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Protecting the Chesapeake

Chesapeake Bay tidal wetlands.

Chesapeake Bay tidal wetlands.

Review examines how to preserve vital natural resource

by MaryAlice Bitts-Jackson

The Chesapeake Bay is North America’s largest estuary, with a shoreline of more than 8,000 miles, several deep-water ports, wetlands and forests that provide homes to many different species of North American marine life, animals and plants. As temperatures rise and carbon dioxide levels increase due to global warming, scientists like Professor of Biology Tom Arnold are searching for ways to protect and preserve the bay and its rapidly declining seagrasses, which are essential to the bay's complex ecosystem.

Professor of Biology Tom Arnold. Photo by Carl Socolow '77.

Professor of Biology Tom Arnold. Photo by Carl Socolow '77.

"We’re at a tipping point for the Chesapeake, and it is clear that continued warming would kill off the dominate species of seagrass that fish and crabs rely on in the coming century,” says Arnold. But with smart conservation efforts, he stresses, we could slow or reverse the course.

A biochemist and physiologist who studies natural toxins, pheromones, odors and anti-microbials, Arnold recently co-published a review of public research on the Chesapeake seagrass as part of a three-year group effort funded by a grant from the Environmental Protection Agency (EPA) to the Maryland Department of Natural Resources.

He became involved in this work through a scientific working group of 50 scientists and managers from universities and state and federal government agencies who joined forces to assess the state of seagrasses in the Chesapeake Bay and make recommendations for future conservation efforts. His review presents a deep well of published work on the subject, including surveys of South Bay, Virginia, by Arnold, with assistance from then-biology majors Kelly Maers ’11, Hannah Leahey ’12 and Chris Mealey Katalinas ’13, and in collaboration with a Smithsonian colleague, Whitman Miller, who designed and built a SCOUT PCO2 instrument the team used to collect data (Dickinson recently purchased one of these instruments with aid from a National Science Foundation grant). GIS Specialist James Ciarrocca aided the project by mapping the information, and Savanna Riley ’17 assisted with proofing and formatting.

The review, “Twenty-first century climate change and submerged aquatic vegetation in a temperate estuary: the case of Chesapeake Bay,” was published by Taylor & Francis Online this summer. In it, Arnold notes that the harmful effects of warming can be offset, in part, when seagrasses are exposed to higher-than-normal levels of carbon dioxide in the water. However, for this CO2-fertilization effect to help seagrasses tolerate warmer waters, sufficient light for photosynthesis must filter through the water and reach the plants.

“It is a really big 'if,' because right now, water clarity is often poor because of excess nutrients running into the Chesapeake,” Arnold says. “So it’s more important than ever that we reduce nutrient input in the Chesapeake to keep the waters clear.”

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Published August 25, 2017