Research Projects

Urban stormwater runoff remains on the of the primary sources of nutrients, sediments, and other pollutants in receiving waters, like the Chesapeake Bay. Stormwater best management practices (BMPs) and green infrastructure (SWGI) have been implemented in urban and suburban areas to re-establish ecosystem functions lost because of urbanization. SWGI treatment trains provide sequential infiltration and treatment of stormwater on the landscape prior to export into nearby waterways and groundwater.

The aquaculture industry in Maryland is far from optimized partly due to the lack of knowledge relating oyster growth and morphology to the physical environment (flow and jostling). For sessile suspension feeders, such as oysters, water flow is critical to optimize under culture conditions as it regulates food delivery and waste export. Additionally, jostling may inhibit feeding activity and influence shell shape, the latter of which may influence product marketability. It is also unknown how different off-bottom cage types affect the flow regime. This lack of understanding is not unique to Chesapeake Bay waters but is a concern for oyster farmers globally.

Rationale: To meet the increasing demands of the world’s growing population under sustainability constrains, optimization of aquaculture methods will be necessary to maximize cost-effective production and minimize ecological impact. One of the supreme strategies for large-scale commercial aquaculture operations is the use of infertile/sterile populations of farmed animals. Sterility carries environmental significance, as the infertile animals are not able to propagate and/or interbreed with wild stocks. In addition, sexual maturation is associated with a substantial decrease in somatic growth due to the diversion of energy into the development of the gonads.

The recent exponential growth in established or planned US closed-containment Atlantic salmon production has been associated with over $1B investment into this aquaculture sector. The success of this dramatic expansion/investment in land-based, RAS salmon production requires a national, coordinated and interdisciplinary effort to ensure that current barriers are eliminated and efficiency and cost-effectiveness are attained. While major progress has been achieved in recent years in RAS technology, its scaling up may face biological, engineering, technological, economical and societal constraints that should be addressed via a fully integrated research, extension, outreach, education and workforce development network.

Identification and development of effective algaecides for commercial use is an active area of research, as the intensity and frequency of harmful algal blooms (HABs) are increasing worldwide. Although algaecides are a focus of HAB mitigation, there are still many unknowns. To this end, we propose the following objectives: 1) identify the algaecides released by barley straw with and without the use of white-rot fungi, Trametes versicolor, in the laboratory, 2) identify the impact of the algaecides on microcystin toxin production (toxin per cell/total toxin) and growth rate of the blue-green algae, Microcystis aeruginosa, and 3) compare algaecides found in the controlled laboratory setting to those found in Lake Williston post barley straw deployment.

Projected increases in intense precipitation events have the potential to alter the amount, source, and timing of stream nitrogen export and associated ecosystem impacts to the Chesapeake Bay. But, relatively little is known regarding amounts and sources of nitrogen exported during precipitation events and possible controls, such as hydrologic flowpaths and land use. The proposed research aims to quantify the amounts and sources of nitrogen along with dominant hydrologic flowpaths both within and among precipitation events in two tributaries of the Chesapeake Bay (one primarily urban and one primarily a mix of forest and agriculture). Isotopes of nitrate and water in stormwater stream samples will be measured to quantify nitrate sources and dominant hydrologic flowpaths, respectively.

Microbial communities govern the transformation of energy, carbon, and nutrients in aquatic ecosystems. In Chesapeake Bay (CB), microbes drives seasonal hypoxia and and forms the base of the foodweb that sustains important commercial and cultural fisheries including oysters, crabs, and striped bass. The efficacy of virtually any management plan that seeks to improve the health and resilience of CB intrinsically requires a fundamental understanding of these tiny but mighty organisms. 

Zooplankton are critical food sources for marine fish, and climate-driven changes in their abundance, diversity, and quality can have profound effects on larval recruitment and fisheries productivity in coastal oceans and estuaries. Despite the importance of prey for understanding variation in fisheries recruitment, accurate identification of zooplankton species remains challenging and a lack of information on prey quality and prey selectivity by fish may hinder the discovery of relationships between zooplankton and fish productivity. In Chesapeake Bay, two copepods, Acartia tonsa and Eurytemora carolleeae, are critical components of bay anchovy (Anchoa mitchili), larval striped bass (Morone saxatilis), and other fish diets.

Hatchery-based enhancement of marine fisheries is being undertaken on a worldwide scale, but the genetic impacts of these practices, specifically their effects on diversity and long-term population resilience, are often not fully understood and rarely monitored. Intensive hatchery-based restoration is underway in the Chesapeake Bay supplement depleted eastern oyster Crassostrea virginica populations, but the potential genetic impacts of this program remain poorly understood. While previous and ongoing work in the Harris Creek sanctuary has generated baseline data on genetic impacts at one planted reef, it remains difficult to draw conclusions about the genetic impact of the restoration program with so few samples.

The Anacostia River is among the most polluted tributaries in Chesapeake Bay. With substantial algal blooms and bacterial contamination, it has placed those who recreate on the water at considerable health risk. The first phase of a recently completed, multi-billion dollar infrastructure project, the Anacostia River Tunnel, which will retain and divert sewage and storm water effluent is due to be operational by March 2018. The tunnel project is award-winning from the perspective of the engineering community, but the environmental outcome is yet to be determined. While it may be years before the full infrastructure project is complete or full ecosystem recovery is seen, changes in phytoplankton and bacteria should be clearly evident in these first two years of project implementation.

There is a concerted effort to move away from traditional single species fisheries management in Chesapeake Bay toward a more holistic management framework that considers the interactions between fishery and non-fishery species and how their dynamics are linked to their environment. This framework, termed ecosystem-based fisheries management (EBFM), requires an understanding of the role of forage in sustaining upper trophic levels and the goal of this proposed research project is to fill important knowledge gaps related to the forage base of key commercial and recreational fish species in Chesapeake Bay.

Although external 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. 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.

Microbial biofilms are formed for protection from grazing, the mitigation of competition between species, the facilitation of gene transfer and the overall increase of the possibilities of survival. Biofilm formation on plastic is no exception, and microplastics provide further advantages for microbes as these particles can subsist for decades in aquatic environments. Microplastics are polymer particles that are smaller than 5 mm and their existence and prevalence in aquatic environment has been the focus of many studies in the last few years. Microbial communities that form biofilms on particles can potentially lead to the transport of pathogenic and harmful bloom forming species, as well as have an impact on global biogeochemical cycles.

The eastern oyster, Crassostrea virginica, has historically been a species of tremendous importance to the Chesapeake Bay economically and ecologically and provides numerous ecosystem services, including water filtration, habitat and food for many other Bay species. Significant hatchery and aquaculture efforts are currently underway to recapture the economic and ecological benefits of a robust oyster population within Chesapeake waters, whether for human consumption or to promote improvements in water quality and benthic habitat. The presence of microplastics (MP) in Bay waters may negatively impact these efforts.

This research aims to aid communities in addressing the question, “are our climate adaptation investments increasing our community’s resilience?” The state of Maryland and its communities are acutely interested in this question because they are being, and will continue to be, impacted by a range of climate impacts. As a result, Maryland has been aggressively setting reduction targets to mitigate greenhouse gases emissions and developing adaptation strategies to increase its resilience to the human health, economic, and environmental impacts of climate change.

Government agencies have expressed concerns about the potentially negative impacts of contaminants of emerging concern (CECs), such as pharmaceuticals and personal care products, on coastal ecosystems. Few data are currently available on the sources, levels, and spatiotemporal distribution of these contaminants in the Chesapeake Bay. The proposed project will evaluate (1) the use of fluorescent dissolved organic matter (FDOM) components to be used as tracers for urban and agricultural inputs to the Chesapeake Bay and (2) CEC concentrations in Chesapeake Bay water, sediment, and Eastern oyster (Crassostrea virginica).

Rock Creek is a tidal tributary to the Patapsco River in Anne Arundel County, Maryland and has historically had poor water quality including the development of water-column anoxia. An aeration system was installed into the creek in 1988 to help alleviate the water quality problems. Several recent studies have been conducted on the creek in order to view how aeration affects sediment nitrogen and oxygen fluxes, but less emphasis was placed on the associated production of problematic compounds. For example, with the establishment of anoxia hydrogen sulfide (H₂S) is released from anoxic sediments, which can inhibit nitrification and negatively impact other aquatic life.

While existing research addresses many of the important issues of oysters in Chesapeake Bay (CB), the fate and effects of resuspended oyster biodeposits in aquaculture areas on the nutrient, light, zooplankton and phytoplankton dynamics have not been taken into account when the use of oysters in mitigation of eutrophication in CB is examined. Currently, models do not include the effects of biodeposit resuspension on the ecosystem, nutrient dynamics and light and experimental data are not available.

This project has demonstrated the effectiveness of environmentally benign methods for biofouling control. There are many methods of biofouling control which have been suggested, with varying degrees of effectiveness and commercial applicability. Some may be highly species-specific, while others may target a range of species. In order for a biofouling management technique to be widely adopted, it must have the potential to be applied commercially without adding unreasonable labor demands, and it must be effective in controlling biofouling with disrupting the crop of interest, the oysters.

As the world’s climate changes, rural coastlines are becoming more vulnerable to sea level rise. Consequently, these ecosystems are undergoing major disruptions in nutrient cycling. Tidal salt marshes, riparian forests, and farmland converge on coastlines, forming ecotones, or unique transitional ecosystems. With centuries of farming and fertilizer additions, nitrogen (N) and phosphorus (P) in excess of plant demand can accumulate in soils (known as legacy nutrients). Sea level rise and associated saltwater intrusion following storm events can remobilize legacy nutrients years or even decades after application, supplying a persistent but unpredictable source of nutrients to downstream waterways.