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Pollution has led to a decline of benthic invertebrate biodiversity of Narragansett Bay, raising questions about effects on ecosystem functions and services including shellfish production, energy flow to fishes, and biogeochemical cycles. Changes in community composition and taxonomic distinctness (biodiversity) were calculated from the 1950s—when quantitative benthic invertebrate data first became available—to 2015. Change in community composition of the bay was correlated with changes in dissolved inorganic nitrogen, dissolved oxygen, and sediment contaminants. A mid-bay reference site showed moderate changes in community composition but no change in biodiversity. In contrast, a more impacted site in the upper bay showed substantial differences in community composition over time and a decline in taxonomic distinctness. Bay-wide, as inputs of some stressors such as nutrients and sediment contaminants have declined, there are signs of recovery of benthic biodiversity but other stressors such as temperature and watershed development are increasing. [ABSTRACT FROM AUTHOR]

Dramatic changes occurred in Narragansett Bay during the 1980s: water clarity increased, while phytoplankton abundance and chlorophyll concentration decreased. We examine how changes in total suspended solids (TSS) loading from wastewater treatment plants may have influenced this decline in phytoplankton chlorophyll. TSS loading, light and phytoplankton observations were compiled and a light- and temperature-dependent Skeletonema -based phytoplankton growth model was applied to evaluate chlorophyll supported by TSS nitrogen during 1983–1995. TSS loading declined 75% from ~ 0.60 × 10 6 kg month − 1 to ~ 0.15 × 10 6 kg month − 1 during 1983–1995. Model results indicate that nitrogen reduction related to TSS reduction was minor and explained a small fraction (~ 15%) of the long-term chlorophyll decline. The decline in NBay TSS loading appears to have increased water clarity and in situ irradiance and contributed to the long-term chlorophyll decline by inducing a physiological response of a ~ 20% reduction in chlorophyll per cell. [ABSTRACT FROM AUTHOR]

Due to nitrogen load reduction policies, wastewater treatment facilities (WWTFs) have upgraded to tertiary treatment — where denitrification reduces and removes nitrogen. Changes to the stable isotopic composition of nitrate inputs after upgrades or how it transfers to the estuary have not been assessed in Rhode Island. We investigate whether these upgrades impact the isotopic signature of nitrate inputs to Narragansett Bay. Samples from rivers and WWTFs discharging to Narragansett Bay characterize the anthropogenic source nitrate (NO 3 − ) isotopic composition (δ 15 N–NO 3 − and δ 18 O–NO 3 − ) and temporal variability. At one WWTF, tertiary treatment increased effluent nitrate δ 15 N–NO 3 − and δ 18 O–NO 3 − values by ~ 16‰. Riverine values increased by ~ 4‰, likely due to the combination of decreases in N and upgrades. Combined river and WWTF flux-weighted isotopic compositions showed enriched values and an amplitude reduction in monthly variability. When seasonal isotopic means are significantly different from other sources, δ 15 N–NO 3 − may be a useful tracer of inputs. [ABSTRACT FROM AUTHOR]

The article discusses a study on the densities of wintering scoters relative to benthic prey assemblage in Narragansett Bay, Rhode Island, an urbanized North Atlantic estuary. The study involves sea duck surveys during the winter of 2010 to 2011. It showed that lower densities of scoters were related to mixed-sand-gravel-mud substrates that supported patchily distributed infauna and epifaunal assemblages.

Abstract: When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Previous inventories of nitrogen (N) inputs to Greenwich Bay found that N inputs from Narragansett Bay exceeded those from the local watershed, suggesting that recent efforts to reduce local watershed N loads may have little effect on estuarine water quality. We used stable isotopes of N to characterize watershed and Narragansett Bay N sources as well as the composition of primary producers and consumers throughout Greenwich Bay. Results were consistent with previous assessments of the importance of N inputs to Greenwich Bay from Narragansett Bay. As multiple N sources contribute to estuarine water quality, effective management requires attention to individual sources commensurate with overall magnitude, regardless of the political complications that may entail. [Copyright &y& Elsevier]

The article discusses a study which investigated the δ13 values of filter-feeding hard clams Mercenaria mercenaria from 13 locations in Greenwich Bay, Rhode Island. The values of δ13 of the clams showed a linear gradient of two percent over the four kilometer (km) length of Greenwich Bay. Study authors conclude that their findings suggest that δ13 values may be sensitive to the changes in inorganic carbon in estuarine systems. They add that the δ13 values in Mercenaria mercenaria may depict ecosystem metabolism variation.

Abstract: The Narragansett Bay in Rhode Island is a complex mosaic of human activities and environmental features and while spatial distributions of physical, chemical, and biological elements are well documented in the Bay, there are limited data on spatial distributions of human activities. In this study, human uses of coastal waters in the upper Narragansett Bay are examined using an approach for characterizing and analyzing fine scale spatial and temporal data on human activities. Shipboard transect surveys of active water activities were conducted in the upper Bay on 50 days during the summer months of 2006–2007. The composition and configuration of different vessel types (recreational motor, recreational sail, row boat, commercial fishing, industrial, service, and official) were analyzed, and the impacts of proposed changes in land use policies and wastewater treatment technologies were investigated. Results indicated that recreational boaters comprised almost two-thirds of the upper Bay''s users and used over one-half of the study area. Industrial activity was concentrated near Providence where RI''s main port is located, and there was an active commercial fishery in the southern portion of the study area. Conditions like increasing cloud cover, weekend days, and the July 4th holiday were related to increased recreational use, while the closure of an upper Bay beach to swimming was associated with fewer commercial fishing vessels and more official boats, recreational motor boats, and service vessels. Findings indicated that upper Bay waters near land converted from industrial zones to zones where residential housing or marinas are encouraged are likely to see a change in composition of vessels, with fewer industrial and official boats and more recreational motor boats, row boats, and service vessels. Enhanced wastewater treatment technologies and the resulting improvements in water quality are likely to make more waters in the upper Bay available to shellfish harvesting, spreading out existing fishing grounds and potential pressures on the ecosystem and on other users. By characterizing the spatial and temporal heterogeneity of human uses in the marine environment and analyzing how these uses relate to the complex human and natural systems in which they are embedded, this study and others like it can positively contribute to marine spatial planning and management efforts designed to achieve ecological, economic, and social objectives. [Copyright &y& Elsevier]

The present state of knowledge regarding the input of anthropogenic pollutants into Narragansett Bay, Rhode Island was reviewed and benthic infaunal communities present at four depositional environments within the upper Bay were characterized. Inter-station differences in species composition and abundance of these assemblages were examined in relation to established pollution gradients. Using diversity curves and multivariate statistics, evidence of significant anthropogenic impact on the structure of benthic macrofaunal communities in Narragansett Bay was identified. The magnitude of this impact was greatest at stations closest to the Bay’s urban centers, where exposure to multiple stressors had resulted in communities of opportunistic taxa which persisted in a state of low faunal diversity characteristic of early stages of species succession. As was expected based on historic models of faunal succession; the apparent maturity of benthic assemblages in Narragansett Bay increased along the north-south gradient of decreasing anthropogenic stress. [Copyright &y& Elsevier]

The frequency and duration of macroalgal blooms have increased in many coastal waters over the past several decades. We used field surveys and laboratory culturing experiments to examine the nitrogen content and δ 15N values of Ulva and Gracilaria, two bloom-forming algal genera in Narragansett Bay, RI (USA). The northern end of this bay is densely populated with large sewage treatment plant nitrogen inputs; the southern end is more lightly populated and opens to the Atlantic Ocean. Field-collected Ulva varied in δ 15N among sites, but with two exceptions had δ 15N above 10‰, reflecting a significant component of heavy anthropogenic N. This variation was not correlated with a north–south gradient. Both Ulva and Gracilaria cultured in water from across Narragansett Bay also had high signals (δ 15N=∼14–17‰ and 8–12‰, respectively). These results indicate that inputs of anthropogenic N can have far-reaching impacts throughout estuaries. [Copyright &y& Elsevier]

Abstract: Stable nitrogen isotope ratios were used to study the incorporation of anthropogenically-derived nitrogen into the food webs of salt marsh systems along a contamination gradient in Narragansett Bay. Nitrogen isotope ratios (δ 15N) were measured in six estuarine species collected from three marshes along this gradient, monthly from June to October between 1997 and 1999. A significant decrease in δ 15N was found with distance along the estuary for four of the six species. Significant differences were found among monthly isotope ratios for some species. Nitrogen isotope ratios in sea lettuce (Ulva lactuca) increased during the summer season with highest δ 15N values measured during September and October. This trend was most pronounced at the station receiving the highest nutrient inputs. Elevated δ 15N values at this station appeared to correlate with seawater ammonia/nitrate concentration ratios. The temporal variations in δ 15N suggest that care should be taken in species selection and the design of sampling schemes of studies using δ 15N for monitoring anthropogenic nutrients in aquatic systems. Sampling programs designed to determine long-term trends should consider species that do not show rapid fluctuations in isotope ratios. The mud snail, Nassarius obsoletus, responded this way in the present study. Studies designed to measure short-term changes should include species such as U. lactuca, which rapidly respond to isotope changes. The results from this study also help to establish a baseline for nitrogen isotope values in Narragansett Bay. This information can be used to monitor future trends in nitrogen inputs to this estuary. [Copyright &y& Elsevier]

Abstract: Food chain and food web have been, thus far, depicted by number of individuals, matter (biomass) and energy, but not by the concept concerning to the second law of thermodynamics. The present paper takes up three U.S. mid-Atlantic estuaries and delineates marine trophic structure in the term of the concept of this missing link: the second law of thermodynamics. Homeostatic structure and function of living systems is maintained by chemical, physical and organic activities in biotic systems. These activities are supported by chemical energy released by decomposition of macromolecules in organisms by oxygen incorporated from the outside (respiration). This chemical energy finally becomes heat energy and is discarded to the outside. This heat energy is dissipation function in thermodynamics, and dissipation function divided by absolute temperature of organism–water is entropy production. As example, mid-Atlantic estuaries on the eastern U.S. coast are analyzed, based on the study of (Monaco, M.E., Ulanowicz, R.E., 1997. Comparative ecosystem trophic structure of three U.S. mid-Atlantic estuaries. Mar. Ecol. Prog. Ser. 161, 239–254). They give 13–14 trophic compartments in each estuaries, and respiration and other characteristic quantities for each trophic compartments. Trophic position of compartment in each estuary is adopted and arranged in accord to the food web diagrams of (Monaco, M.E., Ulanowicz, R.E., 1997. Comparative ecosystem trophic structure of three U.S. mid-Atlantic estuaries. Mar. Ecol. Prog. Ser. 161, 239–254). Plots of trophic number versus respiration become of half-pyramid shape, which is also applied to dissipation function because respiration is equal to dissipation function in thermodynamics. Annual average temperature at average depth in Narragansett estuary is, for example, 10.0°C (=283.2K). The difference between maximum and minimum temperature at averaged depth is 14.2°C (=287.4K). This difference is small compared with the absolute temperature scale. Hence let us make an approximation that the temperature of the water body of this estuary is about constant and uniform over a year and 10.0°C=283.2K. Entropy production is obtained by dividing dissipation function by this value. Pattern of trophic position versus entropy production multiplied by the temperature is of similar shape to dissipation function: half-pyramid. Other two estuaries show similar results. [Copyright &y& Elsevier]

Abstract: Sediment cores were taken at three locations in Narragansett Bay, Rhode Island, USA in 1997 and analyzed for a variety of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlordanes, linear alkyl benzenes (LABs), benzotriazoles (BZTs) and dichlorodiphenyltrichloroethanes (DDTs) and metabolites. The distributions of these chemicals at Apponaug Cove and in the Seekonk River indicate that there was a disturbance in the depositional environment relative to cores collected at these locations in 1986 demonstrating the potential for buried contaminants to be remobilized in the environment even after a period of burial. Sharp breaks in the concentration of several organic markers with known dates of introduction were successfully used to determine the sedimentation rate at Quonset Point. Both the Quonset Point and Seekonk River cores had subsurface maximums for DDTs, PCBs, PAHs and BZTs, which are consistent with expected inputs to the environment. The Apponaug Cove core showed an increase of most contaminants at the surface indicating a recent event in which more contaminated sediments were deposited at that location. [Copyright &y& Elsevier]

Polycyclic aromatic hydrocarbons (PAHs) were measured in 41 surface sediments from Narragansett Bay, RI. All the analytes generally decrease down bay from the Seekonk, Providence and Taunton Rivers at the head of the bay. Total PAHs ranged from 0.569 to 216 μg/g with 27% exceeding the effects range median (ERM) of 44.8 μg/g and 73% of the stations exceeding the effects range low (ERL) of 4.02 μg/g ().Based on principal component analysis, the major source of the contaminants in Narragansett Bay was the Providence River while the coves and Taunton River/Mt. Hope Bay appeared to only have a limited influence on the open bay. PAH source ratios indicate that creosote and/or coal may be the most significant contributor of pyrogenic high molecular weight PAHs in Narragansett Bay, along with significant contributions from diesel exhaust. [Copyright &y& Elsevier]

Astrangia poculata inhabits coasts near dense human populations in the northeastern United States and may be exposed to elevated pollutants. No studies have assessed heavy metal concentration in temperate corals despite their proximity to anthropogenic activity. We collected colonies four times in one year and analyzed coral tissue for As, Cd, Cr, Pb, and Zn. Most heavy metals except for As were 1.5–3.3 times lower in summer compared to other seasons. Pb, As, and Cd were three orders of magnitude higher than concentrations for other Narragansett Bay benthic species, suggesting that A. poculata bioaccumulates more readily and/or inhabits more contaminated areas of the Bay. Zn, Pb, and As had similar concentrations to tropical corals inhabiting anthropogenically polluted sites. While physiological impacts are unknown, this population of A. poculata may have a higher tolerance for heavy metal pollution than most scleractinians, making it an interesting candidate for future studies. • Heavy metals varied seasonally in tissue of the temperate coral, Astrangia poculata. • Pb, As, and Cd were 1000× higher than reported for other Narragansett Bay species. • Road dust, legacy pollution, and river discharge are likely sources of heavy metals. • Zn, Pb and As were similar to concentrations of tropical corals from polluted sites. • Pb was 4× higher than toxicity tests that reduced fertilization in other coral spp. [ABSTRACT FROM AUTHOR]

The article discusses Computer-Aided Tomography (CT) scanning technology was applied to intact sediment cores to study estuary benthic communities. It discusses use of attenuation of X-rays to differentiate between sediment and water contained in macrobenthic tubes and tunnels. It also mentions measurement of percentage of tube and tunnel area (PTTA) to assess and monitor the effects of organic carbon loading on benthic communities in Narragansett Bay, Rhode Island.