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 leave 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 economic 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.


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.


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: Margaret Petruny-Parker, 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.

Margaret Petruny-Parker 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.


Photo: Robert Rheault, Flickr

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 | $80,000
  • Understanding, predicting and mitigating beach erosion in Rhode Island
    PI: Reza Hashemi, University of Rhode Island | $80,000
  • Marine resource user response to ecological impacts of offshore wind energy
    PI: Julia Livermore, Rhode Island Department of Environmental Management | $56,000
  • Consumer preferences and purchasing trends of local seafood
    PI: Lori Pivarnik, University of Rhode Island | $48,000
  • Consumption of underutilized local seafood in Rhode Island
    PI: Elin Torell, University of Rhode Island | $80,000


Research Projects 2014–2016 >>