Fixed-station water quality monitoring at Cumberland Island National Seashore: 2010 data summary

Gregory, M.; Dingle, Julie; Wright, Christina; Thompson, Emma

In 2006, the National Park Service (NPS) Southeast Coast Network (SECN) Inventory and Monitoring Program began collecting water-quality data in the estuarine waters near Cumberland Island National Seashore (CUIS) as part the NPS Vital Signs monitoring program. Three continuous monitoring stations were operational during parts of 2010 at CUIS. Two were decommissioned and a new station at the Sea Camp dock began operating in partnership with the U.S. Geological Survey to provide real-time meteorological and tidal data as well as near-real time water quality data. These data are currently available internally at the SECN SharePoint. Stations collected pH, dissolved oxygen, temperature, salinity, conductivity, turbidity and water level data. Additional water quality measurements were made by SECN staff and include monthly measurements of water clarity conditions, nutrients (total dissolved phosphorus [TDP] and total dissolved nitrogen [TDN]), and chlorophyll a levels. Methods used are adapted from the water-quality monitoring program established by the National Estuarine Research Reserve Program (Wenner and Geist 2001). The Cumberland Island National Seashore fixed-station water quality monitoring sites are part of the SECN estuarine water quality monitoring program, which collects data in the vicinity of nine coastal parks located along the Southeastern U.S. coast (DeVivo et al. 2008). Information provided by this monitoring program is designed to help managers understand trends and variability related to water-quality conditions in and around park waters. Summary data are presented in annual data reports published by the SECN. Continuous and discrete water quality data collected at CUIS during 2010 includes partial-year data from three sites. Two stations were operational January-September; the third site, established during September, recorded data through December. Mean daily dissolved oxygen concentrations commonly dropped below 5 mg/L during the spring and summer months at Old House and Plum Orchard and during the fall at Sea Camp Dock. All sites experienced dissolved oxygen levels less than 2.0 mg/L for extended periods during this same time period, primarily during the night. pH levels were higher at all three sites during the winter months and slightly lower during the late summer and fall seasons when organic acids from decaying organic matter naturally contribute more to the make-up of water chemistry. Although monthly mean turbidity levels were similar at Old House Creek and Plum Orchard during the winter, turbidity levels at the more inland Old House Creek were greater than twice the levels of those at Plum Orchard. The range of turbidity values observed at the Sea Camp dock during the fall were similar in range to those observed at Plum Orchard and Old House Creek. Salinity levels indicated some variability in Old House Creek and Plum Orchard during the spring with very little salinity variability at Sea Camp during the fall. Monthly nutrient sampling indicated elevated TDP levels (Poor conditions) at all three sites, primarily during the late summer. TDN levels at all sites and samples during 2010 Chlorophyll a levels ranged from Good to Poor with most samples indicating Fair conditions. The highest chlorophyll a levels occurred during late summer in the vicinity of Old House Creek and Plum Orchard and coincided with the occurrence of elevated phosphorus levels.

Fixed-station water quality monitoring at Cumberland Island National Seashore: 2010 data summary

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