MEPS 241:13-21 (2002)  -  doi:10.3354/meps241013

Fate of cyanobacterial toxins in the pelagic food web: transfer to copepods or to faecal pellets?

M. Lehtiniemi1,*,**, J. Engström-Öst1,*, M. Karjalainen1,*, B. Kozlowsky-Suzuki2, M. Viitasalo3

1Department of Ecology and Systematics, Division of Hydrobiology, University of Helsinki, PO Box 65, 00014 Helsinki, Finland
2Department of Biology and Environmental Sciences, University of Kalmar, Barlasgatan 1, 39182 Kalmar, Sweden
3Finnish Institute of Marine Research, PO Box 33, 00931 Helsinki, Finland
*Present address: Finnish Institute of Marine Research, PO Box 33, 00931 Helsinki, Finland **E-mail:

ABSTRACT: Toxic cyanobacterial blooms are a common phenomenon in the Baltic Sea. The fate of the toxin in the food web is largely unknown. We studied the effect of algal diets on production of pellets and toxin content of the calanoid copepod Eurytemora affinis in the northern Baltic Sea. Field-collected copepods were fed with (1) cultured toxic cyanobacteria Nodularia spumigena; (2) cultured non-toxic flagellates Brachiomonas submarina; and (3) a natural phytoplankton assemblage. Natural phytoplankton was dominated by non-toxic cyanobacteria Aphanizomenon flos-aquae, but also remnants of toxic N. spumigena were found. Pellet production was highest on cultured B. submarina, second highest on N. spumigena and lowest on natural phytoplankton. Because pellets were produced on cultured N. spumigena, this shows that toxic cyanobacteria are consumed if no other food is available. The toxin content of E. affinis was highest in copepods fed with cultured N. spumigena, but toxin was also found in lower concentrations in animals fed with natural phytoplankton. Results indicate that an accumulation of toxins mainly occurs during a growing phase of cyanobacterial blooms. The toxin concentration in the pellets was approximately 6 to 12 times lower than in the copepods. We suggest that a large part of the ingested toxin accumulates in copepod tissues, although some is egested with pellets. This may lead to transport and, possibly, accumulation of cyanobacterial toxin in higher pelagic trophic levels in the Baltic Sea.


KEY WORDS: Cyanobacterial toxin · Nodularia spumigena · Toxin transfer · Copepods · Faecal pellets


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