The ecological impact of chemical contaminants in the Chesapeake remains the most challenging area for scientists and managers. Demonstrating the connection between even well documented inputs of contaminants and ecosystem responses to those contaminants relies on the science of aquatic toxicology, an evolving discipline that evaluates responses at hierarchical levels, from molecules to ecosystems. This research also found that organisms, populations and communities in the vicinity of CCA-treated materials showed reductions in biomass and limited species composition, leading to lower biological diversity and less productivity in the area.
Contaminants can affect phytoplankton at the base of the Bay's food web.
Research in the Patuxent River, for example, has shown that phytoplankton blooms can concentrate trace metals, which are then passed to the zooplankton that graze on them. Unconsumed algae and other organic matter that fall to the Bay floor can decay so rapidly that the contaminants bound to that matter can remain in the water column. Whether contaminants remain longer in the water column or more quickly join bottom sediments depends on physical processes and obviously influences the kind of effects toxic compounds will have on an ecosystem like the Chesapeake Bay. The cellular link between contaminants and biological responses allows researchers to anticipate and predict effects at higher levels, from the individual to entire ecosystems. Chemically induced changes in a biochemical system or cellular function can serve as markers of both exposure and effect.