Figure 3: Biotoxins like domoic acid from harmful algal blooms are transferred throughout the food web when toxic algal cells are eaten by zooplankton, fish, and shellfish that are, in turn, eaten by other animals and humans. The small micrograph at the upper left shows chains of Pseudo-nitzschia cells (Source: Gary Wikfors; http://www.whoi.edu/redtide/impacts/ecosystems).