Research 2016–2018

Research Projects 2016–2018

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For this funding period, Rhode Island Sea Grant is placing research emphasis on improved understanding of shellfish (bivalve and gastropod) stock assessment and population dynamics with resource management implications, as well as impacts of changing climate on finfish and shellfish population dynamics in Rhode Island waters, with special interest on Narragansett Bay species and fisheries.

The selected projects began February 1, 2016.


Lobster Shell Disease impacts the outer shell. While it doesn't harm the meat, it does harm its marketability.Finding New Probiotic to Fight Lobster Shell Disease Outbreak

PI: Kathleen Castro, URI
Affiliates: Marta Gomez-Chiarri, David Rowley, David Nelson, URI

Southern New England lobster (Homarus americanus) stocks are being severely impacted by epizootic shell disease, which also appears to be increasing in Maine. The disease is “characterized by moderate to deep erosions on the carapace, which in severe cases may spread to the other parts of the lobster.” Heavily affected animals literally can be covered with a rotted, weakened shell that leaves them more vulnerable to bacterial infections.

Although it is not considered harmful for consumption, the unattractive appearance of infected shells makes it hard to sell this species that supports one of the largest shellfish fisheries in the world, estimated at more than $400 million.

There are currently no tools to deal with wild stocks, leaving some fishermen culling infected lobsters in the hope that it would reduce the spread causing loss of reproductive females and sub-legal animals to the stock and loss of yield to the fishery.

Dr. Kathleen Castro and her team will be investigating bacteria that could act as probiotics against those associated with epizootic shell disease (ESD) in lobsters, and will test effects of treatment on progression of the disease on live lobsters in the hopes of providing a method to control the disease. This probiotic treatment approach, a safe and economical alternative to treatment with antibiotics, takes a step towards providing a tool and will help determine the potential feasibility of using probiotics to treat lobsters on fishing boats before lobsters are returned back to the water. By slowing down the disease progression, lobsters may be able to recover and reduce direct and indirect mortality caused by the disease.

An Ounce of Prevention: Probiotics Hold Potential for Shellfish Disease

Three teams from the University of Rhode Island FAVS, Microbiology, and Pharmacy departments worked in isolating bacteria, sequencing genomes, culturing, challenge with pathogens, and testing.

Exposure of lobster post-larvae to 5 of the candidate strains isolated from lobsters and a probiotic isolated from the eastern oyster, Crassostrea virginica (Phaeobacter inhibens S4) showed that, with the exception of one isolate (a Loktanella species) these isolates did not negatively impact growth, survival, or molting frequency of the lobster larvae, but may protect them against challenging environmental conditions (temperature and water quality stress).

Adult lobsters with moderate to severe Epizootic Shell Disease exposed to weekly treatments with probiotics showed no effect on mortality, molting, growth, or disease progression. Further testing will be done to determine if the candidate probiotics can prevent lesion progression when lobsters are treated before lesions have developed.

New information has been produced on the microbiology, reaction to pathogens and effectiveness on the actual organism. This new information will allow for further study of the disease as well as the possible use of probiotics in the treatment of the disease. The information from this project has also been shared with stakeholders, such as lobster fishers. These fishermen have contributed innovative ideas on how these probiotics could be incorporated into fishing practices.


flounderEffects of Climate on Declining Winter Flounder in Narragansett Bay

PI: Jeremy Collie, URI
Affiliates: Mark Gibson, RI Fish and Wildlife

Winter flounder has historically been a dominant species in Narragansett Bay that has supported commercial and recreational fisheries. However, populations have recently declined to historically low levels. Several factors may be attributed to this such as overfishing and predation, but warming water temperatures resultant of climate change may also be restricting the population.

Dr. Jeremy Collie and Mark Gibson will be investigating the life-cycle stages of winter flounder that have experienced increased mortality (as a result of climate change) in order to identify stressors, such as temperature, and changes in key habitats for spawning.

It is unclear to what extent survival can be enhanced to support sustainable fisheries, and which life stages to target, but this project will aim to identify which life history stage(s) are the bottlenecks for winter flounder survival and whether they have remained the same over time, and which habitats to protect in order to sustain a winter flounder population in Narragansett Bay

The results should also be applicable to the Southern New England – Mid Atlantic stock complex of winter flounder.


The Murder Mystery of Narragansett Bay’s Winter Flounder


The project team conducted year two of a fish larval survey in Narragansett Bay, continuing a larval-fish survey that had been conducted by Rhode Island Department of Environmental Management Division of Fish and Wildlife from 2001 to 2008. After a gap of eight years, the team found that the Providence River is still the most important spawning area, despite a continued decline in winter flounder abundance. Spawning habitat has contracted to upper Narragansett Bay.

Numerous larval and age-one Atlantic cod larvae were also found in Narragansett Bay. These larvae were likely
spawned offshore and advected into Narragansett Bay. These preliminary results suggest that there is a local, self-reproducing sub-population of Atlantic cod.

Preliminary results suggest that warming water temperatures may be shortening the spawning season for winter flounder, restricting the species’ overall habitat in Narragansett Bay and food availability, as well as potentially introducing more predators.


oyster_baggingWhat is the Limit for Oysters in RI Waters Now and in the Future?

PI: Robinson Fulweiler, Boston University

The rapid growth of the oyster aquaculture industry in Rhode Island has raised questions about how many oyster farms Narragansett Bay and the state’s salt ponds can support. And while past research has shown that there is room to grow, Narragansett Bay has already seen significant decreases in productivity in the mid-Bay. With current nitrogen reductions, it is likely that productivity will decrease in the Providence River Estuary. While it is unlikely that oyster populations are food limited today, in the future, this may not always be the case.

Since food availability is key to understanding the ecological carrying capacity, Dr. Robinson Fulweiler will be investigating food sources and abundance to determine what dominates oyster diets in the Bay across seasonal changes.

Determining the diet of oysters in Rhode Island waters will inform models for oyster ecological carrying capacity, as well as shellfish management strategies. In addition, Fulweiler will be measuring sediment metabolism at six oyster-dominated habitats to determine how nutrients are recycled to the water column or removed through denitrification across oyster habitat types, which may highlight what types of habitats remove nutrients most efficiently thus providing information for aquaculturists who wish to partake in future nitrogen trading credit plans.



Pathogens, Nitrogen, and Changing Climate
Impacts on Narragansett Bay shellfish

PI: Serena Moseman-Valtierra, URI
Affiliates: Marta Gomez-Chiarri, URI

The eastern oyster (Crassostrea virginica) and blue mussel (Mytilus edulis) are commercially, culturally, and ecologically significant shellfish in New England. In response to stakeholder interest on the potential effects of environmental change on shellfish populations, Dr. Moseman-Valtierra will lead research investigating how two key drivers of coastal ecosystems –nitrogen and warming– impact the health and function of C.virginica and M. edulis.

Shellfish perform significant nitrogen cycling functions but are potentially overlooked as major sources (or sinks) of nitrous oxide due to microbial associates in their guts and on their shells.

This project will examine potential relationships among nitrogen loading, nitrous oxide emissions, and shellfish disease to help sustain local aquaculture and evaluate their effectiveness at nitrogen remediation, as well as minimize potential feedback from managed and natural shellfish populations on global climate.

Field experiments at Point Judith Pond will directly involve Rhode Island shellfishermen and will incorporate a high quality, time series of environmental data made available via the URI Watershed watch laboratory and the Rhode Island Salt Ponds Coalition.

Results may reveal the potential of shellfish in nutrient control, as well as help identify pathogens of the greatest threat to two major bivalve species and at what thresholds of nitrogen and/or warming shellfish populations may be severely impacted by disease.


quahog_boatFishermen-Based Research Fleet for Quahog Management 

PI: Anna Malek, Commercial Fisheries Research Foundation
Affiliates: Dale Leavitt (Roger Williams University), Anna Malek (Commercial Fisheries Research Foundation), Jeffrey Mercer (RI DEM), Frederick Mattera (Commercial Fisheries Research Foundation)

The primary goal of this project is to blend fishermen knowledge and science in a more formal way that will initiate new collaborative management approaches for the quahog fishery in Narragansett Bay.

In order to do this, a research fleet must be equipped with knowledge, tools, and validity to contribute to the current RI-DEM quahog stock assessment data collection program. This will help support sustainable management of the quahog (northern hard clam, Mercenaria mercenaria) fishery, the single most valuable fishery in Narragansett Bay, by addressing the need to reduce uncertainties in the current quahog stock assessment that are attributable to data limitations and spatial gaps. If successful, a new model will be available for industry-based data collection that can be duplicated in other fisheries and regions, as well as greater capacity for Rhode Island shellfishermen involvement in coastal monitoring and other types of marine research.

Anna Malek of Commercial Fisheries Research Foundation and her team will be investigating whether bullrake and hydraulic dredge sampling are appropriate for stock assessments and whether bullraking data significantly impacts estimates of quahog abundance and spatial distribution. Additional results will also help yield answers as to whether sampling at fishermen-selected stations (fishery-dependent data) vs. assigned sampling stations (fishery independent data) reveal distinct distributions/abundances of quahogs throughout Narragansett Bay.


Quahog Research Fleet Video Release



Photo: Robert Rheault, Flickr

Where is Vibrio Now and Where is it Going?
Protecting the health of oysters and consumers

PI: Roxanna Smolowitz, Roger Williams University
Affiliates: Dale Leavitt and Tim Scott (RWU), Robert Rheault (East Coast Shellfish Growers Assoc.)

As filter feeders, eastern oysters can accumulate nutrients and pathogens present in the water column. And while most are harmless some pathogens are not, such as Vibrio parahaemolyticus, a bacteria that can cause gastrointestinal illness for consumers of raw oysters, and in rare cases, death for those with compromised immune systems.

Rhode Island aquaculture has not yet suffered from closures due to human infections and the industry has taken important preventative handling steps, but as sea temperatures increase, it is likely that the accumulation of Vibrio parahaemolyticus will increase in aquacultured oysters.

Dr. Roxanna Smolowitz and her team will investigate current levels of Vibrio parahaemolyticus and pathogenic genes in aquacultured animals under different culture conditions commonly used in Rhode Island, as well as whether certain diseases increase the likelihood of Vibrio parahaemolyticus accumulation in tissues, which could support the use of different types of oysters that are disease resistant for aquaculture.

Results will provide guidance for depuration or probiotic treatment methods currently being discussed in order to protect consumers and maintain healthy seafood in the state.


Program Development projects 2016-2018:

  • Values of recreational boating activities associated with the Block Island Wind Farm
    PI: Tracey Dalton, University of Rhode Island
    Few studies have explored how on-the-water users will be affected by social and ecological impacts of wind farms, like perceived safety risks associated with boating near turbines and changes in catch availability of targeted organisms. Rhode Island provides an ideal setting to study preferences of wind farms, as the nation’s first off-shore wind farm is in its state waters with another much larger wind farm planned for development near RI and MA state waters in the next few years. This project will provide knowledge on how recreational boaters might respond to potential social and ecological impacts of the Block Island wind farm.
  • Understanding, predicting, and mitigating beach erosion in Rhode Island
    PI: Reza Hashemi, University of Rhode Island
    Beach profile surveys and aerial photographs show an accelerated erosion rate of sandy beaches and dunes, especially along Rhode Island’s southern coast. Recent climate models simulating various sea level rise and global warming scenarios predict an increasing frequency of larger and more damaging tropical and extra-tropical cyclones, which could worsen this alarming erosional trend not only in Rhode Island but along the U.S. eastern coastline.  The focus of this project is to better understand the physics of shoreline recession in relation to sea level rise and storm intensification, which is not well understood, by develope a comprehensive quantitative framework to assess and predict storm-induced shoreline erosion in the context of climatic change.
  • Marine resource user response to ecological impacts of offshore wind energy
    PI: Julia Livermore, Rhode Island Department of Environmental Management
    The Block Island wind farm presents the first opportunity to identify biological and marine environmental changes to the local ecosystem caused by an offshore wind farm in U.S. waters and to determine human response to these changes. This project looks to determine how the wind farm is impacting the local ecosystem to gain a deep understanding of how humans will be impacted, and how future wind projects may affect Rhode Islanders.

  • Consumer preferences and purchasing trends of local seafood
    PI: Lori Pivarnik, University of Rhode Island
    The Department of Environmental Management is looking toward local seafood branding as a way to bolster seafood harvested and landed in Rhode Island, however, little is known about consumer preference, perceptions, and understanding of local alternatives. This project seeks to further understand consumer attitudes, concerns, and knowledge of local seafood options to assess current purchasing choices in order to more effectively promote a local seafood industry in Rhode Island.

  • Scup: Consumption of underutilized local seafood in Rhode Island
    PI: Elin Torell, University of Rhode Island
    This project responds to the need to understand the “flow” of seafood from the dealer to destinations locally, regionally, and beyond. While fish landing data are available to the public, there is no database or requirement for reporting where seafood goes once dealers purchase it. More specifically, the market potential for underutilized species such as scup, butterfish, and mackerel—which are in healthy states of abundance in the ecosystem—is not clear. As a result, groups such as the Rhode Island Seafood Marketing Collaborative, the Northwest Atlantic Marine Alliance, and the Rhode Island Department of Environmental Management have requested research to better understand the flow of seafood landed in Rhode Island and to promote these products (or tailor promotional efforts) to consumers. Additionally, this project will investigate finding additional local markets for underutilized species to communities that desire these products.
  • Relative Sea-Level Changes in Rhode Island and Land Subsidence
    PI: Simon Engelhart, University of Rhode Island
    As projections of relative sea level rise rapidly increase, significantly impacting Rhode Island’s low-lying coastline, more information regarding sea level rise changes in the past (prior to 1930) is needed to help coastal managers build a resilient coastline in the face of accelerated sea level rise. Rhode Island Sea Grant funded Engelhart to support a project investigating relative sea level rise during the last 3000 years in Rhode Island, focusing on the time of acceleration and spatial variability in land subsidence related to deglaciation.Initial findings analyzing various salt marsh peat cores suggest that the current rate of relative sea-level rise in Rhode Island is faster than at any point in the last 3300 years and that Rhode Island is sinking about 1 millimeter annually, which has impact current nuisance flooding events near the coast.

A Sinking State and a Rising Sea: Salt Marshes Provide the Answer


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