MEPS 571:121-138 (2017)  -  DOI: https://doi.org/10.3354/meps12094

ABSTRACT: Habitat heterogeneity is increased in natural systems via habitat loss and fragmentation, which decreases the patch size and alters the amount of edge relative to interior. However, our understanding of how increased habitat heterogeneity influences population dynamics, particularly set within a large scale marine landscape, is relatively incomplete. Eastern oyster Crassostrea virginica populations have drastically declined resulting in fragmentation within and among reefs, thus altering reef size and distances from edge to interior. Over 2 yr (2011 to 2012), we evaluated oyster populations relative to varying distances from the reef edge to interior locations, habitat patch size, and reef type on naturally occurring intertidal fringing and patch reefs in southeastern North Carolina. Additionally, the influences of distance from edge to interior locations and habitat patch size were examined for oyster populations on 3 size classes of created intertidal reefs at 2 locations. The habitat characteristics examined significantly influenced oyster populations, with increased densities towards interior locations on a reef, a trend of overall higher densities on intermediate sized reefs, significantly greater densities on natural patch reefs compared to natural fringing reefs. Density and recruitment patterns suggested differences between edge and interior locations. However, other population characteristics, such as oyster condition and shell height, indicated there may be ecological trade-offs among the habitat characteristics examined. These results suggest intertidal reefs cannot be considered a uniform whole and may have substantially different habitat characteristics, which should be taken into account when further examining habitat fragmentation and restoration success.

KEY WORDS: Landscape · Habitat heterogeneity · Patch size · Edge effect · Eastern oyster · Crassostrea virginica · Habitat fragmentation · Habitat restoration