Limnology and the management of the freshwater ponds of Cape Cod National Seashore : Final report

Soukup, Michael

This study looks at water quality trends in the kettle ponds of Cape Cod Natioanl Seashore, some of which have homesites and heavily used public beaches along their shoreline. Objectives include: (1) limnological characterization of these ponds, thereby establishing baseline data for future comparison; (2) enhancement of a simultaneous study of swimmer-related pathogenic bacteria by providing information relating to dispersion and survival in the ponds; and (3) evaluation of the extent of cultural eutrophication, and formulation of management policy for recreational use consistent with resource preservation. Dissolved oxygen and dissolved silica depletions, free CO2, hardness, total and soluble reactive phosphorus, chlorophyll a, pH, conductivity, selected cation, and temperature data are reported. Preliminary phytoplankton species identifications are made, and a sedimentation rate for Duck Pond is estimated. A study of photosynthetic pigment profiles has been completed and reported by Ludlam (1977) as Part B of the study. The twenty ponds under investigation are all seepage ponds with soft, acidic water. Among the ponds a wide summer range of Secchi transparencies (0.5 to 14 m), chlorophyll a (0.01 to 100 mg m-3) and total phosphorus concentrations was found. Several ponds (with 10 to 18 m depths) have stable summer stratification - Long, Gull, Great (T), Ryder, and Round (West) - and the latter four of these have substantial hypolimnetic anoxia and other characteristics of cultural eutrophication. It is recommended that: (1) proper sanitary facilities be made available at all public beaches; (2) several ponds must be immediately provided with control measures for erosion and septic tank effluent; (3) recreational use must be redistributed on the basis of the vulnerability of each pond to nutrient stimulation of plant growth for long-term preservation of the resource.