Fixed-station water-quality monitoring at Cape Lookout National Seashore: 2012 data summary

Rinehart, Aaron; Gregory, M.; Wright, Wendy

doi:10.36967/2195313

In 2007, the National Park Service (NPS) Southeast Coast Network (SECN) Inventory and Monitoring Program began a partnership with the North Carolina National Estuarine Research Reserve (NCNERR) to collect water-quality data in the estuarine waters near Cape Lookout National Seashore (CALO). Two continuous-monitoring stations have been operational since 2008 in the Shackleford Banks Dock and in the Middle Marshes area. Methods used are adapted from the water-quality monitoring program established by the National Estuarine Research Reserve Program. The Cape Lookout National Seashore fixed-station water-quality monitoring sites are part of the SECN estuarine water-quality monitoring program, which routinely collects data in the vicinity of seven coastal parks along the southeastern U.S. coast. Salinity, dissolved oxygen, pH, turbidity, water temperature, specific conductance (to compute salinity), and water-level data were collected at two stations at CALO. Monthly measurements of water clarity conditions, and the collection of a grab sample analyzed for total dissolved phosphorus, dissolved inorganic phosphorus, total dissolved nitrogen, dissolved inorganic nitrogen, and chlorophyll a levels were also made at both sites. Discrete water-quality samples collected monthly at both sites indicated good conditions with respect to water clarity with one fair reading in February at CALOshak. Chlorophyll a, readings were also good throughout the year, with one fair reading in October at CALOshak, where data were available. Dissolved inorganic nitrogen and phosphorus levels were good at CALOshak. Orthophosphate levels were slightly elevated at CALOshak2 during November. Salinity concentrations followed the same general pattern throughout the year at both sites, generally declining after periods of high rainfall and runoff. Individual and monthly mean low readings at CALOshak occurred in November at 25.82 and 39.9 ppt, respectively, compared to individual and monthly mean lows at CALOshak2 in September (22.20 and 27.8 ppt respectively). Conversely, individual and monthly high readings at CALOshak were 36.98 and 36.2 ppt respectively in May, whereas individual and monthly high readings at CALOshak2 were 38.41 and 35.6 ppt respectively in July. Mean monthly dissolved oxygen levels were similar between sites ranging from 5.4 to 8.8 mg/L at CALOshak and from 6.1 to 9.0 mg/L at CALOshak2. The season lows at each site occurred during the summer months; however, individual readings below 5.0 mg/L were common at CALOshak2 occurring between March and October. Mean daily dissolved oxygen (DO) levels were never below 5.0 mg/L at CALOshak2, but were below 5.0 mg/L at CALOshak for six days in August. Monthly mean pH values were similar between sites ranging from 8.0 to 8.1 at CALOshak and from 7.9 to 8.1 at CALOshak2. Average monthly turbidity at both CALOshak and CALOshak2 never exceeded 8.0NTUs. Mean daily turbidity values at CALOshak did not exceed 36 NTUs, and CALOshak2 values did not exceed 26 NTUs. Water temperatures at CALOshak2 were more variable than those at CALOshak. Individual readings at CALOshak2 ranged from 3.1°C (37.5°F) in January to 33.5°C (92.2°F) in August, while temperatures at CALOshak ranged from 7.3°C (45.1°F) in January to 30.8°C (87.5°F) in August. Monthly mean water temperatures ranged from 11.0°C (51.8°F) to 28.8°C (83.84°F) from January to July at CALOshak2, versus 11.3°C (52.34°F) to 28.2°C (82.76°F) from January to July and August at CALOshak.

Fixed-station water-quality monitoring at Cape Lookout National Seashore: 2012 data summary

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