Meeting Abstract
Large accumulations of green seaweeds are occurring with increasing frequency on shores worldwide. These blooms, known as “green tides”, have a number of impacts on planktonic and benthic organisms in habitats where the blooms occur. Although the best-known impacts involve smothering or shading other organisms, blooms can alter the environment by affecting seawater chemistry. In addition to altering the pH and changing CO2 and oxygen concentrations in the surrounding seawater via respiration and photosynthesis, the algae comprising the blooms produce natural products that can be consumed by herbivores or released into the surrounding air or water. Some of the best studied compounds produced by green tide seaweeds include the sulfur compound dimethylsulfoniopropionate (DMSP), the neurotransmitter dopamine, and a variety of reactive oxygen species (ROS). These compounds and their breakdown products have ecological, physiological, and environmental effects, which can include deterring feeding by herbivores; acting as allelopathic agents and toxins towards potential competitors, fouling organisms, and other species in the environment; and, potentially acting as intra- or interspecific signaling molecules. Here, I will examine factors affecting the production and release of these natural products as well as their known and potential impacts on other organisms in the environment in order to assess whether these deleterious effects are incidental or have adaptive value.
