Submerged Aquatic Vegetation Return is Sentinel of Chesapeake Bay Ecosystem Recovery

A new research article published today in the Proceedings of the National Academy of Sciences analyzes the positive impact of long-term nutrient reductions on an important and valuable ecosystem in the Chesapeake Bay. The research indicates that a resurgence of underwater grasses is due to nutrient reductions from the U.S. Environmental Protection Agency’s Total Maximum Daily Load along with conservation incentives which have resulted in a healthier Chesapeake Bay.

Jonathan Lefcheck of the Bigelow Laboratory for Ocean Science, along with 13 co-authors, showed that a 23 percent reduction of nitrogen and an eight percent reduction of phosphorus has resulted in more than a threefold increase in abundance of submerged aquatic vegetation in the Chesapeake Bay.

This ecosystem recovery is an unprecedented event; based on the breadth of data available and a sophisticated data analysis, this is the biggest resurgence of underwater grasses ever recorded in the world.

One of the co-author of the article is Brooke Landry, Maryland Department of Natural Resources biologist and chair of the Chesapeake Bay Program Submerged Aquatic Vegetation Workgroup.

The researchers employed advanced analytical tools to definitively show how the reduction of excess pollutants like nitrogen and phosphorus are the cause of this ecosystem recovery. To link land use and Chesapeake Bay status, researchers analyzed data in two different ways: one focusing on the cascade of nutrients from the land to the waterways, and one showing what happens to submerged aquatic vegetation (SAV) once the nutrients are in the water.

These findings are a collaborative effort between: the Bigelow Laboratory for Environmental Science, Virginia Institute of Marine Science, University of Maryland Center for Environmental Science, Environmental Protection Agency Chesapeake Bay Program, U.S. Geological Survey, National Socio-Environmental Synthesis Center, St. Mary’s College of Maryland, Smithsonian Environmental Research Center, Maryland Department of Natural Resources and Texas A&M University Corpus Christi.

Dr. William Dennison of University of Maryland Center for Environmental Science and Dr. Robert “JJ” Orth of Virginia Institute of Marine Science at the College of William and Mary are senior co-authors and have worked on underwater grasses and water quality reporting for bay ecosystem restoration over decades. Dr. Dennison is the recipient of the first Margaret A. Davidson Award for Stewardship from the Coastal Estuarine Research Federation of the University of Maryland and Dr. Orth will receive the outstanding scientist of Virginia award March 1.

“J.J. and I have had the distinct privilege of facilitating research that confirms a direct correlation between conservation actions undertaken by a broad partnership and ecosystem responsiveness that is leading to positive ecological outcomes.” said Dennison. “The Environmental Protection Agency Chesapeake Bay Program is working and can serve as a model for the rest of the world.”

Orth noted: “I am proud of our team of young and experienced researchers who worked in a collaborative environment to produce these exciting results. I really feel the torch is being passed to a next generation of scientists who bring both the passion and knowledge needed to continue the vital work of marine science required to keep our Chesapeake Bay flourishing. What has been a lifetime of work for Bill and me can now be analyzed and managed with analyses of long term data sets in creative ways to highlight this wonderful recovery.”

“It’s a humbling and unique opportunity,” said lead author Lefcheck. “These efforts began before I was even born, but we are at a stage now where the all these different threads can be pulled together to unveil a picture of unprecedented success. This is a message of hope, and I look forward to a future when the Bay is filled with grasses, something I never thought I would see during my lifetime!”