Research: Healthy Coastal Ecosystems. Understanding how human development impacts long-term ecosystem health.
 

Finding solutions to protect Delaware's coastal ecosystems and enhance the natural services they provide

The Delaware estuary and surrounding wetlands are prime habitat for commercial fish species, a winter home for migrating birds, an outlet for recreation and tourism, and a natural barrier against coastal storms. Delaware Sea Grant is funding research that investigates how coastal ecosystems have changed over time in response to human activity and how communities can act to produce positive change in our environment.

 

Current Research Projects

 Dredging of a marsh.

Physical Dynamics of a Tidal Wetland Restoration Site: Prime Hook National Wildlife Refuge

Investigators: Drs. Chris Sommerfield and Carlos Moffat

The Prime Hook National Wildlife Refuge is undertaking a $38 million restoration project to return the 10,000-acre area to a naturally functioning tidal marsh and barrier beach capable of harboring migrating birds while preventing coastal flooding. Delaware Sea Grant is funding research on how the Refuge will be affected by climate change, sea level rise, and human pressures in order to improve the resiliency of the Refuge following the restoration effort.

Physical Dynamics of a Tidal Wetland Restoration Site: Prime Hook National Wildlife Refuge

Investigators: Drs. Chris Sommerfield and Carlos Moffat

The Prime Hook National Wildlife Refuge is undertaking a $38 million restoration project to return the 10,000-acre area to a naturally functioning tidal marsh and barrier beach capable of harboring migrating birds while preventing coastal flooding. Delaware Sea Grant is funding research on how the Refuge will be affected by climate change, sea level rise, and human pressures in order to improve the resiliency of the Refuge following the restoration effort.

Drs. Chris Sommerfield and Carlos Moffat will measure sediment and water movement within the marsh. Tides, sediment loads, wind, and circulation patterns are all shifting as this restored ecosystem re-establishes balance, and ongoing data collection is necessary to keep resource managers aware of the progression of the restoration. In particular, it is important to monitor the delivery of sediment to the marsh since this directly determines the stability of tidal wetlands.

The research is being completed in partnership with the U.S. Fish and Wildlife Service and the Delaware Department of Natural Resources and Environmental Control. As data is collected, Drs. Sommerfield and Moffet will create a conceptual model of how the coastal ocean influences the exchange of sediment between Refuge and Delaware Bay.

While the science of restoration is advancing, many questions remain regarding how much of the original ecosystem functions and services will return or how long the restoration process will take. This research project will provide data critical to managing this restoration effort as well as advance the state of restoration science generally.

 

Hydrodynamics and Beach Morphology During Extreme Events

Investigator: Dr. Jack Puleo

Beaches provide not only recreation and leisure opportunities, but play an important role in protecting communities during intense storm events. At the same time, storms can dramatically alter the shape, extent, and height of beaches by moving sand along-shore and offshore. Delaware Sea Grant is funding Dr. Jack Puleo to develop self-contained sensor systems for quantifying water and sand movement that can be rapidly deployed ahead of a storm event.

Hydrodynamics and Beach Morphology During Extreme Events

Investigators: Dr. Jack Puleo

Beaches provide not only recreation and leisure opportunities, but play an important role in protecting communities during intense storm events. At the same time, storms can dramatically alter the shape, extent, and height of beaches by moving sand along-shore and offshore.

While beach characteristics and water movement around along a beach have been measured in detail before and after storm events, little data exists about how beach features change during a storm. Delaware Sea Grant is funding Dr. Jack Puleo to develop self-contained sensor systems for quantifying water and sand movement that can be rapidly deployed ahead of a storm event. Dr. Puleo will collect data using these sensor systems during at least two storm events on Delaware beaches, and then use modeling to predict how different shapes of beaches may respond to storm events of varying intensities.

This research will inform how vulnerable individual Delaware beaches are to erosion from coastal storms, allowing coastal managers to better direct efforts towards reducing beach loss. Dr. Puleo’s work will culminate in meetings with Delaware DNREC, US Army Corps of Engineers, and local town managers to ensure they benefit from the research findings.

 Eroded beach after a storm.
 
 Atlantic sturgeon underwater.

Conservation and Recovery of Atlantic Sturgeon in the Delaware River Estuary

Investigators: Drs. John Madsen and Dewayne Fox

The current population of Atlantic Sturgeon is less than 0.5% of the estimated historical stock in the Delaware River. The lower estuary hosts one of the largest remaining populations of Atlantic Sturgeon, although the reason why sturgeon congregate there is unknown. Delaware Sea Grant is funding research to better understand the habitat preference of Atlantic Sturgeon in order to more effectively manage the estuary for the recovery of this endangered species.

Conservation and Recovery of Atlantic Sturgeon in the Delaware River Estuary

Investigators: Drs. John Madsen and Dewayne Fox

At the start of the 20th century, the Delaware River supported the world’s largest caviar fishery dependent upon Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus). From a historic population numbering approximately 360,000 spawning adults, the current population is less than 0.5% of the estimated original stock. These declines and lack of recovery in this iconic species led to it being listed as endangered under the Endangered Species Act in 2012. Since Atlantic Sturgeon are not considered a sportfish, the State of Delaware has very limited means to support research and recovery activities for this species. Yet at the same time, the state, in addition to the federal government, has regulatory requirements to conserve and restore this population.

To allow for effective management of this species, fisheries scientists and decision makers need a more detailed picture of sturgeon habitat in Delaware waters. Researchers John Madsen and Dewayne Fox, from the University of Delaware and Delaware State University, respectively, will examine why adult and large sub-adult Atlantic Sturgeon congregate in the lower portion of the Delaware River estuary. That habitat area may host one of the largest remaining populations of Atlantic Sturgeon.

Drs. Madsen and Fox will use several techniques to collect data on the habitat preferences of adult and large sub-adult Atlantic Sturgeon during different life history stages. The research team will (1) deploy acoustic telemetry coupled with side-scan sonar to examine the distribution of sturgeon in space and time in the lower estuary; (2) catch and release sturgeon to examine their gut contents and determine their food sources while in the lower estuary; and (3) use side-scan sonar imagery, seafloor sediment sampling, and high-resolution bathymetry mapping to characterize the physical seafloor environment in the lower estuary.

Understanding why Atlantic Sturgeon congregate in the lower Delaware River estuary will greatly aid in stock assessment and survey design as well as support management decisions to minimize potential risks to this endangered species in this heavily utilized portion of the estuary. Specifically, the research will provide data that can be used to make science-based decisions concerning the designation of critical habitat for this endangered species. The project’s results will also help to meet the long-term goals of the Delaware Division of Fish and Wildlife, the Atlantic State Marine Fisheries Commission, of which the State of Delaware is a member, and the National Marine Fisheries Service of recovering the species to the point of delisting it as an endangered species and ultimately developing a sustainable Atlantic Sturgeon fishery.

 

Morphology and Tidal Inundation of Tidal Wetlands in the Delaware Estuary

Investigators: Drs. Tom McKenna, Naomi Bates, and John Callahan

An expanse of tidal wetlands fringes the Delaware Estuary and provides ecosystem services such as preserving water quality, mitigating flood hazards, and providing outdoor recreation. However, these wetlands are highly sensitive to tidal inundation, which depends on factors such as coastal development, land use practices, coastal storms, and sea level rise. Delaware Sea Grant is funding research to conduct precise elevation mapping of these wetlands in order to determine their susceptibility to inundation.

Morphology and Tidal Inundation of Tidal Wetlands in the Delaware Estuary

Investigators: Drs. Tom McKenna, Naomi Bates, and John Callahan

An expanse of tidal wetlands fringes the Delaware Estuary and provides Delaware, Pennsylvania, and New Jersey with ecosystem services such as preserving water quality, mitigating flood hazards, and providing outdoor recreation. However, these wetlands, particularly tidal saltmarshes, are highly sensitive to tidal inundation, which depends on factors such as coastal development, land use practices, coastal storms, and sea level rise.

Understanding the vulnerability of tidal saltmarshes to inundation requires precise mapping of the elevations of these wetlands relative to sea level. Currently, the Delaware Digital Elevation Model is the most widely used map of marsh elevations – however, this model is based on LIDAR measurements and has not been ground-truthed in many Delaware marshes, where thick vegetation may inhibit LIDAR’s accuracy.

Delaware Sea Grant is funding a team of Delaware Geological Survey researchers, led by Drs. Tom McKenna, Naomi Bates, and John Callahan, to improve our understanding of how tidal saltmarshes in the Delaware Estuary with respect to inundation. The research team will focus on four tidal saltmarshes: Blackbird Creek, Leipsic River, St. Jones River, and Murderkill River tributaries. In each marsh they will: (1) measure tidal cycles within the saltmarshes to determine how water moves through the marsh; (2) use spatial modeling to estimate marsh health and vulnerability to continued inundation; (3) identify systematic mistakes in the Delaware Digital Elevation Model caused by the thick vegetation present in saltmarshes; and (4) revise the Delaware Digital Elevation Model for Delaware saltmarshes from the City of New Castle to Broadkill Beach based on their findings.

Results from the study will be shared with natural resources managers and coastal scientists, particularly at the Delaware National Estuarine Research Reserve and the US Fish and Wildlife Service. Additionally, the team will work closely with the North Bay Adventure Camp and other groups to help develop K-12 and higher education materials to provide high quality educational programming. Overall, this study will aid coastal managers in planning long-term resilience to sea level rise using tidal saltmarshes as a natural barrier.

 Egret in marsh.
 
 Dr. Jon Cohen working with zooplankton tow nets at sea.

A Risk Assessment Analysis of Microplastics in Delaware Bay: Physical Controls and Biological Effects of an Emerging Pollution Issue

Investigators: Drs. Tobias Kukulka and Jon Cohen

Plastic marine debris is an emerging pollutant of concern both in the Delaware estuary and around the globe. Delaware Sea Grant is funding research to quantify the distribution of microplastic debris in the Delaware Bay and its effect on marine organisms.

A Risk Assessment Analysis of Microplastics in Delaware Bay: Physical Controls and Biological Effects of an Emerginc Pollution Issue

Investigators: Drs. Tobias Kukulka and Jon Cohen

Plastic marine debris, particularly in the form of microplastics less than 5 millimeters in size, is an emerging pollutant of concern both in the Delaware estuary and around the globe. Microplastic debris can present serious hazards to individual marine organisms, but less is known about how microplastics impact entire communities and ecosystems – particularly with respect to important species in the Delaware Bay.

Delaware Sea Grant is funding Drs. Tobias Kukulka and Jon Cohen to quantify the distribution of microplastic debris in the Delaware Bay as it varies through space and time. In addition, the research team will develop a risk assessment model to quantify how increasing concentrations of microplastic debris impact the dominant zooplankton in the Delaware Bay, the copepod Acartia tonsa. The researchers will also develop an outreach program to engage and inform the public about the effects of microplastic debris on marine life, with emphasis on the ongoing work in Delaware Bay.

 

Phytoplankton Dynamics and the Role of Heterosigma akashiwo in Promoting Blooms of the Toxic Dinoflagellate, Dinophysis acuminata

Investigators: Drs. Tye Pettay and Kathyrn Coyne

Dinophysis acuminata is a toxic microalgae found in Delaware’s Inland Bays that can bloom to concentrations that are harmful to fish and other wildlife and may pose a threat to shellfish aquaculture in the bays. Researchers suspect that a controlling factor in blooms of this organism may be the abundance of another, non-toxic algae, Heterosigma akashiwo, since blooms of Dinophysis typically occur simultaneously with blooms of Heterosigma and the latter could serve as prey for Dinophysis. Delaware Sea Grant is funding Drs. Tye Pettay and Kathy Coyne to better understand the relationship between these two algae in order to improve our ability to predict, respond to, and treat harmful algal blooms and manage the risk to the shellfish aquaculture industry.

Phytoplankton Dynamics and the Role of Heterosigma Akashiwo in Promoting Blooms of the Toxic Dinoflagellate, Dinophysis Acuminata

Investigators: Drs. Kathyrn Coyne and Tye Pettay

Dinophysis acuminata is a toxic microalgae found in Delaware’s Inland Bays that can bloom to concentrations that are harmful to fish and other wildlife and may pose a threat to shellfish aquaculture in the bays. Little is known about the ecology of Dinophysis, including the environmental factors that enable it to bloom. However, researchers suspect that a controlling factor may be the abundance of another, non-toxic algae, Heterosigma akashiwo, since blooms of Dinophysis typically occur simultaneously with blooms of Heterosigma and the latter could potentially serve as prey for Dinophysis.

Delaware Sea Grant is funding Drs. Kathy Coyne and Tye Pettay to better understand the relationship between these two algae in order to improve our ability to predict, respond to, and treat harmful algal blooms and manage the risk to the shellfish aquaculture industry. The research team will use molecular tools coupled with laboratory feeding experiments to determine whether Dinophysis uses Heterosigma as a source of prey. Field sampling will identify how resting stages of Dinophysis may survive in bay-floor sediments during the winter, and how these resting stages trigger a bloom. Intensive sampling during blooms will further help to evaluate environmental drives of Dinophysis and Heterosigma blooms, and will help to predict the risk of Dinophysis spreading to shellfish aquaculture operations within the Inland Bays. In addition, the research team will establish a Mid-Atlantic working group on Dinophysis to bring together regional experts on toxic algae, shellfish biology, and aquaculture.

 Dr. Kathy COyne working with flasks in the lab.