Marine Biotoxins and Harmful Algae:
A National Plan



EXECUTIVE SUMMARY


Marine biotoxins and harmful algae represent a significant and expanding threat to human health and fisheries resources throughout the United States. These phenomena take a variety of forms. From a public health standpoint, four human illnesses are associated with toxic algal blooms and consumption of toxin-contaminated shellfish in the United States: paralytic, neurotoxic, amnesic, and diarrhetic shellfish poisoning (called PSP, NSP, ASP, and DSP respectively). Except for ASP, all are caused by biotoxins synthesized by a class of marine algae called dinoflagellates. ASP is produced by another class of marine algae (diatoms) that until recently were thought to be harmless. A fifth human illness, ciguatera fish poisoning (CFP) is caused by biotoxins produced by epibenthic dinoflagellates attached to surfaces in many coral reef communities. Ciguatera toxins are transferred through the food chain from herbivorous reef fishes to larger carnivorous, commercially valuable finfish. In a similar manner, the viscera of other commercially important fish such as herring or sardines can contain PSP toxins, endangering human health following consumption of whole fish. Whales, porpoises, seabirds, and other animals can be victims as well, receiving toxins through the food chain via contaminated zooplankton or fish.

Marine fauna can be affected by a variety of algal species that release toxins or other compounds into the water or that kill by physically damaging gills. Problems associated with harmful algal species and farmed fish have increased considerably in recent years, due in part to the simultaneous expansion of the fish-farming industry. Furthermore, the death and decay of algal blooms can lead to anoxia through decompositional oxygen demand, resulting in widespread mortalities of fish, shellfish, and invertebrates. An additional problem is that of benthic or planktonic macroalgae that can proliferate in response to anthropogenic nutrient enrichment. This can lead to major negative impacts due to displacement of indigenous species, habitat alteration, or oxygen depletion.

The National Academy of Sciences recently issued a report expressing serious concerns about the quality of the nation's seafood (Ahmed, 1991), emphasizing the need for attention to marine biotoxins and harmful algae. In response to this directive and to a heightened public and governmental awareness of the changing nature of the coastal marine environment, governmental funding is being targeted towards marine biotoxins, harmful algae, and their impacts. The optimum allocation of these resources can benefit greatly from scientific guidance as the new programs are formulated and implemented. A workshop on Marine Biotoxins and Harmful Algae was thus convened in Charleston, South Carolina, from 21-24 April 1992, to bring scientists and regulatory officials together to evaluate U.S. research knowledge and capabilities, and to identify areas where research funds should be directed for maximum benefit.
From a number of nationally recognized leaders in the areas of marine biotoxins, harmful algae, seafood safety, and public health, 24 participants were selected to represent the critical scientific disciplines and all regions of continental North America. Position papers on 12 relevant topics, written by the participants and distributed before the workshop, formed the basis for discussions within the three working groups. Conclusions of the working groups were presented to all participants in two plenary sessions.

Twenty-eight major impediments to progress were identified. These can be summarized as follows:

Deficiencies related to the biotoxins: Toxin standards are largely unavailable; standard sample preservation and handling protocols do not exist; existing assay methods are inadequate for monitoring and research; molecular pharmacology and pharmacokinetics of marine biotoxins are poorly understood; diminution or loss of toxin production can occur in laboratory algal cultures; mass culturing of most toxic species is difficult.

Lack of information on harmful algae: Algal bloom dynamics and species succession are complex and not yet predictable; the relative effects of natural versus anthropogenic influences on population size, species composition, bloom longevity, and toxin production are unknown; knowledge of the physiology of growth and toxin production is inadequate; toxin standards and rapid assay methods are lacking; availability of isolates of toxic or harmful algae is limited.

Lack of information on impacted fisheries resources and protected marine resources: Toxin uptake, metabolism, and depuration in shellfish, fish, and other marine animals is poorly known; toxin sensitivities of different life history stages, and long-term effects of algal metabolites on growth, reproductive success and recruitment are unknown; movement of toxins through the food web is poorly understood; databases are inadequate and not readily accessible to potential users; methods for rapid field assays of fish or shellfish are lacking; toxin standards are often unavailable; analytical methods for toxin detection in animal tissue need improvement.

Inadequate mechanisms and knowledge to protect public health fully: Early warnings of known and unknown toxins are required to protect consumers and industry; assay methods need improvement; toxin standards are not always available; sampling programs are inadequate for bloom detection or characterization; the extent of seafood poisonings is poorly documented; the fate and metabolism of toxins in humans is unknown.

In every category, the lack of sensitive, specific assays (for research and/or shipboard and dockside testing) and toxin standards were identified as major impediments.

The working groups met and proposed recommendations to address each of the impediments. These recommendations, too numerous to list here, are described in detail in the report. They are also embodied in the following goal and objectives (non-prioritized) of the National Plan for Marine Biotoxins and Harmful Algae.


GOAL : Effective management of fisheries, public health, and ecosystem problems related to marine biotoxins and harmful algae.

SPECIFIC OBJECTIVES: