Vital Signs: Estuarine Sediment Chemistry, Estuarine Water Chemistry, Estuarine Water Clarity, Estuarine Water Quality

Importance / Issues

Nutrient enrichment of the coastal zone is a worldwide consequence of human population growth. The population density of Northeast coastal fringe is more than double that of any other region of the country, and it continues to grow. The consequent residential, agricultural, and urban expansion will result in a continued increase in anthropogenic nutrient loading to the region’s coastal zone. Estuaries can generally assimilate some degree of enrichment without major ecological ramifications, but excessive nutrient inputs typically lead to dense blooms of phytoplankton and fast-growing macroalgae, loss of seagrasses, and decreased oxygen availability in sediments and bottom waters. Cascading effects may include changes in the species composition and abundance of invertebrates, decline in fish and wildlife habitat value, and the collapse of commercially harvestable fin- and shellfish stocks.

A protocol is being developed by the Network to create a scientifically-based estuarine water quality monitoring program that is capable of diagnosing local causes of nutrient enrichment, detecting changes in nutrient loads, and determining if nutrient inputs are near to exceeding thresholds that would result in shifts in ecosystem structure and function.

Preliminary Monitoring Objectives

Determine long-term trends in summertime levels of dissolved oxygen concentration, turbidity, attenuation of photosynthetically active radiation, temperature, salinity and suspended chlorophyll concentrations in estuarine waters and organic carbon in estuarine sediment in selected NCBN park sites.

Parks to be Monitored

• Assateague NS
• Cape Cod NS
• Colonial NHP
• Fire Island NS
• Gateway NRA
• George Washington Birthplace NM
• Sagamore Hill NHS

Approach

Estuarine nutrient monitoring variables have been limited to those that are well justified scientifically and deemed feasible from both practical and economic perspectives. Two of these variables - sediment organic carbon content and benthic faunal species composition - are sampled on infrequent time scales (i.e., every five years). The remaining variables (chlorophyll a, dissolved oxygen concentration, attenuation of photosynthetically active radiation, and the required ancillary data of temperature and salinity) will be measured annually or biennially

This protocol includes probability-based spatial sampling strategies, methods for incorporating non-Park Service data, and instruction on reporting and interpreting results. This protocol is also compatible with the NPS National Marine Water Quality Monitoring Effort and the EPA National Coastal Assessment.

Contact Information