THE RESPONSE OF BENTHIC COMMUNITIES IN NARRAGANSETT BAY TO CHANGING NITROGEN INPUT AND TEMPERATURE

Author

Shaina Harkins, University of Rhode IslandFollow

Date of Award

2023

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Specialization

Biological Oceanography

Department

Oceanography

First Advisor

Jeremy Collie

Abstract

Marine ecosystem changes are often driven by different forces simultaneously, making it challenging to evaluate the individual contributions of each force. In Narragansett Bay, nitrogen input from wastewater treatment facilities (WWTF) was successfully decreased by 50% from 2005 to 2013. In the last 50 years, surface water temperature in the Bay has also increased by 1.6°C. The response of the benthic community to either of these changes has yet to be determined. We replicated the historical methodology of diver collected cores for infaunal macrofauna, organisms living in sediment, and included beam trawl sampling to catch larger, more mobile epifauna, organisms living on sediment. Replicate samples were collected from three stations along the north-south nutrient gradient of the West Passage to understand the effects of nitrogen and temperature on the species composition of the macrofaunal community. Historically, a more advanced successional stage of benthic communities was found further south along the north-south gradient of the Bay’s West Passage. We found three distinct communities along the north-south gradient, with the upper Bay community resembling the mid Bay community more over time. Change in nitrogen was identified as the environmental variable with the highest correlation to change in benthic community abundance over time (ρ = 0.605), followed by dissolved oxygen (ρ = 0.605) and temperature (ρ = 0.597). Results suggest high epifaunal biomass and late summer hypoxia from increased rainfall in 2021 caused a decrease in macrofaunal community abundance and biomass, as well as a responding decrease in epifaunal biomass, in the upper Bay community between years of sampling. The results of the current study reveal the impacts of environmental variables on the benthic community in Narragansett Bay following successful nutrient reduction, which can be used to inform management practices of other temperate estuaries experiencing similar ecosystem changes.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 License.

Recommended Citation

Harkins, Shaina, "THE RESPONSE OF BENTHIC COMMUNITIES IN NARRAGANSETT BAY TO CHANGING NITROGEN INPUT AND TEMPERATURE" (2023). Open Access Master's Theses. Paper 2321.
https://digitalcommons.uri.edu/theses/2321