Variations Of Epipelic Diatom Community During The Savannah Harbor Expansion Project In Port Wentworth, GA
Abstract
Estuaries are naturally diverse systems mixing freshwater and marine habitats in addition to getting constant tide shifts. Anthropogenic alternations that are occurring on the Savannah River are expected to change the hydrology of the ecosystem and effect algal community structure and composition. The Savannah Harbor Expansion Project recently began, which entails the widening and deepening of the river by 1.5m. It is anticipated that tidal height, influx of salt water, and sedimentation rates will be affected, which will disturb algal inhabitants. Baseline data from the Savannah River mudflats was obtained in 2011 to accurately understand the ecosystem before the disturbance. Algal community indices were assessed along with live to dead algal proportions, where live diatoms were defined as frustules possessing evidence of physiologically active chloroplasts. Living algal species were classified as freshwater, marine, or brackish in addition to planktonic, epipelic, and benthic. In 2011, deposition of marine planktonic species and high amount of dead diatom frustules were documented. In 2016, repeated sampling at the original location followed the same standard protocols. In the analyses of the whole algal community there was a reduction of 59% of live diatoms. These decline lead to overall increase in species richness and diversity. Live diatoms were replaced by filamentous cyanobacteria genera like Phormidium and green coccoid algae, classified as freshwater. There was a decrease in abundance of chain forming marine plankton species potentially due to higher sedimentation rates. Species richness within cleaned diatom communities decreased by 15.3%, but Cymatosira belgica Grunow remained the dominant species with average 40% relative abundance. Other marine epipelic diatoms, like Tryblionella granulata (Grunow) Mann, and Rhaphoneis amphiceros Ehrenberg did decline significantly. Due to the negative affects of dredging and more sediment deposition, diatom communities show significant change due to increased turbidity, lower light availability, higher temperature, and waste.
Variations Of Epipelic Diatom Community During The Savannah Harbor Expansion Project In Port Wentworth, GA
Estuaries are naturally diverse systems mixing freshwater and marine habitats in addition to getting constant tide shifts. Anthropogenic alternations that are occurring on the Savannah River are expected to change the hydrology of the ecosystem and effect algal community structure and composition. The Savannah Harbor Expansion Project recently began, which entails the widening and deepening of the river by 1.5m. It is anticipated that tidal height, influx of salt water, and sedimentation rates will be affected, which will disturb algal inhabitants. Baseline data from the Savannah River mudflats was obtained in 2011 to accurately understand the ecosystem before the disturbance. Algal community indices were assessed along with live to dead algal proportions, where live diatoms were defined as frustules possessing evidence of physiologically active chloroplasts. Living algal species were classified as freshwater, marine, or brackish in addition to planktonic, epipelic, and benthic. In 2011, deposition of marine planktonic species and high amount of dead diatom frustules were documented. In 2016, repeated sampling at the original location followed the same standard protocols. In the analyses of the whole algal community there was a reduction of 59% of live diatoms. These decline lead to overall increase in species richness and diversity. Live diatoms were replaced by filamentous cyanobacteria genera like Phormidium and green coccoid algae, classified as freshwater. There was a decrease in abundance of chain forming marine plankton species potentially due to higher sedimentation rates. Species richness within cleaned diatom communities decreased by 15.3%, but Cymatosira belgica Grunow remained the dominant species with average 40% relative abundance. Other marine epipelic diatoms, like Tryblionella granulata (Grunow) Mann, and Rhaphoneis amphiceros Ehrenberg did decline significantly. Due to the negative affects of dredging and more sediment deposition, diatom communities show significant change due to increased turbidity, lower light availability, higher temperature, and waste.