In freshwater kettle ponds, increased nutrient inputs can lead to algal blooms, low oxygen in the water, and changes in thermal layer formation. In brackish and salt waters, nutrient enrichment leads to a cascade of events, including algal blooms, low oxygen conditions, loss of seagrass meadows, and fewer invertebrates and fish. Changes in climate, as well as mercury and other particles deposited from the atmosphere through wind and rain, contribute to declining water quality across the region. Monitoring water quality of aquatic resources aids in developing management strategies for protection and mitigation by identifying the source and level of impacts to a given ecosystem.
Natural resources in National Park Service units are facing unprecedented challenges. Water quality of aquatic ecosystems within Cape Cod National Seashore are threatened by the combined effects of climate change, adjacent development, mercury deposition, acid rain, oil spills, and visitation by the public. An increasing proportion of the 5 million annual visitors to the park use the salt and fresh-water resources for swimming, fishing, boating and other recreational activities, and there are many private homes with individual septic systems that contribute nutrients to the adjacent waters.