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Focus Areas

Climate Change

The marine and coastal ecosystem are evolving in response to changes in increased water temperatures and ocean acidification that are having a variety of impacts.

Sea Grant-funded research focuses on the changing ecosystem dynamics in order to better understand the shifting baseline associated with harmful algal blooms, hypoxic events, and nutrient exchange within the system.

Human-Induced Changes

As marine and coastal ecosystems are changing at unprecedented rates from climate change, other human activities such as mircoplastics and wastewater discharge as are also impacting the biology and chemistry of these sensitive systems.



Microplastics as Vectors for Organic Pollutants & Marine Disease




Principal Investigator (PI):
Andrew Davies, University of Rhode Island
Marta Gomez-Chiarri, University of Rhode Island
Rainer Lohmann, University of Rhode Island

High levels of micro-plastics in the marine environment have prompted a critical need to understand the potential health risks they pose to oysters and the industries and communities they support. Within Rhode Island, micro-plastics are a potentially significant threat to the health of Narragansett Bay, and the organisms within.

This project aims to study environmental plastic load assessments with controlled microcosm and mesocosm experiments to better understand the roles that micro-plastics play as vectors for pollutants and pathogens in coastal oyster-based food webs both under present-day conditions and future ocean warming scenarios.

These data will support an enhanced risk-assessment capability regarding the overall impacts of micro-plastics and temperature on commercially valuable organisms within Rhode Island.

This information will better arm stakeholders, policymakers, and the general public with knowledge and data to better understand the fate and impact of micro-plastics within Rhode Island and New England.

Drivers of Domoic Acid in Narragansett Bay





Principal Investigator:
Matthew Bertin, University of Rhode Island

Certain plankton species of diatom phytoplankton can produce the neurotoxin domoic acid, which can be filtered through shellfish and is responsible for amnesic shellfish poisoning in humans and marine life.

While strains of the diatom, Pseudo-nitzschia, have been present in Rhode Island waters, the detection of significant quantities of the domoic acid is a recent and troubling development, which represents a significant risk to the state’s shellfish industry and local populations. 

Little is known with respect to the ecological drivers of domoic acid production in Narragansett Bay as areas with high Pseudo-nitzschia cell counts may have little domoic acid production.

The goal of this project is to identify abiotic and biotic drivers of Pseudo-nitzschia bloom formation and domoic acid production from strains of diatoms that persist in Narragansett Bay. Researchers will use time-series sampling at several sites in Narragansett Bay to created chemical profiles of domoic acid and genetic profiles of Pseudo-nitzschia strains
associated with toxic and non-toxic events.

Researches will also investigate the association of certain environmental parameters with toxic and non-toxic time periods.

Results will be used to inform our understanding of harmful algal blooms in Narragansett Bay and add predictive power to environmental events that have a significant economic impact on Rhode Island fisheries.


Macroalgae & Kelp Connection to Marine Disease




Principal Investigator (PI):
Robinson Fulweiler, Boston University
Roxanna Smolowitz, Roger Williams University

Many oyster farmers are expanding their crop to include kelp species that hold promise as safe and sustainable seafood. Some species of macroalgae, such as rockweed, that are used in clambakes and to pack lobsters and other shellfish for transport.

All of these macroalgae species, even ones that must be cleaned from the cages, may be a source of Vibrio, a bacteria found in coastal waters.

Recent studies reported increased pathogenic Vibrio spp. abundance associated with the macroalga Gracilaria vermiculophylla (Gonzalez et al. 2014).

Other studies have shown varying degrees of antibacterial activity of algae in regard to Vibrio species. Thus, little is known if macroalgae are a reservoir pathogenic Vibrio spp. in general, and in Rhode Island in particular.

This research project will address this knowledge gap by quantifying the role macroalgae play in altering the abundance of pathogenic Vibrio sp. in coastal ecosystems.

Side Effects of Breeding Disease-Tolerant Oysters





Principal Investigator: Marta Gomez-Chiarri, PhD
Professor & Department Chair Department of Fisheries, Animal and Veterinary Science, University of Rhode Island

Co-PI: Dina Proestou, PhD Research Geneticist National Cold Water Marine Aquaculture Center, USDA Agricultural Research Service

Co-PI: Rob Hudson Shellfish Hatchery Manager Marine and Natural Science, Roger Williams University

Co-PI: Tal Ben-Horin, PhD Assistant Professor Department of Clinical Science, North Carolina State University

The U.S. eastern oyster (Crassostrea virginica) aquaculture industry is rapidly expanding. In several Atlantic states, industry value has increased >10-fold in the last 15 years (Buetel 2018). Moreover, due to the ecosystem services they may provide, oysters are the focus of intensive restoration efforts. Despite this expansion, production is constrained by the lack of commercial seed available for specific growing environments and losses from naturally-occurring diseases. Furthermore, changes in climate are expected to augment existing constraints even further.

Sea Grant funded-researchers will be investigating how to quantify disease-responsive traits in hatchery-derived and wild oyster stocks with long-term mesocosm studies representing field trials to evaluate oyster performance under varying environmental conditions and its driving influence on disease risks.

Positive Feedbacks From Hypoxic Events




PI: Rebecca Robinson, University of Rhode Island
Co-PI: Bethany Jenkins, University of Rhode Island

Development along the coast has led to increased nutrient inputs (e.g. nitrogen and phosphorus) from human activity such as sewage treatment.

Excess nutrients in coastal waters have promoted harmful algal blooms and hypoxic (low-oxygen) events that are harmful to marine life. As a result, wastewater treatment facilities throughout Rhode Island have made a concerted effort to reduce nutrient loading into Narragansett Bay.

However, we know relatively little about the return of nutrients from the sediments to the overlying water and how these processes may respond to environmental variabilities such as temperature and oxygenation changes.

Previous studies have shown a variety of ecosystem responses in estuarine systems like Narragansett Bay, including biologically-driven positive feedbacks that exacerbate the nutrient loading conditions.

Researchers will investigate the roles of benthic nutrient fluxes from the sediment in generating positive feedbacks during hypoxic episodes in Narragansett Bay, which is representative of many estuarine systems worldwide. They will conduct field sampling and use manipulated mesocosm studies where benthic nutrient fluxes and microbial response during normoxic and hypoxic events in Narragansett Bay will be measured.

Data from this project will be combined with local water column monitoring data to quantify the relative importance of these benthic microbial processes for nutrient budgets of coastal systems.

Project results will be used by a variety of stakeholders and ecosystem modelers interested in the nutrient budget of Narragansett Bay.

This research will inform the contribution of benthic metabolism to nutrient cycling as researchers examine this process under nutrient- and temperature-sensitive oxygenation conditions in Narragansett Bay.

Effects of Coastal Stressors on Oyster Recruitment





PI: Jonathan Puritz, University of Rhode Island

Commercial oyster seed is limited to specific environments and vulnerable to disease and changes in climate are expected to augment existing constraints even further.

The U.S. eastern oyster aquaculture industry is rapidly expanding with a value that has increased over 10-fold in some Atlantic states in the last 15 years. In addition to their economic value, oysters also provide tremendous ecosystem services and are the focus of intensive restoration efforts.

State-funded breeding programs and commercial hatcheries can accelerate local adaptation and select oysters that perform best in their rearing location as broodstock for subsequent generations.

This project focuses on the major issues facing the Northeast eastern oyster aquaculture industry by investigating whether oyster hatcheries and selective breeding programs select for disease resistance or tolerance, and what this may mean for disease dynamics in coastal marine ecosystems.

Results from this research also aim to identify oyster stocks with the best potential for the development of lines with improved performance in the Northeast region. Results may also help to broaden Rhode Island’s Shellfish Initiative both by building capacity to integrate the impacts of aquaculture and restoration to surrounding marine ecosystems into sustainable ocean planning and by identifying traits of oyster stocks that perform well for aquaculture production and restoration under environmental conditions in Rhode Island and the Northeast region now and into the future.

Shellfish Response to Warming Waters




PI: Candace Oviatt, University of Rhode Island

Shellfish response to warming trends has not been fully investigated in Narragansett Bay due to the challenges in disentangling the various influences on populations.

Recent reductions of phytoplankton production that may influence shellfish populations have been attributed to both reduced nutrients and warmer temperatures, making it challenging to quantify the relative impact of each concurrent factor. Additionally, other factors outside food availability may influence shellfish; for example, legacy pollutants may be limiting the reproductive potential of shellfish in urban portions of the bay, and the influence of other correlated environmental stressors (e.g., hypoxia) and crowding on shellfish have been challenging to assess.

Researchers will investigate whether a reduced phytoplankton food supply to hard clams is hypothesized to reduce the reproductive potential of bivalves reducing annual recruitment in years without a winter-spring bloom. The most important changes that will influence their reproduction and growth are changes in temperature, food quantity and timing, and sediment quality.

Researchers will include the awning clam in mesocosm experiments, testing the effect of temperature and legacy pollutants on their growth, as well as to better assess their impact on sediment geochemistry (i.e., hydrogen sulfide).

Quahog life history rates under different environmental conditions will provide useful information for stakeholders concerned with resources that support their livelihood and for scientists conducting a quahog stock assessment model.

The results of the awning clam experiments will represent the first measurement of their growth rates or impact on pore water chemistry over an annual, seasonal cycle.

Seafloor Communities as Indicators of Water Quality





PI: William Helt, The Nature Conservancy

Sedentary organisms on the seafloor are most vulnerable to local changes in the marine environment and are key indicators of water quality.

Nitrogen from sewage treatment has been considered the primary nutrient to drive harmful algal blooms and low-oxygen conditions (hypoxia) in Narragansett Bay over the last few decades. 

Recently, nutrient inputs have been significantly reduced in Narragansett Bay following legislation that required wastewater treatment facilities to
reduce nitrogen loads by 50%, but the ecosystem effects of these are
not well understood.

Though research looking at how benthic communities are changing along the seafloor, there has not been a comprehensive, coordinated effort
among research groups to establish uniform protocols, a data repository, and synthesize benthic community data in the context of nutrient reductions.

Researchers will collect records of previous studies and surveys to describe historical benthic conditions, collect more data to continue recording benthic habitat quality, and relate benthic community data to changes in nutrient inputs and other ecosystem stressors over time using the Biological Condition Gradient (BCG) framework.

This project aims to addresses the
the important question of whether the Bay is improving after large public investments in treatment facilities and inform coastal

Results will contribute to an improved understanding of changes in the benthic communities and their response to human activities and will advance the state of benthic monitoring in Narragansett Bay through the development of innovative sampling and analysis methods with a focus on generating data that may be compared to existing historical records.

Nitrogen Fixation May Drive Future Productivity in Narragansett Bay




PI: Robinson Fulweiler, Boston University

Preliminary evidence suggests nitrogen fixation may be occurring in the post-nutrient reduction water column during the growing season.

Nitrogen fixation is a process from which nitrogen in the air is converted by microbes in the soil or water into organic compounds (ammonia) that can be metabolized as fuel for other organisms. 

The current and future role of nitrogen fixation as a source of fixed nitrogen for fueling primary and secondary production in Narragansett Bay plankton is not fully understood as an assessment of water column nitrogen fixation has not been
done in the Bay since the 1980s. Since then, major ecosystem changes have occurred and methods for measuring water column nitrogen fixation have improved significantly.

Researchers will employ these new methods and determine how much nitrogen could be added to Narragansett Bay through water column nitrogen fixation with relation to nutrient reduction measures and changing climate conditions using both in-field observations and via mesocosm experiments.

Results are anticipated to help nitrogen management decisions in Rhode Island and provide managers with information about nitrogen availability and timing, which will help with forecasting and understanding harmful algae bloom dynamics, as well as our understanding of the ecological carrying capacity for shellfish aquaculture in Narragansett Bay.

Additionally, the mesocosm work will allow researchers to generate an understanding of how nitrogen fixation will change under climate warming scenarios, which will improve modeling efforts and help us
prepare for future change.

Response of Seafloor Organisms to Changing Environment





Jeremy Collie, University of Rhode Island
Candace Oviatt, University of Rhode Island
Conor McManus, RI Dept. of Env. Mgmt
Austin Humphries: University of Rhode Island

This project is a complement to other ongoing research to improve understanding of the change in benthic communities along the seafloor of Narragansett Bay over time as it relates to nutrient reduction programs, changing water temperatures and their synergistic effects.

The present knowledge base is insufficient to measure and project the combined
effects of nutrient reduction and temperature increases on the benthic communities of Narragansett Bay.

To address this knowledge gap, researchers will compile historical data sets of benthic community structure and biomass of Narragansett Bay in relation to temperature change, nutrient inputs, and water quality and compare the abundance and species before and after the 50% decrease in nutrient input, which occurred from 2005 to 2013.

New benthic samples (infaunal and epifaunal macroinvertebrates including shellfish and bottom fish) will be collected and existing samples analyzed in the context of a north-south gradient in Narragansett Bay. This transect will provide an updated baseline against which to measure future changes in the benthic community. Estimates of benthic biomass and production will improve the empirical basis of food-web models of the Narragansett Bay ecosystem.

Results will be valuable for state management in assessing ecosystem responses to nutrient reductions, and what further nutrient reductions could mean for the ecosystem.


For more information or application questions please contact Alan Desbonnet at


Rhode Island Sea Grant has funded scientific research relevant to the Narragansett Bay and Rhode Island Sound in service of residents who conserve, enjoy, and make these coastal and marine resources.

The funded projects advance scientific knowledge through the publication of peer-reviewed journal articles.

Current and past publications can be accessed through the National Sea Grant Library.

National Sea Grant Library