Narragansett Bay Research Articles

Factors influencing expanded use of urban marine habitats by foraging wading birds

Urban marine habitats are often utilized by wildlife for foraging and other activities despite surrounding anthropogenic impact or disturbance. However little is known of the ecological factors that determine habitat value of these and other remnant natural habitats. We examined the preferential use of urban marine habitats in a northeast US estuary to try to elucidate the factors driving enhanced foraging activity at these sites. Using a bioenergetic model, we compared energy intake to energy expenditure and examined differences in behavior and foraging success of great egrets Ardea alba at three urban and three rural salt marshes in Narragansett Bay, Rhode Island USA. Mean per site available nekton energy averaged 4.44 ± 0.97 GJ site−1 and was significantly higher at urban than at rural sites. While energy expenditure by birds was similar across all sites, mean strike and prey capture rate were significantly greater at urban sites, and 70.1 ± 12.2 % of strikes by egrets at urban sites were successful. Egrets foraging at urban sites consumed significantly more energy (23.2 ± 6.62 W bird−1) than those at rural sites. Model results indicated a net energy gain by egrets foraging at urban sites, versus a net energy loss at rural sites. Our results may help explain previously observed increases in the numbers of egrets foraging at urban marine habitats, and help provide input into decisions about the extent to which these areas should be considered for restoration or protection.

Measurement and modeling of Scholte waves in shallow water

Shear speeds in semi-consolidated and consolidated shallow water sediments can significantly impact compressional wave attenuation and arrival times of acoustic normal modes. In addition shear properties of sediments are directly related to the strength of the sediments in geotechnical applications. All of these factors emphasize the importance of estimating shear speeds in shallow water sediments. One of the most promising approaches to estimate shear speed is to invert the shear speed profile using the dispersion of interface waves (Scholte waves). The propagation speed and attenuation of the Scholte wave are closely related to shear-wave speed and attenuation over a depth of 1–2 wavelengths into the seabed. Data from the tests conducted in Narragansett Bay and off Block Island in water depths ranging from 10 m to 25 m will be presented. Modeling of interface waves will be carried out using Finite Element Method (FEM) and a wave number integration model (OASES). Sediment properties will be inferred based on the modeling and data-model comparison. [Work supported by Office of Naval Research.]

Phytoplankton and the balance of nature: An opinion

Recent European Court rulings in the context of eutrophication viewed proliferation of a particular species of algae as a disturbance to the balance of aquatic ecosystems and the proliferation of one or more species as a cause of a reduction in other species. We discuss the scientific basis for this opinion in relation to the growth of marine primary producers and current debates about ecosystem stability. Opposing views in this debate are those of (a) the ‘balance of nature’ paradigm, in which communities of organisms tend towards a stable climax composition, and (b) communities as dynamic systems that may be governed by ‘basins of attraction’ in state space. We use data from the Irish Sea and Narragansett Bay, together with a review of the literature, to show that: the dynamics of temperate marine phytoplankton, with seasonal successions, corresponds more to (b) than to (a); the temporary dominance of any one species of micro-alga or cyanobacterium is part of the natural dynamics of phytoplankton communities and does not permanently impact on other species. Understanding the phytoplankton as a dynamic system suggests its status should not be assessed against a 'climax' model and that eutrophication should be diagnosed from fundamental (nutrient-induced) perturbations of ecosystem state and function rather than from changes in fixed assemblages of species and thresholds of abundance.

Drivers of protistan grazing pressure: seasonal signals of plankton community composition and environmental conditions

Rates of heterotrophic protist grazing and phytoplankton growth were measured weekly to bi-weekly in Narragansett Bay, Rhode Island, USA, from January 2010 to February 2011. In situ sensor data and species composition were collected concomitantly to link patterns in plankton dynamics with ancillary environmental and biological processes. Annual average phyto- plankton growth rates were 0.69 ± 0.58 d �1 , and heterotrophic protist grazing rates were 0.79 ± 0.61 d �1 . Phytoplankton growth rates were at times negative in both winter and spring. Nutrient limitation was only detected during summer, and negative growth rates in winter did not result from nutrient limitation. On an annual average, grazing removed 96% (20 to 200%) of primary production, with peaks in both phytoplankton growth and heterotrophic protist grazing rates dur- ing summer. There was no relationship between protistan herbivory rates and initial chlorophyll a concentration. Dominant grazer taxa changed seasonally. Heterotrophic dinoflagellates domi - nated in summer and were associated with significantly higher than average grazing rates (>1 d �1 ). Seasonal changes in grazing rates were most significantly characterized by seasonal changes in both temperature and plankton community composition. The relative effects of temperature and species composition could not be distinguished statistically. The magnitude of protistan grazing and subsequent effects on trophic transfer and primary production rates as well as phytoplankton community composition may be better understood and parameterized when grazing pressure is evaluated in relation to species composition and environmental conditions rather than bulk measures of biomass.

Toxic Alexandrium peruvianum (Balech and de Mendiola) Balech and Tangen in Narragansett Bay, Rhode Island (USA)

Phytoplankton monitoring in Wickford Cove, Rhode Island, US (41°34′10.13″N, 71°26′45.76″W), located in Narragansett Bay, detected an unusual species of Alexandrium in the spring of 2009. Thecal plate analysis using brightfield and SEM microscopy revealed a plate morphology consistent with that of Alexandrium peruvianum (Balech and de Mendiola) Balech and Tangen. Molecular analyses indicated that the sequences of the SSU, ITS1, 5.8S, ITS2 and LSU through the D region of the 18S gene were similar to those of A. peruvianum from North Carolina. Toxin analyses of cells brought into culture revealed saxitoxins, gymnodimine and fast-acting spiroimines were present in the cultured clone. Saxitoxins detected included GTX 2, GTX3, B1, STX, C1 and C2. Also present in the Wickford cove isolates of A. peruvianum were 12-methyl gymnodimine and 13-desmethyl spirolide C. A. peruvianum was detected at four sites in lower Narragansett Bay: at two sites in Wickford and two sites in Jamestown, RI. A. peruvianum was observed in the spring of 2009, 2010, 2011 and 2012 at maximum abundance levels ranging from tens of cells per liter to 14,000cells L−1. The discovery of A. peruvianum in Rhode Island coastal waters, with its potential threat to public health, is notable as it appears to be an emergent bloom species globally. The presence of A. peruvianum in Narragansett Bay is the third confirmed observation of this species on the Atlantic coast of North America. Monitoring efforts in the southern New England region should incorporate measures to detect the presence of A. peruvianum toxins.

Metal Concentrations in Tissues of American Lobsters (Homarus americanus, Milne-Edwards) with Epizootic Shell Disease

Environmental contaminants have been suggested frequently as causative factors in crustacean shell disease. This study explored the relationship of environmental contaminants to epizootic shell disease in the American lobster (Homarus americanus). Trace metal loads were analyzed in lobsters showing signs of shell disease and those without signs of shell disease collected from Narragansett Bay, Rhode Island Sound, and Long Island Sound in 2007. In addition, trace metals were analyzed in lobsters collected in 2008 from a single station in Narragansett Bay and a reference site in Maine for a multiparameter, multiinvestigator study (the “100 Lobsters” project). Analyses focused primarily on hepatopancreas and hemolymph tissues, but muscle, shell, gills, and ovaries were also analyzed to examine the partitioning of metals between various component tissues. Sediment from the “100 Lobsters” collection site was also analyzed. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure 10 different contaminant elements, including arsenic, cadmium, cobalt, chromium, copper, manganese, molybdenum, nickel, lead, and vanadium. Mercury was determined using a direct mercury analyzer. Overall, there was no systematic difference seen in contaminant metal burdens between those lobsters with signs of shell disease and those without signs, and hepatopancreas concentrations were generally similar to other reported values for field-collected lobsters. Contaminant metals were found to be partitioned between tissues differentially. Hepatopancreas tissue generally contained the greatest concentrations of contaminants, but exoskeleton contained the highest levels of manganese, nickel, and lead. Sediment collected from the “100 Lobster” sampling site showed that concentrations of several metals were similar to or exceeded the suggested sediment quality guidelines, consistent with a site that is moderately impacted by metals. Based on these data, the presence or absence of shell disease cannot be attributed to the magnitude or patterns of metal accumulation and disposition.

The “100 Lobsters” Project: A Cooperative Demonstration Project for Health Assessments of Lobsters from Rhode Island

The emergence of epizootic shell disease in the American lobster (Homarus americanus) has been devastating to the fishing industry in southern New England. In response, research was initiated to understand the roles of the environment, pathogens, and pollutants in the ecology and etiology of the disease. A comprehensive project was initiated in which tissues and hemolymph from 100 lobsters were collected from an endemic area of disease, Narragansett Bay, RI. The project has moved forward with the purpose of compiling, synthesizing, and propagating the findings from the ''100 Lobsters'' Project. The resulting tissue bank and Web-based data repository and instructional tools serve as a nascent demonstration project to both the scientific community working on this disease as well as to members of the lobster industry.

Histological Assessment of the Lobster (Homarus americanus) in the “100 Lobsters” Project

The emergence of epizootic shell disease in the American lobster (Homarus americanus) has been devastating to the industry in the coastal waters of southern New England. A comprehensive assessment of the disease syndrome, known as the “100 Lobsters” Project, was initiated to examine health and physiological parameters among laboratories involved in the research on lobster shell disease. A histological study of the 100 lobsters was undertaken as part of that assessment. Tissues from 90 lobsters from Rhode Island and 19 lobsters from Maine were examined as a general health assessment of the 100 lobsters. Approximately half the lobsters from Rhode Island were selected because they had frank epizootic shell disease, whereas none of the lobsters from Maine exhibited the syndrome. In addition to epizootic shell disease, the histological findings revealed 3 other idiopathic syndromes—necrotizing hepatopancreatitis, idiopathic blindness, and nonspecific granulomas—in higher prevalences in lobsters from Rhode Island compared with those from Maine. Necrotizing hepatopancreatitis, a newly described disease syndrome in lobsters, was observed in 15% of the lobsters from Rhode Island. Idiopathic blindness was present in 54% of the lobsters from Rhode Island, and 16% of the animals from Maine. This is the first report of the syndrome in lobsters from Maine. None of the idiopathic syndromes was associated with epizootic shell disease. The detection of multiple disease syndromes such as epizootic shell disease, necrotizing hepatopancreatitis, and idiopathic blindness may be indicative of exposure to environmental stressors in Narragansett Bay, RI.

A Fisherman's Perspective

A Fisherman's Perspective

Relationships between watershed emergy flow and coastal New England salt marsh structure, function, and condition

This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI, USA. The field-collected data were obtained during several years of vegetation, invertebrate, soil, and water quality sampling. The use of emergy as an accounting mechanism allowed disparate factors (e.g., the amount of building construction and the consumption of electricity) to be combined into a single landscape index while retaining a uniform quantitative definition of the intensity of landscape development. It expanded upon typical land use percentage studies by weighting each category for the intensity of development. At the RI salt marsh sites, an impact index (watershed emergy flow normalized for marsh area) showed significant correlations with mudflat infauna species richness, mussel density, plant species richness, the extent and density of dominant plant species, and denitrification potential within the high salt marsh. Over the 4-year period examined, a loading index (watershed emergy flow normalized for watershed area) showed significant correlations with nitrite and nitrate concentrations, as well as with the nitrogen to phosphorus ratios in stream discharge into the marshes. Both the emergy impact and loading indices were significantly correlated with a salt marsh condition index derived from intensive field-based assessments. Comparison of the emergy indices to calculated nitrogen loading estimates for each watershed also produced significant positive correlations. These results suggest that watershed emergy flow is a robust index of human disturbance and a potential tool for rapid assessment of coastal wetland condition.

Benthic Geologic Habitats of Shallow Estuarine Environments: Greenwich Bay and Wickford Harbor, Narragansett Bay, Rhode Island, U.S.A

Abstract Oakley, B.A.; Alvarez, J.D., and Boothroyd, J.C., 2012. Benthic geologic habitats of shallow estuarine environments: Greenwich Bay and Wickford Harbor, Narragansett Bay, Rhode Island, U.S.A. An integrated mapping approach using high-resolution side-scan sonar, surface sediment grab samples, digital aerial and orthophotography, and underwater video imagery was used to map Holocene sediment cover and Late Wisconsinan glacial outcrop in two shallow embayments in Narragansett Bay, Rhode Island, U.S.A. The use of side-scan sonar to characterize the seafloor has become common in a variety of different marine environments. Challenges remain in classifying side-scan or other acoustic data into a naming convention that is useful to scientists and managers. We characterize the benthic geologic habitats of these areas utilizing a flexible naming convention that combines information about geologic processes, morphologic form, particle size, biota, and anthropogenic impacts. Benthic geologic habitats were sep...

Shear wave speed inversions using scholte wave dispersion

Shear speeds in semi-consolidated and consolidated shallow water sediments can significantly impact compressional wave attenuation and arrival times of acoustic normal modes. In addition, shear properties of sediments are directly related to the strength of the sediments in geotechnical applications. All of these factors emphasize the importance of estimating shear speeds in shallow water sediments. One of the most promising approaches to estimate shear speed is to invert the shear speed profile using the dispersion of interface waves (Scholte waves). The propagation speed and attenuation of the Scholte wave are closely related to shear-wave speed and attenuation over a depth of 1-2 wavelengths into the seabed. Data from the tests conducted in Narragansett Bay and off Block Island in water depths ranging from 10 m to 25 m using the shear measurement system, developed at the University of Rhode Island, will be presented. Combustive Sound Source (CSS) was be used to generate interface waves during these tests. An inversion algorithm to estimate the shear wave speed profile in the sediment will be presented. Estimates of the shear speed will be compared with ground truth data. [Work supported by Office of Naval Research]

Quantifying variation in water column photosynthetic quotient with changing field conditions in Narragansett Bay, RI, USA

Quantifying variation in water column photosynthetic quotient with changing field conditions in Narragansett Bay, RI, USA

Indicators of sediment and biotic mercury contamination in a southern New England estuary

Total mercury (Hg) and methylmercury (MeHg) were analyzed in near surface sediments (0–2cm) and biota (zooplankton, macro-invertebrates, finfish) collected from Narragansett Bay (Rhode Island/Massachusetts, USA) and adjacent embayments and tidal rivers. Spatial patterns in sediment contamination were governed by the high affinity of Hg for total organic carbon (TOC). Sediment MeHg and percent MeHg were also inversely related to summer bottom water dissolved oxygen (DO) concentrations, presumably due to the increased activity of methylating bacteria. For biota, Hg accumulation was influenced by inter-specific habitat preferences and trophic structure, and sediments with high TOC and percent silt–clay composition limited mercury bioavailability. Moreover, hypoxic bottom water limited Hg bioaccumulation, which is possibly mediated by a reduction in biotic foraging, and thus, dietary uptake of mercury. Finally, most biota demonstrated a significant positive relationship between tissue and TOC-normalized sediment Hg, but relationships were much weaker or absent for sediment MeHg. These results have important implications for the utility of estuarine biota as subjects for mercury monitoring programs.

Geopolitics and the Northern Sea Route

Experimental transit voyages along the Northern Sea Route to the north of Russia are breaking new ground each year and the route is already significant for the export of raw materials from Russian ports. National and corporate interests are now driving Russia's Arctic policy, rather than, as formerly, an exclusive focus on security, and the Russian government has ambitious plans for the development of the route. Future regular transit of the Northern Sea Route between Europe and Asia, at present facing serious obstacles, could be accelerated not only by climate change, but by overload on, or interruptions to, the existing route through the Suez Canal, which passes through some of the world's most volatile regions. Despite the formidable impediments to regular year round transit of the Northern Sea Route, governments of the non-Arctic states with most at stake, particularly Germany and China, appear to be taking no chances, and to be jockeying for influence in the Arctic region. The interests of the non-Arctic trading states, and of the European Union, more inclined to view the Arctic Ocean as part of the ‘common heritage of mankind’, are however potentially different from those of Russia, and indeed of Canada in respect of the North East passage, both determined to maintain their exclusive national jurisdiction over emerging sea lanes through their territorial waters. Great issues are at stake here. The emergence of new sea lanes has historically impacted heavily on the international balance of power. Where the merchant fleets go, navies will shortly follow.

Freely dissolved PBDEs in water and porewater of an urban estuary

Polyethylene passive samplers (PE) were deployed in Narragansett Bay, RI, to examine freely dissolved concentrations of polybrominated diphenyl ethers (PBDEs) in surface, bottom, and sediment porewater. PBDE congeners in the water column and porewater were below 3 pg L −1. In the surface water, only PBDE congeners containing up to 5 bromines were detected, while in the deeper water congeners 153 and 154 (6 bromines) were also detected. Activity ratios of surface-bottom water and porewater-bottom water suggested that lower brominated (di-tetra) congeners reached Narragansett Bay from surface waters and sediments. PBDEs in the surface water probably originated from a combination of air–water exchange, freshwater runoff, rivers, and wastewater treatment plants. It is suggested that deep water was the source of higher brominated PBDEs to the Bay implying that the more hydrophobic PBDEs reached depth on particles and/or that these congeners were degraded in sediments. On-going sources supply PBDEs to Narragansett Bay.

Estimation of shear speed using interface wave dispersion

Our recent work has highlighted the effect of shear on the dispersion of acoustic normal modes. Specifically, sediment shear speed can significantly impact compressional modal arrival times near the airy phase. In addition to underwater acoustic propagation effects, shear properties of sediments are directly related to the strength of the sediments in geotechnical applications. All of these factors emphasize the importance of estimating shear speeds in semi-consolidated shallow water sediments. One of the most promising approaches to estimate shear speed is to invert the shear speed profile using the dispersion of interface waves (Scholte waves). The propagation speed and attenuation of the Scholte wave are closely related to shear-wave speed and attenuation over a depth of 1–2 wavelengths into the seabed. Results from the tests conducted at Narragansett Bay in water depths ranging from 10 to 25 m using the shear measurement system, developed at the University of Rhode Island based on this concept, will be presented. Combustive sound source (CSS) will be used to generate interface waves. Data collected during these tests will be shown and preliminary estimates of the shear speed will be presented and compared with ground truth data. [Work supported by Office of Naval Research.]

Net sediment N2 fluxes in a southern New England estuary: variations in space and time

Over the past three decades, Narragansett Bay has undergone various ecological changes, including significant decreases in water column chlorophyll a concentrations, benthic oxygen uptake, and benthic nutrient regeneration rates. To add to this portrait of change, we measured the net flux of N2 across the sediment–water interface over an annual cycle using the N2/Ar technique at seven sites in the bay for comparison with measurements made decades ago. Net denitrification rates ranged from about 10–90 μmol N2–N m−2 h−1 over the year. Denitrification rates were not significantly different among sites and had no clear correlation with temperature. Net nitrogen fixation (−5 to −650 μmol N2–N m−2 h−1) was measured at three sites and only observed in summer (June–August). Neither denitrification nor nitrogen fixation exhibited a consistent relationship with sediment oxygen demand or with fluxes of nitrite, nitrate, ammonium, total dissolved inorganic nitrogen, or dissolved inorganic phosphate across all stations. In contrast to the mid-bay historical site where denitrification rates have declined, denitrification rates in the Providence River Estuary have not changed significantly over the past 30 years.

Steve Schock and the Narragansett Bay Project

One of the first tasks for Steve Schock's sub bottom measurement system was with the Naval Undersea Warfare Center at Newport, RI. A research CRADA was established between NUWC and Precision Signals (Dr. LeBlanc and Dr. Schock) to measure the bottom sediment beneath the torpedo test range. The measurements were successful. The bay at the test range was measured down to bed rock at 64 m. The results indicated that the bay had been a glacial lake from the time the ice receded; until the sand bar that blocked the mouth of the bay eroded and the lake became a salt water bay, open to the ocean. Dr. Schock and Dr. LeBlanc authored a number of technical papers detailing the technology and its application. They founded the Chirp Lab at Florida Atlantic University in Boca Raton, Florida, where the technology has been advancing. Some of the latest techniques were presented in a special session at the May 2011 ASA meeting in Seattle.

The evolution of the chirp sonar high resolution sub-bottom sonar

Professor Steven G. Schock completed his Ph.D. Graduate program of studies under our guidance in the Department of Ocean Engineering, University of RI. The Chirp Sonar research project that supported Stevens graduate studies was proposed to, and supported by ONR (Dr. Joseph Kravitz) in the early 1980s The PIs were Professors Lester Leblanc (Ocean Engineering) and Professor Larry Mayer (Ocean Engineering and Geological Oceanography). Dr. Mayer and I shared a common interest in improving the quality of sub-bottom sonars so as to provide high quality quantitative data for imaging and classification of the sea floor. It was Stevens hard work at programming the signal processing and assembling and building of components to the chirp sonar that greatly contributed to making this program a success. The initial system, housed in two large racks was tested by Steven in Narragansett Bay RI, and unprecedented high resolution images of the sub-bottom seafloor were generated with the data collected for his research pr...