Research Projects

Atlantic menhaden (Brevoortia tyrannus) plays an important role in linking production from lower trophic levels to diverse marine predators and supporting the largest commercial fishery on the U.S. east coast. A significant management controversy has arisen because of uncertainties over their movement into and out of the Chesapeake Bay and the size or age-dependent vulnerability of fish to the commercial fishery. A landmark mark-recapture study of Atlantic menhaden was conducted during the 1960s–70s, which allows estimation of movement rates. Over one million menhaden were tagged, and over 200,000 tags were recovered, but the data were never fully analyzed. Using these data, this study will obtain estimates of migration rates and selectivity patterns, develop maps of the menhaden's range, and obtain estimates of the impact of the spatial distribution of the fishery on menhaden. These results will substantially improve our knowledge of menhaden population dynamics (migration and mortality rates), reduce uncertainty in estimates of stock status, and advance ecosystem-based management of the fishery.

Recent analyses suggest trends of increasing particulate P and N loading from Susquehanna River to upper Bay. These trends, which appear related to sediment infilling of Conowingo reservoir, represent a large impediment to achieving TMDL allocations needed for improved Bay water quality. To assess ecological consequences of increased PP and PN, this project will examine how bioavailability changes in time and space and especially within the Bay's largest SAV bed, which is potentially capable of huge nutrient retention during the spring/summer. These data will help to improve model simulation of key processes and to assess alternative management actions to minimize ecological impacts of planned reservoir modification.  

The Susquehanna River represents the largest single source of excess nutrients and sediments flowing into the Chesapeake Bay. But to understand how this tributary might affect the Bay’s water quality in the future, scientists first need to grasp how nutrients and sediments have flowed through the river in the past. In this project, researchers are developing an up-to-date nutrient and sediment “budget” for the Susquehanna, exploring how nutrients and sediments in this river have historically affected downstream environments and what impact storms have had on that relationship.  

Development has led to the degradation of many streams in Maryland, often by altering how water flows through stream channels and is stored in flood plains. Through field observations, remote sensing, and computer modeling, researchers are examining stream restoration projects in Maryland to determine how those projects have influenced the flow of water. The results could give scientists a better understanding of the restoration practices that most effectively improve the structure of local streams.

Winter blooms of algae add substantial energy, in the form of carbon, to the Chesapeake watershed. Scientists do not know, however, how that additional energy impacts the ecosystem as a whole. Researchers are investigating whether such winter blooms could fuel the growth of populations of copepods and other small crustaceans. Because those animals, in turn, provide energy for spawning fish, winter algae growth could be important to the success of many Bay fisheries.

Atlantic menhaden are one of the most important prey species for striped bass and other large fish in the Chesapeake Bay. In this project, researchers harvest menhaden and, using new DNA analyses, identify the species of plankton that the fish have recently eaten. The results will give scientists a better understanding of the food sources important to menhaden and how changes to those food sources, due to climate change or other impacts, could affect the fish. 

Forest “buffers,” or trees planted along the edge of a waterway, can help to trap the excess nutrients and sediments in runoff before they enter a local stream. But forest buffer trees often have poor survival rates because their environments are prone to frequent flooding and other disturbances. In this study, researchers are exploring the particular tree species that grow the best under different stream conditions. The results could help restoration experts to decide what trees to plant in a particular environment to help improve water quality.

Blue crabs are important to Maryland’s culture and economy. This study will monitor rivers around the Bay for outbreaks of a viral pathogen that targets blue crabs, called the reo-like virus, or RLV, which kills 25 percent of the crabs it infects. Preliminary evidence indicates that crab shedding operations may aid in the spread of this pathogen, and researchers are exploring whether incidences of disease are high in rivers near shedding facilities.

Bay-grass beds along the Susquehanna Flats in the upper Chesapeake Bay, near the mouth of the Susquehanna River, have experienced a large resurgence since the 1980s, even as bay grass populations have continued to struggle elsewhere in the estuary. Understanding the reasons for this resurgence may become important as scientists try to restore Bay grasses to other locales around the Bay. This study will draw from field studies and computer modeling to assess the relationship between changes in the concentrations of nitrogen and phosphorus in the Susquehanna Flats and the growth of bay grasses.

In the Chesapeake Bay region, environmental policies are often hotly debated, in part because it is not clear how such policies could affect job growth or key industries in the near and long term. Researchers are developing a suite of computer models that explore the connections between environmental processes in the Bay ecosystem and the region’s human residents. Such modeling work could help to inform decision-makers about how particular policies might impact local economies in Maryland and elsewhere.

Communities around the Delmarva Peninsula are facing choices about how to develop their lands and manage their resources. Those decisions could, in turn, have impacts on how much excess nutrients will be delivered to the region’s coastal lagoons. Researchers are developing a computer model that will address this relationship, estimating how land use changes might influence the water quality of these important ecosystems. Such a model could help communities to develop land-use plans that conserve the local environment.

This study will explore whether certain species of macroalgae, or seaweeds, could be integrated effectively into local oyster aquaculture industries. While expected to benefit water quality in the Bay in general, oyster growing could add excess nutrients to local ecosystems. Seaweeds, however, might be able to trap some of those nutrients, limiting the potentially negative environmental impacts of oyster aquaculture operations. The seaweeds themselves could be sold for use in a range of products. 

By looking at the biological communities living in streams across Maryland, scientists can learn a lot about the health of these waterways. In this study, researchers are drawing from state data to map the distribution of fish and small animals in streams across Maryland and the factors that potentially influence that distribution, such as urban growth. Such a map could be used to pinpoint particular stream reaches that are particularly sensitive to the negative effects of development. 

This study will explore the differences between various strategies for stabilizing shorelines in Maryland. By analyzing existing sites with structural or “living” shoreline protections, researchers will assess how well a range of methods guard shorelines against waves and slow erosion. This issue will come to the forefront as sea level rise accelerates around the Chesapeake Bay, exposing communities and natural ecosystems to greater damage from storm surges.

The Chesapeake Bay’s striped bass fishery is the region’s second-most profitable fishery, although populations of these fish have declined in some years, partly because of overfishing. Researchers are validating a new and non-lethal tool, called BIA, that can be used to assess the nutritional status of striped bass caught in the estuary. The tool could give fisheries managers a dependable method of determining the health of the Bay’s striped bass, helping those experts to manage the fishery more effectively.

The Pilot Bridge to Marine Science REU program’s goal is to increase interest and participation by Hispanic early stage undergraduate students from different disciplines in marine science.

Non-native Phragmites reeds have displaced native plants from many marshes around the Chesapeake Bay region. But environmental changes, such as rising levels of carbon dioxide (CO2) in the atmosphere, might affect this plant’s invasion success. Through controlled experiments, researchers are investigating whether elevated CO2 and nitrogen pollution levels in the environment might help Phragmites to outcompete native marsh plants. That will provide scientists with a better understanding of how the plant could spread in the future.

The blue crab fishery is an important industry in Maryland, generating around $500 million in economic benefits for the state annually. Researchers will develop an updated computer model of blue crab stocks that will help fishery managers to assess whether proposed policies, such as catch limits, are likely to have a desired effect on the fishery. The model will also generate information on how precautionary catch limits and other actions might impact the Bay’s local economies by increasing or decreasing fishery revenues.

Restoring the Chesapeake Bay’s oyster reefs will likely have large benefits for both the Bay ecosystem and local economies, scientists say. Currently, to build a new oyster reef, restoration experts typically seed Bay habitats with larvae attached to hard surfaces, including recycled oyster shells. Such a technique, however, may not work well in all scenarios. This study will explore the effectiveness of a new restoration strategy in which free-floating larvae are added to an existing reef in the wild. 

This ongoing project has examined the risk of aquatic invasive species introductions to the Mid-Atlantic via the live bait trade. Researchers have quantified the diversity of species found in baitboxes shipped to the Mid-Atlantic so as to determine the best intervention strategies to minimize the introduction of unwanted and harmful species to the region.

Scientists developed a new analytical approach that improves detection and measurement of changes in biological communities in Chesapeake Bay tributaries over time and at different locations. This line of research may help researchers and local and state officials to plan better to prevent and manage the effects of development and urbanization on that plants and animals in Maryland’s streams.

OBJECTIVES: Our overall objective is to quantify how suspension-feeding organisms living attached to the hard substrate formed by oyster reefs serve to remove phytoplankton from the water column and thereby help improve water quality. Specifically, for hooked mussels and tunicates, two of the most abundant (by biomass) organisms on oyster reefs, we will: • Determine biomass-specific, temperature-dependent, and seston concentration-dependent rates of water filtration and biodeposition • Assess filtration efficiency for particles between 1 _ 50 μm • Develop a spreadsheet model that estimates non-oyster "filtration capacity," in terms of both total volume of water cleared of particles and mass of particles transferred to the sediments.

This ongoing project seeks to synthesize research on stream restoration so that information on effective strategies is accessible to managers working to improve water quality in Maryland.

Large investments in water quality and fisheries monitoring on the Potomac River have resulted in extensive datasets that cover a long time period. In this ongoing project, researchers have created a model that can use these data to answer questions and help with the management and restoration of the estuary.

Researchers have developed a model to predict which locations have the greatest likelihood of receiving above-average oyster spatfall (settling of larvae onto hard substrate), taking into account the effect of wet versus dry years. This model would allow managers to better focus restoration efforts by identifying the locations where oyster bar rehabilitation will result in the greatest increase in oyster abundance. The model also should be useful to commercial aquaculture operators seeking to maximize their production.