Effects of habitat alteration on blue crabs

Abstract

Blue crabs, Callinectes sapidus, are an estuarine and coastal species subject to a wide range of environmental conditions. Their survival, growth, reproduction, and abundance are influenced by both natural processes and events and by human activities. How such activities might affect the survival and abundance of blue crabs is the focus of this discussion. Because the life cycles and growth of blue crabs and other crustaceans are relatively complex, they are vulnerable to chemical and physical alterations to their habitat in different ways during their life. Not only are insults to the different life stages important, but negative impacts to the food webs that support them may also be damaging. When dealing with human-induced alterations to the environment, we often become preoccupied with the introduction of toxic chemicals and pesticides and their effects on individual organisms, and overlook less emotionally charged but more widespread threats, such as nutrient loading, alterations of freshwater inflow, and physical destruction of estuarine and coastal habitat. Increasing human population densities and development near the Atlantic and Gulf of Mexico coasts may pose the greatest threat to blue crab populations through alterations of upland watersheds with increased runoff, erosion, and turbidity, and increased nonpoint-source runoff of chemicals and nutrients. Unless these activities are adequately controlled, the degradation of coastal habitat necessary for the survival and growth of blue crab populations will grow.