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Role of Genotypic and Phenotypic (allelopathy) Diversity of Harmful Algal Blooms (habs): Case of the Dinoflagellate Alexandrium Tamarense
| Content Provider | Semantic Scholar |
|---|---|
| Author | Legrand, Catherine Alpermann, Tilman J. Béchemin, Christian Fragoso, Bruno Hülskötter, Jennifer John, Uwe Müller, Annegret Rudström, Maria Weissbach, Astrid Wohlrab, Sylke Cembella, Allan |
| Copyright Year | 2010 |
| Abstract | The adverse effects of harmful algal blooms (HABs) in marine ecosystems have focused attention on defining the role of factors that determine their increasing abundance and distribution. The dinoflagellate Alexandrium tamarense blooms regularly in cold temperate waters and can produce a suite of potent neurotoxins that cause paralytic shellfish poisoning (PSP) in humans, and have serious deleterious impacts on public health, ecological and economic resources. These toxins can accumulate to dangerous levels in shellfish and affect plankton food webs. Chemical interactions (allelopathy) among A. tamarense and other marine protists are an important biological factor for the dominance of Alexandrium, not solely restricted to the competition for nutrients under laboratory conditions. We tested the ecological significance of allelopathy in the regulation of Alexandrium population dynamics at a larger scale (15 x 2.5 m 3 mesocosms) in the semi-enclosed bay of Hopavagen, Norway, during July 2009. Mesocosms bags were filled with filtered seawater to eliminate large zooplankton (< 200 µm in 12 bags) and both grazers and zooplankton (< 0.2 µm in 3 bags). Two different isolates of A. tamarense (lytic and non-lytic) were inoculated (100-200 cells L -1 ) separately (2 x 3 bags, < 200 µm) and together (1 x 3 bags, < 200µm and 1 x 3 bags, < 0.2µm). Three bags were left without A. tamarense as controls. Nutrients (nitrate and phosphate) were added daily to all mesocosms. Multi-variable sampling revealed that both A. tamarense grew for two weeks in all inoculated bags (1000 cells L -1 ) but never formed a dense bloom. The coccolithophorid Emiliania huxleiyi outcompeted other phytoplankton after 2 weeks and bloomed in all bags, favored by the disappearance of appendicularians. Important results include gene expression profiles of Alexandrium and the prevalence of two different genotypes in mixed communities, PSP toxin profiles in different trophic levels meta-, micro-zooplankton, phytoplankton), protistan grazing on A. tamarense and the impact of lytic A. tamarense of nanoflagellate bacterivory, and large datasets on both marine eukaryotic microplankton and prokaryotic diversity. Our study provides a platform for further studies on allelopathy in aquatic systems and its implication in ecological processes. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://hydralab.eu/uploads/proceedings/NTNU-20_Legrand.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
