A biological condition gradient model for historical assessment of estuarine habitat structure.
Coastal ecosystems are affected by ever-increasing natural and human pressures. Because the physical, chemical, and biological characteristics unique to estuarine ecosystems control the ways that biological resources respond to ecosystem stressors, we present a flexible and adaptable biological assessment method for estuaries. The biological condition gradient (BCG) is a scientific framework of biological response to increasing anthropogenic stress that is comprehensive and ecosystem based and evaluates environmental conditions and the status of ecosystem services in order to identify, communicate, and prioritize management action. Using existing data, we constructed the first estuarine BCG framework that examines changes in habitat structure through time. Working in a New England (U.S.) estuary with a long history of human influence, we developed an approach to define a reference level, which we described as a "minimally disturbed" range of conditions for the ecosystem, anchored by observations before 1850 AD. Like many estuaries in the U.S., the relative importance of environmental stressors changed over time, but even qualitative descriptions of the biological indicators' status provided useful information for defining condition levels. This BCG demonstrated that stressors rarely acted alone and that declines in one biological indicator influenced the declines of others. By documenting the biological responses to cumulative stressors, the BCG inherently suggests an ecosystem-based approach to management. Additionally, the BCG process initiates thinking over long time scales and can be used to inspire scientists, managers, and the public toward environmental action.
Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett Bay, RI, 02882, USA, emily.shumchenia@gmail.com.
Emily J
EJ
Shumchenia
Marguerite C
MC
Pelletier
Giancarlo
G
Cicchetti
Susan
S
Davies
Carol E
CE
Pesch
Christopher F
CF
Deacutis
Margherita
M
Pryor
D017753:Ecosystem; D004784:Environmental Monitoring / Q000266:history* / Q000379:methods; D063366:Estuaries / Q000266:history*; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D049674:History, 21st Century; D006802:Human Activities; D006801:Humans; D008954:Models, Biological; D014481:United States