Irish Marine Institute biotoxin, phytoplankton and remote sensing data for Harmful Algal Event monitoring Identification Information (NCEI Accession 0000668)

The presence of harmful algal species, which produce toxins, pose a significant threat to public health and coastal aquaculture activities. For example, estimated losses due to biotoxin closures have cost the Irish shellfish industry $4 million in 2000. Biotoxins, which have the potential to cause the following human illnesses: diarrhetic, paralytic, amnesic and azaspiracid shellfish poisoning (known as DSP, PSP, ASP and AZP respectively) have been detected in shellfish in Ireland. The toxic phytoplankton species of concern in Irish waters are: Dinophysis spp. (DSP), Alexandrium spp. (PSP), and Pseudo-nitzschia spp (ASP). The only locations where blooms of A. tamarense and accumulation of toxins occur are Cork Harbour and Belfast Lough. The marine source of AZP has still to be confirmed. The Marine Environment and Health Services Division of the Irish Marine Institute is responsible for monitoring water samples collected from shellfish production areas for the presence of potentially harmful algal species. This information is used by the Marine Institute as an early warning of potential harmful algal events, as an indicator of what type of toxin analysis needs to be carried out and as scientific evidence to supplement the results of toxin analysis of shellfish. However, due to a variety of reasons, it has not been possible to demonstrate a direct correlation between numbers of potentially toxic phytoplankton in water samples and the presence of toxins in shellfish. Therefore, phytoplankton counts on their own are not used to decide the toxicity status of shellfish production areas. Symptoms of DSP appear after 30 mins to a few hrs of consumption and include nausea, vomiting, diarrhea and abdominal pain. Ingestion of shellfish containing the PSP biotoxin acts quickly (within 30 mins of consumption) and can cause numbness, and tingling of the lips, tongue, face and extremities, difficulty in talking, breathing, swallowing and muscle spasms. In severe cases death can occur due to respiratory paralysis. The Biotoxin Unit of the Marine Institute regularly monitors shellfish for the presence of toxins using both mouse bioassays and analytical chemistry methods. Production areas are closed for shellfish harvesting if the mouse bioassays are positive, i.e., 2 out of the 3 mice die within 24 hours of being injected intraperitonally with a Di Ethyl Ether (Note: Di Ethyl Ether replaced Acetone as the chemical extractant in 2001) extraction of toxins from the homogenised shellfish hepatopancreas.

In addition, the use of remote sensing data has been identified as one of the key components of the Marine Institute's proposed HAE forecasting system. To evaluate the application of this technology, SeaWiFS images that have been compiled as part of the EU funded BIOCOLOR project by the Remote Sensing Data Analysis Service (RSDAS) in Plymouth, U.K., have been re-analysed by NOAA/NOS and Marine Institute personnel. The re-analysed images were taken in 1998 during a large bloom of Karenia mikimotoi formerly known as Gyrodinium aureolum) that extended across the northern Celtic Sea and a region of the Irish shelf adjacent to the large bays of southwestern Ireland.