Crustaceans and molluscs are very good markers for natural marine toxins in the environment, which can accumulate up the food chain from marine algae and bacteria. Dinoflagellate toxins have been reported in several species of crustaceans and molluscs in Australia, but the source of these toxins is unknown (Llewellyn and Endean, 1991). The presence of toxins could be a natural occurrence or may be linked to exotic species of dinoflagellate, introduced via the ballast water of ships. Introduction of toxic dinoflagellates (‘red tide’ organisms) may pose a threat to human health and place valuable commercial fisheries at risk (Hallaegraeff and Bolch, 1991).

In this project, toxins produced by marine algae will be examined, the identification and distribution of natural toxins in molluscs and crustaceans will be assessed, and algae from natural sources and ballast samples analysed for toxins. So far, extracts from 190 crabs and shellfish have been screened for paralytic shellfish toxins and tetrodotoxins using two radio-labelled affinity assays (sodium channel and saxiphilin). High performance liquid chromatography (HPLC) was also used to examine the toxin composition. This is the first study to combine these rapid toxin assays and the HPLC analysis. The assay methods correlated well with the HPLC analysis. The toxicity of each extract was explained by the presence of saxitoxin and decarbamoyl saxitoxin and possibly tetrodotoxins in some extracts.

Toxins were detected in sixteen species of crabs and shellfish. Eight of these species have not previously been described as toxic and include one commercial species of crab (Blue Manna). The levels of toxicity were low to medium in comparison with extracts from Asia and were similar to those from samples collected on the Great Barrier Reef. The highest levels and frequency of toxins were detected in samples from Port Hedland and Dampier, with much lower levels in samples from the pristine Ningaloo Reef and Broome. Port Hedland and Dampier are two of Australia’s highest receivers of ballast water, which may harbour exotic toxin-producing dinoflagellates, a possible source of toxins in crabs and shellfish.

Collaborations with Dampier Salt (Operations) Pty. Ltd., Edith Cowan University, the University of Tasmania and microbiologists at AIMS will enable this project to examine the source(s) of these toxins. Macroalgae, bacteria and dinoflagellates from Port Hedland will each be tested for toxin production. An agreement has also been reached with the Australian Quarantine and Inspection Service (AQIS) to access dinoflagellate cysts from foreign vessels. These cysts will be germinated and cultures established for toxicity testing. The toxin analysis will be performed at AIMS Dampier and will help in the assessment of risk posed by the introduction of exotic organisms to our northern ports.

Llewellyn L.E. and Endean, R. (1991). Paralytic shellfish toxins in the xanthid crab Atergatis floridus collected from Australian coral reefs. Journal of Wilderness Medicine 2:118-126.

Hallegraeff, G.M and Bolch, C.J. (1991). Transport of toxic dinoflagellate cysts via ship’s ballast water. Marine Pollution Bulletin 22: 27-30.