Publication Date:
2015-06-18
Description:
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.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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