MEPS 586:57-72 (2018)  -  DOI: https://doi.org/10.3354/meps12385

ABSTRACT: The specific biological impacts of anthropogenic activities and associated fragmentation of estuarine habitats remain understudied. We compared nekton communities and fish movement at 9 road crossings (with culverts) and a tenth crossing (‘reference’ crossing that lacked a road or a culvert) in first-order Spartina alterniflora-dominated tidal creeks in coastal North Carolina. Sample sites were located on both sides of each crossing. Percent salt marsh and increasing water depth were factors that most contributed to dissimilarities in biological communities among sample sites; the resident salt marsh fish Fundulus heteroclitus dominated the catch at sites with high percentages of marsh and inherently shallow depths while a transient species Lagodon rhomboides dominated at deeper sites where marsh was absent. F. heteroclitus was marked with injectable elastomer to determine factors influencing its movement probability to sites on sides of crossings opposite from where it was tagged. The probability of F. heteroclitus moving was positively related to the percentage of marsh-fringed shoreline within its published home range and was highest at intermediate water depths. The results show that preserving salt marsh adjacent to road crossings will maintain communities and movement rates reflective of non-impacted habitats in tidal creeks in the US South Atlantic coastal plain and emphasize habitat connectivity as an ecological factor important to community structure and movement.

KEY WORDS: Salt marsh · Fundulus heteroclitus · Habitat fragmentation · Culverts