Research 2014–2016

Research Projects 2014–2016

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Alan Desbonnet
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Rhode Island Sea Grant is placing research emphasis in the areas of shellfish biology, the ecology of the resources that support shellfish, and shellfish management. This emphasis was chosen based upon requests from resource managers, permitting agencies, commercial and recreational shellfish harvesters, and shellfish aquaculture business owners for new knowledge and improved understanding of shellfish and shellfish resources.

Outcomes of Sea Grant-funded research will be used in support of an initiative undertaken by the R.I. Coastal Resources Management Council and the R.I. Department of Environmental Management, in partnership with Sea Grant and other entities, to develop the Rhode Island Shellfish Management Plan. Our understanding of the important role that shellfish play in the economy and ecology of Rhode Island will also be enhanced by outcomes of this research agenda.



Whelks are large marine snails that are rapidly becoming a market commodity in both the U.S. and Asia.


To effectively manage whelk as a sustainable resource, we need to better understand their ecology. Some of the basic ecology and biology of New England whelks has been described, but there is still much that needs to be known to manage these species as sustainably harvestable resources in Rhode Island.

Kathleen Castro from URI, in collaboration with the Rhode Island Whelk Fishermen’s Association, will capture the knowledge of local whelk fishermen, and conduct targeted research that will better define the biology of the species in Rhode Island waters.

Outcomes of the research will be used to help the Whelk Fishermen’s Association harvest, and the R.I. Department of Environmental Management manage, the species on an ecologically and economically sustainable basis, and to inform whelk management initiatives now being formulated by the Atlantic States Marine Fisheries Commission.

Somers lowers collector cage off URI GSO pier to study whelk behavior

Somers lowers collector cage off URI GSO pier to study whelk behavior

Kathleen Castro and her team have begun conducting a predator-prey analysis of whelk in quahog using six replicates at the URI GSO aquarium lab. Each replicate has one whelk and 5 quahogs of varying sizes, and are monitored daily for feeding activity. Half of the replicates are testing channeled whelk and the other half are testing knobbed whelk.

Over the course of a week, little results were yielded with lab conditions being suspect. Only one whelk ate one quahog. The cause is suspected to be external stressors from artificial lighting and lack of sediment in the lab setting.

“Whelks were not feeding in the tanks,” said Barbara Somers from the URI Fisheries Center. “We think lighting may be the biggest factor, but not having sediment in the tanks could also be a problem”

To test this, Castro and her team added a field component with collector cages off of the GSO pier. Again, no luck was had in getting whelks to feed despite using various habitats.

“We have not had any success in getting [whelks] to feed,” said Somers. “We have tried a few different habitats with no success to date.”

“The irony is that [whelks] will eat horseshoe crabs all day … they just won’t touch the quahogs, which is supposed to be their main food according to fishermen,” said Castro.

Somers will test different scenarios within the lab using different lighting sources and sediment-based bottoms to figure out which factor is having the strongest influence on whelk behavior.


Matunuck Oyster Farm

Matunuck Oyster Farm


Excess nutrients in marine waters, particularly nitrogen, can lead to conditions that promote algal blooms, reduce oxygen availability in the water column, and contribute to fish kills. Shellfish incorporate nitrogen into their tissues while feeding; the nitrogen is then removed from the ecosystem when the shellfish are harvested.

Robinson Fulweiler from Boston University, in collaboration with several Rhode Island oyster growers, will experiment with optimal nitrogen removal based on farm site characteristics.

“I’m interested in what oysters do to nitrogen,” said Fulweiler. “They indirectly remove nitrogen by filtering carbon out of the water, depositing feces on the bottom, which fuel bacterial processes that remove nitrogen. On the flip side, if oysters aren’t being taken care of you can get the opposite process and actually add nitrogen to the system.”

Her research will help oyster growers determine how to best configure their farms for optimal nitrogen removal, which also means fastest oyster growth. Fulweiler’s research will help Rhode Island’s growing aquaculture industry improve performance in providing the additional service—above and beyond that of providing jobs and fresh seafood—of improving water quality in Narragansett Bay and the south shore coastal lagoons.

Fulweiler has identified test sites based on farm site characteristics. These farms range in age from 0-3 years, 3-5 years, and greater than five years. The goal is to determine the duration each rack and bag setup should remain in one place to maximize nitrogen removal processes to improve water quality.

The first sampling occurred this past summer at all sites to collect data on summer oxygen demands, nutrient fluxes, and nitrogen fluctuations from core samples, as well as samples from the water column to characterize sites based on dissolved oxygen, salinity, and chlorophyll levels.

Sample data analysis is currently underway and will help inform the next steps, which include getting the data out to people, especially aquaculturists.

“My goal is to make this data available as fast as we can to the shellfish aquaculturists,” she said, noting that the shellfishermen have been extremely helpful in collecting information. “They work on the ponds everyday and know the systems better than we can.”



The hard clam, familiar to most Rhode Islanders as the quahog, supports more than 500 active shellfishers and has a market value in excess of $5 million annually. It is suspected that parts of the Bay act as sanctuaries for adult clam spawning, others as settlement areas for the next generation of clams; both areas are important to the long-term sustainability of the species.

Scott Rutherford from Roger Williams University, in collaboration with Chris Kincaid and Dave Ullman from the URI Graduate School of Oceanography, will use sophisticated oceanographic models and biological data on quahog larval characteristics to locate spawning sanctuaries and areas where clam larvae settle on the bottom to grow to adult size. This information can be used to develop prudent management strategies for the quahog—an important, iconic Rhode Island species.

Drifter to measure surface current flow direction.

Drifter to measure surface current flow direction.

Rutherford and his team developed drifters to mimic behavior of floating quahog larvae to get an idea of where they might end up based on the direction of the currents.

Over 30 drifters, both at 1 meter and 3 meters in length, were deployed from Ohio Ledge this past summer to get a sense of how different layers of the water column impact dispersal. All of the drifters were shown to end up somewhere in the East Passage of the Bay, which is contrary to general thinking that Bay circulation flows counter-clockwise.

“The general idea is that the Bay circulates counter-clockwise; water comes in the East Passage and flows out the West Passage. But we’re not seeing that happen with drifter tracks. Almost all of them go out the East Passage,” said Rutherford, noting that the drifters only indicate surface flow whereas the model is looking at the overall direction of circulation. “So is this a surface versus depth discrepancy? Or is it related to a particular time of year? It’s an interesting discrepancy.”

– Next Steps –

The team will be looking more closely at the tracks of each individual drifter and incorporate the wind vector to get a clearer picture of surface circulation patterns in the Bay. The team will also as well as incorporating data from 2007 and 2008, as well as 2014, into the ROMs model to get a range of environmental conditions, such as warming water temperatures, which impact larval behavior.



The blue mussel is a common item on the menu of restaurants specializing in seafood around the globe, and Rhode Island is well poised to be a major player in that market. Naturally occurring pathogens have been known to decimate natural mussel beds, and could be a major risk to mussel aquaculture endeavors. The circumstances leading to mussel mortality however, are not well known.

Roxanna Smolowitz from Roger Williams University will explore the prevalence and life history traits of mussel pathogens common to Narragansett Bay. The information gleaned from this research will bring understanding of the interplay between mussel population densities and the growth and spread of pathogen populations. Resulting findings can be used by prospective mussel growers to design and implement husbandry practices that will minimize the probability of, or better yet exclude, on-farm disease outbreaks.

Smolowitz and her team collected blue mussels of three sizes (15 to 30 mm, 30-45 mm, and >45 mm) from Arnold Point, Hope Island, Roger Williams University Dock, East Passage, and West Passage at five time periods between May and September, 2014.

The first three sites evaluated wild harvests to compare to the latter sites with cultured animals.

“One of the interesting findings was the significant increase in the number of animals containing trematodes, and the number of trematodes in each animal over the sampling time period,” said Smolowitz, explaining that while statistical evaluations have not yet be done, the trend indicated that males were more often infected than females. “Severe infections appeared to correlate with a sharp decrease in population of mussels in August and September.”

The majority of the data is still being processed to evaluate overall physiological condition, reproductive status and commercial meat yield, as well as growth and survival rates.


Seed oysters


When shellfish aquaculture is proposed, it is not generally the ability of the ecosystem to accommodate the farm that is a limiting factor in granting the permit, but the perceptions of adjacent landowners and user groups. Perceptions, and sometime misperceptions, influence decisions to support or oppose siting of aquaculture operations.

Tracey Dalton and Robert Thompson from URI, in collaboration with Di Jin from the Marine Policy Center at the Woods Hole Oceanographic Institution, will identify the key influences on people’s perceptions to support or oppose aquaculture in Rhode Island waters. This information will improve understanding of why people support or don’t support aquaculture endeavors, which can then be used to minimize conflict where possible and practical, and to suggest changes to current aquaculture practices that could lead towards improved support.

In July and August, 2014 Dalton and her team have worked on developing a mail survey that focuses on various types of aquaculture and locations.

Two different sites, one in the bay and one in a coastal pond, are being used in photo simulations for the survey to depict farm size and operations.

“Our plan is to develop a survey of Rhode Island residents, targeting commercial harvesters, aquaculture farmers, waterfront property owners, and then a general sample of coastal residents to understand their level of support,” said Dalton, explaining that answers to the survey questions can help them understand whether certain characteristics of people correlate with opposing aquaculture in all forms or support.

“Aquaculture can look different in different places, and people have different attachments to different places, which is why we’re focusing on two different places,” she said.

The mail survey is undergoing refinements and will go out in late-winter/early-spring of 2015.

The general sample of residents is random, but commercial harvesters and farmers can help by responding and providing the necessary feedback for this research. If you’re interested in participating please contact Tracey Dalton or Azure Cygler.



Rhode Island’s coastal ponds are highly valued for a range of recreational and commercial activities, but have a limited capacity. How people use the coastal ponds, why, and with what intensity will help resource managers develop plans to minimize conflict and preserve, or enhance, assets users value most.

“I can tell you there are a lot of people there and what they’re do, generally, but I can’t tell you why they’re doing it there, and what they think about it,” said Robert Thompson, researcher at the University of Rhode Island.

Robert Thompson, Tracey Dalton and James Opaluch of URI, in collaboration with John Lake and Eric Schneider of the R.I. Department of Environmental Management Division of Fish and Wildlife, will inventory and map coastal resources and their recreational and commercial uses along Rhode Island’s south shore. They will improve this inventory with information about how users value the resource, for instance for boating and shellfishing.

“We’re trying to collect high resolution spatial data of human uses of coastal ponds that can be built into models of ecosystem services,” he said, explaining that people respond to fish activity and other biological factors. We’re tying to include people as part of the ecosystem.”

This information will assist resource managers in developing plans of use that avoid, or at least minimize, conflicting uses, and that will help develop management strategies that preserve and enhance those assets that users value highest.

Binoculars with laser locators were used to identify GPS points of various activities in the coastal ponds.

Binoculars with laser locators were used to identify GPS points of various activities in the coastal ponds.

Thompson and his team completed 30 observational days on Point Judith Pond, Potter Pond, Ninigret Pond and Quonochontaug Pond to observe daily activities.

Multiple surveys, which include observational and in-person interviews, have been developed to compare human activities and biological abundance in ponds. Many activities overlap but are not generally in conflict with each other.

“The misconception is that people view overlapping uses as in conflict,” said Dalton, noting that’s not always the case. Part of the survey, she said, focuses on what people think about other uses around them, and targets specific areas of use to evaluate areas that are more highly impacted by humans.

“Not everyone is using the same space at the same time,” said Thompson.

The team will process information this winter of 2015, and will continue surveys in the spring and summer of 2015 to increase the database and correct any gaps.

“There are a lot of activities originating from private marinas and beaches that we’re not intercepting, and we need to access them and learn what they think,” said Thompson.

This project will incorporate findings from Dalton’s work on the perceptions of aquaculture to help manage potential conflicts as operations expand, and will also look at the recreational value of different sites based on travel costs.



What impacts do aquaculture operations have on Rhode Island’s salt ponds?

URI researcher, Mark Stolt, will be evaluating whether oyster aquaculture benefits ecosystem functioning in southern Rhode Island’s coastal salt ponds – specifically, Ninigret, Winnapaug, and Potter Pond.

These submerged ponds represent areas with and without aquaculture, and will be compared based on submerged soil types, water quality, and aquatic organisms to decipher environmental impacts of aquaculture.

“We’re trying to get a picture of what’s happening to these soils as a reflection of the aquaculture that’s going on,” said Stolt, explaining that the condition of the soils are indicative of the water quality, the tidal fluctuation, and how much energy (food) is coming in.

This research will provide information for specific regulatory decisions in regards to shellfish aquaculture, and the capacity of the environment to sustain increased production.

Stolt is evaluating several aquaculture sites of different ages from 3 to 17 years to better understand the interaction between bivalve growth and soil condition over time, which will reflect the health of the environment. He will also be evaluating the benthic communities on the same soil type in areas where there is no aquaculture.

“We’ve identified our sites, and have just started sampling for benthic organisms to characterize the soils under different age [aquaculture farms], and those in areas with no aquaculture,” he said.

Stolt and his students will continue to sample, “until it becomes too cold.”

Another goal of this project is to get an idea of how things would change if growers increase numbers of animals per area. Stolt will be collecting “bio-feces” from oysters reared at Roger Williams University to test on the four different soil types.

“The ideal is high productivity with no environmental impacts,” said Stolt, noting that tradeoffs may include nitrogen influx from waste coming from too many organisms that can overload the system. “We’ll look at the bio-feces and benthic community response.”



Recognizing that some issues are best addressed at the regional scale, the Sea Grant Programs in the
Northeast (New York, Connecticut, Rhode Island, MIT, Woods Hole, New Hampshire, and Maine),
through the Northeast Sea Grant Consortium, have set aside funds (approximately $350,000) for social
science research proposals that have relevance to

Coastal populations are growing, adding to the mounting strain on coastal ecosystems.

This trend is particularly problematic given that habitats naturally distributed in coastal ecosystems that contribute a disproportionately large array of highly valuable ecosystem services.

Jonathan Grabowski, associate professor at Northeastern University, will be working to identify whether human vulnerability in coastal populations is tied to shoreline development and the integrity of coastal and marine habitats.

This research seeks to identify the degree to which social capital, environmental connectedness, and adaptive capacity in coastal communities is linked to human and ecological resilience to provide managers with insights regarding 1.) the degree to which shoreline armoring influences perceptions of and acceptance of ocean-based wind energy development, and 2.) the efficacy of coastal policy at protecting shorelines and reducing human vulnerability in order to reveal which coastal shoreline policies should be implemented vs. those that are less successful



Research Projects 2012-2014
Research Projects 2010-2012  


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