title: Dangerous Relations in the Arctic Marine Food Web: Interactions between Toxin Producing Pseudo-nitzschia Diatoms and Calanus Copepodites.
abstract: Diatoms of the genus Pseudo-nitzschia produce domoic acid (DA), a toxin that is vectored in the marine food web, thus causing serious problems for marine organisms and humans. In spite of this, knowledge of interactions between grazing zooplankton and diatoms is restricted. In this study, we examined the interactions between Calanus copepodites and toxin producing Pseudo-nitzschia. The copepodites were fed with different concentrations of toxic P. seriata and a strain of P. obtusa that previously was tested to be non-toxic. The ingestion rates did not differ among the diets (P. seriata, P. obtusa, a mixture of both species), and they accumulated 6%-16% of ingested DA (up to 420 µg per dry weight copepodite). When P. seriata was exposed to the copepodites, either through physical contact with the grazers or separated by a membrane, the toxicity of P. seriata increased (up to 3300%) suggesting the response to be chemically mediated. The induced response was also triggered when copepodites grazed on another diatom, supporting the hypothesis that the cues originate from the copepodite. Neither pH nor nutrient concentrations explained the induced DA production. Unexpectedly, P. obtusa also produced DA when exposed to grazing copepodites, thus representing the second reported toxic polar diatom.
authors.affiliation: Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, 1307 Copenhagen, Denmark. Sara.Hardardottir@snm.ku.dk.|National Institute of Aquatic Resources, Technical University of Denmark, Charlottenlund Slot, Jægersborg Allé 1, 2920 Charlottenlund, Denmark. Sara.Hardardottir@snm.ku.dk.
authors.forename: Sara
authors.initials: S
authors.lastname: Harðardóttir
authors.affiliation: Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, 1307 Copenhagen, Denmark. tgin@aqua.dtu.dk.|National Institute of Aquatic Resources, Technical University of Denmark, Charlottenlund Slot, Jægersborg Allé 1, 2920 Charlottenlund, Denmark. tgin@aqua.dtu.dk.
authors.forename: Marina
authors.initials: M
authors.lastname: Pančić
authors.affiliation: Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, 1307 Copenhagen, Denmark. atammilehto@snm.ku.dk.
authors.forename: Anna
authors.initials: A
authors.lastname: Tammilehto
authors.affiliation: Alfred-Wegener-Institut für Polar- und Meeresforschung, Ökologische Chemie, Am Handelshafen 12, 27570 Bremerhaven, Germany. bernd.krock@awi.de.
authors.forename: Bernd
authors.initials: B
authors.lastname: Krock
authors.affiliation: Arctic Research Center, Department of Bioscience, Roskilde, Aarhus University, Frederiksborgvej 399, P.O. Box 358, 4000 Roskilde, Denmark. efm@bios.au.dk.
authors.forename: Eva Friis
authors.initials: EF
authors.lastname: Møller
authors.affiliation: National Institute of Aquatic Resources, Technical University of Denmark, Charlottenlund Slot, Jægersborg Allé 1, 2920 Charlottenlund, Denmark. tgin@aqua.dtu.dk.
authors.forename: Torkel Gissel
authors.initials: TG
authors.lastname: Nielsen
authors.affiliation: Natural History Museum of Denmark, University of Copenhagen, Sølvgade 83S, 1307 Copenhagen, Denmark. nlundholm@snm.ku.dk.
authors.forename: Nina
authors.initials: N
authors.lastname: Lundholm
mesh_terms: D000818:Animals; D033342:Copepoda / Q000502:physiology*; D017377:Diatoms / Q000502:physiology*; D020387:Food Chain; D006863:Hydrogen-Ion Concentration; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000633:toxicity; D008387:Marine Toxins / Q000633:toxicity*
chemical_list: D008387:Marine Toxins; C012301:domoic acid; D007608:Kainic Acid
keywords: Calanus copepodites; P. obtusa; Pseudo-nitzschia seriata; chemical ecology; domoic acid; grazing; induction; toxin production