Block Island Sound Research Articles

The benthic macroinvertebrates of the Block Island Sound

The benthic invertebrates of Block Island Sound have not been adequately studied, in contrast to other adjacent southern New England sounds. This study examines the species composition, abundance and biomass of benthic macrofaunal invertebrates at nine locations within Block Island Sound. The sites sampled, represent a wide range of subtidal habitats within the Sound, and were visited in February and September. Some 224 species were identified, of which almost half (104) were polychaetes. The benthic assemblages at most stations were dominated numerically by tube dwelling, surface detritus or suspension feeding amphipods, e.g. Ampelisca agassizi and A. vadorum, as well as the protobranch bivalve, Nucula proxima. This dominant Ampelisca-Nucula assemblage was associated with silty fine sand sediments. The average macrofaunal biomass for all stations was 158 g (wet weight) m −2, two thirds the average benthic biomass of Georges Bank, an important fishery area. Based on the examination of the records of earlier surveys in Block Island Sound, there is evidence that this silty-sand, ampeliscid-dominated assemblage has persisted since at least the mid-1940s.

A nested numerical tidal model of the southern New England Bight

A nested, barotropic numerical tidal model has been applied to the southern New England Bight to include Long Island Sound (LIS), Block Island Sound (BIS), Rhode Island Sound (RIS), Buzzards Bay (BB) and a portion of the southern New England shelf. An explicit finite difference representation of the two-dimensional vertically averaged equations of motion and continuity, employing forward time and centered spatial differences with the bottom friction term being evaluated at both time levels, is applied to the study area to predict tidal circulation dynamics. Horizontal friction and advective terms have been neglected. Tidal height data along the open boundaries is specified from available data. Model predictions of corange and high and low cophase lines agree with available data and show the strongly co-oscillatory behavior of LIS. Tidal current ellipses agree reasonably well with available data showing rectilinear motion in LIS, BIS and BB and rotary motion in RIS.

Fronts, stratification, and mixing in Long Island and Block Island sounds

Spatial patterns of bulk stratification in Long Island and western Block Island sounds observed near the fall equinox of 1978 show a strong correlation (r = 0.79) with contours of the h/U3 stratification index derived from tidal stream and depth charts. The index delineates stratified, transitional, and mixed regions with apparent good accuracy, with the marginally stratified frontal zones being characterized by log10 h/U3 ∼ 1.5 m−2 s3. These results and theoretical considerations suggest that the index may be a useful parameter in corroborating and predicting frontal boundaries in other moderately stratified estuaries where local buoyancy fluxes are derived from fresh water sources.

Tidally-induced residual currents in Long Island and Block Island Sounds

The tidally-induced residual currents in the Long Island Sound-Block Island Sound (LIS-BIS) tidal channel are investigated using a previously-developed analytic model. Known first order tidal properties of LIS-BIS are matched using three different models, chosen to isolate the effects of the factors potentially controlling the second order currents, either breadth, depth or eddy viscosity variations. The residual currents driven by these first order models agree to within roughly a factor of two, indicating that the model is not overly sensitive to these parameters. Tidally-induced currents on the order of observed currents in eastern LIS and BIS are predicted. The outstanding structural feature of the predicted residual currents is a region of strong surface flow divergence and bottom flow convergence centered at a sharp constriction in the channel. Eulerian and Lagrangian observations in eastern LIS and BIS are reviewed; indirect support for the theoretical results is found.

Tectonic development of southern Narragansett Bay and offshore Rhode Island

Research Article| October 01, 1980 Tectonic development of southern Narragansett Bay and offshore Rhode Island Robert L. McMaster; Robert L. McMaster 1Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode Island 02881 Search for other works by this author on: GSW Google Scholar Jelle de Boer; Jelle de Boer 2Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06457 Search for other works by this author on: GSW Google Scholar Barclay P. Collins Barclay P. Collins 3Gulf Science and Technology Company, P.O. Box 2030, Pittsburgh, Pennsylvania 15230 Search for other works by this author on: GSW Google Scholar Author and Article Information Robert L. McMaster 1Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode Island 02881 Jelle de Boer 2Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06457 Barclay P. Collins 3Gulf Science and Technology Company, P.O. Box 2030, Pittsburgh, Pennsylvania 15230 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1980) 8 (10): 496–500. https://doi.org/10.1130/0091-7613(1980)8<496:TDOSNB>2.0.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Robert L. McMaster, Jelle de Boer, Barclay P. Collins; Tectonic development of southern Narragansett Bay and offshore Rhode Island. Geology 1980;; 8 (10): 496–500. doi: https://doi.org/10.1130/0091-7613(1980)8<496:TDOSNB>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Total magnetic intensity and seismic refraction are used to define tectonic features on the inner shelf beneath Block Island and Rhode Island Sounds. Magnetic lineaments suggest a tectonic pattern of rhombo-hedral basement blocks controlled by northwest and north-northeast to northeast fault sets. Similar patterns predominate in the basement complexes of Rhode Island and Connecticut.From the geophysical data, the Narragansett Basin is inferred to continue at least 16 to 22 km off the Rhode Island coast. Here grabens or half grabens, filled with Pennsylvanian(?) metasediments may lie on either side of a central basement horst. Another Carboniferous basin may exist farther seaward on the Long Island platform.The Narragansett Basin probably evolved in early Carboniferous time as a pull-apart basin between en echelon zones of left-lateral northeast-trending faults. Later episodes affecting the basin include a Permian compressional event, the consequence of a regional change to dextral shear along the same fundamental faults; a second phase of east-west extension in Late Triassic–Jurassic time; and a post-Cretaceous event during which regional fracture systems were reactivated by vertical movements. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Comparison of Spawning Seasons, Age, Growth Rates, and Food of Two Sympatric Species of Searobins, Prionotus carolinus and Prionotus evolans, from Long Island Sound

Prionotus carolinus and Prionotus evolans were collected from many locations within Long Island Sound in 1971–1973, and in 1976–1977. Data from earlier collections in Block Island Sound (1943–1945) were also included. A total of 1751 specimens, 960 P. carolinus and 791 P. evolans was examined within these two time periods.

Origins of oceanic plankton in the middle Atlantic Bight

Expatriated species of zooplankton found in the mid-Atlantic Bight include Arctic-Boreal species derived from shelf waters northeast of Cape Cod, transition zone species from the adjoining Slope Water and tropical-subtropical species that commonly reside in the Gulf Stream, and Sargasso Sea. Introduction of expatriates is largely associated with the pattern of advective movements of water onto the shelf: Arctic-Boreal species are brought in from the northeast largely by over-shelf transport; transition zone species by Slope Water penetration at the surface when horizontal density gradients are minimal and at mid-depth in response to physical processes such as estuarine-type circulation, wind-driven upwelling, cold shelf water ‘bubble’ formation and movement out into the Slope Water or to shelf-Slope Water interactions associated with warm core rings; warm water species by injection of warm core ring surface water in over the shelf. There is little evidence that Carolinian species are introduced into the mid-Atlantic Bight directly around Cape Hatteras. In general, the occurrence of expatriate warm water species is more important in terms of species numbers and total biomass when compared to the occurrence of expatriate cold water species. The Bight region can be divided into three regions with regard to oceanic influences: (1) the band of low salinity water along the coast south of the mouth of the Hudson River, extending to the mouth of the Chesapeake; (2) the Continental Shelf edge extending from about 37 ° 30′N to 40 °N and extending shoreward towards the eastern half of the Long Island and Block Island Sound, but not including the region south-east of Cape Cod and Nantucket: (3) the southern sector, including the shelf edge south of 37 °N and extending landward south of Chesapeake Bay. Each of these regions is characterized by types of expatriate species and by hydrographic features. A mechanism is postulated whereby warm water species which cannot withstand harsh winter conditions in the mid-Atlantic Bight can ‘overwinter’ by the movement offshore of adults or larvae in shelf water entrained at Cape Hatteras in late summer or early fall, by transit alongside or within the Gulf Stream, by incorporation into a warm core ring and by return to shelf waters in the spring when the ring impinges on the shelf margin.

The effects of gastropod shell availability and habitat characteristics on shell utilization by the intertidal hermit crab Pagurus longicarpus Say

The shell utilization patterns of two intertidal populations of the hermit crab, Pagurus longicarpus Say, were studied. The populations differed with respect to the physical characteristics of their habitats and the availability of empty gastropod shells. The first population was in an estuary connected to Narragansett Bay. This population had few, if any. empty shells available in the area. The second population was in a rock-cobble area directly on Block Island Sound. There were large numbers of empty gastropod shells available for this population. The consistently high gastropod mortality on this shore appears to be caused by the animals being washed up on the beach, where they die due to desiccation. Data from samples collected from June to November of both 1974 and 1975 showed that there were distinct differences in the shell utilization patterns of the two populations. A greater proportion of the animals collected from the estuary population inhabited damaged shells and/or shells with symbionts compared to the individuals from the population with large numbers of empty shells available. The results of shell selection experiments indicated that individuals from both populations inhabited less than preferred shells. The population with large numbers of empty shells available was qualitatively shell-limited because of the effect of physical factors on the morphology of the gastropod species of that area. In addition, the shell selection experiments showed that individuals from the two areas had significantly different shell preferences. This result may be explained by the effects of the environment on the growth rates of the hermit crabs and/or as an indication that shell preferences may vary in response to the physical factors of a given habitat.

Seasonal vitamin B12 and phytoplankton distribution near Napeague Bay, New York (Block Island Sound)1

Vitamin B12 levels in seawater were assayed over a 13‐month period with Thalassiosira pseudonana Hasle et Heimdal, clone 3H. Concentrations at four different stations ranged from undetectable to 10.6 ng·liter−1. Concentrations during November– December 1975 were undetectable and may have limited the growth of B12 auxotrophic phytoplankters. A positive significant correlation, on a seasonal cycle, was found between B12 levels and dinoflagellate cell numbers and negative significant correlations between B12 and chlorophyll a concentrations at the same two stations. B12 levels were highest during summer when other nutrients (NO3−‐N, PO43−‐P) were low. Bacterial production is suggested as a source of the summer concentrations.

An Annual Phytoplankton Study in Coastal Waters off Eastern Long Island (Block Island Sound)

An Annual Phytoplankton Study in Coastal Waters off Eastern Long Island (Block Island Sound)

The Distribution of Polystyrene Spheres and Nibs in Block Island Sound during 1972-1973

Recent investigations have shown the pelagic distribution of plastic particles in the ocean to be widespread; and their source and fate have been the subject of considerable discussion in the United States. In the waters of Block Island Sound there is a seasonal fluctuation in their abundance. Their source appears to be Long Island Sound, probably originating from the rivers on the Connecticut Shore. They are transported out to sea by the action of the tidal currents in the upper 10–15 meters of the water column.

Freshwater-lake sediments beneath Block Island Sound

Seismic-reflection and bottom-sample data indicate that large freshwater lakes occupied most of northern Block Island Sound during part of Pleistocene time.

Suspended material transport: Narragansett Bay area, Rhode Island

Net circulation patterns and routes of suspended material transport in lower Narragansett Bay and its approaches were investigated utilizing sea-bed drifters, transmissometer measurements, grain size distributions, suspended material concentration data and compositional analyses. In general, seaward flowing near-surface currents carry silt through lower West and East Passages, west across the Bay mouths and then south along Point Judith Neck. Very fine silt is carried along this route with little deposition but medium silt settles toward the Bay mouths. At the entrances to Narragansett Bay, the landward-flowing direction of bottom currents is modified by coastal currents and topographic influences. Near-bottom suspended material is carried into all three Narragansett Bay passages as well as eastward and westward across the entrances. The westward setting component transports suspended matter from East and West Passage across the passage mouths, southward adjacent to Point Judith Neck and then westward into Block Island Sound. Coarse silt suspended by turbulence at East and West Passage mouths is deposited along this path in the sandy silt bed (McMaster, 1960) east of Point Judith Neck. Some of the very fine silt carried along this route may be deposited in the sandy silt bed as well as in Block Island Sound. The eastward component, influenced by the nearshore circulation in Buzzards Bay, flows along the south-eastern Massachusetts coast. Coriolis acceleration may cause the dextral movement of near-surface and near-bottom suspensates from the mouths of estuaries, based on results of this study and investigations of other workers.

Mode enhancement using a vertical array of transmitters: Theory and experiment

A vertical transmitting array was implanted in Block Island Sound in November 1970. Tests conducted in 1972 and 1973 in the Block Island area used this array to transmit energy at 1700 Hz and used a vertical array of receivers to probe the sound field in range and depth. The measurements served as a test of the possibility of enhancing selected modes in the sound field by weighting the transmitting array elements in a manner which matched the field of a selected mode. In addition, they tested the ability of an acoustic model to predict propagation loss as a function of range and depth for a vertical array of sources. Long-term oceanographic data were also taken using temperature sensors attached to the tower containing the transmitting array. These data were used to determine both the long- and short-term temporal stability of the medium and the resulting effect on mode enhancement as a function of frequency. [This project was funded by NAVSEA (SEA 06H1-4).]

Helicopter launching of surface and sea‐bed drifters

The semi‐enclosed nature of Long Island Sound makes it ideal for surface and sea‐bed drifter studies. A U.S. Coast Guard H‐3 helicopter provided a “synoptic” launch within a half tidal cycle. Drifter releases were conducted on 18 June 1973 at a total of 50 stations in Long Island and Block Island Sounds. Drops were made at various altitudes and speeds in order to determine optimum release conditions.

Survival of copepods passing through a nuclear power station on northeastern Long Island Sound, USA

About 70% of the copepods entering the cooling water system of a nuclear power plant on northeastern Long Island Sound (USA) are not returned to the Sound in the effluent. Copepod mortalities are caused by the mechanical or hydraulic stresses of passage, although our experimental design could not determine whether heat or chlorination could cause mortality in the absence of mortality induced by hydraulic stress. After passing through the power plant, copepods sink rapidly (ca. 2.5 times faster than controls). This leads to an increase in concentrations of copepods suspended in the deep water (25 to 30 m) of the effluent pond. About half of the live copepods collected at the discharge and held in situ died within 3.5 days, and 70% died within 5 days, whereas only 10% of those from the intake died in 5 days. About 60% of the copepods observed suspended in deep water in the pond were dead. The copepod mortality caused by the power plant reflects the loss in secondary production occurring below about 270×103 m2 of sea surface in Long Island Sound annually. This loss represents a reduction of about 0.1% in the annual secondary production over a 333 km2 area of Long Island Sound adjacent to the power plant. Highest losses occurred during the spring (April, 1.4×106 g dry weight), the lowest in autumn (November, 45.8×103 g). If the same copepod loss rate exists for all power plants in Long Island Sound, then secondary production in 1.69×106 m2, or 0.05% of the total copepod production may be lost annually. A comparison of the surface outflow from Long Island to Block Island Sound with the water entrained through Millstone Unit One, and the 70% copepod loss rate in the latter area, indicates that Unit One eliminates about 0.1 to 0.3% of the copepod production in eastern Long Island Sound. This calculation compares favorably with losses computed from production data.

Drowned and buried valleys on the southern New England continental shelf

Bathymetry and seismic reflection profiling have revealed a sequence of seven post-Jurassic drowned or buried drainage systems on the southern New England shelf. The basement and younger stream patterns have a dominant southward trend with preferred drainage avenues from the mainland to the middle shelf indicated by superposed valley ground positions from unconformity to unconformity over time. Fluvial action under stable tectonic conditions is inferred by low valley height/width ratios with higher ratios related to ice modification of inner shelf pre-glacial river valleys. Fluvial processes responding to sea-level withdrawals have greatly influenced the shelf's later development. Periodically during post-Paleocene time, sediment from subaerial erosion has been transported to the shelf edge by streams. Deltaic deposition on a subsiding base has controlled outbuilding on the outer shelf where the frequent presence of overlying drainage networks is the result of numerous sea-level regressions. Since Eocene time, sediment has been channelled to the deep sea via Block Canyon and its progenitor. Locally structures created by erosion and glacial deposition have governed drainage direction. On the inner shelf, late Tertiary - early Pleistocene streams were diverted southeastward and southwestward by the magnitude of Long Island's Coastal Plain escarpment and by secondary cuestas between eastern Long Island and Block Island. The probable eastern reach of Dana's southern Sound River valley can be traced from northeastern Long Island across Block Island Sound. An early Woodfordian end moraine of the Wisconsin stage impounded melt waters in Block Island and Rhode Island Sounds. Where the moraine was breached near Block Island, fans were formed adjacent to the water gaps. In Rhode Island Sound the earlier and later Woodfordian end moraines deflected some mainland drainage toward the southwest.

The demersal fish of Narragansett Bay: An analysis of community structure, distribution and abundance

Monthly samples of demersal fish were collected from nine regular and 13 occasional stations in Narragansett Bay, Rhode Island throughout a year. While over 9000 individuals representing 99 species were taken, the 10 most abundant species made up 91% of the catch. Taxonomic composition and dominance of the fish community were generally similar to that reported for adjacent Block Island Sound and Long Island Sound, though diversity was slightly higher in the bay. Winter flounder, Pseudopleuronectes americanus was by far the most abundant species, and accounted for 36% of the total catch. Multiple regression analysis of fish numbers and biomass for total catch and for the dominant flounder indicated that of 14 environmental variables considered, only depth, sediment organic content, temperature and wind speed were significant in explaining distribution within the bay. No clear pattern of fish abundance was apparent, except for higher diversity near the mouth of the bay. The mean annual standing crop of 117 ± 151 fish/acre and 28·5 ± 16·0 lbs/acre (wet weight) was comparable to values reported for a variety of New England coastal and offshore areas. The total biomass of fish remained remarkably constant throughout the year when compared to adjacent coastal environments, while the abundance of particular species varied substantially with season.

Utilization of a Transmitting Array Matched to Individual Modes

A vertical transmitting array was implanted in Block Island Sound in November 1970. A theoretical study was undertaken to determine the optimum utilization of such an array to excite individual normal modes. The results of this study are described. Amplitude and phase matching, the two basic methods to emphasize individual modes, are outlined. In matching to amplitude, either a course or more exact fit to the mode amplitude may be utilized. These three approaches to emphasize individual modes were considered. Simple cases of these approaches were evaluated for the physical characteristics of the implanted array using a computer program. BIFI velocity profiles typical for summer and winter were used. Propagation loss was calculated for individual modes when the array was matched in turn to modes 1–4 for each profile and mode. In this manner, the relative signal levels corresponding to each approach were obtained and their effectiveness evaluated.

THE ANNUAL CYCLE IN QUANTITY AND COMPOSITION OF THE ZOOPLANKTON OF THE SARGASSO SEA OFF BERMUDA. I. THE UPPER 500 M1

A year‐round quantitative and qualitative study has been made of the zooplankton collected by oblique 0–500‐m tows with a meter net of No. 2 and No. 8 mesh nylon at semimonthly intervals from 16 March 1961 to 7 April 1962 at station “S,” 24 km southeast of Bermuda in 3,200 m of water. Highest dry weights and displacement volumes were obtained in March 1961 and April 1962, but total numbers remained fairly high for most of the year, with a January–February minimum. Seasonal cycles of all the more numerous organisms are described.In the Sargasso Sea off Bermuda the annual cycle of zooplankton abundance is related to the degree of seasonal change; when the water column is mixed down to the permanent thermocline, greater quantities of phytoplankton and zooplankton are produced. In 1961– 1962 the mean standing crop of zooplankton was 70% of that recorded for Long Island Sound and Block Island Sound and 30% that of Georges Bank.Specific diversity in plankton populations was investigated by means of MacArthur’s information‐theory model and values for the coefficient of equitability obtained for the copepods and pteropods in the Sargasso Sea and for copepods in Long Island Sound, Block Island Sound, and Texas coastal waters. A seasonal cycle in equitability of plankton populations is apparently typical of waters where there is a sufficient degree of seasonal environmental change to produce unstable conditions or to permit changes in species composition during a year. The evenness of distribution of copepod species is more dependent on environmental stability than on number of species. The equitability of the copepod populations in the Sargasso Sea appears to be inversely correlated with productivity.