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Georgia Journal of Science

Article Title

PREDICTING THE EFFECTS OF SEA-LEVEL RISE AND INCREASING SALINITY ON THE DISTRIBUTION OF CRAYFISH ON SAPELO ISLAND, GEORGIA

Abstract

Barrier islands have great ecological and economical importance. Their formation has been studied in the past and is mostly thought to be caused by sea-level increasing and submerging backdune areas, leaving the dunes exposed above sea-level to form barrier islands. In addition, longshore currents and offshore shoals may also play a role in shaping and creating these islands. Increasing sea-level due to climate change is certain. Although the extent and timing are unknown, Sapelo Island in Georgia will not be spared from these effects. Loss of the existing freshwater lens and ocean inundation could greatly change freshwater availability on the island. This could have significant ecological impacts, particularly with respect to freshwater macroinvertebrates such as crayfish like Procambarus lunzi, which are complexly intertwined into the trophic web of the island. This study seeks to investigate the salinity tolerances and preferences of crayfish found on Sapelo Island, Georgia. Crayfish were collected in March, June, and September 2019. A total of 172 crayfish were divided into a freshwater group, a saline group, and an intermediate group. The saline group had salinity increased by 3 ppt each week, while the intermediate group increased by half this rate throughout the duration of the study. Preliminary results have shown that this crayfish species has a surprising tolerance of increased salinity levels, with no mortality up to 30 ppt, while beginning to decline by 36 ppt (which approximates an ocean-level threshold). This conveys the potential for P. lunzi to tolerate some increase in salinity, though they may be outcompeted by other marine organisms more readily adapted to these conditions.

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