EFFECTS OF FALL VEGETATION DIE OFF ON WATER QUALITY PARAMETERS IN THE OLGETHORPE ELEMENTARY SCHOOL WETLAND

Wetland water quality is a function of various physicochemical conditions and biological processes in wetlands, which may include: rainfall, contaminant sources, atmospheric conditions, flora, and fauna. Aquatic vegetation and algal communities drive biogeochemical cycles in isolated and semi-isolated wetlands because these systems do not regularly mix with surface water inflows and outflows. Daily photosynthesis cycles in particular drive dissolved oxygen and carbon dioxide levels in isolated wetlands which in turn influences pH levels. Additionally, fall senescence may also seasonally influence wetland water quality though cessation of growing season photosynthesis and influxes of coarse organic matter (e.g. leaf litter).

Our objective is to establish baseline water quality data and quantify changes during / after plant senescence in a small, semi-isolated, freshwater wetland on Saint Simons Island, GA.

Dissolved oxygen, pH, specific conductivity, temperature, and turbidity were measured weekly beginning 10/19/2018 (prior to plant senescence) through 11/30/2018 (late stages of senescence). Dissolved oxygen, pH, specific conductivity and temperature were measured with a Hydrolab MS5 sonde. Turbidity was measured with a HACH 2100Q turbidimeter.

Preliminary analysis indicates that dissolved oxygen has increased during plant senescence which is most likely a function of decreasing temperatures. Specific conductivity values decreased which may be a result of increased precipitation diluting soil water inputs during late autumn. Turbidity and pH have not yet shown a response to plant senescence which could be a function of continued algal photosynthetic activity.

Measurements will continue through the winter and into the next growing season. Our findings provide baseline conditions to compare future water quality monitoring in this small semi-isolated wetland on the Georgia Coast. Additionally, freshwater wetlands on barrier islands are understudied relative to nearby saltmarshes; to the best of our knowledge this is the first investigation of freshwater wetland water quality in context of plant senescence on a Georgia barrier island.