Benthic macrofauna in Narragansett Bay, Rhode Island: An examination of factors causing variability in community structure

Christopher John Calabretta, University of Rhode Island

Abstract

Benthic macrofaunal communities in the upper Narragansett Bay, Rhode Island have been sampled annually since 2000 as part of the Narragansett Bay Benthic Study (NBBS). This work explored the natural and anthropogenic drivers underlying spatial and temporal variability in benthic community structure. Spatial variability in the structure of Narragansett Bay's benthic macrofaunal communities was related to the degree of exposure to anthropogenic stress. Results suggested a progression in the structure of benthic assemblages from early successional stages in the areas of Mt. Hope Bay and Conimicut Point, to an intermediate stage at the mouth of Greenwich Bay and culminating with late stage succession north of Jamestown. This north-south successional gradient mirrors expectations based on historic models of faunal succession that describe predictable changes in the structure of benthic assemblages with spatial or temporal distance from a disturbance. ^ In order to test the hypothesis that temporal variability in water column production affected the structure of the bay's benthic communities, methods for estimating inter-annual differences in the phytoplankton production during the winter–spring (December–May) period prior to each benthic sampling event were developed. Inconsistencies in the response of faunal abundance to changes in pelagic production, when compared to historic models describing benthic community response to organic enrichment, suggested that other factors were influencing temporal variability within these assemblages. Inter-annual differences in communities of adult macrofauna were best explained by measures of epibenthic predation and winter–spring surface water temperature and a model containing these variables along with station location was able to capture the most salient patterns of variability in benthic community structure. Epibenthic predation pressure also explained a significant portion of the temporal variability in the composition and relative abundance of juvenile macrofaunal communities; however evidence suggested the importance of additional factors not included in the present analysis. The specific pattern of inter-annual variability in benthic community structure differed among sampling locations and depended on the successional status of the assemblage. Correlations were also identified between the North Atlantic Oscillation (NAO) Index lagged by one year and the abundance and diversity of communities in the late stages of faunal succession. ^

Subject Area

Biology, Ecology|Biology, Oceanography|Environmental Sciences

Recommended Citation

Christopher John Calabretta, "Benthic macrofauna in Narragansett Bay, Rhode Island: An examination of factors causing variability in community structure" (2009). Dissertations and Master's Theses (Campus Access). Paper AAI3378083.
http://digitalcommons.uri.edu/dissertations/AAI3378083

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