Coastal Ecosystem Ecology Lab

We study seagrass and marsh ecosystem dynamics in Chesapeake Bay and beyond

St. Mary's College of Maryland

Environmental Studies Program


We are an undergraduate-driven research lab based at St. Mary’s College of Maryland (SMCM) located on the St. Mary’s River, just across the Southern Maryland peninsula from Chesapeake Bay. Our area of focus is ecosystem ecology, which takes a holistic approach in studying the environment. It involves integrated investigation of living and nonliving components of ecosystems, how those components interact, and how those interactions affect ecosystem structure and function.

The SMCM Coastal Ecosystem Ecology Lab investigates how human stressors, like climate change and nutrient pollution, affect coastal foundation species, such as seagrass (also known as submersed aquatic vegetation, or SAV) and salt marshes. We also investigate how changes in marsh and SAV abundance, in turn, affect coastal ecosystem processes. Our goal is to understand the underlying mechanisms of coastal ecosystem decline, recovery, and resilience, and to quantify the effects of ecological change on ecosystem functions, such as nutrient cycling.

This is important work because many of the functions that SAV and marshes carry out are valuable to people. For example, in the Chesapeake Bay region, federal, state, and local jurisdictions are spending a lot of time and money to reduce nutrient inputs to the estuary through one of the most ambitious coastal restoration programs in the world. Research that aims to understand how human activities affect marshes and SAV, and how these systems, in turn, affect estuarine nutrient cycling, informs these restoration efforts.

Because our home institution is a small, teaching-centered liberal arts college, the lab’s emphasis is on undergraduate student research training. Funded research projects involve student research assistants, who play an integral role in coordating and completing field and lab work. We also support a diverse range of coastal science-focused senior research projects (known as St. Mary’s Projects, or SMPs), directed research projects completed for course credit, and SMCM-funded St. Mary’s Undergraduate Research Fellow (SURF) projects.


Last day of fieldwork

We just completed our last day of field sampling for our SAV beds as nutrient sinks project. It was a gorgeous, calm day and the SAV at Susquehanna Flats seemed to be doing fine, even after all the flooding that occurred on the Susquehanna River last year. We’re still processing samples and will begin to really dig into the data this fall. My collaborator Cindy Palinkas, her graduate student Miles Bolton, and I will all be presenting a portion of the project at the Coastal and Estuarine Research Federation biennial conference in Mobile Alabama this November.

Gurbisz quoted in Chesapeake Bay Journal

Cassie Gurbisz was quoted in an article that was recently published in the Chesapeake Bay Journal. The article, titled Scientists fear steep loss of Bay grasses lies ahead, discusses how Chesapeake Bay SAV is doing this year after major flooding flushed tons of nutrients and sediment into the bay last year. Dr. Gurbisz mentions in the article how grass coverage at some of our field sites seemed to be patchier this year compared to last, like in the video below.

St. Mary's Undergraduate Research Fellow completes summer fieldwork

Colleen McGuire, a student researcher funded by SMCM’s St. Mary’s Undergraduate Research Fellowship (SURF) program, just wrapped up her summer fieldwork. She has been investigating the extent to which a restored oyster reef just off the campus shoreline improves water clarity. Because SAV need clear water to grow, and oysters can clear the water, she hypothesizes that oyster restoration could potentially enhance SAV restoration. Our goal for this research is to explore whether further research into desigining oyster restoration plans to facilitate SAV restoration is feasible.

End of the year SMP celebration

In celebration of my SMP students completing their senior research projects, we went for a hike and had dinner at my place. With all of the hard work they put into their projects, they deserved a little R&R! Congrats!

Students present their SMPs at student research symposium

Gurbisz Lab senior research students presented their St. Mary’s Projects (SMPs) at St. Mary’s College of Maryland this week. Five students presented posters on a diverse range of topics at the student research symposium. Isaac Page studied shorebird phenology, Dylan Powell worked on developing methods for local non-destructive marsh vegetation sampling, Kajsa Newton analyzed coastal forest and marsh landscape dynamics, Chelsea English investigated sediment trapping in SAV beds, and Tyler Scott measured sediment accretion rates in a local marsh.



Coastal landscape dynamics

Salt marshes protect coastal infrastructure from sea level rise and storm events associated with climate change. However, they are also vulnerable to climate change if environmental forcings overwhelm stabilizing feedbacks between marsh vegetation and the environment. For example, rapid marsh loss has occurred in regions of Chesapeake Bay and the New England coast due to edge erosion and interior drowning. However, other studies suggest that marshes are largely stable or can even increase in area due to accretion or transgression into uplands.

SAV beds as nutrient and sediment sinks

Although nutrient load reductions have been a primary management strategy for Chesapeake Bay restoration, internal ecological processes, such as seasonal nutrient retention in submersed aquatic vegetation (SAV) beds, may also play an important, complementary role. For example, if SAV increasingly retain nitrogen and phosphorus as they recover, they could potentially limit regional phytoplankton production, thereby decreasing the magnitude of seasonal bottom-water hypoxia. However, we lack sufficient details about the factors controlling the magnitude of an important mechanism of SAV-mediated nutrient sequestration–particulate nutrient trapping–to make inferences about its importance relative to total loads to the system.

Upper Chesapeake Bay SAV recovery

My PhD dissertation focused on the dynamics of a large bed of submersed aquatic vegetation (SAV) in the upper Chesapeake Bay. What makes this particular SAV bed so special is 1) it’s huge (in fact it’s the largest SAV bed in the Bay) and 2) it suddenly recovered about 10 years ago. My goal was to identify factors that contributed to its recovery and resilience. I used a variety of approaches to answer these questions, including retrospective data analysis, observational and experimental fieldwork, and numerical simulation modeling.

Recent Publications

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Submersed aquatic vegetation in Chesapeake Bay: Sentinel species in a changing world

Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated …

Interactive Effects of Physical and Biogeochemical Feedback Processes in a Large Submersed Plant Bed

Submersed plants are sensitive to nutrient loading because excess algal growth creates light-limiting conditions. However, submersed …

Resilience indicators support valuation of estuarine ecosystem restoration under climate change

Economic valuation of ecological restoration most often encompasses only the most tangible ecosystem service benefits, thereby omitting …

Mechanisms of Storm-Related Loss and Resilience in a Large Submersed Plant Bed

There is a growing emphasis on preserving ecological resilience, or a system’s capacity to absorb or recover quickly from …


  • (240) 895-4473
  • 47645 College Drive, St. Mary's City, MD 20686
  • Wednesday 1:00 to 3:00