Future consequences of climate change for the Chesapeake Bay ecosystem and its fisheries

Chesapeake Bay supports a number of valuable fisheries within its boundaries and serves as an important nursery area and seasonal feeding ground for many coastal Atlantic species, despite substantial anthropogenic modifications to the ecosystem for more than two centuries. Ecosystem managers are now confronting the fact that future climate changes may be superimposed upon continued coastal development, resource exploitation, and regional human population growth. As an estuarine ecosystem, Chesapeake Bay is particularly sensitive to long-term changes in three major hydro-climatic variables: temperature, sea level, and precipitation/riverflow. Based upon historical trends and model projections, relative sea level will likely continue to rise and temperature is more likely to increase than decrease. Future changes in precipitation and riverflow are highly uncertain. As relative sea level continues to rise, erosion of coastal margins will likely increase turbidity and may decrease the extent of submerged and emergent vegetative habitats. This-would have far reaching effects because these habitats are important nursery areas for many Chesapeake Bay and coastal Atlantic fish populations. Increased temperature would likely result in increased utilization of Chesapeake Bay by subtropical species such as brown shrimp (Farfantepenaeus aztecus) and decreased utilization by cooler water species like striped bass (Morone saxatilis). Changes in riverflow would affect nutrient and dissolved oxygen levels, salinity distribution, and estuarine circulation. Also discussed are more complex changes that are dependant upon the rate of change, magnitude, and seasonal timing, of these climate variables. Within the context of precautionary management principles, Chesapeake Bay ecosystem management must consider that future climate changes could alter species composition, distribution, and diversity within the Bay and influence Chesapeake Bay and coastal Atlantic fisheries production.