Do Habitat Corridors Influence Animal Dispersal and Colonization in Estuarine Systems?

Abstract

Studies investigating animal response to habitat in marine systems have mainly focused on habitat preference and complexity. This study is one of the first to investigate the affect of benthic habitat corridors and their characteristics on dispersal and colonization by estuarine macrofuana. In this study, mark-recapture field experiments using artificial seagrass units (ASUs) assessed the effects of seagrass corridors, interpatch distance (5 m vs. 10 m), and the ratio of corridor width to patch width (0.5 m:1 m vs. 0.25 m:1 m) on dispersal of two benthic organisms: the highly mobile grass shrimp, Palaemonetes sp., and the less mobile bay scallop, Argopecten irradians, in two estuarine systems in southeastern North Carolina (NC). The presence of a seagrass corridor, interpatch distance, and corridor width to patch width ratios did not significantly affect shrimp or scallop dispersal to receiver patches. Bay scallop dispersal to receiver patches was significantly higher at one site (Drum Shoals) with relatively high flow, compared to a second site (Middle Marsh) with lower flow. We then examined colonization of estuarine macrofauna to seagrass patches with and without corridors to determine which, if any, taxonomic groups respond positively to corridors at scales of 10 m and over 1 month. Colonization of estuarine macrofauna to seagrass patches was enhanced in the presence of corridors at a relatively large interpatch distance (10 m), which was statistically significant for relatively slow moving polychaete worms. Thus, although benthic habitat corridors may facilitate dispersal of relatively slow moving estuarine animals between otherwise isolated seagrass patches, several common seagrass fauna such as grass shrimp and bay scallops apparently use water currents to rapidly disperse across the seagrass/sand landscape.