Associations Between Nekton Assemblages and Ribbed Mussel (Geukensia demissa) Patches in a South Carolina Salt Marsh

Asa R. Julien^1,2,*, Daniel J. McGlinn², Andrew W. Tweel¹, and Peter R. Kingsley-Smith¹

¹Marine Resources Research Institute, South Carolina Department of Natural Resources, 217 Fort Johnson Road, Charleston, SC 29412. ²Grice Marine Laboratory, College of Charleston, 205 Fort Johnson Road, Charleston, SC 29412. *Corresponding author.

Southeastern Naturalist, Volume 19, Issue 1 (2020): 45–61

Abstract
Geukensia demissa (Ribbed Mussel) is an important foundation species in the salt marsh ecosystem, providing habitat for resident invertebrates and influencing ecosystem functioning. Our goal was to determine whether Ribbed Mussels increase the abundance and diversity of the nekton assemblage at high tide. We sampled an area of marsh in Charleston, SC, using drop-net traps to compare nekton abundance, species richness, species diversity, and species composition in plots with and without Ribbed Mussels. Over the course of 1 year, there were no significant differences between plots with and without mussels in any of the metrics of nekton abundance or diversity, although ordination results suggested that the species composition was distinct in each plot type. Season and tidal height were more important in influencing nekton assemblage abundance and diversity. Our findings suggest that the Ribbed Mussel does not act as a foundation species for nekton at the patch scale, although it does influence the composition of the nekton assemblage, as do season and tidal height. The role of the Ribbed Mussel as a foundation species for the nekton assemblage at the landscape scale remains untested.

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