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........ published in NEWSLETTER # 67
PHYSIOLOGICAL ECOLOGY OF HARMFUL ALGAL BLOOMS
By Dr. D.M. Anderson, Woods Hole Oceanographic Institute, Woods Hole MA (U.S.A.)
Throughout the world, coastal countries are heavily impacted by phenomena now termed "harmful algal blooms" or HABs. Commonly called "red tides", these outbreaks take many forms and have many impacts. Some algal species produce potent neurotoxins which accumulate in shellfish, resulting in poisoning of humans and other consumers in the marine food chain. HAB toxins can also alter marine ecosystem structure and function from the lowest to the highest levels.
Some toxic blooms kill wild and farmed fish populations, while non-toxic algal species can cause problems through biomass effects - shading of submerged vegetation, disruption of food web dynamics and structure, and oxygen depletion as the blooms decay.
HAB phenomena are not new. Harmful red tides are recorded in the Bible and other early documents, and the fossil record includes forms identical to species known to cause toxic outbreaks today. What is new is the apparent proliferation of these phenomena over the last several decades. There are more toxic species, more toxins, more resources affected, more areas affected, and larger economic costs from HAB outbreaks. The HAB problem is global, significant, and growing.
This book (NATO ASI SERIES G41) documents a NATO Advanced Study Institute convened to address the physiological ecology of harmful algal blooms. More than 30 papers were prepared by the world's leading experts on HABs, focusing on two theme areas: 1) Autecology (i.e., what do we know about individual HAB species in relation to their environment?); and 2) Ecophysiological Processes and Mechanisms (i.e., what niche-defining strategies can be identified among HAB species?). The Autecology section contains detailed reviews of all the major HAB organisms and groups, including the Alexandrium complex, fish-killing species such as Gymnodinium breve, Heterosigma akashiwo, Chrysochromulina polylepis, and Pfiesteria piscicida, and other important species or groups such as Dinophysis, Pseudo-nitzschia, Gambierdiscus toxicus, and Noctiluca. Recognizing that most HABs are more or less monospecific events, and thus that the manner in which a species interacts with its environment and the co-occurring organisms is critical to bloom development, these papers attempt to explain why, where, and when particular HAB species bloom. The emphasis is on interpreting and reviewing field and laboratory studies of bloom phenomena in widely different environments in order to identify common principles or survival strategies.
The second half of the book attempts to define common physiological and behavioral strategies and community interactions which might explain the successes of different HAB species in widely varying environments. HAB species are capable of exploiting a bewildering array of ecological niches, survival strategies, and nutritional modes, and many of these were the subject of review papers. Topics such as the roles of toxin production, zooplankton grazing, mixotrophy, and swimming behavior are addressed, as are interactions with intracellular and extracellular bacteria. A particularly topical set of papers addresses the nutrition of HAB species, including the potential stimulation of HAB organisms by pollution.
Overall, these papers represent a unique compilation of current information on a significant and growing problem. All other HAB books published to date contain short papers in conference proceedings format. These ASI papers provide deep and thorough coverage of the many topics that make HAB research so interesting and challenging. As human reliance on the coastal zone for food, commerce, and recreation continues, toxic and harmful algae will continue to serve as reminders of the fragile nature of coastal ecosystems, and of the problems that human activities can sometimes cause. This book will serve as a valued resource to those struggling to understand and manage those problems.
Reference books: G22, G41
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