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26.04.2013 - Natural Sciences Sector

Addressing the most pressing problems caused by harmful algae

© Dr Donald Anderson. Harmful algal bloom

About 300 hundred species of micro algae are reported at times to form mass occurrence or blooms which can cause anoxia and indiscriminate kills of marine life after reaching dense concentrations. Nearly one fourth of these species are known to produce toxins, which can contaminate seafood or kill fish. The scientific community refers to these events with a generic term, Harmful Algal Bloom (HAB), which covers a broad range of organisms and phenomena such as phytoplankton blooms, micro-algal blooms, or red tides.

In view of the global interest in issues caused by harmful phytoplankton, and the associated mass mortality of marine organisms, public health problems, and economic impacts, UNESCO’s Intergovernmental Oceanographic Commission (IOC-UNESCO) formed an Intergovernmental Panel on Harmful Algal Blooms (IPHAB). The Panel was requested to identify resources for a sufficiently broad programme to address the most pressing problems caused by harmful algae.

During its 11th Session, on 28-30 April 2013, IPHAB will decide on a revised plan for international coordinated research to foster the effective management of, and scientific research on, harmful algal blooms in order to understand their causes, predict their occurrences, and mitigate their effects. The panel will discuss major emerging issues requiring intergovernmental cooperation, such as the need for further research to address Ciguatera Fish Poisoning, strengthening food safety, improving HAB forecasting and the impacts of HABs on desalination facilities.

Ciguatera: a neglected tropical disease
While we have made enormous progress on monitoring and managing shellfish biotoxins, we still have much to learn about the most debilitating human seafood illness: Ciguatera Fish Poisoning (CFP). This human illness impacts human health and fisheries most severely in poor tropical nations. It is caused by eating tropical seafood contaminated by ciguatoxins (CTX) which biotransform and bioaccumulate: produced by benthic Gambierdiscus dinoflagellates (plankton), the toxins move up the food chain, from plankton to herbivorous species, then to carnivorous fish and humans. There is no immunity; toxins are cumulative, persistent, and human symptoms often recur.

Principally tropical in nature, ciguatera is now spreading as the causative organism and toxin-production appears in new regions and through globalised seafood trade between nations. Coastal and near shore infrastructure development associated with ports, seabed extraction of oil and gas, and tourism, as well as coral bleaching and global warming are all believed to increase ciguatera.

Ciguatera poses a major hurdle to fisheries and seafood market development throughout both the tropical Pacific and Caribbean (estimated $20 M loss p.a.), causing fish markets to ban product sales based upon species, size and geographic locations.

Recent technological breakthroughs have triggered a resurgence of interest in ciguatera: it is now possible to address long-standing ecological questions of species-specific habitat preferences, seasonality and environmental effects on cell abundance. However, the medical community’s interest has been declining and CFP is under-reported in endemic regions. Significant finances and sustained international efforts are needed to develop and validate reliable and cost-effective monitoring tools for causative organisms (qPCR), toxic fish (improved CTX screening and analytical methods) and disease confirmation in victims.

The benefits of such efforts would include:

  • Improved human health protection;
  • Increased yield of safe seafood into markets;
  • Diversification of seafood source by allowing fishing in previously disreputable locations;
  • Targeted management of newly at-risk locations; and
  • Increased economic benefits associated with safe seafood products to ciguatera endemic areas and their export markets.

Impacts of HABs on desalination plants and freshwater supply
More than 150 countries worldwide operate desalination plants to produce drinking water from seawater. Global desalination capacity is expected to grow rapidly in coming years as the demand for freshwater increases.  Harmful Algal Blooms had serious impacts on desalination plants in recent years: the cessation of operations due to clogging of filters, fouling of surfaces, damaging reverse osmosis membranes, and causing taste and odour problems. There are also concerns that HAB-derived toxins could be present in the freshwater produced, rendering it unsafe.

Recent research indicates that, when dense blooms of toxin producing HAB species occur in the vicinity of desalination plants, levels of HAB-derived toxins in the treated water could approach the levels of toxins that have been of concern in shellfish. There is a growing risk to public health and to plant operations, which would in turn impact freshwater supply and local economies.

Research on this topic is limited; it is therefore difficult to provide the detailed guidance that Member States need to address these issues. There is a clear need for further research to address the gaps in scientific understanding, engineering solutions, and a consensus on methodologies to reduce risks.

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