algae and seagrasses), as they have the sessions in the middle of feasts or bike travels potential to dramatically transform native ecosys- through lakes and rivers, (ii) storytelling initiatives, tems. The lack of selective and effective methods for e.g., literature and music productions relating to the eradication of these invasive species makes early aquatic ecology and micro-organisms, and (iii) small detection, monitoring and dissemination essential for outreach projects at schools of any degree. These adequate management and control. We have devel- actions targeted different age-classes. Therefore, we oped a project based on the design and implementa- modulated our language and message specificity, tion of a citizen-based system of information and based on the actual audience, for instance, by taking monitoring of invasive seaweeds in the Spanish advantage of educational games (i.e., the aquatic Mediterranean coasts. The project is based on two food-web game) when speaking to children, and by main pillars: 1) to develop outreach activities that using anecdotal communication (i.e., by intersecting educate different societal groups (schools, environ- “ ” local ecological tradition) when speaking to elderly mental educators, scuba diving clubs, tourism com- people. In this paper, we present our years-long panies, etc.) on the issues of marine invasions and 2) experience and show the usefulness of bottom-up to develop a citizen science platform (Seawatchers; strategies in communicating phytoplankton relevance http://www.observadoresdelmar.es) that involves all to human society. the different stakeholders in the collection of data on the distribution, abundance and ecology of inva- 14OR.3 sive macrophytes. Methods, challenges and successes of this project will be discussed. TEACHING IN ORDER TO LEARN ABOUT DISTRIBUTION OF INVASIVE MACROPHYTES IN THE MEDITERRANEAN SEA: USING 14OR.4 OUTREACH AND CITIZEN SCIENCE FIND INVASIVE SEAWEED: AN OUTDOOR Fiona Tomas1,2 ([email protected]), Laura GAME TO ENGAGE CHILDREN IN SCIENCE Royo1 ([email protected]), Maria Garcia3 ACTIVITIES THAT DETECT MARINE ([email protected]), Jorge Terrados1 (terrados@ime- BIOLOGICAL INVASION 4,5 dea.uib-csic.es) and Elisabetta Brogglio (elisabetta. Roberta Skukan 1,2,3 ([email protected]), Yaisel [email protected]) J. ([email protected]), Jose Manuel Rico Ordás3 ([email protected]) and Laura 1Instituto Mediterráneo de Estudios Avanzados (UIB-CSIC), C/ Miquel Marques 21, 07190, Esporles, Islas Baleares, Spain; (Miralles1,[email protected]) 2Dept. Fisheries and Wildlife, Oregon State University. 104 Nash Hall, Corvallis, 97331, OR, USA, 3Centro de Estudios 1Department of Functional Biology, University of Oviedo, Avanzados de Blanes (CSIC), C/d’accés a la Cala St. Francesc, Oviedo, 33006, Asturias, Spain; 2Neoalgae Micro Seaweeds 14, 17300, Blanes, Girona, Spain, 4Center for Genomic Products, Polígono de Lloreda, C/Carmen Leal Mata 191, Regulation, Barcelona Institute of Science and Technology, C/ 33211, Gíjon, Asturias; 3Department of Organisms and Dr. Aiguader, 88, 08003, Barcelona, Spain and 5Institut de Systems Biology, University of Oviedo, Oviedo, Asturias, Spain Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta, and 4Ecohydros S.L., Polígono Industrial de Cros, Edif. 5-Nave 37-49, 08003, Barcelona, Spain 8. 39600 Maliaño, Cantabria

The introduction of invasive alien species is a major Invasive species threaten worldwide biodiversity. component of global change. Invasive species have Success in facing this problem may be possible EUROPEAN JOURNAL OF PHYCOLOGY 101 through the engagement of younger audiences. Here, surveys led by scientists are more frequent in recent a game was designed to teach children how to recog- times and with them data set can be a few times nize invasive seaweed and to encourage them to par- greater than collect only by scientists. All volunteers ticipate in marine citizen science activities. The game need to receive basic training for research and was first tested in a pilot study, and then it was before analysis of their data, all sets require a pass carried out in Salinas High School (Asturias, Spain). through strict main-researchers filter. During the Game-based training consisted of an explanation of summer of 2017 in Mljet National Park, Operation invasive species, followed by the ‘Find invasive sea- Wallacea expedition took place. During the expedi- weed’ game and was evaluated with tests before and tion, students-volunteers have been trained accord- after the activity. After training, students spent 3 ing to the Operation Wallacea security standards months looking for invasive species. Four invasive and robust scientist framework. Research methods species were detected in the study area. Results had to be understandable for volunteers SCUBA- showed a positive impact on knowledge gains and divers, as groups would stay only for a week. significant differences in marine environmental During 7 weeks a large set of data has been collected. awareness and conservation actions. With a standard LIT methodology for Posidonia meadows research, data on meadow density (422 quadrants) and meadow consistence (119 transects) 14OR.5 was collected. Comparison between researchers and ’ NEED FOR INCREASED EFFORT - COULD volunteers data showed similar results and variation RECREATIONAL DIVERS ENHANCE among sites. It validates the global relevance of the EFFICIENCY OF SEAGRASS MONITORING? scientist and citizen scientists sampling work. Not regarding the origin of the data, results demon- Č ž 1 Hrvoje i mek ([email protected]), strated an increase of density compared to former 1 Barbara Čolić ([email protected]) and research. Therefore, only multiannual research Victor Buchet2 ([email protected]) based on the exact same procedures could give dynamic trends. Volunteers’ involvement was lim- 1Marine Explorers Society - 20000 leagues, Put Bokanjca 26a, 2 ited due to security standards, depth, equipment and 23000 Zadar, Croatia and Deep Blue Explorers, Zaglav 1/56, Miholašćica, 51556 Martinšćica, Croatia staff requirements. Nonetheless, they were able to perform straight-forward tasks in a shallow and safe One of the most frequent habitats in the marine environment. For this expedition, the focus was on protected areas in the Eastern Adriatic are training the volunteers, as well on consistence of Posidonia oceanica seagrass meadows. Volunteer volunteers’ data to researchers. 102 KEYNOTE AND ORAL PAPERS

15. Evolutionary genetics and genomics in macro- and microalgae

15KN.1 Netherlands, 3 Department Marine Sciences, University of Gothenburg, Box 461, SE 405 30 Göteborg, Sweden, 4Marine THE EVOLUTIONARY DYNAMICS OF BROWN Research Centre, Finnish Environment Institute, Agnes 5 ALGAL SEX CHROMOSOMES Sjöbergin katu 2, 00790, Helsinki, Finland, Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Susana Coelho ([email protected]) Comunale, Napoli, Italy and 6 Environmental and Marine Biology, Abo Akademi University, BioCity, Artillerigatan 6A Sorbonne Université, CNRS, Algal Genetics Group, UMR 8227, 20520 Åbo, Finland Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France Genetic diversity is an important requirement for populations to adapt to and persist in a changing Sexual reproduction is a pervasive phenomenon in environment. In the Baltic Sea, historic bottle-neck nearly all eukaryotic lineages. In genetically con- effects and harsh environmental conditions have been trolled sexual systems, sex is determined by sex chro- suggested to reduce genetic diversity and negatively mosomes, which have emerged independently and affect the capacity of populations to withstand envir- repeatedly during evolution. We are exploiting the onmental changes. Here we present empirical and exceptional richness of sexual features of the brown experimental data on genetic structure and phenoty- algae to gain novel insights into the evolution of sex pic diversity of two Baltic phytoplankton bloom spe- determination in this group of organisms. The sex- cies, Alexandrium ostenfeldii and Skeletonema chromosomes of several brown algal species that have marinoi and discuss these in the context of their life diverged over a 160-MY time frame were compared, cycle strategies. Field surveys revealed that Baltic and this analysis has revealed the unique evolution- populations of both species are highly differentiated ary, structural and gene expression patterns of these along spatial and temporal scales and show signifi- genomic regions compared with autosomes. Finally, cant genetic diversity despite supposedly suboptimal using the brown alga model Ectocarpus sp., we have conditions of their marginal habitats. Genetic diver- revealed how the sex chromosomes, together with sity is coupled to high variation in phenotypic traits autosomal loci, play a critical role not only on sex related to nutrient uptake, defense and response to determination and differentiation but also on the environmental stressors, facilitating selection and sta- regulation of other key reproductive process such as bility of ecological functions under altered salinity asexual reproduction via gamete parthenogenesis. conditions in experiments. The unexpected presence of high intraspecific diversity in Baltic populations of 15KN.2 A. ostenfeldii and S. marinoi may be explained by their life cycle strategies. Both species produce dor- GENETIC DIVERSITY, PHENOTYPIC mant resting stages which accumulate in sediments. VARIATION AND THE ROLE OF COMPLEX Here they form seed banks that serve as reservoirs of LIFE CYCLES IN EVOLUTIONARY diversity. Sexual reproduction involved in ADAPTATION OF BALTIC PHYTOPLANKTON A. ostenfeldii resting cyst production contributes to POPULATIONS this diversity through recombination which can be Anke Kremp1 ([email protected]), expected to attenuate the selective effects of the Karen Brandenburg2 ([email protected]. bloom phase. S. marinoi, on the other hand, repro- nl), Anna Godhe3 ([email protected]), duces sexually when released from dormancy. This is Jacqueline Jerney4 ([email protected]), interpreted as a preventive strategy to prepare for selection effects and respective loss of diversity hap- Marina Montresor5 ([email protected]) and pening in different phases of the bloom. The exam- Conny Sjöqvist6 ([email protected]) ples presented here emphasize that biology is 1Biological Oceanography, Leibnitz Institute for Baltic Sea a crucial part of adaptive responses and needs to be Research Warnemuende (IOW), Seestr. 15, 18119 Rostock, considered in our efforts to understand and predict 2 Germany, Department of Aquatic Ecology, Netherlands phytoplankton adaptation to environmental change. Institute of Ecology (NIOO-KNAW), Wageningen, The EUROPEAN JOURNAL OF PHYCOLOGY 103

15OR.1 1Alfred Wegener Institut – Helmholtz-Zentrum für Polar- und Meeresforschung, Marine Biogeosciences/Chemical Ecology, Am UNRAVELLING ASEXUAL REPRODUCTION IN Handelshafen 12, Bremerhaven, Germany, 2Aquatic Ecosystem TWO SYMPATRIC MORPHS OF THE Research, University of Duisburg-Essen, Universitätsstr.5, Essen, Germany; 3University of Bremen, FB2, Bibliothekstraße 1, AUSTRALIAN KELP (ECKLONIA RADIATA) Bremen, Germany and 4Helmholtz Institute for Functional USING GENOMICS Marine Biodiversity (HIFMB), Ammerländer Heerstraße 231, Oldenburg, Germany Sofie Vranken1 ([email protected]), 2 Armin Scheben ([email protected]), Progressing climate change and concurrent fast altera- 1 Thomas Wernberg ([email protected]), tions of environmental conditions pose large challenges 2 Jacqueline Batley ([email protected])and of adaptation on organisms and ecosystems. Arctic phy- Melinda A. Coleman3 ([email protected]. toplankton, being the base of the foodweb in one of the gov.au) most rapidly changing regions on the planet, is especially faced with such large transformations, but has been 1 Oceans Institute and School of Biological Sciences, University shown to be largely resilient towards them. In this of Western Australia, Perth 6009, WA, Australia, 2Institute of Agriculture and School of Biological Sciences, University of study, we tried to tackle the question of how this resi- Western Australia, Perth 6009, WA, Australia and 3Fisheries lience may be explained with a specific focus on the role and National Marine Science Centre, 2 Bay Drive, Coffs and functioning of intraspecific selection and population Harbour 2450, NSW, Australia dynamics of the diatom Thalassiosira hyalina. Intraspecific composition and diversity can greatly influ- Evolution of asexual reproduction is considered ence the productivity and resilience of a species, but a response to environmental conditions where it incurs selective processes driving such dynamics in phytoplank- less cost than sex, maintains adapted genotypes, and ton are methodologically still difficult to resolve, espe- allows rapid proliferation into new areas. In rare cir- cially in diverse natural contexts and at temporal cumstances, distinct asexual morphs have evolved in resolution. Within this work, we introduce new avenues response to ubiquitous environmental conditions. for the use of microsatellites as an efficient population Understanding the implications and the genetic genetic tool, allowing the analysis of bulk community mechanisms underlying reproduction does not only samples in experimental and natural contexts at close provide a fundamental understanding of life cycle evo- temporal resolution. Through those new methodologies, lution and regulation but is also essential to assess the we were able to resolve detailed selection dynamics in vulnerability of populations to climate change. We simplified diatom populations and found that their out- examined morphological and genomic variation comes are not predictable from responses recorded in between unique co-occurring sexual and asexual single-strain cultures. Instead, selective dynamics were morphs of the kelp Ecklonia radiata. Asexual morphs reproducibly altered by the applied environmental con- were morphologically distinct and less morphologically ditions. Furthermore, in experiments with natural popu- variable. We used ddRAD sequencing to identify 10,356 lations as well as in field samples from two spring single nucleotide polymorphisms (SNPs) that revealed blooms, our new method, microsatellite poolSeq barcod- widespread clonality in the asexual morphs. These ing (MPB), revealed surprising allelic stability in diverse morphs had lower genetic diversity and an excess of populations over time. Sudden shifts of their allelic com- heterozygotes relative to sexual morphs. Clustering position under specific environmental conditions, how- analysis and phenology suggested that asexual morphs ever, hint towards possible tipping points that limit this are still able to reproduce sexually, indicating ongoing stability. Our results also suggest that dynamics within gene flow between the two morphs. An association and populations are likely driven by more complex processes Fst analysis identified candidate SNPs in coding regions than clonal dominance in highly diverse phytoplankton segregating the morphs strongly suggesting functional populations and introduce a new tool to gain a better differences between these morphs. understanding of such fundamental but often hidden mechanisms of adaptation. 15OR.2 REVEALING POPULATION AND SELECTION 15OR.3 DYNAMICS IN AN ARCTIC DIATOM TO ASSESS ADAPTIVE POTENTIAL TO CLIMATE SUBTLE DIFFERENTIATION MAINTAINS CHANGE HAPLODIPLONTIC LIFE CYCLES … UNTIL IT ’ Klara K. E. Wolf1 ([email protected]), Clara DOESN T J. M. Hoppe1 ([email protected]), Florian Leese2 Stacy A. Krueger-Hadfield1,2 ([email protected]), Will ([email protected]), Björn Rost1,3 (bjoern.ros- H. Ryan1 ([email protected]), Guido Bonthond3 [email protected]) and Uwe John1,4 ([email protected]) ([email protected]), Jared DeForest4 104 KEYNOTE AND ORAL PAPERS

([email protected]), Cynthia G. Hays5 (chays@keene. 15OR.4 edu), Leoni Adams2 ([email protected]), Kathryn 2,6 PHENOTYPIC PLASTICITY VERSUS GENETIC E. Pack ([email protected])andNovaSTRUCTURATION IN DINOFLAGELLATE 2,7 Mieszkowska ([email protected]) NATURAL POPULATIONS 1,2 1University of Alabama at Birmingham, Department of Biology, Gabriel Metegnier ([email protected]), 2 1300 University Blvd, Birmingham, AL, 35294, USA; The Christophe Destombe2 ([email protected]) and Marine Biological Association of the United Kingdom, The 1 Laboratory, Citadel Hill, Plymouth, PL1 2PB, United Mickael Le Gac ([email protected]) Kingdom, 3GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105, Kiel, Germany; 4 1Ifremer, Dyneco-Pelagos, ZI Pointe du Diable, 29280 Plouzané, Department of Environmental and Plant Biology, Ohio France and 2CNRS, Sorbonne Université, Pontificia Universidad University, Athens, OH, USA, 45701; 5 Keene State College, Catolica de Chile, Universidad Austral de Chile, UMI 3614, 229 Main St., Keene, New Hampshire 03435, 6 Ocean and Evolutionary Biology and Ecology of Algae, Station Biologique Earth Science, National Oceanography Centre Southampton, de Roscoff, Place Georges Teissier, CS90074 29688, Roscoff University of Southampton, European Way, Southampton, Cedex, France SO14 3ZH, United Kingdom and 7 Department of Earth, Ocean and Ecological Sciences, University of Liverpool, England Environmental fluctuations may impact microbial populations in two distinct ways. First, the organisms Genetic models suggest haplodiplontic life cycles are may adjust their phenotype to cope with environmen- transitory states on the way to diploidy or haploidy. tal fluctuations. Second, environmental fluctuations The diversity of lineages maintaining haplodiplontic may select different genotypes with variable ecological life cycles suggests they are not transitory states, but capabilities. Here, we followed the temporal popula- evolutionarily stable. It is only when ecological pro- tion dynamics of the toxic dinoflagellate Alexandrium cesses are considered that models predict stability. minutum in situ during three consecutive years. Using There are, however, few empirical tests of ecological a metatranscriptomic dataset, we analyzed: 1. the glo- niche differentiation between macroalgal ploidies or bal gene expression dynamics as a proxy for phenoty- sexes. Here, we used the widespread, non-native, red pic plasticity in situ, and 2. the temporal genetic seaweed Agarophyton vermiculophyllum (synonym: structure using SNPs. Gene sets showing dynamic Gracilaria vermiculophylla), which throughout the expression correlated to environmental factor fluctua- Northern Hemisphere has been shown to undergo tions were identified. Cellular functions traditionally dramatic demographic shifts following the invasion studied using in vitro approaches, for instance, related of soft-sediment habitats. Almost all soft-substratum to nutrient uptakes and metabolisms, did not display habitats in the non-native range are dominated by extensive expression dynamics in situ. Of special inter- tetrasporophytes, despite the likelihood that both tet- est were gene sets showing higher expression in cold, rasporophytes and gametophytes were introduced low irradiance and salinity environments. One may be together. We sampled thalli from a site in northern related to motility behaviors. The other one suggests California, and then subjected male gametophytes, increasing cell-to-cell interactions toward the end of female gametophytes, and tetrasporophytes to the blooming period. The genetic structure was not a factorial combination of temperature, salinity, and correlated with environmental factors but would light level. We measured growth rates, bleaching rates, rather tend to display a plurennial dynamic related to protein concentration, chlorophyll a concentration, the species ecological success, with a temporally stable phycobiliprotein concentration, tissue strength, C:N, genetic structure associated with dense populations, dry mass, ash free dry mass, and fatty acid composi- and a temporally unstable genetic structure associated tion following 30 days within the treatments. The with low-density populations. This study illustrates combined stress of high temperature and high salinity how population structure and phenotypic plasticity reduced growth and increased bleaching risk. Female may underlie microbial population dynamics. gametophytes and tetrasporophytes tolerated these conditions better than male gametophytes, which showed a higher propensity to bleach overall. Less stressful environments led to higher tissue quality 15OR.5 (e.g., increased protein, carbon, and pigment concen- POTENTIAL MECHANISMS DRIVING THE trations), which interacted with phase-specific differ- GEOGRAPHIC DISTRIBUTION PATTERN OF ences. In the case of A. vermiculophyllum, the invasion SECONDARY METABOLITES IN THE HIGHLY of soft-substratum habitats uncouples the life cycle in CHEMICALLY-DEFENDED RED SEAWEED which tetrasporophytic phenotypes are consistently PLOCAMIUM “CARTILAGINEUM” more robust. These differences, however, are subtle 1 2 and may not be captured accurately if the wrong Sabrina Heiser ([email protected]), Andrew Shilling phenotypes are investigated. ([email protected]), Charles D. Amsler1 EUROPEAN JOURNAL OF PHYCOLOGY 105

([email protected]), Margaret O. Amsler1 (mamsler@- Naves2 ([email protected]), uab.edu), James B. McClintock1 ([email protected]), Estela M. Plastino2 ([email protected]) and Mariana Stacy A. Krueger-Hadfield1 ([email protected]) and Bill C. Oliveira2 ([email protected]) J. Baker2 ([email protected]) 1Department of Phycology. Botany Institute of São Paulo. Av. 1 Miguel Stéfano, 3687, 04301-902, São Paulo, Brazil and University of Alabama at Birmingham, Department of Biology 2 (UAB), 1300 University Blvd, CH464, Birmingham, Alabama, Department of Botany, Institute of Biosciences. University 35294, USA and 2University of South Florida, Department of of São Paulo. Rua do Matão 277, 05508-090, São Paulo, Chemistry, 4202 E Fowler Ave., CHE 205, Tampa, Florida, Brazil 33620, USA In Brazil, taxonomic studies based on molecular Inter- and intraspecific interactions between organ- markers led to the description of a new species isms can either be a form of communication, envir- Hypnea pseudomusciformis to accommodate three onmental sensing, or defense and are often mediated morphologically divergent species occurring on by chemicals such as secondary metabolites. Sessile coast, H. musciformis, H. nigrescens and marine organisms such as macroalgae commonly H. valentiae. In this work, we investigate further produce chemical defenses against grazers, patho- this divergence of the phylogenetic and morpholo- gens, as well as biofoulers. Plocamium “cartilagi- gical species concepts for these species using neum” is a finely branched red understory alga that a polyphasic approach. Specimens from two mor- is common in Antarctic macroalgal forests. It sup- phological variations of H. pseudomusciformis were ports a very high abundance of amphipods of which collected in the field, isolated and kept in unialgal most are not able to feed on the heavily chemically cultures (photoperiod of 14 h, 25°C and 30±10 μmol − − defended P. ”cartilagineum” except for Paradexamine photons m 2s 1). Crossing experiments were con- fissicauda. Different P. “cartilagineum” individuals ducted between specimens with the typical morphol- produce differing mixtures of halogenated secondary ogy for “musciformis” and “nigrescens” to use the metabolites which are referred to as chemogroups. biological species concept to verify the molecular Around Palmer Station in 2016 to 2018 a total of 16 data. Growth rates (GRs) and photosynthesis para- different chemogroups were identified. The 16 che- meters were also evaluated after a period of 28 days mogroups fit well into two distinct genetic groups of culture (n=3). All crosses performed were positive (but not different enough to be considered different evidenced by the presence of cystocarps in all-female species) identified by the cox1 and rbcL genes. These gametophytes used. Carpospores were released and data suggest that chemogroups are to some extent site germinated in tetrasporophytic plants, which specific, they have some correlation with depth and became fertile after 40 days of culture. These tetra- that there is an underlying genetic differentiation. In sporophytic plants “musciformis”, “nigrescens” and order to determine the mechanisms driving the geo- “F1” presented physiological differences on GRs and graphic pattern of secondary metabolites in photosynthetic performance, which the variant P. “cartilagineum”, a variety of different approaches “nigrescens” showed higher GRs in relation to the were taken. Transplant experiments were conducted “musciformis”. The F1 generation presented an to assess the role of environmental factors. intermediate performance between the previous Additionally, transects were run in order to describe two.Thesamepatternswereobservedinrelation fine-scale distribution of chemogroups and the asso- to the photosynthetic parameters: maximum quan- ciated population genetics. tum yield and light saturation. However, the variant “musciformis” showed higher maximum electron transport rates, while no difference was observed 15OR.6 for the photosynthetic efficiency. The results from the crossing experiments confirm that, for Brazil, POLYPHASIC APROACH TO ADDRESS H. nigrescens and H. musciformis,belongtothe HYPNEA MULTIPLE SPECIES CONCEPTS FOR same species, H. pseudomusciformis,whichdisplays PSEUDOMUSCIFORMIS (GIGARTINALES, great phenotypic and physiological plasticity what RHODOPHYTA) can favor colonization of different environments Fabio Nauer1 ([email protected]), Fabiana and making this species very successful and wide- Marchi2 ([email protected]), Matheus spread along the coast. 106 KEYNOTE AND ORAL PAPERS

16. Algal culture collections in the -omics age

16KN.1 The Australian National Algae Culture Collection, ANACC, manages over 1000 strains of microalgae HOW CAN WE MAKE CULTURE COLLECTIONS and cyanobacteria, from freshwater, wastewater, SUSTAINABLE? brackish and marine, hypersaline and acidophilic Willie Wilson ([email protected]) environments from the tropics to the poles, since inception in the late 1960’s with representatives Marine Biological Association, The Laboratory, Citadel Hill, from most established taxonomic classes. Particular Plymouth, PL1 2PB, UK species of beneficial or deleterious environmental, social and economic consequence have been studied Collections of algae represent an essential foundation in particular detail and as a result have a deeper for research and for the future bio-economy. Indeed, biogeographic replication and coverage. In Jan 2019 they are often described as heritage assets. Collections ANACC accessioned its first tranche of a well-curated range from small personal research collections ran- macroalgae collection from the University of ging from a few specific strains to several hundred Melbourne - a strategic move into macroalgae. The strains that provide cultures to collaborators (usually broad diversity of ANACC has necessitated at no or little cost), to large service centers that a polyphasic approach to strain characterization, provide cultures to the wider community for a fee. including morphological and life-history documenta- Globally, algal culture collections have different busi- tion being more recently joined by genomic typifica- ness models, from full (or heavily subsidized) govern- tion (single and concatenated barcode genes, 16S, ment support to a more corporate model where full 18S, LSU, COI, rbcL, ITS), and in a limited number cost recovery from culture fees are required. There is of species (cyanobacteria) by whole genome sequen- no silver bullet for making a collection sustainable, cing. Beyond identity, logistics and research goals though ultimately market forces (either academic or dictate the priority of broader phenotype analyses commercial) dictate their success in the long-run. that match species to their expected amplified traits; I would posit that those collections that are adaptable, e.g. filamentous freshwater cyanobacteria screened have diverse funding streams, and market their for toxins and toxin gene expression but only oppor- unique selling points have more chance of surviving. tunistically for essential polyunsaturated fatty acids. This should not be a surprise since it is based on Examples will be given of core contributions by standard business principles. Building on his experi- ANACC to wider CSIRO initiatives to optimize strain ence as Director of the National Center for Marine selection for targeted microalgae bioproducts. Algae and Microbiota (NCMA) in the US; Director of ANACC supplies cultures to academia and industry the MBA that hosts the CPR Survey plankton archive in over 70 countries through the Australian National and MBA phytoplankton culture collection; as well as Algae Supply Service (ANASS). The two core regula- his role as a committee member on the CCAP science tory compliance issues for ANACC in the context of advisory board; Willie Wilson will explore different an Australian living biorepository open for exploita- models to sustain algal culture collections. tion involve Biosecurity and the Convention on Biological Diversity - Nagoya Protocol (NP). The 16OR.1 NP is proving a very challenging article for ventures THE ANACC AND AUSTRALIAN with prospective commercial interests in ANACC PERSPECTIVES ON DELIVERING RESEARCH strains given that at the time of this abstract IMPACT FROM AN ALGAL CULTURE Australia has signed on to but not ratified Nagoya. COLLECTION Ian Jameson ([email protected]), Anusuya Willis 16OR.2 ([email protected]), Cathy Johnston (cathy. AQUATIC VIRUS CULTURE COLLECTION- AN [email protected]) and Ros Watson (ros.watson@c- INITIATIVE FOR THE FUTURE siro.au) Jozef I. Nissimov ([email protected]), CSIRO, Australian National Algae Culture Collection, CSIRO, Christine Campbell ([email protected]) Castray Esplanade, Hobart, Tasmania, Australia, 7000 and Michele Stanley ([email protected]) EUROPEAN JOURNAL OF PHYCOLOGY 107

Scottish Association for Marine Science, Scottish Marine Luc Cornet3,4 ([email protected]) and Denis Institute, Dunbeg, Oban, Argyll, PA37 1QA, Scotland, UK Baurain4 ([email protected])

Culture collections are an essential resource for scien- 1BCCM/ULC, InBios-Centre for Protein Engineering, tists globally. They provide a centralized infrastructure University of Liège, Allée du 6 août, 13 4000 Liège, Belgium; 2BCCM/MUCL, Croix du Sud 2, box L7.05.06, 1348 Louvain- for the depository and continuous maintenance of dif- 3 la-Neuve, Belgium; Astrobiology, Department of Geology, ferent microbial species, their long-term storage, curate University of Liège, Allée du six Août, 14, 4000 Liège, updated bioinformatic, phylogenetic, and physiological Belgium and 4 InBioS—PhytoSYSTEMS, Eukaryotic data on different strains, and provide services and Phylogenomics, University of Liège, Bd du Rectorat, 27, 4000 Liège, Belgium advice to the academic and industrial scientific com- munity. Crucially, they ensure the long-term viability of The BCCM/ULC public collection of cyanobac- isolates, their associated physiological traits, and the teria aims to gather a representative portion of preservation of their metabolic and genetic potential Polar cyanobacterial diversity from different eco- (all aspects, which can be lost if not regularly and logical origins (microbial mats, soil crusts, cryoco- properly maintained). One such resource is the nites, endoliths, etc.) and ensure their ex-situ Culture Collection of Algae and Protozoa (CCAP), conservation in a context of global change. These which maintains ~3000 strains (across 600 genera) of strains are available for researchers to study the cyanobacteria, microalgae, protozoa, and seaweed, from biodiversity, taxonomy, evolution, adaptations to diverse marine, freshwater and terrestrial environ- harsh environmental conditions, and genomic ments. Recently, viruses were deemed as the most abun- make-up of Polar cyanobacteria. Currently, there dant biological entities on the planet, reaching more 6 are 120 unicyanobacterial strains of Polar origin in than 10 virus-like particles in a milliliter of seawater. the collection (catalogue: http://bccm.belspo.be/cat With the development of new methodologies for virus alogues/ulc-catalogue-search). The collection is isolation, and the advancement of high-throughput ISO 9001 certified for depositing and distributing sequencing technologies, we now know that viruses strains, as part of the multi-site certification of the also encode for functionally important genes involved Belgian Co-ordinated Collections of Micro- in lipid and carbohydrate metabolism, photosynthesis, organisms (BCCM) consortium. Morphological nutrient acquisition, and the general diversification of and molecular identification (based on 16S rRNA life through horizontal gene transfer. Viruses are now sequences) indicate that the strains belong to the also used as a tool to control certain pathogens, and as orders Chroococcales, Chroococcidiopsidales, transgenic vehicles for the delivery of genes in the Nostocales, Oscillatoriales, Pleurocapsales, and biotechnology sector. Moreover, the exponential Synechococcales. This broad genotypic distribu- increase in aquatic virology research has revealed their tion makes the BCCM/ULC collection particularly central role in biogeochemical cycles and climate pro- interesting for phylogenomic studies. The first cesses. Nevertheless, although biomedically relevant genome of an axenic Antarctic strain, pathogenic virus depositories are available, Phormidesmis priestleyi ULC007, was sequenced. “ ” a centralized bank or culture collection for the grow- To investigate the occurrence of genes involved in ing aquatic virus research community does not exist. the cold stress response, a selection of 42 PEGs Here we present our vision for the development of the (protein-encoding genes) linked to cold adaptation first of its kind aquatic virus culture collection (AVCC), was studied in 72 cyanobacterial genomes. By showcase its preliminary integration (with chloro-, dia- comparing the genes copy numbers as a proxy of tom-, and coccolithoviruses) into the CCAP, and high- adaptation, our results underline the importance light the benefits that this will have to the scientific of different functions in the adaptation mechan- community. isms to the polar environment (e.g. DNA repair, Heat shock proteins, EPS biosynthesis). We also 16OR.3 described a metagenomic pipeline that enables the easy recovery of genomes from non-axenic cul- BCCM/ULC: GENOMIC RESEARCH ON POLAR tures, tested on 17 cyanobacterial strains from CYANOBACTERIA the BCCM/ULC collection. In parallel, we 1 1 Annick Wilmotte ([email protected]), Kim Beets assembled 31 co-cultivated bacteria (12 nearly ([email protected]), Véronique Simons2 (veronique. complete) from the same cultures and showed [email protected]), Yannick Lara1,3 (ylara@u- that they mostly belong to Bacteroidetes and liege.be), Benoit Durieu1 ([email protected]), Proteobacteria. 108 KEYNOTE AND ORAL PAPERS

16OR.4 on the ACUF strains are also planned as ICT activ- ities on the ACUF website (ww.acuf.net) for better ACUF: THE MICROALGAL COLLECTION AT usability by the scientific community and industrial THE UNIVERSITY OF NAPLES FEDERICO II stakeholders. Angelo Del Mondo1 ([email protected]), Antonio Luca Langellotti1,2 ([email protected]), Mariagioia Petraretti1 (mariagioia.petraretti@unina. 16OR.5 1,3 it), Claudia Ciniglia (claudia.ciniglia@unicampa- THE NAGOYA PROTOCOL ON ACCESS AND nia.it), Gabriele Pinto1 ([email protected]) and BENEFIT SHARING: IMPLEMENTATION Antonino Pollio1 ([email protected]) STATUS IN ALGAL BIOLOGICAL RESOURCE CENTRES 1ACUF Collection, University of Naples, Department of 1 Biology, University of Naples Federico II, Via Cinthia 21, Maike Lorenz ([email protected]) , 80126 Naples, Italy; 2CAISIAL Centre, University of Naples 1 “ ” Tatyana Darienko ([email protected]) and Federico II , Via Università 133, 80055 Portici (NA) Italy 1,2 and 3Department of Environmental, Biological and Ana Tzvetkova ([email protected]) Pharmaceutical Science and Technology, University of Campania “L. Vanvitelli”, 81100 Caserta, Italy 1Experimental Phycology and Culture Collection of Algae (SAG), Albrecht-von-Haller Institute for Plant Science, Georg- August-University Goettingen, 37073 Goettingen, Germany and In situ conservation of aero-terrestrial microbial com- 2Institute of Bioinformatics, University Medicine Greifswald, munities is generally not considered in conservation 17475 Greifswald, Germany policy, and is particularly problematic, due to present lack of understanding of microbial ecosystems (1). To The Nagoya Protocol (NP) on Access and Benefit achieve affordable results, the protection of microbial Sharing (ABS) is a legally binding agreement supple- diversity needs to be complemented by ex-situ collec- menting the Convention on Biological Diversity. Its tions, to guarantee long-term preservation and poten- objective is the fair and equitable sharing of benefits tial exploitation. Indeed, the bioprospection of arising from the utilization of genetic resources, microalgae from terrestrial environments spread thereby contributing to the conservation and sustain- over diverse habitats and geographical regions can able use of biodiversity. lead to the formation of banks of selected strains, Today, 116 countries are a party to Nagoya Protocol. particularly useful for the development of biotechno- National ABS focal points and competent national logical applications. The Algal Culture Collection at authorities are defined in 172 resp. 105 countries. the University of Naples “Federico II” (ACUF) was The ABS Clearing House (https://absch.cbd.int/) pro- established in 1973 by Professor Roberto Taddei and vides information about these institutions and coworkers. The collection is specialized in the culture national legislations plus a huge variety of adminis- of aero-terrestrial algae, and has more than 800 trative documents. But only two national ABS proce- strains, mostly belonging to Cyanobacteria, dures are documented and many countries still did Rhodophyta and Chlorophyta. Special attention has not implement ABS legislation yet.. It is often not been paid to Cyanidiophytina (Rhodophyta) from clear what is needed to legally access, use and transfer thermal-acidic environments: Cyanidium, Galdieria genetic resources and how to proof due diligence. and Cyanidioschyzon. Presently, about 400 selected Definitions of genetic resources and utilization vary. strains belonging to these latter genera are main- However, collectors, depositors, researchers and bio- tained in culture and have shown a relevant cryptic prospectors must ensure legal clarity in how they can genotypic diversity (2). Most ACUF strains have been (or cannot) use genetic resources. Algal culture col- extensively used for taxonomic, physiological, and lections are specialized biological resource centers eco-toxicological studies; instead others resulted pro- (BRCs) and main stakeholders to follow NP legisla- mising as potential candidates for biodiesel produc- tion and raise awareness. They actively participate in tion, biological sequestration of CO2 and wastewater national and international developments on the treatment also cultivated in high tech photobioreac- implementation of ABS legislation and Best Practice tors. Lastly, some selected strains are under pilot Guidelines. Decisions to the current discussion on development for the production of long-chain poly- defining basic research as utilization and on expand- unsaturated fatty acids, protein, sugars and secondary ing NP scope to include digital sequence information metabolites (such as pigments and vitamins) to be will effect not only algal BRCs but also most fields of used as high-value ingredients for food, cosmetic, phycological research. European Union Regulation nutraceutical and pharmaceutical industries. 511/2014 implemented NP legislation for EU users Metadata and active links to scientific information including a ‘register of collections’. Such registered EUROPEAN JOURNAL OF PHYCOLOGY 109 collections prove to meet a number of specific, registration has practical implications for many BRCs nationally defined criteria and their users automati- that currently exceed their scope and resources. Best cally demonstrate due diligence when sourcing mate- practices of NP implementation in algal BRCs and rial (e.g. living algal cultures or DNA). Nevertheless, their use will be discussed. 110 KEYNOTE AND ORAL PAPERS

Workshop 1: Measuring photosynthesis with light: application and new insights in active fluorescence techniques

W1KN.1 W1KN.2 PULSE AMPLITUDE MODULATED (PAM) APPLICATION OF FAST REPETITION RATE FLUOROMETRY: THE MEASUREMENT FLUOROMETRY (FRRF) IN PRIMARY PRINCIPLE, THE PARAMETERS, THE PRODUCTIVITY STUDIES: A TUTORIAL RELATION TO ELECTRON TRANSPORT RATES 1 AND ITS USE TO STUDY Jacco Kromkamp ([email protected]), Greg 2 ř š 3 NON-PHOTOCHEMICAL QUENCHING (NPQ) Silbe ([email protected]), Ond ej Prá il (prasi- [email protected]), Kevin Oxborough4 (koxborough@chelsea. Bernard Lepetit1 ([email protected]), co.uk) and David Suggett5 ([email protected]) Jochen Buck1 ([email protected]), Jonathan Sherman2 ([email protected]), 1Royal Netherlands Institute for Sea Research, PO box 140, 2 Angela Falciatore3 ([email protected]), 4400 AC Yerseke, The Netherlands; Centre for Environmental 4 Science, University of Maryland, PO Box 775, 2020 Horns point Johann Lavaud ([email protected]), Rd, Cambridge, MD 21613, United States; 3Centrum 2 ALGATECH, Institute of Microbiology, Czech Academy of Maxim Y. Gorbunov ([email protected]. 4 2 Sciences, 37901 Třeboň, Czech Republic; Chelsea Technologies edu), Paul G. Falkowski ([email protected]) Group, 55 Central Avenue, West Molesley, Surrey, KT8 2QZ, and Peter G. Kroth ([email protected])1 UK and 5Climate Change Cluster (C3), University of Technology, Sydney, PO Box 123 Broadway, NSW 2007 1Plant Ecophysiology, Department of Biology, University of Australia Konstanz, 78457 Konstanz, Germany; 2Environmental Biophysics and Molecular Ecology Program, Department of Phytoplankton primary production is a sensitive eco- Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA; 3Sorbonne Université, system indicator and in coastal systems driven by Centre National de la Recherche Scientifique, Institut de local drivers which can be very different in adjacent Biologie Paris-Seine, Laboratory of Computational and systems. As phytoplankton primary production deli- Quantitative Biology, F-75005 Paris, France and 4UMI 3376 Takuvik, CNRS/ULaval, Département de Biologie, Pavillon vers the organic matter which fuels aquatic foodwebs, Alexandre-Vachon, Université Laval, Québec (Québec), G1V knowledge of primary production (PP) is essential to 0A6, Canada understand ecosystem change and functioning. Unfortunately, PP measurements are on the decline, In this introductory talk, the major parameters which most likely because the 14C-method, i.e. the most can be obtained by PAM analyses will be explained. commonly method to measure PP is not easily applic- What do they mean? What can they tell and what able in monitoring programs and health and safety not? How are they measured correctly? Besides this regulations make it more and more difficult to use general methodological part, new data regarding the this technique. In this tutorial we suggest an alter- understanding of NPQ (Non-Photochemical native to measure primary production, based on the Quenching) processes in diatoms will be presented. application of FRRF. This technique measures the By having created mutants with varying NPQ capa- quantum efficiency of photosynthesis of PSII, and cities in Phaeodactylum tricornutum, we could study can be used to derive primary production and can in-depth their NPQ properties by PAM. Combining be used to derive information about the physiological these data with data obtained by Fast Repetition Rate status of the phytoplankton. It is now possible to Fluorometry (FRRF) enabled us to get deep mechan- measure concentrations of reaction center-II and to istic insights into NPQ and to specify the exact sub- measure the absorption properties per unit volume. types of NPQ. These results enlarge our In this lecture we will describe the principles of the understanding of the molecular regulation of thermal technique and show how recent developments make dissipation in diatoms substantially. it possible to derive absolute rates of photosynthetic EUROPEAN JOURNAL OF PHYCOLOGY 111 electron transport (ETR) and how these can be con- occurring under steady state illumination (that is verted to rates of C-fixation. We will also discuss the the case in the dinoflagellate Amphidinium carterae). assumptions and uncertainties of this method and In the ones where CEF exists, it can be independent how they may be related to the physiological status of LEF (e.g. the dinoflagellate Symbiodinium)or of the algae. Despite the remaining uncertainties, dependent on LEF (e.g. the green alga which are not only due to conversion factors from Chlamydomonas reinhardtii). This method can be ETR to C-fixation, but also to inherent uncertainties used to explore how CEF depends on physiological in the C14-method, we suggest that this method can and environmental conditions. be generally adopted as a standardized method to measure primary production, allowing better com- parison between PP estimates. W1KN.4 THE FLUORESCENCE-BASED ESTIMATIONS OF GROSS AND NET PRIMARY W1KN.3 PRODUCTIVITY IN A MARINE DIATOM - THE COMBINING FLUORESCENCE AND EFFECTS OF DYNAMIC NUTRIENT STRESS ABSORPTION SPECTROSCOPY TO Ondrej Prasil1 ([email protected]), Ewelyn Lawrenz1 INVESTIGATE CYCLIC ELECTRON FLOW ([email protected]) and Jacco C. Kromkamp2 (Jacco. AROUND PHOTOSYSTEM I IN VARIOUS [email protected]) MICROALGAE 1 1Institute of Microbiology CAS, Centre Algatech, Suzanne Ferté ([email protected]), Laure ř ň 3 Opatovický mlýn, CZ 37981 T ebo , Czech Republic and Guillou ([email protected]), Ginga 2Royal Netherlands Institute of Sea Research (NIOZ), 4400 Himakawa3 ([email protected]), Anja AC Yerseke, the Netherlands Krieger-Liszkay3 ([email protected]) and 3- Benjamin Bailleul1 ([email protected]) We have studied the effect of NO limitation on the electron transfer and carbon fixation and allocation 1 IBPC, UMR7141, CNRS, 13, rue Pierre et Marie Curie, 75005, in marine diatom Chaetoceros muelleri. In order to 2 Paris, France; Station Biologique de Roscoff, UMR7144, Place simulate nutrient changes occurring under natural Georges Teissier, 29680 Roscoff and 3 I2BC, Institut de Biologie Intégrative de la Cellule (I2BC), Avenue de la Terrasse, 91190 conditions, we manipulated the concentration of the Gif-sur-Yvette nitrate from fully replete to severely limiting. This created a dynamic continuum of physiological states It is commonly assumed that in plants and green of balanced and unbalanced growth that were algae, cyclic electron flow (CEF) around photosystem sampled on daily basis for suite of photosynthetic, I (PSI) plays a crucial role in optimizing photosynth- cellular and growth parameters. The primary produc- esis. CEF increases the electrochemical proton gradi- tivity was quantified using several methods: by the ent and is therefore believed to have two main roles, FRR-based algorithm, by the coincident C and O2 (i) regulating the photosynthetic control and non- (MIMS) isotopes based estimations of gross (GPP) photochemical quenching in photosystem II (PSII), and net (NPP) primary productivity. Overall, we and (ii) providing the extra ATP required for carbon observed strong correlation between the fluorescence- fixation. However, several decades of research did not based estimates of ETR and the simultaneously mea- provide a clear-cut answer about the mechanism, sured carbon fixation during nutrient replete and the extent, regulation and conservation of CEF among dynamic, non-steady states of the onset of nitrate different photosynthetic clades. This is mostly due limitation, but uncoupling between these proxies for to the absence of a consensus method to estimate GPP under late phases of nutrient limitation. The this flow in physiological conditions. The most wide- relationship between the optical cross section deter- spread approach compares the quantum yield of PSII, mined spectrophotometrically and the optical cross- through fluorescence techniques, and the one of PSI, section of PSII (aLHII) remained linear, apart from through the absorption changes associated with var- a short period during the transfer from moderate to iations of the redox state of its special pair, P700. But strong-N-limitation, suggesting that the Ka remained we could show that the latter method tends to under- constant during most of the unbalanced growth estimate the quantum yield of PSI, leading to aber- phases. We observed much larger variability between rant conclusions regarding CEF. We propose an the ETR and the “standard” method to estimate GPP alternative method based on the electrochromic shift using 30-min 14C incubations: both coincided for the of photosynthetic pigments, to test for the presence of nutrient replete state, but increasingly deviated (3-4x) CEF and, where appropriate, describe the relationship with the progress of nutrient stress. The deviation is between LEF and CEF. We could highlight 3 beha- well correlated with the instantaneous growth rate. viors: in some photosynthetic species, CEF is not Interestingly, the growth efficiency, determined from 112 KEYNOTE AND ORAL PAPERS the ratio of NPP to ETR was low (12%) under replete however, counteracted by strongly lowered growth conditions but doubled under moderate nitrate stress. and particulate organic carbon production rates of Under extreme nutrient stress, when the growth the diatom relative to the prymnesiophyte. The prym- effectively stopped, the growth efficiency has also nesiophyte also possessed high photoprotective cap- declined dramatically. To our knowledge, this is the abilities, with strong alternative electron cycling first study to reveal the dynamics of photosynthetic activities (electron cycling around photosystem I, electron transfer rates and carbon storage efficiency Mehler and/or photorespiration) being more impor- in diatoms under variable nutrient conditions. tant than xanthophyll cycling. Overall, our results suggest that P. antarctica could outcompete C. debilis in Fe-deficient waters at all light regimes. W1KN.5

PHOTOPHYSIOLOGICAL STRATEGIES TO W1OR.1 IRON LIMITATION AND HIGH LIGHT DIFFER BETWEEN TWO ANTARCTIC KEY EFFECTS OF PS I FLUORESCENCE AND PHYTOPLANKTON SPECIES CHLOROPLAST RELOCATION ON CHLOROPHYLL FLUORESCENCE Scarlett Trimborn1,2 ([email protected]), Silke Thoms1 ([email protected]), Sara Beszteri1 Erhard Pfündel ([email protected]) 2 ([email protected]) and Kai Bischof (kbischo- Department of Customer Support, Heinz Walz GmbH, [email protected]) Eichenring 6, 91090 Effeltrich, Germany

1Biogeosciences section, Alfred Wegener Institut, Am 2 Higher plant studies have demonstrated that PS Handelshafen 12, 27570 Bremerhaven Germany and Marine I fluorescence contributes up to 50% to total Fo Botany department, University of Bremen, Leobener Straße NW2, 28359 Bremen, Germany fluorescence, and that chloroplast movements can reduce the Fo level by 30%. Quantifications of these As iron (Fe) and light availability strongly influence factors and their effects on saturation pulse analyses phytoplankton species distribution in low Fe-waters, will be reviewed. PAM chlorophyll measurements to we investigated the combined effects of increasing study circadian chloroplast movements in algae (e.g., − − light (20, 200 and 500 μmol photons m 2 s 1)in Ulva lactuca, Acetabularia mediterranea) will be conjunction with different Fe (0.4 and 2 nM Fe) discussed. availability on the physiology of two ecologically rele- vant phytoplankton species in the Southern Ocean, W1OR.2 Chaetoceros debilis (Bacillariophyceae) and Phaeocystis antarctica (Haptophyceae). Combining BLINDED BY THE LIGHT: DARKNESS REVEALS Fast Repetition Rate fluorometry, elemental composi- THE COMPLEXITY OF ARCTIC DIATOMS tion and pigment analyses with cell-based modelling, PHOTOADAPTATIVE STRATEGY new insights on the photophysiological strategies of Dany Croteau ([email protected]), Sébastien the two tested species were gained. Fe-deficient cells Guérin ([email protected]), of P. antarctica displayed similar high growth rates at all irradiances. In comparison, Fe-deplete C. debilis Flavienne Bruyant ([email protected] cells grew much slower under low and medium irra- val.ca), Marcel Babin ([email protected]. diance and were unable to grow at the highest irra- ca) and Johann Lavaud ([email protected] diance. Interestingly, Fe-deficient C. debilis cells were val.ca) better protected against short-term excessive irra- Takuvik Joint International Laboratory, Université Laval diances than P. antarctica. Next to similar electron (Canada) - CNRS (France), UMI3376, Département de transfer rates, Fe-deplete C. debilis cells displayed Biologie, Université Laval, Québec, Québec G1V 0A6, Canada faster re-oxidation of the primary electron acceptor Qa, indicating operation of a putative plastid plasto- Pulse Amplitude Modulated (PAM) fluorometry is quinol terminal oxidase, known to create a proton a widely-used technique in studies of photosynthesis gradient in the thylakoid lumen. In line with this, with various light treatments. It allows to distinguish high xanthophyll activity was shown by its high cel- the amount of light energy channeled into an electro- lular diadinoxanthin content along with very high chemical gradient from the excess, potentially harm- NPQ activities. Such strategy was especially efficient ful, one dissipated as heat via the non-photochemical after short-term exposure to high irradiance, as seen quenching (NPQ). Applying PAM fluorometry once by the high potential of Fv/Fm recovery (~70-80%), growing or stressful irradiance is turned off, can also pointing towards a high tolerance of C. debilis to give tremendous insights on subtler physiological short-term high light stress. This tolerance was, reactions ongoing in darkness or under recovering EUROPEAN JOURNAL OF PHYCOLOGY 113 low light. Diatoms of the Arctic Ocean exploit an energy absorbed in excess under constant light. extreme light environment, controlled by the seasonal Under balanced growth at moderate and high irradi- dynamics of the snow/ice cover coupled with extreme ance, NPQ is often sustained (hours-days kinetics photoperiod contrasts. Therefore, adaptations to fre- relaxation) and the quenching efficiency (QE) of Dt quent light fluctuations and prolonged periods of or Z is very low. We investigated the characteristics of obscurity are to be expected, but few studies have NPQ in the haptophyte Tisochrysis lutea and in the been conducted on the matter. To address this ques- Arctic diatom Thalassiosira gravida under various tion, we grew five arctic diatoms species in the lab, growth conditions (Low Light, high light, representative of distinct niches over the seasonal N starvation, N limitation in a chemostat, continuum of the light environment: from the snow- P starvation, L/D cycles). Both species showed sus- covered dimly lit bottom ice to the autumnal strati- tained NPQ (NPQs) at moderate/high irradiance, fied waters. Using different light exposures, dark which is very difficult to quantify using PAM fluoro- incubations and inhibitors, we tried to determine metry. When cells were suddenly exposed to an how highly contrasted light environments could increasing light gradient, a new NPQ (NPQd) devel- have shaped diverse photoadaptative strategies. As oped due to additional Dt synthesized from Dd de- usually observed in diatoms, all species relied heavily epoxidation (as proven by DTT effect). The QE of the on fast responding NPQ to shift between light har- newly synthesized Dt was much higher than the QE vesting and photoprotective states. However, clear of the preexisting Dt. NPQd extent was inversely discrepancies were revealed when comparing their proportional to NPQs. The potential role of NPQs long-term relaxation kinetics following light expo- in the photophysiological plasticity of microalgae, sures. Sustained NPQ, chlororespiration and photo- especially under adverse growth conditions, is system repair cycle were differentially expressed discussed. across species and photoacclimations. Through struc- tural modulations of photosystem II and plastoqui- none redox reactions, these mechanisms influence W1OR.4 fluorescence emissions and were monitored by PAM ENHANCEMENT OF PHOTOSYNTHESIS IN fluorometry. These unusual photoadaptative features, SYNECHOCOCCUS BACILLARIS BY alongside strong «classical» NPQ, could explain how SPONGE-DERIVED AGELADINE A: arctic diatoms tread the thin line between meeting A THEORETICAL PERSPECTIVE metabolic demands and mitigating photo-oxidative stress in a harsh light environment at freezing Silke Thoms1 (silke.thoms@awi), Ulf Bickmeyer1 (ulf. temperatures. [email protected]), Florian Koch1,2 (florian. [email protected]), Liliane Petety Mukagatare1 (mukaga- [email protected]), Romaston Silalahi1 (Romaston. W1OR.3 [email protected]) and Franz Josef Sartoris1 (Franz- [email protected]) THE ROLE OF SUSTAINED PHOTOPROTECTIVE NON-PHOTOCHEMICAL 1 Alfred Wegener Institute Helmholtz Center for Polar and QUENCHING IN MICROALGAE Marine Research. Department of Biosciences. Am 2 1, Handelshafen 12, 27570 Bremerhaven. Germany and Thomas Lacour ([email protected]) Marcel University of Applied Sciences Bremerhaven, An der Karlstadt Babin 2 ([email protected]) and Johann 8, 27568 Bremerhaven, Germany Lavaud ([email protected]) Marine sponges harbor many symbionts, which con- 1 Ifremer, Laboratoire Physiologie et Biotechnologies des Algues, stitute a large amount of the sponge’s dry weight. Rue de l’île d’Yeu, BP 21105, 44311 Nantes cedex 3, France and Symbionts of sponges, such as the cyanobacterium 2Takuvik Joint International Laboratory, Université Laval (Canada) - CNRS (France), Université Laval, Québec, Québec, Synechococcus, likely serve a role similar to that of Canada. the gut microbiome in mammals. The sponge Agelas sp. produces a brominated pyrrole alkaloid, Ageladine Xanthophyll cycle (XC) related non-photochemical A, which accumulates in acidic cellular compart- quenching (NPQ), which is present in most photo- ments and has previously been used as a pH sensitive, autotrophs, allows dissipating excess light energy. fluorescent dye. Ageladine A, may therefore also Generally, it can be reversed for photosynthesis to accumulate in the acidic thylakoid space of photo- resume when light intensity is brought back to more synthetic cells. The ecophysiological role of Ageladine optimal intensity. The presence of diatoxanthin (Dt) A in the sponge biome, however, is still unresolved. or Zeaxanthin (Z) at steady state in photoautotrophs This study shows that Ageladine A acts as an addi- acclimated to moderate and high irradiance suggests tional light harvesting molecule for photosynthesis of that they use XC related NPQ to dissipate light the symbionts. A joint modeling and experimental 114 KEYNOTE AND ORAL PAPERS approach revealed that Ageladine A facilitates photo- respectively. While the absorbance of Ageladine A is synthesis of Synechococcus, when the cells are exposed in the UV range, it fluoresces blue, matching the blue to UV light. Due to the presence of Ageladine A, absorbance of chlorophyll a. This study, for the first photosynthetic production of O2 increased 2.54 and time, presents a type of symbiosis in which light is the 3.1-fold, in the experiments and the model, major currency of species interaction. EUROPEAN JOURNAL OF PHYCOLOGY 115

Workshop 2: Handling large genomic datasets

W2KN.1 phylogenomic, comparative transcriptomic/genomic, population genomic, and physiological experiments ASSEMBLY AND ANALYSIS OF THE using the Emiliania/Gephyrocapsa complex to under- LAMINARIA DIGITATA GENOME AND stand this ongoing evolutionary story. Phylogenomic TRANSCRIPTOME studies reveal with involving all five species in the Shivani Rana1 ([email protected]), Daniel Emiliania/Gephyrocapsa complex show E. huxleyi Liesner2 ([email protected]), Klaus Valentin2 forming a monophyletic clade only in nuclear multi- ([email protected]), Inka Bartsch2 (inka. gene coalescent phylogenies, not in organellar phylo- [email protected]), and Gernot Glöckner (gernot. genies. The incongruence of the chloroplast, mito- [email protected])1 chondrial, and nuclear phylogenies suggests incomplete lineage sorting in large populations and 1Department of Biochemistry, Medical Faculty University of a history of introgressive hybridization. Of the SNPs Cologne, Joseph-Stelzmann-Straße 52, D-50931 Cologne, which distinguish nuclear clades within the species Germany, 2Alfred Wegener Institute, Division of Biosciences, Am Handelshafen 12 D-27570 Bremerhaven, Germany complex, between 9% and 25% occur in protein- coding sequences, with average Ka/Ks ratios ranging Kelp species can form forests which provide impor- from 1.26 to 2.62, suggesting positive selection on tant benefits for other species. We set out to analyze a small number of genes is driving diversification in the genome of Laminaria digitata and to assess the these organisms. We also found that strains living in variability within and between populations. The gen- lower latitude regions further from the coast where ome is estimated to be around 700 MB long prevent- the abundance of their conspecifics remains low to ing the complete assembly from short reads only. have a tendency to lose genes specific for the haploid Thus, we not only prepared DNA for short Illumina motile phase. RadSeq studies of genetics nearby based reads but also high molecular weight DNA for populations with and without the tendency to lose Nanopore sequencing from female and male gameto- 1N strains suggested that loss of haploid genes might phytes. Hybrid assembly of raw reads resulted in correspond to obligate parthenogenesis. Finally, we ~700 Mb scaffolds indicating near full coverage of are exploring whether such genomic changes corre- the haploid genome. Transcript data were used to late with physiological differences in response to enhance the reliability of gene prediction. I will dis- nutrient starvation. In summary, a history of several cuss challenges of genome assembly of such large evolutionary processes is recorded in E. huxleyi and genomes and characterize it in comparison to already its close relatives, providing a model for understand- published brown algae genomes. ing the evolutionary processes involved in phyto- plankton sympatric speciation, range expansion, and adaptation to new environments. W2KN.2 ECO-EVOLUTIONARY DRIVERS AFFECT LIFE CYCLE CHANGES AND MICROEVOLUTION OF W2KN.3 THE EMILIANIA/GEPHYROCAPSA SPECIES COMPLEX LEVERAGING SEQUENCE AND EXPRESSION INFORMATION FROM DE NOVO Uwe John ([email protected]) TRANSCRIPTOMES; STRATEGIES AND CASE STUDIES FROM THE BROWN ALGAE Alfred-Wegener-Institute for Polar and Marine Research, Chemical Ecology, Am Handelshafen 12, 27570 Bremerhaven, Gareth A. Pearson ([email protected]), Ester Germany A. Serrão ([email protected]) and Neusa Martins Emiliania huxleyi has become the numerically domi- ([email protected]) nant or co-dominant coccolithophore in essentially CCMAR, Universidade do Algarve, Gambelas, 8005-139 Faro, all of the surface ocean since its first appearance only Portugal 291000 years ago. In contrast, its closest living rela- tives in the genus Gephyrocapsa exhibit much more For the vast majority of algae, genome sequences are restricted distributions. We have conducted a set of unavailable, while access to the resources and 116 KEYNOTE AND ORAL PAPERS expertise to generate them are in many cases still It is unknown which innovations explain the diversi- limited. Given this, transcriptome sequencing fication of mesophiles given their highly reduced (RNAseq) will remain an important and accessible gene inventory. To address this important issue, we tool to generate sequence information for coding combined a significantly improved long-read assem- genes, and to allow expression analysis in experimen- bly from the unicellular red alga Porphyridium pur- tal studies. Focusing on brown algae (a group for pureum with a variety of other algal genomes to which some genomes are becoming available), we reconstruct ancient endosymbiotic gene transfer will discuss strategies for generating de novo tran- (EGT) and gene duplication events. We report evi- scriptomes using short-read RNAseq data. Raw de dence of ancient EGTs associated with the plastid novo transcriptomes tend to be large and complex. translocons and core photosynthetic machinery that Therefore, post-assembly curation strategies based on likely played a fundamental role in plastid establish- re-mapping, transcript quality assessment and clus- ment. More significant to the major focus of our tering are useful to reduce redundancy and complex- study is the finding of extensive duplications and ity. Additional challenges arise due to potential diversification of nuclear-encoded phycobilisome lin- contamination of field-collected, non-axenic or non- ker proteins that play central roles in stabilizing light- unialgal samples, which complicate gene expression harvesting functions. We interpret these latter results and sequence-based (phylogenetics, hybridization) as evidence that the origin of complex phycobilisome applications. Finally, specific challenges are associated linker proteins in mesophilic red algae allowed them with brown algal genome organization that can result to adapt and radiate under different light regimes. in “polycistronic” transcripts that must be addressed This finding addresses a key question about red prior to downstream analysis. To illustrate some of algal evolution and more broadly, illuminates how these issues and solutions to deal with them, we draw a major group of eukaryotes “escaped” from two recent case studies involving kelp transcrip- a depauperate gene inventory to conquer a large tomes (Phaeophyceae, Laminariales). The first is an swath of the near-shore marine ecosystem. analysis of gametogenesis in Saccharina latissima,to identify sex-specific and -independent processes underlying the gametogenic developmental programs W2OR.1 of male and female gametophytes. The second is an USING GENOME SCALE METABOLIC analysis of homoploid hybrid sporophytes derived NETWORKS TO STUDY ALGAL BIOLOGY AND from crosses between Laminaria digitata and EVOLUTION L. pallida; two hybridizing kelp species with different 1 thermal optima. Simon Dittami ([email protected]) , Arnaud Belcour ([email protected])2, Meziane Aite ([email protected])2, Hetty KleinJan (hetty. 1 W2KN.4 [email protected]) , Gabriel Markov (gabriel.mar- [email protected])1, Clémence Frioux2 (clemence. EXPANSION OF PHYCOBILISOME LINKER [email protected]), Catherine Boyen (boyen@sb-roscoff. GENE FAMILIES IN A MESOPHILIC RED ALGA, fr)1 and Anne Siegel ([email protected])2 PORPHYRODIUM PURPUREUM 1 JunMo Lee1,2 ([email protected]), Dongseok Sorbonne Université, CNRS, Integrative Biology of Marine 1 Models (LBI2M), Station Biologique de Roscoff, 29680 Roscoff, Kim ([email protected]), Debashish France and 2 Univ. Rennes, INRIA, CNRS, IRISA, Institute for Bhattacharya2 ([email protected]) and Research in IT and Random Systems, France Hwan Su Yoon1 ([email protected]) Large-scale genomic and metagenomic projects 1Department of Biological Sciences, Sungkyunkwan University, today can comprise hundreds or even thousands of 2 2066 Seobu-ro, Jangan-gu, 16419 Suwon, Korea, Department different genomes. Metabolic networks can provide of Biochemistry and Microbiology, Rutgers University, 59 Dudley Road, Foran Hall 102, New Brunswick, 08901 New a useful tool to filter this wealth of information and Jersey USA extract biologically and evolutionarily relevant fea- tures of the metabolism of the different species. Here The common ancestor of the ecologically and eco- we present a suite of tools (AuReMe, Compare) to nomically important red algae (Rhodophyta) under- automatically generate robust metabolic models went massive genome reduction over 1 billon years from heterogenous genomic data and to compare ago, whereby ca. 25% of the gene inventory shared and analyze them. The tools were designed to simul- with their sister green algae and plants was lost. This taneously deal with several tens of eukaryote and was followed by the split of Rhodophyta into the hundreds of prokaryote genomes. By including species-poor extremophilic Cyanidiophytina and the gene orthology information in comparisons of meta- highly successful (>7000 species) mesophilic lineages. bolic models, we minimize the impact of qualitative EUROPEAN JOURNAL OF PHYCOLOGY 117 differences between the genomes and their annota- metabolic networks can be used to interpret tions. We then give two examples of how these tools a complex metagenomic and meta-transcriptomic can be applied to answer biological questions. First, dataset of the brown alga Ectocarpus subulatus inter- we discuss a global comparison of 39 metabolic net- acting with different bacterial communities. The aim works of representative multi- and unicellular algae was to identify bacterial metabolic functions likely from the green-, red-, and stramenopile lineages to related to the capacity of the alga to grow in fresh- identify metabolic specificities of selected groups water and metabolic maps were reconstructed for and species. These analyses highlight, for instance, different bacterial communities identified in differences between uni- and multicellular strame- response to this stress. These analyses suggest the nopiles with respect to oxylipin- and cell wall meta- importance of maintaining selenoamino acid meta- bolism. They also pinpoint subtle differences at the bolism, but also underline the production of bacter- metabolic scale between closely related brown algal ial quorum sensing molecules in cultures that are species.Inasecondexampleweshowhow maladapted to fresh water.