Salt Marsh Habitat Size and Location Do Matter: the Influence of Salt Marsh Size and Landscape Setting on Nekton and Estuarine Finfish Community Structure

Abstract

Do estuarine habitat size and landscape setting influence community structure and the habitats’ ability to support certain species? Small-island marshes (SIM) ~ 400–1000 m2 and large-island marshes (LIM) ~ 3000–10,000 m2 were paired with expansive-fringing marshes (EFM), each > 76,000 m2 in size, to assess nekton and estuarine finfish use related to marsh habitat size and factors contributing to use patterns. Marsh-dependent nekton, which have limited larval and adult dispersal ability, demonstrated density patterns directly related to marsh area size, which was indicative of available interior marsh space, with population persistence subject to minimum marsh size thresholds. Estuarine-resident nekton typically demonstrated negative density to marsh size patterns representing increased use of marshes with low area:perimeter ratios, suggesting the importance of marsh edge. SIM and EFM had significantly higher species richness and densities of estuarine-resident nekton species over LIM demonstrating area:perimeter-related marsh edge influence on use by nekton from the surrounding open-water habitats inundating SIM with associated species, while the more complex nature of EFM, based on size, allowed accumulation of species and provided adequate resources for populations. Estuarine landscape-level factors for individual sites were more influential in determining finfish marsh site use than habitat-specific factors. Island marshes are significant marsh/open-water trophic exchange areas because of the greater accessibility to island marshes versus EFM for larger predator fishes.