Body Condition and Foraging Patterns of Nekton from Salt Marsh Habitats Arrayed Along a Gradient of Urbanization

Abstract

Coastal salt marsh landscapes have undergone rapid urbanization that may impact the suitability of salt marsh ecosystems for the maintenance and regulation of estuarine faunal communities. This paper examines the body condition (a surrogate for growth) of blue crab, brown shrimp, spot, and Gulf killifish in response to increasing levels of urbanization in salt marsh landscapes in coastal Mississippi. Blue crab and brown shrimp condition did not differ among landscapes. Conversely, both Gulf killifish and spot body condition was markedly reduced in highly urbanized salt marsh landscapes, and these differences were likely linked to landscape-specific foraging patterns. In completely urbanized landscapes, empty stomachs were more frequent and larger bodied brown shrimp were characteristic of Gulf killifish diets. In contrast, smaller grass shrimp and fish were key diet components in both intact natural and partially urbanized salt marsh landscapes. Similarly, spot had a greater frequency of empty stomachs and appeared to delay a dietary ontogenetic shift toward feeding on large prey upon recruitment to salt marsh habitats in completely urbanized landscapes. Overall, these results indicate that highly urbanized salt marshes, while providing sufficient resources to support healthy brown shrimp and blue crab populations, were not functional habitats for all nekton.