UNESCO publication takes stock of harmful algae blooms and efforts to mitigate them

Paris, 19 September—UNESCO has published the first ever global compendium on harmful algal blooms (HAB), microorganisms that deplete fish stocks, destroy fish farms and bring disease and death both to humans and to large sea animals.

In a case-by-case review of data on major harmful algal bloom incidents, the publication sounds the alert on increasing trends, as observed, for example, along the coasts of Florida (U.S.A.), where data has been compiled since the mid-19^th century, India and Oman. In the Adriatic and Baltic seas, harmful algal incidents are on the increase despite governmental awareness and decisions to restrict the production and discharge of phosphate and other harmful chemicals.

Toxic and Harmful Microalgae of the World Ocean (IOC Manual and Guides no. 68, 523 pages), by marine biologists and toxin chemists Patrick Lassus, Nicolas Chomérat, Philipp Hess, and Elisabeth Nézan, examines trends in the spread of these toxic marine microorganisms and evaluates policies to contain them.

The HAB increase is closely coupled with the intensified exploitation of coastal zones for aquaculture, tourism and other human activities bringing people and resources in contact with toxic microalgae. Also, these activities alter conditions favouring the development of HAB through an overload of nutrients from human waste and chemical runoff, overfishing and increased maritime transport.

Not all is bad news. Decreases have been observed in places where policy decisions led to improvements in the treatment of waste waters and fish-farming technology. The Seto Inland Sea of Japan, where a HABs monitoring programme has been in place for 50 years, is a case in point. Harmful algal incidents in Seto have stabilized at 100 per year, primarily due to national regulations to control nutrient and waste discharge. In many European countries,* HAB reductions are primarily due to management action based on observations and early warnings. Greatly helped by EU legislation since 1991, these countries implemented effective monitoring following severe and extensive poisoning cases during the 1980s.

In its review of the environmental factors, the publication examines in particular the impacts of eutrophication (high concentration of nutrients in the water), overfishing, globalized maritime traffic and climate change.

The new compendium provides data identifying 174 algal and 100 toxin-producing species grouped in 24 chemically different classes responsible for 11 different human health conditions. Over 50 photographic plates illustrate 62 species and the authors of the compendium hope that the work will stimulate further research and the identification of more species.

Available in both English and French, the guide has been designed to be a useful companion to a large audience including fish and shellfish farmers, monitoring agencies and HAB scientists.

The compendium is a joint publication of UNESCO’s Intergovernmental Oceanographic Commission and the International Society for the Study of Harmful Algae. It was sponsored by the Prince Albert II of Monaco Foundation alongside a number of regional, national and international organizations.