Research

Principal Investigator (PI):
Andrew Davies, University of Rhode Island
Co-PI:
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.

Principal Investigator (PI):
Robinson Fulweiler, Boston University
Co-PI:
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.

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.

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.