Current Research Projects

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.

Anadromous alosine fishes (river herrings and shads) are critically important to ecosystem function, economies, and cultures of coastal communities, but have seen major declines in the mid-Atlantic region and the Chesapeake Bay in particular. We have developed and demonstrated the effectiveness of new monitoring tools for river herring (alewife and blueback herring) including environmental DNA (eDNA) and sonar image-based run counts that are rapidly improving our ability to study these species. However, additional eDNA monitoring of American shad and hickory shad, which lacks baseline data, is needed to establish habitat use in rivers across the mid-Atlantic.

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 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.

Salinization is increasingly affecting many watersheds, significantly impacting drinking water resources and infrastructure, reducing stability and resilience of aquatic ecosystems, and potentially hindering stream and river restoration efforts. Salinization is related to deicer use on roadways with additional contributions from accelerated weathering of impervious surfaces, water softeners, and sewage. The concentrations of chloride observed in many urban streams in Maryland now exceed the limit of 250 mg/L established by the U.S. EPA for chronic toxicity to freshwater life. These observed ranges and extreme fluctuations in salinity can mobilize nitrogen, phosphorus, base cations, and toxic metals from sediments to streams due to enhanced ion exchange and solubility.

Blue Crabs and their meat are an iconic cultural export for the Chesapeake area, and make a huge economic contribution to local fishing industry. Compared to unprocessed crabs, processed crab meat can promote the added value of blue crabs. However, currently, commercial meat is still hand-picked, which is an arduous and dangerous process. The shortage of skilled labor further impedes the healthy development of the crab industry. Targeting to these problems, an undergoing project in the lab is to design an automated crab meat processing machine integrating advanced machine vision and automation techniques to minimize the potential injury risk of human pickers, alleviate the labor force shortage, maximize the market value of blue crabs, and promote the development of crab industry.

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.

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.

We have developed a technology to efficiently produce infertile fish by disrupting primordial germ cell development in fish embryos. The technology uses a bath immersion to administer a Morpholino oligomer (MO) against Deadend (Dnd), an essential protein for early germ cell development in fish. This approach has been successfully used in the zebrafish, trout and salmon. The goal of this proposal is to examine the feasibility of applying this technology to sablefish. This goal will be achieved via the following two specific objectives: 1) Identify a suitable sablefish dnd-MO for immersion protocol development; 2) Implement the embryo immersion protocol, evaluate the level of sterility achieved, and optimize treatment conditions to achieve 100% sterility.

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.

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).

Triploid eastern oysters are an important component of the Maryland aquaculture industry because of their fast growth and sustained high meat yield. Commercially, triploids are produced by mating tetraploid oysters with normal diploid oysters. Developing tetraploid stock is crucial to meeting the growing demand for Maryland triploid oysters. However, it is challenging to produce and maintain excellent tetraploid lines for the benefit of industry. In short, there is a clear and pressing need for triploid and tetraploid lines that have region-specific beneficial characteristics, especially tolerance to low-salinity environments. In this project, we will establish the first generation of tetraploid stock derived from Maryland local oyster populations.

The net environmental impacts of oyster aquaculture are strongly related to the transport and fate of biodeposits, though little is known of their physical and biological properties. Biodeposits exported from aquaculture sites may result in net denitrification elsewhere while mitigating the impacts of organic matter over-enrichment at the aquaculture site. Consequently, the susceptibility of biodeposits to erosion and long range transport is key to determining the ecological effects of oyster aquaculture. Current oyster biodeposit models do not use realistic values of critical shear stress, (?c), or values of the cumulative suspended mass (CSM) available for export at aquaculture sites.

As Chesapeake Bay (CB) submersed aquatic vegetation (SAV) recover and oyster aquaculture operations in Maryland expand, the potential for these important shallow-water resources to spatially overlap and come into conflict is increasing. Until recently, the Code of Maryland Regulations has restricted installation of aquaculture gear in areas occupied by SAV and further requires that aquaculture operations cease if SAV expands into an existing lease. These regulations were intended to support SAV restoration under the assumption that aquaculture will impair SAV growth. However, the extent to which aquaculture is detrimental to SAV growth and the mechanisms by which it impacts SAV habitat are poorly understood at present.

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.

Atlantic menhaden (Brevoortia tyrannus) is a migratory forage fish that plays a vital role in Chesapeake Bay and Mid-Atlantic marine ecosystems by linking production at lower trophic levels with piscivorous predators. Given the critical ecosystem services menhaden provide as forage, the Atlantic States Marine Fisheries Commission is currently developing an Ecosystem-Based Fisheries Management (EBFM) approach to stewardship of the menhaden resource. Managers and stakeholders are particularly interested in potential impacts of menhaden management on its primary predator, Atlantic striped bass (Morone saxatilis).

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 existence of spatial structure in populations of exploited marine fishes challenges our ability to develop reliable stock assessments. Using the northern stock of Black Sea Bass (BSB - Centropristis striata) on the US Atlantic coast as a model species, I will combine empirical and analytical approaches to explore the impacts of the spatial resolution of population and assessment models on the reference points generated by assessments. In this region, the distribution of BSB is highly structured during summer months when the fish are inshore, but the distribution is more widely dispersed when offshore in the winter.

This study looks to elucidate the diets and drivers of interspecific interactions between dominant ctenophores and forage fishes in the Maryland Coastal Bays. Samples of zooplankton, ctenophores, bay anchovies and silver perch will be taken from various sites in the five predominant bays along Ocean City and Assateague Island in Maryland. Assessment of dietary overlap will be evaluated through stable isotope analysis of carbon and nitrogen. Additionally, measurements of salinity, temperature and dissolved oxygen will be taken to analyze possible correlative relationships between abiotic factors and interspecific interactions within the coastal bays.

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.

Pharmaceutical and personal care products (PPCPs) are concentrated in wastewater and sorb to microplastics (MPs) to concentrations magnitudes higher than the surrounding water. However, there is a large knowledge gap concerning PPCPs and their association with MPs found in wastewater. Ecotoxicity studies conducted on the effects of MPs and sorbed organic contaminants (OCs) have shown conflicting results, largely due to the lack of MP standards. Therefore, the objectives of this project are to: 1) validate methodology for creating standard MP particles; 2) quantify the sorption distribution of four PPCPs; and 3) measure the temporal variation of MPs from effluent, and their loading of nine PPCPs, from an advanced wastewater treatment plant (WWTP).

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. 

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.

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.

Current efforts to restore natural oyster reefs and a growing oyster aquaculture industry in Maryland will serve to support an increased prevalence of oysters in Chesapeake Bay. While these activities will support continued commercial harvests and restored natural habitats, elevated oyster numbers will also lead to changes in estuarine biogeochemistry relevant to water quality restoration. Recent studies have illustrated that oyster communities are associated with extremely high rates of nitrogen removal and newly proposed BMP guidelines will serve to give nitrogen removal credits to aquaculture activities.