Grazing on a toxic Alexandrium catenella bloom by the lobster krill Munida gregaria (Decapoda: Galatheoidea: Munididae)

- The pelagic phase of the lobster krill Munida gregaria was observed grazing on the toxic dinoflagellate Alexandrium catenella in the field and in the laboratory.
- M. gregaria sequestered paralytic shellfish toxin (PST) with a congener profile similar to that of the dinoflagellate.
- M. gregaria is consumed by a diversity of pelagic and demersal predators and facilitates food chain transmission of PST to higher trophic levels.

Specimens of Munida gregaria were collected within and in the vicinity of a bloom of the toxic dinoflagellate Alexandrium catenella in Queen Charlotte Sound, New Zealand. The crustacean contained paralytic shellfish toxin (PST) with an analogue profile dominated by N-sulfocarbamoyl analogues (C1,2 and GTX5) and carbamate gonyautoxins (GTX1,4), similar to that of the dinoflagellate. A feeding experiment showed that M. gregaria is capable of actively grazing on A. catenella and it may play a role in controlling population growth of the dinoflagellate. This is the first account of the accumulation of PST by M. gregaria. When it is periodically abundant, M. gregaria is an important food item for fish, birds and other marine fauna and they are a vector by which PST may be transferred to higher trophic levels.