Deposit-feeders accumulate the cyanobacterial toxin nodularin

Blooms of toxic cyanobacteria may potentially affect food web productivity and even be a human health hazard. In the Baltic Sea, regularly occurring summer blooms of nitrogen-fixing cyanobacteria are often dominated by Nodularia spumigena, which produces the potent hepatotoxin nodularin. Evidence of sedimentation of these blooms indicates that benthic fauna can be exposed to nodularin. In a one month experiment, we simulated the settling of a summer bloom dominated by N. spumigena in sediment microcosms with three species of sediment-dwelling, deposit-feeding macrofauna, the amphipods Monoporeia affinis and Pontoporeia femorata and the bivalve Macoma balthica, and analyzed nodularin in the animals by HPLC–ESI–MS (high-performance liquid chromatography–electrospray ionization–mass spectrometry). We found nodularin in quantities of 50–120 ng g−1 DW. The results show that deposit-feeding macrofauna in the Baltic Sea may contribute to trophic transfer of nodularin.

► Benthic fauna feed on the toxic cyanobacterium Nodularia spumigena.
► Settling blooms of toxic cyanobacteria are not directly harmful for deposit-feeders.
► Deposit-feeders can contribute to trophic transfer of the potent cyanotoxin nodularin.