Nekton Assemblage Responses to An Anthropogenically Fragmented, Coastal Landscape: Differential Responses of Resident and Transient Nekton

It is critical to understand how the cumulative impacts of adding man-made structures to the coastal zone affects the nursery value of salt marsh habitats in terms of both habitat quality and quantity.  We used aerial imagery and land cover maps to classify salt marsh tidal creeks into three patch-types along a gradient of alteration in Mississippi’s Pascagoula River and Biloxi Bay estuaries; completely fragmented (CF; high development and little salt marsh habitat), partially fragmented (PF; moderate development and moderate salt marsh habitat), and intact natural (IN; no development and expansive salt marsh habitat) salt marsh patches with tidal creeks of similar size and creek order. Nekton were collected from these creeks over a four week period in Spring 2010. Though not all species responded similarly to alteration, ecologically important species such as grass shrimp and gulf menhaden were more abundant in IN than either PF or CF. Further, comparison of transient (i.e. blue crab and spot) and resident nekton (i.e. Gulf killifish) suggests differential responses to salt marsh fragmentation. Our results indicate that smaller, isolated salt marsh patches nestled within a human-dominated landscape do not function similarly to unaltered continuous patches of salt marsh.