Marine biological excursion University of Innsbruck & Kiel Calvi, Corsica 2016 August 20th – september3rd Pictures: Daniela Spielmann; Fabian Wolf Participants Trainers Students Reinhold Hanel Innsbruck Kiel Bert Hobmayer Mattia Baraldo Shaomin Chen Philip Bertemes Rafael Meichßner Assistant Laura-Sophie Frommelt Alica Ohnesorge Belinda Artes Stefanie Pfeifenberger Serra Örey Jana Ribitsch Nora-Charlotte Pauli Attendee Daniela Spielmann Fabian Wolf Elio Hobmayer Julia Vorhauser Stephanie Waich 1 Design: Philip Bertemes Excursio Contents Introduction ................................................................................................................................................... 3 Daily protocols Algea .............................................................................................................................................................. 5 Boulder Field ................................................................................................................................................ 12 Coralligène ................................................................................................................................................... 18 Fish diversity ................................................................................................................................................ 24 Plankton ....................................................................................................................................................... 39 Macrofauna of the sandy beach .................................................................................................................. 46 Seagrass ....................................................................................................................................................... 55 Girolata & Fango .......................................................................................................................................... 66 Projects Sea urchin development ............................................................................................................................... 74 I) Body axis manipulation of Arbacia lixula .............................................................................................. 75 II) Reaggregation of sea urchin embryos ................................................................................................. 95 III) F-actin dynamics in the sea urchin Arbacia lixula from the fertilized egg to the pluteus larva ...... 106 Fishes of Corsica – Who are they and what are they feeding on? ............................................................... 121 2 Introduction The “station de Recherche Océanographiques et sous Marines” (STARESO) founded by the university of Liege is a marine biological center on the North-Western coast of Corsica that offers direct access to the sea combined with a research facility for scientists and students from all over the world. Here students and scientist are welcome to study the marine environment under various aspects. The station offers two dry and one wet lab as well as sleeping quarters that serve amongst others the University of Innsbruck and Kiel as base for a cooperative marine biological excursion. The course, that takes place every two years, gives students the possibility to get an insights in the biodiversity of the Mediterranean Sea as well as in the existing habitats and their different environmental conditions. Therefore the participants get background information in daily lectures and learn to determine diverse species during snorkeling sessions in the first week. In the second week the students work on individual projects in groups. In the STARESO lab the students are able to perform their own experiments in the field of developmental biology and fish biology. 3 Daily protocols 4 Algea Serra Örey, Rafael Meichßner Introduction Macroalgae are a polyphyletic group of photosynthetic organisms consisting of Phaeophyta (brown algae), Chlorophyta (green algae) and Rhodophyta (red algae). These groups are phylogenetically far apart descending from different unicellular ancestors (Cock et al. 2010). As a result they have different accessory photosynthetic pigments which are responsible for their typical color. From polar to subtropical regions macroalgae dominate shallow benthic areas with hard substrate (Lüning 1985). In places like the island of Corsica with a lot of rocky coastline algae represent the main benthic primary producers of the shallow water ecosystem (Ballesteros 1989). On our excursion to the Marine Biological Station STARESO in the northwest of Corsica we spent one day on exploring the local macroalgal flora. Generally, the ecological niche of an algal species in coastal habitats is defined by its resistance to desiccation on one hand and its light demand on the other hand. Due to these two factors algal communities arrange in girdles of typical, sometimes almost monospecific composition (Lüning 1985). In our study area in Corsica, there were no significant tidal changes to create advantage for desiccation resistant species. Therefore, in Stareso, we expected light to be the main driver and hence macroalgal species to arrange along a light gradient. As light conditions change with depth and also with the morphology of the rocks, we aimed to assess the present algal community with respect to different depth zones and daylight exposure. Methods The explored habitat was a boulder field with larger rocks in adjacent areas, also including a harbor wall. Sampling was done by collecting the algae species by snorkeling. Three depth zones were decided as following: 0-1 m, 1-3 m and 3-5 m. Each zone was sampled by two people twice. During sampling, it was noted if the sampled algae were from a shadowed area or an area highly exposed to direct daylight. Specimens were brought to land, stored in buckets filled with seawater and identified with the help of Riedl (1983). 5 RESULTS There were in total 19 algae species identified during the study. We found four species in all water depth zones that were: Dictyota dichotoma, Halopteris scoparia, Padina pavonica, Udotea petiolata. More than half of the species were specific to their depth zone. The only species never found in shadowed conditions was Chaetomorpha sp.. On the other hand the following species were only found in areas of limited light exposure due to rock structure: Peyssonnelia squamaria, Lithothamnion sp., Caulerpa racemosa, Codium adherens, Codium bursa, Cryptonemia sp., Halimeda tuna, Pseudolithophyllum expansum. Table 1- Total species list with distribution among depths and different light conditions Phylum Class Species Total Light Conditions distribution 0-1m 1m-3 m 3m-5m Ochrophyta Phaeophyceae Dictyota dichotoma All Both Light Light Ochrophyta Phaeophyceae Halopteris scoparia All Both Both Both Ochrophyta Phaeophyceae Padina pavonica All Both Both Light Chlorophyta Ulvophyceae Udotea petiolata All Both Both Both Rhodophyta Florideophyceae Corallina Top Both - - mediterranea Rhodophyta Florideophyceae Jania rubens Top Both - - Rhodophyta Florideophyceae Peyssonnelia Top Dark - - squamaria Chlorophyta Ulvophyceae Chaetomorpha sp. Top-Mid Both Light - Chlorophyta Ulvophyceae Cladophora prolifera Top-Mid Dark Both - Ochrophyta Phaeophyceae Cystoseira sp. Top-Mid Light Light - Rhodophyta Florideophyceae Lithothamnion sp. Mid - Dark - Rhodophyta Florideophyceae Amphiroa rigida Mid-Deep - Dark Both Ochrophyta Phaeophyceae Dictyota linearis Deep - - Light Chlorophyta Ulvophyceae Caulerpa racemosa Deep - - Dark Chlorophyta Ulvophyceae Codium adherens Deep - - Dark Chlorophyta Ulvophyceae Codium bursa Deep - - Dark Rhodophyta Florideophyceae Cryptonemia sp. Deep - - Dark Chlorophyta Ulvophyceae Halimeda tuna Deep - - Dark Rhodophyta Florideophyceae Pseudolithophyllum Deep - - Dark expansum 6 DISCUSSION In general, the results reveal that light is a driving factor for the species distribution on the rocky shore of Corsica, because the species composition differed between sites of different light regime. However, the species number did not change with depth or daylight exposure. There were similar numbers of species (6- 9) in all depth zones as well as in shadowed and light exposed sites in each respective depth zone. The uppermost 30 cm close to the water surface were dominated by Corallina mediterranea, especially on wave-exposed sites (Figure 2). More sheltered sites also showed specimens of Dictyota dichotoma and Jania rubens (Figure 1) Filiform green algae dominate in even more sheltered areas like rock holes (Figure 2). Reasons may be that this species can survive desiccation but doesn´t have a very high light demand and is therefore able to live in holes. On the other hand it may be less resistant to strong water movement and therefore be not able to grow on exposed (and hence sunny) sites. This is a good example for the weakness of the used method, because species composition in areas with different light levels can be explained by other factors (water movement, grazing, substrate type etc.), as well (Ruitton et al. 2000). These factors were not recorded and therefore cannot be part of the analysis. Consequently, the results will be interpreted with respect to light. The reader should keep in mind that other factors can be drivers for the distribution of species, too. Figure 1-: Typical algae community close to the water surface with J. rubens and D. dichotoma 7 Figure 2- C. mediterranea, growing in a hole close