Long-term survival of dinoflagellate cysts in anoxic marine sediments. Ellegaard, Marianne; Lundholm, Nina; Ribeiro, Sofia; Ekelund, Flemming; Andersen, Thorbjørn Joest Publication date: 2008 Document version Publisher's PDF, also known as Version of record Citation for published version (APA): Ellegaard, M., Lundholm, N., Ribeiro, S., Ekelund, F., & Andersen, T. J. (2008). Long-term survival of dinoflagellate cysts in anoxic marine sediments.. Abstract from Eight International Conference on Modern and Fossil Dinoflagellates - Dino8, Montreal, Canada. Download date: 02. okt.. 2021 0 DINO8 Eighth International Conference on Modern and Fossil Dinoflagellates May 4 to May 10, 2008 Université du Québec à Montréal Complexe des Sciences Pierre Dansereau Building SH, 200 Sherbrooke Street West, Montreal, Quebec, Canada Abstracts 1 TABLE OF CONTENTS ABSTRACTS……………………………………………………………………………………...2 LIST OF PARTICIPANTS………………………………………………………………………66 Organizing commitee Organizers : Anne de Vernal GEOTOP-UQAM, Canada ([email protected]) André Rochon ISMER-UQAR, Canada ([email protected]) Scientific committee: Susan Carty, Heidelberg College, Ohio, USA ([email protected]) Lucy Edwards, US Geological Survey ([email protected]) Marianne Ellegaard, University of Copenhagen, Denmark ([email protected]) Martin J. Head, Brock University, Canada ([email protected]) Alexandra Kraberg, Alfred Wegener Institute for Polar and Marine Research, Germany ([email protected] ) Jane Lewis, University of Westminster, UK ([email protected] ) Fabienne Marret, University of Liverpool, UK ([email protected] ) Kazumi Matsuoka, University of Nagasaki, Japan ([email protected] ) Jens Matthiessen, Alfred Wegener Institute for Polar and Marine Research, Germany ([email protected] ) Edwige Masure, Université Pierre et Marie Curie, France ([email protected] ) Marina Montresor, Stazione zoologica "Anton Dohrn" di Napoli, Italy ([email protected] ) Vera Pospelova, University of Victoria, Canada ([email protected] ) Suzanne Roy, ISMER-UQAR, Canada ([email protected]) Karin Zonneveld, University of Bremen, Germany ([email protected]) 2 ABSTRACTS Toxic blooms of Alexandrium fundyense in the Monitoring of the regional abundance of cysts may Gulf of Maine: the role of cysts in population thus hold the key to interannual forecasts of A. dynamics and long-term patterns of shellfish fundyense bloom severity in this region. toxicity This presentation will discuss these interannual changes in the context of the blooms that Don Anderson, Bruce A. Keafer, Kerry Norton, occurred before and after the mapping efforts and the Dennis J. McGillicuddy, Ruoying He, Cynthia H. temporal trends in PSP toxicity in the region over the Pilskaln, Darcie Couture and Jennifer L. Martin. last several decades as well. Evidence will be presented in support of the hypothesis that we have Resting cysts play important roles in bloom entered a “new era” that is likely to have sustained initiation, termination, and species dispersal for and significant blooms in the coming years to several important harmful algal blooms (HAB decades. A cyst seedbed-based conceptual model will species). Several studies have examined linkages be presented that is consistent with observed patterns between dinoflagellate cyst abundance and bloom of interannual to decadal variability in the severity of timing and location, but these efforts have typically blooms and shellfish toxicity in the Gulf of Maine. been over relatively small areas due to the difficulties Cyst-forming dinoflagellates and other and expense of mapping cysts over larger regions. phytoplankton species with resting stages are Here we present the results of five mapping surveys responsible for harmful algal blooms throughout the for living Alexandrium fundyense cysts in the Gulf of world. Our ability to map these stages and utilize Maine, each covering hundreds of km in the those observations to initialize hindcasts and forecasts alongshore direction, and 50 – 100 km in the offshore of bloom incidence is a major advancement in HAB (see Figure 1). The first survey in 1997 (augmented management. with Bay of Fundy data from 1982, 1983 & 1984) revealed a widespread cyst distribution, with two centers of abundance, one in the Bay of Fundy, and a The role of resuspension in the nearshore cyst second offshore of Casco and Penobscot Bays in dynamics of Alexandrium minutum (Dinophyceae) western Maine. The second survey (2004) shows a much larger cyst population, with approximately 10X Sílvia Anglès, Esther Garcés, Antoni Jordi and as many cysts in the western Maine seedbed area. Gotzon Basterretxea This was the cyst distribution that existed prior to, and undoubtedly contributed to, a massive 2005 A. Nearshore dinoflagellate blooms have fundyense bloom (“red tide”) in southern New recurrently occurred along the Mediterranean Sea England. The third survey was conducted after the since first blooms were reported back in the 60’s. It is 2005 bloom, and reveals levels of cysts in western a growing problem often associated to cultural Maine that are ~5X the 1997 levels, but ½ of the 2004 eutrophication that strikes with intensity in harbours, levels. No significant geographic expansion of cysts embayments, and coastal lagoons. Among other into southern waters was seen, as had been feared bloom forming species, Alexandrium minutum based on the high motile cell concentrations that (Dinophyceae) is widely distributed in the occurred in those waters during the 2005 bloom. The Mediterranean Sea and events of paralytic shellfish 2006 cyst map showed similar patterns to other years, poisoning (PSP) have been frequently associated with with approximately 30% fewer cysts than observed in this species. 2005. 2007 cyst abundance is 30% higher than the In the context of Mediterranean coastal historically high levels observed in 2004. The overall blooms, water confinement is known to be a pattern is thus one of large interannual variability, favouring factor from which A. minutum, benefits to with an apparent increase in recent years. produce extraordinary outbreaks with abundances Hindcasting studies using a physical- often exceeding 106 cells l-1 and durations that can biological numerical model demonstrate that a major expand for months. Harbours, ports and other cyst deposition or accumulation event was the protection structures confine coastal areas where dominant factor leading to the large A. fundyense turbulence and advective exchange is artificially bloom in the western GOM and southern New reduced. This is the case of Arenys de Mar harbor England in 2005 and that cyst abundance in Gulf of (NW Mediterranean), where recurrent blooms of A. Maine bottom sediments can be a first-order predictor minutum occurr every year since 1996. This of the magnitude of the resulting regional bloom. 3 recurrence is favoured by the existence of resting season, a dinoflagellate-dominated phytoplankton cysts accumulated in the sediment floor. assemblage was observed with few raphidophytes and During dormant stages, cyst abundances are cyanobacteria. Alexandrium minutum, a toxic determined by sediment conditions and dynamics. For microalgal species was observed during this time. In example, similarly to the planktonic stages, natural August, which is well into the southwest monsoon, mortality and grazing control cyst abundances in the two stations were dinoflagellate dominated while the sediment. Burial, reallocation within the substrate and rest were diatom dominated. These findings will be sedimentary transport also determine cyst analyzed together with environmental factors and the abundances. During the life stage transitions, presence of Alexandrium minutum cysts in these areas evidence shows that burial in anoxic sediments, low that may have contributed to such phytoplankton temperature and presence of sulfides in the sediment succession. can temporarily preclude mature cyst germination thereby controlling the bloom onset. In the open sea maximum accumulation of Taxonomic analysis of littke-known thecate dormant stages are often not right under the bloom planktonic dinoflagellates from the tropical shadow but in deep basins at the continental slope or Mexican Pacific in coastal areas. Conversely, in enclosed sites, relationships between planktonic and benthic stages Sofia Barón-Campis, D. Hernandez-Becerril, C. are more straightforward. In general, accumulation of Ramirez-Camarena, R. Rojas-Crisostomo and H. fine sediments in areas of reduced energy present Ramirez-Garcia higher cyst abundances suggesting that dormant stages behave as passive particles becoming part of Thecate dinoflagellates species of the genera the sediment dynamics. Although some of the aspects Ensiculifera, Fragilidium, Heterocapsa, of the mechanisms that regulate the fate of cysts in Pentapharsodinium and Scripssiella are marine and the sediment can be anticipated based on their free-living, solitary forms, small-sized generally (less morphological characteristics (mainly size and than 35 µm), which may produce calcareous cysts, density) most of the features of cyst dynamics remain some also may produce toxins and that are usually to be elucidated. neglected in routine phytoplankton analysis. From the In this study, we investigate the resting cyst existing species of the five genera (5, 5, 12, 2 and 19, dynamics of A. minutum in the Arenys de Mar harbor respectively, from a marine dinoflagellates’s world related to the seiching motion. Seiches are natural list,