Productivity of functional guilds of fishes in managed wetlands in coastal South Carolina

Abstract

In coastal South Carolina, many wetlands are impounded and managed as migratory waterfowl habitat. Impoundment effects on fish production and habitat quality largely are unknown. We used the size-frequency method to estimate summer production of fish guilds in three impoundments along the Combahee River, South Carolina. We predicted that guild-specific production would vary with impoundment salinity, which ranged from 3 to 21 practical salinity units. We expected that marine species that use the estuary as nursery habitat would have greatest production in the impoundment with the highest salinity regime, and that species that inhabit the upper reaches of the estuary would have greatest production in the impoundment with the lowest salinity regime. Finally, we expected that estuarine species would be highly productive in all study impoundments, because these species can reproduce within these structures. We found that guild-specific productivity varied both among years and among impoundments, generally following salinity gradients, though to a lesser extent than expected. Our guild-specific estimates offish productivity fell on the low end of the range of previously published estuarine fish production estimates. Additionally, we observed large mortality events in the study impoundments each summer. The results of our study indicate that during the summer, the study impoundments provided poor-quality fish habitat to all guilds.