Three decades of MBL research at a coupled watershed-salt marsh-estuarine ecosystem on the northern Massachusetts coast will continue, thanks to a six-year renewal grant from the National Science Foundation (NSF).

MBL Ecosystems Center scientists began field research at the Plum Island Ecosystems (PIE) site north of Boston in 1992 and, six years later, it became an NSF Long-Term Ecological Research (LTER) site. 

The goal of the PIE LTER is to advance our predictive understanding of the long-term response of linked land-marsh-estuary- ocean ecosystems to changes in three key drivers: climate, sea level and human activities.

The project is led by MBL Senior Scientist Anne Giblin and includes MBL scientists Zoe Cardon, James McClelland, and Ketil Koop-Jakobsen, as well as MBL research assistants and more than 20 other scientists from 10 institutions.

Sampling for green crabs at the Plum Island Ecosystems LTER. Credit: Kaeryel Dowl
Sampling for green crabs at the Plum Island Ecosystems Long-term Ecological Research site. Credit: Kaeryel Dowl

The PIE LTER site, which connects to the Gulf of Maine, includes a major portion of the largest remaining salt marsh in New England (the Great Marsh), Plum Island Sound, and the Ipswich, Parker and Rowley River estuaries and their watersheds.

This is an area of the world that is changing rapidly. Rates of sea-level rise are accelerating, sea-surface temperatures in the Gulf of Maine are rising faster than most places on earth, and precipitation is becoming more variable. Substantial changes are also occurring in the watershed, due to increases in urbanization as well as in wetland areas due to rapid growth in the population of beaver, whose dams trap sediment and water.

The PIE-LTER research sheds light on how marshes are responding to sea-level rise, as well as controls on carbon storage in marsh and estuarine ecosystems (blue carbon). This information is shared with coastal zone managers from local, regional, and federal agencies and nonprofits. 

Three Questions

This renewal grant for the PIE LTER is organized around three questions that build on previous findings and integrate long-term studies with new observations, experiments, and model development. Activities within the three questions integrate across the entire watershed-marsh-estuary domain to facilitate a broader synthesis of long-term data and new observations.

The team’s first question is, “How are the sources and fates of organic matter and nutrients in the linked watershed/estuary system being altered by changing land use, sea-level rise (SLR), climate, and geomorphology?” To answer this question, they will examine how the linked coastal system influences estuarine production and water quality, and the role of coastal ecosystems in modulating carbon and nutrient fluxes to the nearshore ocean.

Their second question is, “How do coastal marine foodwebs and energy flow respond to new geomorphic configurations, SLR, changing climate, and associated estuarine responses?” This is a new integrative effort to determine how the landscapes’ ability to transfer energy to foodwebs changes with habitat. This will combine long-term species abundance data, stable isotope data on niche size, and mapping of landscape features to model how future changes in the marsh-estuary configuration will modify energy flow. Given the importance of coastal ecosystems in supporting nearshore foodwebs, understanding how this link will change with climate, land use change and SLR is critical.

Finally, they ask, “What internal feedbacks might accelerate, slow down, or even reverse the predicted changes in emergent marsh configuration and the fate of carbon, nutrients and energy?”

“We urgently need to understand more about internal feedbacks, such as a change in the marsh vegetation type, that might increase marsh resilience or compromise marsh survival as sea levels rise, the system warms, and watershed inputs continue to change,” said project leader Anne Giblin. “New collaborations will allow us to take advantage of a large-scale marsh restoration to test some of our hypotheses on feedback mechanisms within the system.”

Plum Island Ecosystems is one of 27 Long-Term Ecological Research projects nationwide funded by the National Science Foundation.