What is SWMP?

In 1995, with the goal of understanding how estuaries change over time, the National Estuarine Research Reserve network implemented a standardized monitoring program across all 30 Reserves known as the System-Wide Monitoring Program (SWMP). This long-term program aims to measure and determine how conditions on the Reserves are changing in both the short and long term. By using this standardized approach, we can better understand how estuaries will respond to change on a local and national scale and make the most effective management decisions possible. Reserves collect data centered around water quality, habitats and land use.  Here, we focus on water quality. We have monitoring stations that are positioned throughout the Bay from the head of tide to the middle of the Bay.

SMWP at Great Bay:
Within Great Bay, we have four SWMP water quality stations and one weather station that are operated in conjunction with the University of New Hampshire’s Jackson Estuarine Laboratory, photos of these stations are included below. Water and weather parameters are collected by our research team and annually, Reserves use the data collected to create a report card that highlights trends that were found in the data collected throughout the year. With this report, we are able to see how the estuary is changing over the  course of the year and make appropriate management decisions based on our findings. This annual data is also being used in regional and national  comparisons of estuarine conditions.

Phot Credit: Chris Peter

Recent SMWP Trends:
Our most recent annual report card highlights trends from 2021. One of the major trends that we observed was the precipitation levels on the Reserve. In the summer of 2021, we saw the highest levels of precipitation that have ever occurred over the last 10 years. Record rainfall created several changes in the ecosystems throughout Great Bay with eelgrass beds being impacted heavily.

Eelgrass is a vital part of the Great Bay Estuary. When eelgrass beds are healthy, they provide oxygen, improve water quality, and serve as habitat for a variety of marine species that are living in the Bay. Eelgrass productivity and health is dependent on water quality and with heavy rainfall comes degraded water quality. Stormwater traveling through rivers carry excess sediment, nutrients, and other dissolved compounds in the Bay causing water quality to decline. With these extra compounds in the water  column, light is blocked from the eelgrass beds causing severe die-off. Excess nutrients also cause blooms of  phytoplankton and macroalgal blooms which can also block light and even smother eelgrass, leading to more die-off events. We continue to monitor the eelgrass beds in the Bay to assess their health and the way they are changing over time.

For more information about SWMP and the trends that are being seen throughout Great Bay, check out our 2021 SWMP report card. For past report cards, visit the monitoring section of our website.

Photo Credit: Anna Lowien