National Park Service

Northeast Coastal and Barrier Network (NCBN)

Estuarine Nutrient Enrichment Monitoring

Seagrass monitoring at Fire Island National Seashore
Seagrass monitoring at Fire Island National Seashore

Resource Brief – Monitoring Nutrient Enrichment

Monitoring Reports

Monitoring Data

NCBN Estuarine Nutrient Enrichment
Monitoring Protocol

For more information contact: Sara Stevens or
Dennis Skidds

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.

Monitoring Objectives

  • Determine long-term trends in summertime levels of the following in selected NCBN park sites:
    • Dissolved oxygen concentration
    • Turbidity
    • Attenuation of photosynthetically active radiation
    • Temperature
    • Salinity
    • Chlorophyll concentrations
    • Organic carbon concentrations in estuarine sediment
  • Determine the distribution and abundance of submerged aquatic vegetation beds in selected areas in NCBN parks.
  • Determine long-term, inter-annual trends in seagrass condition (shoot density percent cover and biomass) in selected estuarine areas of NCBN parks.

Parks Monitored

  • Assateague National Seashore (ASIS)
  • Cape Cod National Seashore (CACO)
  • Colonial National Historical Park (COLO)
  • Fire Island National Seashore (FIIS)
  • Gateway National Recreation Area (GATE)
  • George Washington Birthplace National Monument (GEWA)
  • Sagamore Hill National Historic Site (SAHI)

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.

Data on submerged aquatic vegetation will be available for some of the parks to acquire from outside sources. Where not available, a methodological protocol is being created for the direct collection of these data.

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.

Jamaica Bay Wildlife Refuge
Jamaica Bay Wildlife Refuge

Estuarine Nitrogen Inputs –
Protocol Development Summary

For more information contact: Sara Stevens or
Dennis Skidds

Importance / Issues

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 monitor estuarine nutrient agents of change, or potential sources of nitrogen within the watersheds of each of the parks. These proxy indicators will include such things as: human population numbers, permitted water withdrawals for agriculture, fertilizer consumption, and land use.

Preliminary Monitoring Objectives

Determine long-term trends in nitrogen loading estimations to NCBN park estuaries through nitrogen load modeling that incorporates human population density, atmospheric, fertilizer and wastewater nitrogen sources, non-point source discharge permits, permitted water withdrawals for domestic and agricultural consumption, fertilizer consumption and livestock population data.

Parks Monitored

  • Assateague National Seashore (ASIS)
  • Cape Cod National Seashore (CACO)
  • Fire Island National Seashore (FIIS)
  • Gateway National Recreation Area (GATE)
  • George Washington Birthplace National Monument (GEWA)
  • Sagamore Hill National Historic Site (SAGU)

Approach

Agents of Change variables are already gathered by local, state, and federal agencies. Regional testing involves determining the geographic scope of watershed data relevant for each network park, compiling current and historic (at 10-year intervals back to 1970) data from existing sources, and developing trajectories for each variable over time. This analysis will be used to identify the most useful indicators of nutrient load and to prepare guidance for updating the NPS database from other specific sources.

A monitoring protocol is being developed describing in detail how the historic data were compiled and reviewed as well as how to update this inventory, analyze and evaluate the new information for the network on a scheduled basis.

Last Updated: May 26, 2017 Contact Webmaster