Don Anderson

Alexandrium species of phytoplankton, which is responsible for causing the deadly paralytic shellfish poisoning.

Answers so far have been infrequent and tentative, for a number of reasons. One of the most important reasons is that we still do not know enough about important aspects of the basic biology and ecology of phytoplankton. Studying marine ecosystems presents its own unique challenges, making even such elementary scientific practices as obtaining valid samples far more difficult than land-based sampling. Ocean currents, changing weather patterns and the nature of the aquatic environment mean that phytoplankton populations have much more range and variability than plant species would have on land, for example. Recreating realistic, testable marine conditions in the laboratory is very challenging.

In 1992, a plan was created regarding marine biotoxins and harmful algae, and was hammered out through presentations, discussions and working groups by leading scientists in the field. At the workshop where these issues were discussed, 28 major impediments to progress were identified. These included the following:

• 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.

With these many important elements either poorly understood or still completely unknown, many scientists are hesitant to make decisions on how best to control HABs. However, it is important for scientists to study marine phytoplankton while keeping in mind the health risks and financial havoc that increasing frequency of HABs has caused and will continue to cause until they are controlled.

In 1997, I participated in a study conducted for the National Fish and Wildlife Foundation (NFWF) and the National Oceanic and Atmospheric Administration (NOAA) Coastal Ocean Program, in which I and the other scientists recommended potential ways to reduce or prevent HABs, given our limited knowledge of their biology and ecology. Our final report highlighted several areas that should be examined more closely:

• Although several scientists have suggested that increases in HABs are somehow linked to increased pollution of coastal ocean areas, there is still no definitive proof of this. However, steps should be taken to reduce excess pollutants and nutrients from being released into coastal ocean areas. In addition to making good sense from an environmental perspective, it is likely pollution reduction steps would also reduce HAB occurrences. For HABs, reducing nitrogen release is especially important; however, this is also one of the most difficult pollutants to control as it comes from a wide range of widely used agriculture chemicals such as fertilizers and fossil fuels.
• Controlling HABs using chemicals, fine clay particles or biological agents should be studied further. Although the potential dangers of chemical or biological agents are known, they also hold great promise in controlling unwanted toxic phytoplankton populations. Under some circumstances, dispersal of fine clay particles over a bloom has seen some success, as the clay aggregates with itself and with other particles in the water (including HAB cells) and pulls the harmful algae to bottom sediments. Control techniques in the context of risk assessments, similar to those applied in evaluating land-based agriculture, should be pursued with HABs.
• Better monitoring systems and detection methods must be developed, especially as funding for government monitoring programs is reduced. So far, the conservative procedures used to protect public health from exposure to algal toxins have been largely successful. The incidence of mortality and serious illnesses in the US has been relatively low. Nevertheless, new toxins appear every few years and the costs of monitoring for a diverse array of toxins in a growing range of fisheries products is a serious burden to state budgets. In addition, the medical community should be better informed and prepared to treat individuals suffering HAB toxicity. Individuals visiting or living on the shore or consuming seafood also need to be better informed about the risks, but not unduly alarmed. Responsible public education and communication must receive increased attention.
• Transferring HAB cells and cysts from one area to another through ship ballast water has to be studied, as do the effects aquaculture has on its immediate aquatic surroundings. The food and waste products of large numbers of fish in a confined area with poor water circulation could well encourage HABs because of excess nutrients in the water. When a HAB does occur, confined fish do not have the same evasion mechanisms that fish in the wild have and thus suffer much higher mortality rates.

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• Overall, scientists need to be encouraged to investigate HAB control and mitigation strategies. Sometimes it is easier to pursue basic or fundamental science, rather than taking on the challenging and highly visible practical research that tries to control blooms. There are surely technologies that we have not even considered yet that will be effective if scientists and engineers are given the resources and encouragement to pursue control and mitigation research. There is much to be learned in this respect from those who practice pest control in agriculture, which has a long history of successful chemical and biological mitigation.