Ninigret Pond Research Articles

Habitat benefits of restored oyster reefs and aquaculture to fish and invertebrates in a coastal pond in Rhode Island, US.

Oyster habitat restoration seeks to recover lost ecosystem services including increased provisioning of refuge and foraging habitat for fish and invertebrate communities. The goal of this study was to quantify the ecosystem service benefit of habitat provisioning in Ninigret Pond, RI following oyster restoration. We measured four metrics, abundance, biomass, species richness and diversity, as well as isotopic composition in fish and invertebrates collected seasonally from restored oyster, aquaculture, and bare sediment sites, to examine whether the oyster habitat outperformed the bare sediment habitat. Sampling locations were chosen in Foster's Cove north and south, Grassy Point, South Sanctuary, and an Aquaculture lease; each had two restored oyster sites and one bare sediment site. Each site was sampled using a box trap, seine net, shrimp trap, and minnow trap. Oyster habitats had significantly greater metrics than did bare sediment habitats in some comparisons from the box trap and seine net samples. Restored oyster sites at South Sanctuary had lower metric values than the other oyster sites. Metrics from the Aquaculture sites were comparable to the Foster's Cove and Grassy Point restored oyster sites and often outperformed South Sanctuary restored oyster sites. Seasonally, spring and autumn samples tended to have higher abundance and biomass values than summer. Isotopic composition of five species occurring at both restored oyster and bare sediment sites demonstrated some differences in the trophic levels between species but not between habitat types. In Ninigret Pond, fish and invertebrate abundance, biomass, species richness, and diversity benefit from the use of oyster and bare sediment habitats. Coastal zone managers interested in restoring the ecological function of oyster reefs to support fish and invertebrate communities should consider strategically locating restoration projects within the mosaic of structured habitats and monitoring them for selected ecosystem services.

16S rRNA Amplicon Sequencing of Sediment Bacterial Communities in an Oyster Farm in Rhode Island.

Little is known about the impact of oyster farming on sediment microbial communities. Here, we use 16S rRNA gene sequencing to identify bacterial communities in 24 sediment samples collected from an oyster farm in Ninigret Pond, RI. A total of 13,147 unique operational taxonomic units (OTUs) were assigned, with Proteobacteria being the dominant phyla across all samples.

Assessing the contribution of aquaculture and restoration to wild oyster populations in a Rhode Island coastal lagoon

The decline of the eastern oyster (Crassostrea virginica) has prompted various restoration and aquaculture efforts. Recent field surveys in Rhode Island suggest that wild populations are increasing, yet the factors contributing to expansion are unknown. We used a population genetic approach to characterize genetic differences between wild and cultured oyster populations and explore the extent of connectivity and admixture between groups. Individual oysters from four wild, three farmed, and two restored populations were collected within or just outside Ninigret Pond, a coastal lagoon highly influenced by human activity, and genotyped at 13 microsatellite loci. Results from the multi-locus genotype data showed that wild populations were more genetically diverse than the cultured populations. We also observed significant genetic differentiation between paired wild and cultured populations but not between pairs of wild populations. A cluster analysis detected substantial admixture between wild and cultured groups. As oyster aquaculture and restoration activities are forecasted to increase in the future, this study highlights the potential degree of genetic introgression between remnant wild populations and less diverse, hatchery-reared stocks. Those tasked with preserving our living natural resources should carefully consider how the juxtaposition of aquaculture, restored, and wild populations at small spatial scales will impact the genetic composition and evolutionary trajectories of species in decline for generations to come.

Archaeological Site or Natural Marine Community? Excavation of a Submerged Shell Mound in Ninigret Pond, Rhode Island

ABSTRACTSubmerged shell midden sites and natural shell deposits can have similar characteristics and can be difficult to distinguish archaeologically. We excavated two test units from a large (at least 35 m×70 m) submerged shell mound in Fort Neck Cove in southern Rhode Island to assess whether it was natural or cultural in origin. This mound had been recognized as a potential archaeological feature as early as the 1970s. Excavation, radiocarbon dating, and subsequent laboratory analysis of excavated materials suggest that the mound was a natural oyster reef rather than a submerged archaeological site. No artifacts were found; there was no clear evidence for human modification of any shells; small species that would not have been targeted as food were present; and δ13C values of oyster shells from the mound were consistent with freshwater input into their growth environment, suggesting that they grew in an estuarine environment that did not exist prior to the inundation of the ponds. The stratigraphically oldest radiocarbon date we could obtain (430–190 cal BP, 2σ range), from 70 cm below the pond floor, placed deposition of shells at least 3,000 years after the inundation of the pond. The excavation methods that we used and the process of testing, irrespective of whether the feature is cultural, are valuable contributions to the methodological literature on submerged site archaeology and help provide insight for other researchers working to discern natural from cultural shell midden sites.

An evaluation of the efficacy of radium isotopes as tracers of submarine groundwater discharge to southern Rhode Island's coastal ponds

Submarine groundwater discharge (SGD) represents a significant flux of water and chemical constituents to coastal regions. Because 226Ra and 228Ra are highly concentrated in groundwater relative to surface water, and their signal is well-integrated throughout coastal surface waters, these isotopes have been increasingly utilized to quantify SGD over the past several decades. In this study, a combined radium and salt balance is used to yield estimates of fresh and saline SGD to four of Rhode Island's coastal ponds (Winnapaug, Quonochontaug, Ninigret, and Point Judith Ponds). Fresh SGD rates determined for each pond range between 0 and 17Lm−2d−1. These values largely fall in line with previous estimates made using hydrologic models. The uncertainty of saline SGD estimates for each pond is high; minimum and maximum saline SGD estimates differ by as much as three orders of magnitude. These results echo the discrepancy between two previous radium-based studies from this location. The variability of dissolved radium in the Rhode Island coastal aquifer plays a large role in the uncertainty of these saline SGD estimates. Groundwater dissolved radium activity is dependent upon many different factors, including groundwater salinity and redox conditions, sediment thorium and radium activities, and the amount of time to which the sediment has been exposed to saline groundwater. Due to the heterogeneous nature of glacial outwash sediments, none of these parameters are likely consistent throughout the aquifer in this location. Groundwater 226Ra and 228Ra activities in the coastal ponds vary significantly both laterally and with sediment depth. For example, groundwater samples collected in Ninigret Pond separated by a vertical distance of only 5cm differ by as much as 3×103dpm100L−1 for both 226Ra and 228Ra. The results from this study indicate that a single groundwater sample or suite of samples may not accurately reflect the average radium activity of the groundwater actually discharging into each pond. Targeted sampling in areas where SGD is qualitatively observed can potentially remedy this problem.

Seasonal changes in submarine groundwater discharge to coastal salt ponds estimated using 226Ra and 228Ra as tracers

Submarine groundwater discharge (SGD) to coastal southern Rhode Island was estimated from measurements of the naturally-occurring radioisotopes 226Ra ( t 1/2 = 1600 y) and 228Ra ( t 1/2 = 5.75 y). Surface water and porewater samples were collected quarterly in Winnapaug, Quonochontaug, Ninigret, Green Hill, and Pt. Judith–Potter Ponds, as well as nearly monthly in the surface water of Rhode Island Sound, from January 2002 to August 2003; additional porewater samples were collected in August 2005. Surface water activities ranged from 12–83 dpm 100 L − 1 (60 dpm = 1 Bq) and 21–256 dpm 100 L − 1 for 226Ra and 228Ra, respectively. Porewater 226Ra activities ranged from 16–736 dpm 100 L − 1 (2002–2003) and 95–815 dpm 100 L − 1 (2005), while porewater 228Ra activities ranged from 23–1265 dpm 100 L − 1 . Combining these data with a simple box model provided average 226Ra-based submarine groundwater fluxes ranging from 11–159 L m − 2 d − 1 and average 228Ra-derived fluxes of 15–259 L m − 2 d − 1 . Seasonal changes in Ra-derived SGD were apparent in all ponds as well as between ponds, with SGD values of 30–472 L m − 2 d − 1 (Winnapaug Pond), 6–20 L m − 2 d − 1 (Quonochontaug Pond), 36–273 L m − 2 d − 1 (Ninigret Pond), 29–76 L m − 2 d − 1 (Green Hill Pond), and 19–83 L m − 2 d − 1 (Pt. Judith–Potter Pond). These Ra-derived fluxes are up to two orders of magnitude higher than results predicted by a numerical model of groundwater flow, estimates of aquifer recharge for the study period, and values published in previous Ra-based SGD studies in Rhode Island. This disparity may result from differences in the type of flow (recirculated seawater versus fresh groundwater) determined using each technique, as well as variability in porewater Ra activity.

Landscape-level seagrass–sediment relations in a coastal lagoon

We investigated the relationships between sediment (subaqueous soil) properties and eelgrass ( Zostera marina L.) distribution to develop landscape-level soil-based strategies for choosing eelgrass restoration locations. Subaqueous soils were sampled and eelgrass cover determined for 14 soil-landscape units within a 116 ha area of Ninigret Pond, a coastal lagoon in Rhode Island, USA. Of the 14 soil-landscape units sampled for eelgrass cover, 52% had virtually no eelgrass cover (<10%), while 18% had high eelgrass cover (>90%). The Lagoon Bottom, Shallow Lagoon Bottom, Flood-tidal Delta Slope, and Barrier Cove subaqueous soil-landscape units had the highest eelgrass cover (66–100%). A weak relationship between eelgrass cover and water depths ( r 2 = 0.10) was observed suggesting that properties other than water depth may also control eelgrass distribution. Subaqueous soils on landscapes with >60% eelgrass cover had relatively high levels of acid-volatile sulfides (>90 μg/g), high soil salinity levels (34–44 ppt), fine textures (silt loam), and relatively high total nitrogen levels (>0.15%). Four principal components accounted for 81% of the variability in eelgrass cover. The first component reflected particle-size distribution (i.e. sand, silt, and clay contents) effects and accounted for 43% of the variability. The other components suggested that eelgrass cover is correlated to carbonaceous remains, non-calcareous rock fragments and soil salinity. These data suggest that the current distribution of eelgrass within the study area is strongly influenced by physical and chemical subaqueous soil characteristics. Soil survey techniques proved useful for the delineation of sediment characteristics (e.g. texture, salinity) that influence eelgrass distribution patterns at landscape-level scales.

Nekton habitat quality at shallow water sites in two Rhode Island coastal systems

We evaluated nekton habitat quality at 5 shallow-water sites in 2 Rhode Island systems by comparing nekton densities and biomass, number of species, prey availability and feeding, and abundance of winter flounderPseudopleuronectes americanus. Nekton density and biomass were compared with a 1.75-m2 drop ring at 3 sites (marsh, intertidal, and subtidal) in Coggeshall Cove in Narragansett Bay and two subtidal sites (eelgrass and macroalgae) in Ninigret Pond, a coastal lagoon. We collected benthic core samples and examined nekton stomach contents in Coggeshall Cove. We identified 16 species of fish, 16 species of crabs, and 3 species of shrimp in our drop ring samples. A multivariate analysis of variance indicated differences in total nekton, invertebrates, fish, and winter flounder across the five sites. Relative abundance of benthic invertebrate taxa did not match relative abundance of prey taxa identified in the stomachs. Nonmetric multidimensional scaling plots showed groupings in nekton and benthic invertebrate prey assemblages among subtidal, intertidal, and marsh sites in Coggeshall Cove. Stepwise multiple regression indicated that biomass of macroalgae was the most important variable predicting abundance of nekton in Coggeshall Cove, followed by elevation and depth. In Rhode Island systems that do not experience chronic hypoxia, macroalgae adds structure to unvegetated areas and provides refuge for small nekton. All sites sampled were characterized by high abundance and diversity of nekton pointing to the importance of shallow inshore areas for production of fishes and decapods. Measurements of habitat quality should include assessment of the functional significance of a habitat (this can be done by comparing nekton numbers and biomass), some measure of habitat diversity, and a consideration of how habitat quality varies in time and space.

Using winter flounder growth rates to assess habitat quality in Rhode Island's coastal lagoons

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 201:287-299 (2000) - doi:10.3354/meps201287 Using winter flounder growth rates to assess habitat quality in Rhode Island's coastal lagoons Lesa Meng1,*, Cynthia Gray2, Bryan Taplin1, Erin Kupcha3 1Atlantic Ecology Division, US Environmental Protection Agency, 27 Tarzwell Drive, Narragansett, Rhode Island 02882, USA 2Division of Fish and Wildlife, Rhode Island Department of Environmental Management, 150 Fowler Street, Wickford, Rhode Island 02852, USA 3Roger Williams University, One Old Ferry Road, Bristol, Rhode Island 02809, USA *E-mail: meng.lesa@epamail.epa.gov ABSTRACT: We used growth rates of juvenile winter flounder Pseudopleuronectes americanus, to assess habitat quality in 3 of Rhode Island's coastal salt ponds that had differing levels of nutrients and human development. In each pond, 1 m2 cages were placed in vegetated and unvegetated habitats and growth rates of individually marked fish were measured in three 10 to 15 d experiments from 4 June to 7 July 1997. Water temperature, salinity, dissolved oxygen, and benthic food were also measured. Stable isotopes of C and N were measured in experimental and wild fish. Growth rates were 0.06 to 0.76 mm d-1 and decreased through the experiments. Growth rates of wild fish (0.19 mm d-1 in Point Judith Pond and 0.21 in Ninigret Pond) were similar to the average of the 2nd and 3rd experiments (0.24 mm d-1). Growth rates were the same in vegetated and unvegetated sites. They were also the same in Point Judith and Ninigret ponds but lower in Green Hill Pond. An ANCOVA suggested that Green Hill's lower rates were caused by its higher temperatures, particularly during the 3rd experiment. Benthic food was similar in the different ponds, different habitat types, and in cores taken inside and outside cages. Categories of food consumed by fish were not affected by the presence of vegetation in a cage, although food consumed did differ from pond to pond. Amphipods were the preferred food in all ponds; fish consumed proportionately more amphipods and fewer polychaetes in Ninigret Pond than in the other ponds. Values of δ15N in the fish varied with the degree of development in the watershed but not with total nitrogen in the water column. The results of this study indicate that growth rates of fish can be used as indicators of habitat quality. KEY WORDS: Fish habitat · Habitat quality · Estuaries · Fish growth · Stable isotopes Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 201. Online publication date: August 09, 2000 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2000 Inter-Research.

Tidal Exchange between a Coastal Lagoon and Offshore Waters

A field program was performed to determine the exchange of water between Ninigret Pond and Block Island Sound (BIS) at tidal and subtidal frequencies. Time series on sea level variations in BIS and Ninigret Pond, spatially integrated velocities across the breachway connecting the two (obtained by a GEK) and wind speed and direction were collected from April 21–June 3, 1980. A hybrid hydrodynamic model incorporating a simplified one-dimensional approximation for the breachway channel systems and a two-dimensional vertically-averaged finite element solution on triangular grids for the pond proper was used to model the ponds’ response to ocean forcing. Model predictions were in good agreement with the field data. Both indicated a factor of 5.5 reduction in the semidiurnal tidal amplitude, and a high water shift of 2.5 hr, relative to BIS. Model and field data also show that as the frequency of sea level forcing becomes lower the pond sea level response is in phase and of the same magnitude as that in BIS.

Geology of microtidal coastal lagoons: Rhode Island

The coastal lagoons of Rhode Island are contained behind narrow (200–300 m wide) barrier spits in a microtidal, wave-dominated environment. The major depositional environments within the lagoons are: (1) flood tidal deltas; (2) subtidal storm-surge platforms; and (3) back-lagoon, low-energy basins. The pathways of sediment influx into the coastal lagoons are: (1) tidal inlets (breachways); (2) temporary storm-surge channels cut through the barrier spits; and (3) overwash transport of sand that crosses the spits and builds into the lagoons. Sediment transport in the lagoons is caused by currents generated by windshear within the lagoon basins and by storm-surge generated flow, both of which may be additive to tidal currents. Lagoonal sedimentation was initiated in Ninigret Pond approximately 4100 B.P. (based on radiocarbon dating) as low-energy basins developed on an uneven Pleistocene glaciofluvial surface. Tidal-delta sedimentation began approximately 2500 B.P. The continued existence of the lagoons is dependent on rate of infill and barrier retreat versus rate of sea-level rise. Based on long-term sea-level rise (past 2500 years), calculations indicate that the lagoons will decrease in size as sediment influx exceeds the rate of inundation.

Predation, attack success, and attraction to the bay scallop, Argopecten irradians (Lamarck) by the oyster drill, Urosalpinx cinerea (Say)

Investigation of the intensity of predation by the oyster drill, Urosalpinx cinerea (Say), on the bay scallop, Argopecten irradians (Lamarck), was carried out in field and laboratory studies. Field measurements of densities of the oyster drill and the bay scallop were respectively, 3.6 · m −2, and 21.1 · m −2 on a scallop bed in Ninigret Pond, Charlestown, Rhode Island. The mean density of snails attacking scallops was 1.7 · m −2. In a laboratory study of attack success, an average of 72.3% of drill attacks led to death of the scallop. Snails were also shown to be strongly attracted to scallop effluent in a choice chamber.