title: Intraspecific facilitation by allelochemical mediated grazing protection within a toxigenic dinoflagellate population.
abstract: Dinoflagellates are a major cause of harmful algal blooms (HABs), with consequences for coastal marine ecosystem functioning and services. Alexandrium fundyense (previously Alexandrium tamarense) is one of the most abundant and widespread toxigenic species in the temperate Northern and Southern Hemisphere and produces paralytic shellfish poisoning toxins as well as lytic allelochemical substances. These bioactive compounds may support the success of A. fundyense and its ability to form blooms. Here we investigate the impact of grazing on monoclonal and mixed set-ups of highly (Alex2) and moderately (Alex4) allelochemically active A. fundyense strains and a non-allelochemically active conspecific (Alex5) by the heterotrophic dinoflagellate Polykrikos kofoidii. While Alex4 and particularly Alex5 were strongly grazed by P. kofoidii when offered alone, both strains grew well in the mixed assemblages (Alex4 + Alex5 and Alex2 + Alex5). Hence, the allelochemical active strains facilitated growth of the non-active strain by protecting the population as a whole against grazing. Based on our results, we argue that facilitation among clonal lineages within a species may partly explain the high genotypic and phenotypic diversity of Alexandrium populations. Populations of Alexandrium may comprise multiple cooperative traits that act in concert with intraspecific facilitation, and hence promote the success of this notorious HAB species.
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany uwe.john@awi.de.
authors.forename: Uwe
authors.initials: U
authors.lastname: John
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Urban
authors.initials: U
authors.lastname: Tillmann
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hülskötter
authors.affiliation: Senckenberg Research Institute and Natural History Museum Frankfurt, Senckenberganlage 25, 60325 Frankfurt a. M., Germany.
authors.forename: Tilman J
authors.initials: TJ
authors.lastname: Alpermann
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Sylke
authors.initials: S
authors.lastname: Wohlrab
authors.affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology, PO Box 50, 6700 AB Wageningen, The Netherlands.
authors.forename: Dedmer B
authors.initials: DB
authors.lastname: Van de Waal
mesh_terms: D004141:Dinoflagellida / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D057097:Harmful Algal Bloom; D058086:Microalgae / Q000235:genetics / Q000378:metabolism; D010675:Pheromones / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction
chemical_list: D010675:Pheromones
keywords: Alexandrium fundyense; allele-specific quantitative PCR; associational resistance; grazing protection; harmful algal blooms; phenotypic diversity