Marine Mammals as Sentinels of Environmental Biotoxins

Abstract

Harmful algal blooms (HABs), commonly known as “red tides,” are documented in almost every coastal region of the world. Over the past decade, these toxic blooms appear to have increased in number, magnitude, and seasonal duration, potentially due to the spread of toxic algal species to new areas, eutrophication caused by human development of coastal areas, and global climate change Some of the microscopic, single-celled algae that constitute the base of the marine food chain produce the potent toxins found in these harmful blooms. These toxins can accumulate in fish, shellfish, and other marine organisms, and move through the food chain, at times affecting the highest consumers, including marine mammals and humans. Humans are usually well-protected by federal and state monitoring programs that detect the toxins at an early stage and restrict the harvest or sale of the toxic seafood. However, marine mammal health is not protected by the same routine monitoring programs. Recent evidence has indicated that mass mortalities and strandings of whales, dolphins, sea lions, manatees, and sea otters, in some cases, may be caused by their exposure to marine biotoxins.