Narragansett Bay National Estuarine Research Reserve

Staten Island, RI, United States

Narragansett Bay National Estuarine Research Reserve

Staten Island, RI, United States
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Cole Ekberg M.L.,Save The Bay | Cole Ekberg M.L.,Diablo Valley College | Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Ferguson W.S.,Save The Bay | And 3 more authors.
Estuaries and Coasts | Year: 2017

Wetlands are commonly assessed for ecological condition and biological integrity using a three-tiered framework of landscape-scale assessment, rapid assessment protocols, and intensive biological and physiochemical measurements. However, increased inundation resulting from accelerated sea level rise (SLR) is negatively impacting tidal marsh ecosystem functions for US Northeast coastal wetlands, yet relative vulnerability to this stressor is not incorporated in condition assessments. This article assesses tools available to measure coastal wetland vulnerability to SLR, including measurements made as part of traditional rapid condition assessments (e.g., vegetation communities, soil strength), field and remote sensing-based measurements of elevation, VDatum, and Sea Level Affecting Marshes Model (SLAMM) model outputs. A vulnerability metric that incorporates these tools was calibrated and validated using recent rates of marsh vegetation losses (1972–2011) as a surrogate for future vulnerability. The metric includes complementary measures of elevation capital, including the percentage of high vs. low marsh vegetation, Spartina alterniflora height, elevation measurements, and SLAMM outputs that collectively explained 62% of the variability in recent rates of marsh vegetation loss. Stepwise regression revealed that all three elements (elevation, vegetation measures, and SLAMM outputs) explained significant and largely unique components of vulnerability to SLR, with the greatest level of overlap found between SLAMM outputs and elevation metrics. While soil strength varied predictably with habitat zone, it did not contribute significantly to the vulnerability metric. Despite the importance of determining wetland elevation above key tidal datums of mean sea level and mean high water, we caution that VDatum was found to perform poorly in back-barrier estuaries. This factor makes it difficult to compare elevation capital among marshes that differ in tidal range and poses accuracy problems for broad-scale modeling efforts that require accurate tidal datums. Given the pervasive pattern of coastal wetland drowning occurring in the Northeastern USA and elsewhere, we advocate that compilation of regional data on marsh habitats and vulnerability to SLR is crucial as it permits agencies to target adaptation to sites based on their vulnerability or mixture of habitats, it helps match sites to appropriate interventions, and it provides a broader regional context to site-specific management actions. Without such data, adaptation actions may be implemented where action is not necessary and to the disadvantage of vulnerable sites where opportunities for successful adaptation will be missed. © 2017, Coastal and Estuarine Research Federation.

Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Raposa K.B.,Elkhorn Slough National Estuarine Research Reserve | Raposa K.B.,North Inlet Winyah Bay National Estuarine Research Reserve | Raposa K.B.,Tijuana River National Estuarine Research Reserve | And 11 more authors.
Biological Conservation | Year: 2016

Tidal marshes and the ecosystem services they provide may be at risk from sea-level rise (SLR). Tidal marsh resilience to SLR can vary due to differences in local rates of SLR, geomorphology, sediment availability and other factors. Understanding differences in resilience is critical to inform coastal management and policy, but comparing resilience across marshes is hindered by a lack of simple, effective analysis tools. Quantitative, multi-metric indices are widely employed to inform management of benthic aquatic ecosystems, but not coastal wetlands. Here, we develop and apply tidal marsh resilience to sea-level rise (MARS) indices incorporating ten metrics that contribute to overall marsh resilience to SLR. We applied MARS indices to tidal marshes at 16 National Estuarine Research Reserves across the conterminous U.S. This assessment revealed moderate resilience overall, although nearly all marshes had some indication of risk. Pacific marshes were generally more resilient to SLR than Atlantic ones, with the least resilient marshes found in southern New England. We provide a calculation tool to facilitate application of the MARS indices to additional marshes. MARS index scores can inform the choice of the most appropriate coastal management strategy for a marsh: moderate scores call for actions to enhance resilience while low scores suggest investment may be better directed to adaptation strategies such as creating opportunities for marsh migration rather than attempting to save existing marshes. The MARS indices thus provide a powerful new approach to evaluate tidal marsh resilience and to inform development of adaptation strategies in the face of SLR. © 2016 The Authors

Watson E.B.,Drexel University | Szura K.,U.S. Environmental Protection Agency | Wigand C.,U.S. Environmental Protection Agency | Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | And 2 more authors.
Biological Conservation | Year: 2016

Already heavily impacted by coastal development, estuarine vegetated habitats (seagrasses, salt marshes, and mangroves) are increasingly affected by climate change via accelerated sea level rise, changes in the frequency and intensity of precipitation and storms, and warmer ocean temperatures. Conservation of these sensitive and vulnerable habitats requires the recognition of climate change effects so environmental managers can develop and apply appropriate intervention and adaptation strategies where possible. Here we focus on Spartina patens (saltmeadow cordgrass), a foundation species of New England (USA) coastal marshes. A growing body of evidence suggests this species is disappearing rapidly from wetlands in the region, leading to reductions in habitat quality, plant diversity, carbon sequestration, erosion resistance and coastal protection. We grew S. patens under five inundation and three precipitation regimes, monitored changes in its extent within two Southern New England coastal marshes (2000-2014), and used water level and precipitation data to detect changes in environmental conditions affecting these marshes. Our results suggest that current inundation patterns have reduced the persistence of S. patens, while short-term drought did not appear responsible for vegetation changes or habitat conversion. We conclude that accelerated sea level rise is incompatible with the long-term survival of S. patens within the current landscape footprint of Southern New England's coastal wetlands. We suggest that conservation actions focused on high marsh preservation concentrate on facilitating the process of marsh migration onto uplands by prioritizing buffer conservation, conducting barrier removal and allowing for retreat where feasible. © 2016 Elsevier Ltd.

Carey J.C.,The Ecosystems Center | Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Wigand C.,U.S. Environmental Protection Agency | Warren R.S.,Connecticut College
Estuaries and Coasts | Year: 2015

Northeastern US salt marshes face multiple co-stressors, including accelerating rates of relative sea level rise (RSLR), elevated nutrient inputs, and low sediment supplies. In order to evaluate how marsh surface elevations respond to such factors, we used surface elevation tables (SETs) and surface elevation pins to measure changes in marsh surface elevation in two eastern Long Island Sound salt marshes, Barn Island and Mamacoke marshes. We compare marsh elevation change at these two systems with recent rates of RSLR and find evidence of differences between the two sites; Barn Island is maintaining its historic rate of elevation gain (2.3 ± 0.24 mm year−1 from 2003 to 2013) and is no longer keeping pace with RSLR, while Mamacoke shows evidence of a recent increase in rates (4.2 ± 0.52 mm year−1 from 1994 to 2014) to maintain its elevation relative to sea level. In addition to data on short-term elevation responses at these marshes, both sites have unusually long and detailed data on historic vegetation species composition extending back more than half a century. Over this study period, vegetation patterns track elevation change relative to sea levels, with the Barn Island plant community shifting towards those plants that are found at lower elevations and the Mamacoke vegetation patterns showing little change in plant composition. We hypothesize that the apparent contrasting trend in marsh elevation at the sites is due to differences in sediment availability, salinity, and elevation capital. Together, these two systems provide critical insight into the relationships between marsh elevation, high marsh plant community, and changing hydroperiods. Our results highlight that not all marshes in Southern New England may be responding to accelerated rates of RSLR in the same manner. © 2015 Coastal and Estuarine Research Federation

McKinney R.A.,U.S. Environmental Protection Agency | Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Cournoyer R.M.,University of Connecticut
Landscape and Urban Planning | Year: 2011

Wetlands in urban landscapes provide nesting opportunities for wetland breeding birds as well as enhanced food resources that may be utilized by opportunistic species and those that can tolerate human activity. We investigated the degree to which birds utilize urban wetlands by examining breeding bird communities in urban and rural wetlands and nearby uplands in the northeast US. From mid-May through June in 2008, we conducted 10-min, 50. m radius point counts at 99 randomly chosen sites along a gradient of watershed urbanization. Bird abundance and species richness was significantly higher in wetlands versus uplands, and at urban wetlands versus urban uplands, but not at rural wetlands versus rural uplands. Overall, more species were present at wetland versus upland sites, but the difference between wetland and upland was less for human-tolerant species. While the amount of natural vegetation within a 50. m buffer of a site was significantly negatively correlated with the amount of urban land within 1. km, bird abundance and species richness increased. Species-specific habitat models using general vegetation classes showed differences in bird habitat associations as watersheds became more urbanized. Our findings demonstrate the importance of wetland habitats for birds, and add to the body of evidence that supports the protection and restoration of wetlands as a means towards maintaining or enhancing habitat heterogeneity and biodiversity in urban landscapes. © 2010.

Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Cole Ekberg M.L.,Save The Bay | Burdick D.M.,University of New Hampshire | Ernst N.T.,Rhode Island National Wildlife Refuge Complex | Adamowicz S.C.,Rachel Carson National Wildlife Refuge
Regional Environmental Change | Year: 2016

Salt marshes persist within the intertidal zone when marsh elevation gains are commensurate with rates of sea-level rise (SLR). Monitoring changes in marsh elevation in concert with tidal water levels is therefore an effective way to determine if salt marshes are keeping pace with SLR over time. Surface elevation tables (SETs) are a common method for collecting precise data on marsh elevation change. Southern New England is a hot spot for SLR, but few SET elevation change datasets are available for the region. Our study synthesizes elevation change data collected from 1999 to 2015 from a network of SET stations throughout Rhode Island (RI). These data are compared to accretion and water level data from the same time period to estimate shallow subsidence and determine whether marshes are tracking SLR. Salt marsh elevation increased at a mean overall rate of 1.40 mm year−1 and ranged from −0.33 to 3.36 mm year−1 at individual stations. Shallow subsidence dampened elevation gain in mid-Narragansett Bay marshes, but in other areas of coastal RI, subsurface processes may augment surface accretion. In all cases, marsh elevation gain was exceeded by the 5.26 mm year−1 rate of increase in sea levels during the study period. Our study provides the first SET elevation change data from RI and shows that most RI marshes are not keeping pace with short- or long-term rates of SLR. It also lends support to previous research that implicates SLR as a primary driver of recent changes to southern New England salt marshes. © 2016 Springer-Verlag Berlin Heidelberg

Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Weber R.L.J.,Narragansett Bay National Estuarine Research Reserve | Ekberg M.C.,Save The Bay | Ferguson W.,Save The Bay
Estuaries and Coasts | Year: 2015

Sea level rise is a major stressor on many salt marshes, and its impacts include creek widening, ponding, vegetation dieback, and drowning. Marsh vegetation changes have been associated with sea level rise across southern New England, but most of these studies pre-date the current period of rapidly accelerating sea level rise coupled with episodic events of extreme increases in water levels. Here, we combine data from two salt marsh monitoring and assessment programs in Rhode Island that were designed to assess marsh responses to sea level rise and use these data to document temporal and spatial patterns in marsh vegetation during the current period of extreme water level increases. Vegetation monitoring at two Narragansett Bay salt marshes confirms the ongoing decline of the salt meadow species Spartina patens during this period as it becomes replaced by Spartina alterniflora. Bare ground resulting from vegetation dieback was significantly related to mean high water levels and led to the rapid conversion of mixed Spartina assemblages to S. alterniflora monocultures. A broader spatial assessment of RI marshes shows that S. alterniflora dominance increases at lower elevation marshes toward the mouth of Narraganset Bay. Our data provide additional evidence that S. patens continues to decline in southern New England marshes and show that losses can accelerate during periods of extreme high water levels. Unless adaptive management actions are taken, we predict that marshes throughout RI will continue to lose salt meadow habitat and eventually resemble lower elevation marshes that are already dominated by S. alterniflora monocultures. © 2015 Coastal and Estuarine Research Federation

McKinney R.A.,U.S. Environmental Protection Agency | Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Trocki C.L.,University of Rhode Island
Northeastern Naturalist | Year: 2015

Surveys of wintering waterfowl can aid in both identifying estuarine habitats currently being used by species of conservation concern so that the sites can be targeted for protection and restoration, and in providing a baseline assessment from which the effects of future changes in wintering habitat can be assessed. In an effort to better understand the local distribution of wintering waterfowl during the period 2005-2014, we undertook a study of waterfowl abundance and distribution in Narragansett Bay, RI, a moderate-sized estuary located in the northeastern US within the Atlantic Flyway. Overall waterfowl abundance in the Bay ranged from 15,002 individuals in 2006 to 26,163 individuals in 2010 and averaged 20,062 ± 3393 individuals over the 10-y period. Species richness ranged from 1.80 to 10.8 per site; most of the sites with high species richness were located in the Upper Bay. Based on our counts from 67 ground locations, the Narragansett Bay waterfowl community was dominated by Aythya affinis (Lesser Scaup) and A. marila (Greater Scaup), Branta bernicla (Brant), and Branta canadensis (Canada Geese) over the survey period. Waterfowl-community composition indicated that the Upper Bay, an environment characterized by low wave-energy, shallow coves, sheltered embayments, and salt marshes, supported mostly dabbling ducks, geese, and swans. The Lower Bay, an environment characterized by higher wave-energy, rocky shorelines, and deeper open-water habitats, supported mostly sea ducks and other diving-duck species. Abundance over the survey period was relatively stable, and observed patterns of waterfowl distribution suggest that conservation actions to maintain shallow-water habitats, including efforts to protect and restore salt marsh habitat, will help to maintain resources needed by many of the waterfowl species wintering in the Bay.

McKinney R.A.,Public Health England | Raposa K.B.,Narragansett Bay National Estuarine Research Reserve
Urban Ecosystems | Year: 2013

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. © 2012 Springer Science+Business Media New York (outside the USA).

McKinney R.A.,U.S. Environmental Protection Agency | Raposa K.B.,Narragansett Bay National Estuarine Research Reserve | Kutcher T.E.,101 Coastal Institute Kingston
Urban Ecosystems | Year: 2010

Wading birds (i.e, Ardeidae: herons, egrets, and bitterns) are a guild of waterbirds that forage in coastal habitats which in the US and Europe are often located in close proximity to urban centers. However, the use of urban marine habitats may have consequences for bird populations, as birds can be subject to stress from increased levels of passive and active human disturbance. We examined the effects of human disturbance, available foraging habitat, and prey abundance on wading bird density and species richness at 17 urban coastal sites in Narragansett Bay, Rhode Island USA. The sites represented a gradient of immediately adjacent residential and commercial land use (e.g., 0.0-67.7% urban land use within a 30.5 m buffer of the sites) within an urban matrix (i.e., all sites were located within a suburban center with a population of about 85,000 people). Wading bird density (0.62 ± 0.12 birds ha-1) and species richness (average 4.49 ± 0.37 species across all sites) were not influenced by passive human disturbance as measured by the extent of urban land surrounding a site. However, wading bird density and species richness both decreased significantly as active disturbance (i.e., number of boats moored or docked upstream of the site) increased (r = -0.56, F = 6.85, p = 0.019 and r = -0.73, F = 16.6, p = 0.001, respectively). In addition, both density (r = 0.72, F = 16.2, p = 0.001) and species richness (r = 0.72, F = 16.2, p = 0.001) increased concomitantly with a prey index that combines the density of fish and invertebrates on which the birds feed with the amount of available shallow water foraging habitat at a site. Our results suggest that wading birds i) may not be negatively affected by urban land surrounding estuarine foraging areas in and of itself; and ii) may be utilizing urban areas in the absence of high levels of active disturbance to take advantage of potentially enhanced prey resources. In the case where the benefits of foraging at a site outweigh the costs related to human disturbance, urban marine habitats may need to be considered for restoration or protection from further increases in active human disturbance. © 2009 US Government.

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