RELATIONSHIP BETWEEN SALINITY AND MACROINVERTEBRATE DISTRIBUTIONS ON A BARRIER ISLAND IN GEORGIA

Sapelo Island is one of Georgia’s barrier islands and is almost completely state owned and managed. The island has vast amounts of salt marshes and tidal drainages that are inhabited by living organisms. Salt marshes support large macroinvertebrate biodiversity, and the southeastern coast has the highest number of known crayfish species in the United States. The goal of this research was to study the distribution, abundance and diversity of macroinvertebrates on Sapelo Island, Georgia, and compare this with the salinity (conductivity) and nitrate of surface water and soils. Macroinvertebrates were collected using D-Nets following Georgia Adopt-A-Stream’s sampling protocols. A YSI multi-parameter instrument and a LabQuest Pro were used in the field to measure physical and chemical water parameters (temperature, pH, dissolved oxygen, conductivity, total dissolved solids). Nitrate concentrations were measured using an ISE nitrate specific probe from Vernier LLC. Water and soil samples were collected and transported to the lab where salinity was analyzed. Specific conductance values in surface water ranged from 0.2 to 44 mS/cm while nitrate ranged from 1 to 60 ppm. The surface water bodies generally have very low macroinvertebrate diversity. These preliminary results showed strong negative correlations between salinity and the presence of crayfish and oval water beetles. Crayfish and oval water beetles on Sapelo Island appear to prefer low salinity waters (fresh and brackish water), which also coincided with low nitrate concentrations. Further spatial and temporal distributions and correlations are being carried out. These preliminary results imply that as global temperatures rise and seawater floods barrier islands, there will be a loss of habitats for some of the species of macroinvertebrates.