Jamaica Bay Research Articles

Decoupled shifts of dominant and rarer fish species as a response to warming and extreme events in a large estuary

AbstractDisentangling community responses to multiple stressors in a warming context is one of the most challenging tasks ecologists face. Taking advantage of a long‐term (1989–2017) and intensive fish monitoring survey (N = ~900K from 804 seines‐day), we present a comprehensive analysis on the dynamics of coastal fish communities in Jamaica Bay, New York, by addressing multiple dimensions of community change that although closely related are rarely considered in a single work. Specifically, we tested hypotheses about changes in composition, composition variability and community functional attributes, and the role of environmental drivers acting at different temporal scales. Our analyses suggest two decoupled community dynamics triggered by two different extreme events. First, the 1999 Atlantic Multidecadal Oscillation phase switch caused an abrupt shift from a single‐species dominance to intermittent co‐dominance, with species preferring higher temperatures, a shift that has persisted in time but that may be cyclical at a multidecadal scale. Second, the 2012 heat wave promoted an abrupt collapse of rare and cold‐water species, and the sudden arrival of warmer‐water species in a portion of the community that was already increasingly variable due to long‐term warming. Functionally, the entire community subtly shifted toward species with faster turnover and lower trophic levels. Our work sheds light on the complex responses of biological communities to warming in terms of the impacts on composition, its temporal variability, and its functional dimension, by disentangling the interplay of long‐term environmental trends such as warming, multidecadal cycles, and extreme events on different portions (i.e., dominant and rare thermal species) of the community.

Circulation Dynamics and Dilution in Shallow Estuaries Case Study (1): Dilution Factor Calculations

The ambient conditions of receiving waters such as currents and density stratification influence the dilution of treated wastewater discharged by WWTPs. Hendrix Creek, a semi-enclosed tidal tributary of Jamaica Bay that serves as receiving water of the 26th Ward WRRF, is not well studied. A near-field dilution model was developed and applied to the plant outfall to simulate plume transport and dilution in the initial mixing zone. The long-term ambient field conditions were characterized, and the dilution factor of a tracer was measured to calibrate the model. This was phase one of an integrated dilution and mixing study aimed at understanding the circulation dynamics which contribute to dilution in the creek. Field measurements during the dye release period also aided in the calibration and development of a 3D hydrodynamic model used to accomplish far-field dilution and mixing in phase two of this study. The near-field model results have good agreement with dye survey data and acoustic doppler current profiler (ADCP) measurements in the creek. Under critical conditions, the model predicts a dilution factor of less than 2 in the initial mixing zone, indicating poor dilution. Saline water from Jamaica Bay which served to dilute the treated wastewater appears to be dominated by the high plant discharge resulting in limited dilution in the near-field region of the creek.

Denitrification Potential of Surface Soils of Constructed Wetlands in Newtown Creek, an Urban Superfund Site.

Denitrification, the anaerobic microbial conversion of nitrate (NO3 - ), a common water pollutant, to nitrogen (N) gases, is often high in the soil of natural wetlands. In areas where natural wetlands have been degraded or destroyed, constructed and restored wetlands have been used to restore ecosystem services like denitrification. Thus, denitrification in restored and constructed wetlands could play an important role in treating anthropogenic N sources such as combined sewer overflow (CSO) discharges which can be high in NO3 - . In this study, we measured denitrification potential using an anaerobic slurry assay and made a suite of ancillary measurements (soil moisture content, microbial biomass carbon (C) and N content, potential net N mineralization and nitrification, soil inorganic N pools and soil respiration) in four constructed salt marsh wetlands, and a series of wetland habitat basins in Newtown Creek, NY, an urban superfund site. Samples were also taken from natural salt marshes located at Paerdegat Basin, Jamaica Bay, NY. Our results show that constructed Spartina alterniflora marshes in ultra-urban Newtown Creek support denitrification potential equivalent to rates of natural marshes in Jamaica Bay and reference marshes in other urban estuaries. There were significant positive correlations between microbial biomass C and N content and organic matter content and denitrification potential. Results suggest that constructed wetlandscan support wetland vegetation, soils, and microbial life and contribute to N removal under ultra-urban conditions. This article is protected by copyright. All rights reserved.

Estuarine Sediment Microbiomes from a Chronosequence of Restored Urban Salt Marshes.

Salt marshes play an important role in the global nutrient cycle. The sediments in these systems harbor diverse and complex bacterial communities possessing metabolic capacities that provide ecosystem services such as nutrient cycling and removal. On the East Coast of the USA, salt marshes have been experiencing degradation due to anthropogenic stressors. Salt marsh islands within Jamaica Bay, New York City (USA), are surrounded by a large highly urbanized watershed and have declined in area. Restoration efforts have been enacted to reduce further loss, but little is known about how microbial communities develop following restoration activities, or how processes such as nitrogen cycling are impacted. Sediment samples were collected at two sampling depths from five salt marsh islands to characterize the bacterial communities found in marsh sediment including a post-restoration chronosequence of 3-12 years. We used 16s rRNA amplicon sequencing to define alpha and beta diversity, taxonomic composition, and predicted metabolic profile of each sediment sample. We found significant differences in alpha diversity between sampling depths, and significant differences in beta diversity, taxonomic composition, and predicted metabolic capacity among the five sampling locations. The youngest restored site and the degraded natural sampling site exhibited the most distinct communities among the five sites. Our findings suggest that while the salt marsh islands are located in close proximity to each other, they harbor distinct bacterial communities that can be correlated with post-restoration age, marsh health, and other environmental factors such as availability of organic carbon. IMPORTANCE: Salt marshes play a critical role in the global nutrient cycle due to sediment bacteria and their metabolic capacities. Many East Coast salt marshes have experienced significant degradation over recent decades, thought largely to be due to anthropogenic stressors such as nitrogen loading, urban development, and sea-level rise. Salt marsh islands in Jamaica Bay (Queens/Brooklyn NY) are exposed to high water column nitrogen due to wastewater effluent. Several receding marsh islands have been subjected to restoration efforts to mitigate this loss. Little is known about the effect marsh restoration has on bacterial communities, their metabolic capacity, or how they develop post-restoration. Here, we describe the bacterial communities found in marsh islands including a post-restoration chronosequence of 3-12 years and one degraded marsh island that remains unrestored. We found distinct communities at marsh sites, despite their geographic proximity. Differences in diversity and community composition were consistent with changes in organic carbon availability that occur during marsh development, and may result in differences in ecosystem function among sites.

Effect of Estuary Urbanization on Tidal Dynamics and High Tide Flooding in a Coastal Lagoon

AbstractHigh tide floods (HTFs) are minor, shallow flooding events whose frequency has increased due to relative sea‐level rise (SLR) and secular changes in tides. Here we isolate and examine the role of historical landscape change (geomorphology, land cover) and SLR on tides and HTF frequency in an urbanized lagoonal estuary: Jamaica Bay, New York. The approach involves data archeology, historical (1870s) map digitization, as well as numerical modeling of the bay. Numerical simulations indicate that a century of landscape alterations (e.g., inlet deepening and widening, channel deepening, and wetland reclamation) increased the mean tidal range at the head of the bay by about 20%. The observed historical shift from the attenuation to amplification of semidiurnal tides is primarily associated with reduced tidal damping at the inlet and increased tidal reflection. The 18% decrease in surface area exerts a minor influence. A 1‐year (2020) water level simulation is used to evaluate the effects of both SLR and altered morphology on the annual number of HTFs. Results show that of 15 “minor flood” events in 2020, only one would have occurred without SLR and two without landscape changes since the 1870s. Spectral and transfer function analyses of water level reveal frequency‐dependent fingerprints of landscape change, with a significant decrease in damping for high‐frequency surges and tides (6–18 hr time scale). By contrast, SLR produced only minor effects on frequency‐dependent amplification. Nonetheless, the geomorphic influence on the dynamical response significantly increases the vulnerability of the system to SLR, particularly high‐tide flooding.

Modeling present and future ecosystem services and environmental justice within an urban-coastal watershed

Globally, urban-coastal areas are expected to experience substantial landscape shifts as a result of climate change induced sea level rise. Such changes will impact valuable ecosystem services. We employed sea level rise projections and land cover change mapping to develop a model which quantified present-day carbon sequestration, aboveground carbon storage, and belowground carbon storage ecosystem services and predicted the impact of sea level rise and accretion through 2100 on future ecosystem services in the urban-coastal Jamaica Bay, New York (USA) watershed. Our model predicted that future carbon sequestration, aboveground carbon storage, and belowground carbon storage potential in our watershed will be significantly impacted in wetlands and natural coastal-fringe habitat and have losses up to 0.16%, 15%, and 51%, respectively. We paired our present-day ecosystem services model results with data on socio-economic need (access to open space and poverty level of each census tract in the watershed) and used multivariate clustering analysis to identify clusters in which planning and restoration may help to address issues of ecological conservation and environmental justice. Our work addresses the need for better understanding of urban-coastal ecosystem service flows and the potential impact of future landscape change on these services. Our results provide support to increase coastal resilience through informed design, planning, and management of these ecologically and socially significant landscapes.

Microplastic transfer from the American horseshoe crab to shorebirds through consumption of horseshoe crab eggs in Jamaica Bay, NY.

Microplastic transfer between horseshoe crabs (Limulus polyphemus) and migratory shorebirds through consumption of crab eggs was examined in Jamaica Bay, New York. Fertilized and unfertilized crab eggs, shorebird fecal pellets, beach sand, and bay water were processed with a hydrogen peroxide solution to remove organic material, then stained with a Nile Red to identify microplastics using fluorescence microscopy. Microplastics were present in all samples and ranged from approximately26-1300μm. Unfertilized and fertilized eggs contained significantly higher numbers of microplastic particles per gram than shorebird fecal pellets, beach sand, and bay water. The presence of microplastics in unfertilized egg samples indicates that microplastics undergo maternal transfer during oogenesis. We estimated that 1g of horseshoe crab eggs could contain approximately 426 to 840 microplastic particles, suggesting that shorebirds feeding on this resource could be ingesting a substantial burden of microplastics during their migratory stopover, much of which appears to be retained by shorebirds, rather than being eliminated in their fecal pellets.

Survival rates of two nesting aggregations of diamondback terrapins at neighboring sites in New York City

AbstractThe diamondback terrapin (Malaclemys terrapin) is a charismatic and long‐lived species of the United States eastern coast, and the only North American turtle that exclusively inhabits coastal brackish waters. Many terrapin populations are declining, and these declines have been largely linked to human activities; however, few studies have documented human and natural factors affecting terrapin population demography. Jamaica Bay, an urban estuary located in southern New York City, USA, is home to 2 nesting aggregations of terrapins, located at Ruler's Bar Hassock (RBH) and John F. Kennedy Airport (JFK). We analyzed mark‐recapture data for RBH from 2003–2018 and JFK from 2011–2018 to estimate annual survivorship of female diamondback terrapins and test the effects of 3 factors (a hurricane, water quality represented by nitrogen concentration, and injuries) on survival. The initial estimated annual survival was high (0.93) at RBH but declined to 0.89, while survival remained constant at JFK (0.92). Models examining the effect of Hurricane Sandy (2012) indicated a significant decline in survival in the 2 years following the hurricane in the RBH nesting aggregation but no change at JFK. Water quality did not influence trends in either aggregation, but the presence of major injuries (caused by boat collisions, predators, and the hurricane) significantly reduced annual survival at RBH. We propose increasing terrapin survivorship through mitigation of boat traffic, reducing populations of northern raccoons (Procyon lotor) to reduce injury to female terrapins and decrease egg and hatchling mortality, and increased law enforcement to reduce on‐going poaching and capture as illegal by‐catch.

An agent-based model for evaluating reforms of the National Flood Insurance Program: A benchmarked model applied to Jamaica Bay, NYC.

Coastal flood risk is expected to increase as a result of climate change effects, such as sea level rise, and socioeconomic growth. To support policymakers in making adaptation decisions, accurate flood risk assessments that account for the influence of complex adaptation processes on the developments of risks are essential. In this study, we integrate the dynamic adaptive behavior of homeowners within a flood risk modeling framework. Focusing on building-level adaptation and flood insurance, the agent-based model (DYNAMO) is benchmarked with empirical data for New York City, USA. The model simulates the National Flood Insurance Program (NFIP) and frequently proposed reforms to evaluate their effectiveness. The model is applied to a case study of Jamaica Bay, NY. Our results indicate that risk-based premiums can improve insurance penetration rates and the affordability of insurance compared to the baseline NFIP market structure. While a premium discount for disaster risk reduction incentivizes more homeowners to invest in dry-floodproofing measures, it does not significantly improve affordability. A low interest rate loan for financing risk-mitigation investments improves the uptake and affordability of dry-floodproofing measures. The benchmark and sensitivity analyses demonstrate how the behavioral component of our model matches empirical data and provides insights into the underlying theories and choices that autonomous agents make.

Using object-based image analysis to detect laughing gull nests

ABSTRACT Remote sensing has long been used to study wildlife; however, manual methods of detecting wildlife in aerial imagery are often time-consuming and prone to human error, and newer computer vision techniques have not yet been extensively applied to wildlife surveys. We used the object-based image analysis (OBIA) software eCognition to detect laughing gull (Leucophaeus atricilla) nests in Jamaica Bay as part of an ongoing monitoring effort at the John F. Kennedy International Airport. Our technique uses a combination of high resolution 4-band aerial imagery captured via manned aircraft with a multispectral UltraCam Falcon M2 camera, LiDAR point cloud data, and land cover data derived from a bathymetric LiDAR point cloud to classify and extract laughing gull nests. Our ruleset uses the site (topographic position of nest objects), tone (spectral characteristic of nest objects), shape, size, and association (nearby objects commonly found with the objects of interest that help identify them) elements of image interpretation, as well as NDVI and a sublevel object examination to classify and extract nests. The ruleset achieves a producer’s accuracy of 98% as well as a user’s accuracy of 65% and a kappa of 0.696, indicating that it extracts a majority of the nests in the imagery while reducing errors of commission to only 35% of the final results. The remaining errors of commission are difficult for the software to differentiate without also impacting the number of nests successfully extracted and are best addressed by a manual verification of output results as part of a semi-automated workflow in which the OBIA is used to complete the initial search of the imagery and the results are then systematically verified by the user to remove errors. This eliminates the need to manually search entire sets of imagery for nests, resulting in a much more efficient and less error prone methodology than previous unassisted image interpretation techniques. Because of the extensibility of OBIA software and the increasing availability of imagery due to small unmanned aircraft systems (sUAS), our methodology and its benefits have great potential for adaptation to other species surveyed using aerial imagery to enhance wildlife population monitoring.

Importance of quantifying the full-depth carbon reservoir of Jamaica Bay salt Marshes, New York

Constraining uncertainty in the global carbon cycle requires valid assessment of both surface and stored carbon in marine and coastal ecosystems (Blue Carbon) as well as terrestrial carbon (forests, peatlands, and soils) [Pendleton et al., 2012]. Quantifying the global carbon stock of coastal salt marshes, potentially the most efficient carbon-burying ecosystems in the world per area, is a key area of further research in both of these fields Pendleton et al., 2012. One of the largest challenges is that despite the fact that salt marshes often sequester carbon several meters deep, nearly all estimates of salt marsh carbon stocks consider only the upper 1 m of sediment (Windham-Myers et al., 2015) [54]. This is particularly concerning because coastal wetlands are increasingly at risk due to climate change, sea level rise, and anthropogenic disturbance and destruction (Deegan et al., 2012) [15]. Using full-depth measurements from marsh cores, we estimate the carbon stock of five salt marshes in the highly urbanized estuary of Jamaica Bay, New York and argue that partial-depth measurements can underestimate carbon stocks. These estimates use calculated carbon content and probe depth data of these marshes collected between 2000 and 2019, applying this data across the full area of the marsh obtained from satellite imagery. Carbon density measurements are then multiplied by the full-depth volume of the marshes to create an estimate of total carbon stock. In addition to calculating present-day estimates, we compare our carbon stock estimates to historical Jamaica Bay imagery to calculate historical carbon stocks and carbon loss. The carbon stock estimates presented here show a 95% carbon stock loss between 1885 and 2019 in Jamaica Bay and highlight the severe underestimation of carbon stocks without full-depth calculations. These findings have important implications for disappearing salt marshes with regard to the global carbon cycle and the incorporation of belowground carbon into global climate models. The findings are increasingly relevant for advocacy efforts aiming to conserve these marshes with sea level rise.

The role of algal blooms and community respiration in controlling the temporal and spatial dynamics of hypoxia and acidification in eutrophic estuaries

While hypoxia and acidification can be common occurrences in eutrophic coastal zones, the precise, coupled temporal and spatial dynamics of these conditions are poorly described. Here, continuous measurements of water column pH, pCO2, carbonate chemistry, and dissolved oxygen (DO) concentrations were made from spring through fall across two, temperate eutrophic estuaries, western Long Island Sound (LIS) and Jamaica Bay, NY, USA. Vertical dynamics were resolved using an underway towing profiler and an automated stationary profiling unit. During the study, high rates of respiration in surface and bottom waters (> -0.2 mg O2 L-1 h-1) yielded strongly negative rates of net ecosystem metabolism during the summer (-4 to -8 g O2 m-2 d-1). Ephemeral surface algal blooms caused brief periods (< one week) of basification and supersaturation of DO that were succeeded by longer periods of acidification and hypoxia. In deeper regions, hypoxia (< 2 mg L-1 DO) and acidic water (pH < 7; total scale; pCO2 levels >2000 μatm) that persisted continuously for >40 days in both estuaries was often overlain by water with higher DO and pH. Diurnal vertical profiles demonstrated that oxic surface waters saturated with respect to calcium carbonate and DO during the day transitioned to unsaturated and hypoxic at night. Evidence is presented that, beyond respiration, nitrification in surface water promoted by sewage discharge and oxidation processes in sediments also contribute to acidification in these estuaries. Collectively, this study demonstrates the pervasive, persistent, and dynamic nature of hypoxia and acidification in eutrophic estuaries are likely to shape marine food webs.

Designing (for) Urban Food Webs

Interest is growing in designing resilient and ecologically rich urban environments that provide social and ecological benefits. Regenerative and biocentric designs fostering urban ecological habitats including food webs that provide ecosystem services for people and wildlife increasingly are being sought. However, the intentional design of urban landscapes for food webs remains in an early stage with few precedents and many challenges. In this paper, we explore the potential to design (for) urban food webs through collaborations between designers and ecologists. We start by examining the ecology and management of Jamaica Bay in New York City as a case study of an anthropogenic landscape where ecosystems are degraded and the integrity of extant food webs are intertwined with human agency. A subsequent design competition focusing on ecological design and management of this large-scale landscape for animal habitat and ecosystem services for people illustrates how designers approach this anthropogenic landscape. This case study reveals that both designing urban landscapes for food webs and directly designing and manipulating urban food webs are complicated and challenging to achieve and maintain, but they have the potential to increase ecological health of, and enhance ecosystem services in, urban environments. We identify opportunities to capitalize on species interactions across trophic structures and to introduce managed niches in biologically engineered urban systems. The design competition reveals an opportunity to approach urban landscapes and ecological systems creatively through a proactive design process that includes a carefully crafted collaborative approach to constructing ecologically functioning landscapes that can integrate societal demands. As designers increasingly seek to build, adapt, and manage urban environments effectively, it will be critical to resolve the contradictions and challenges associated with human needs, ecosystem dynamics, and interacting assemblages of species. Ecologists and designers are still discovering and experimenting with designing (for) urban food webs and fostering species interactions within them. We recommend generating prototypes of urban food webs through a learning-by-doing approach in urban development projects. Design and implementation of urban food webs also can lead to research opportunities involving monitoring and experiments that identify and solve challenges of food-web construction while supporting and encouraging ongoing management.

Small-Scale Geochemical Heterogeneities and Seasonal Variation of Iron and Sulfide in Salt Marshes Revealed by Two-Dimensional Sensors

Loss of tidal wetlands is a world-wide phenomenon. Many factors may contribute to such loss, but among them are geochemical stressors such as exposure of the marsh plants to elevated levels on hydrogen sulfide in the pore water of the marsh peat. Here we report the results of a study of the geochemistry of iron and sulfide at different seasons in unrestored (JoCo) and partially restored (Big Egg) salt marshes in Jamaica Bay, a highly urbanized estuary in New York City where the loss of salt marsh area has accelerated in recent years. The spatial and temporal 2-dimensional distribution patterns of dissolved Fe2+ and H2S in salt marshes were in situ mapped with high resolution planar sensors for the first time. The vertical profiles of Fe2+ and hydrogen sulfide, as well as related solutes and redox potentials in marsh were also evaluated by sampling the pore water at discrete depths. Sediment cores were collected at various seasons and the solid phase Fe, S, N, C, and chromium reducible sulfide in marsh peat at discrete depths were further investigated in order to study Fe and S cycles, and their relationship to the organic matter cycling at different seasons. Our results revealed that the redox sensitive elements Fe2+ and S2– showed significantly heterogeneous and complex three dimensional distribution patterns in salt marsh, over mm to cm scales, directly associated with the plant roots due to the oxygen leakage from roots and redox diagenetic reactions. We hypothesize that the oxic layers with low/undetected H2S and Fe2+ formed around roots help marsh plants to survive in the high levels of H2S by reducing sulfide absorption. The overall concentrations of Fe2+ and H2S and distribution patterns also seasonally varied with temperature change. H2S level in JoCo sampling site could change from &amp;lt;0.02 mM in spring to &amp;gt;5 mM in fall season, reflecting significantly seasonal variation in the rates of bacterial oxidation of organic matter at this marsh site. Solid phase Fe and S showed that very high fractions of the diagenetically reactive iron at JoCo and Big Egg were associated with pyrite that can persist for long periods in anoxic sediments. This implies that there is insufficient diagenetically reactive iron to buffer the pore water hydrogen sulfide through formation of iron sulfides at JoCo and Big Egg.

The relationships between spawning horseshoe crabs and egg densities: Recommendations for the assessment of populations and habitat suitability

Abstract Horseshoe crab population sizes and trends have been previously studied using surveys of spawning adults and counts of eggs from surface (top 5 cm) and deep (20 cm) sediment samples. The correlations between surface and deep eggs were studied at two locations, Delaware Bay and Jamaica Bay, USA, and the correlations between egg densities and spawning counts were examined in Jamaica Bay. There were significantly higher densities of eggs in deep sediments than in surface sediments. Only about 10% of the variability in surface egg density was explained by deep egg density. The numerical patterns between surface and deep eggs were similar between Delaware Bay and Jamaica Bay and across sampling dates. Nearly 20% of the deep samples in the combined data from Delaware Bay and Jamaica Bay with an egg density of ≥100,000 m−2 had zero surface eggs. Therefore, the use of surface eggs as an indicator of habitat suitability and spawning intensity may seriously underestimate the importance of a beach for spawning horseshoe crabs. When paired with nearest survey date, Jamaica Bay spawning indices did not predict deep or surface egg densities. This may be related to a temporal mismatch between survey methods, the extreme overdispersion (patchiness) of the eggs, and/or the dynamics of egg distribution after exhumation. Both egg density and spawning surveys can provide useful data on habitat suitability for horseshoe crabs and can offer excellent opportunities for student and citizen scientist engagement. More labour is required for egg surveys than spawning surveys because of the time required to sample, sort, and enumerate the eggs.

Microplastic abundance in gull nests in relation to urbanization

Human activity and urbanization are having profound effects on natural landscapes and ecosystems. The presence and persistence of human-made materials such as microplastics can have major impacts on the health of organisms in both marine and terrestrial environments. We quantified microplastics in herring gull (Larus argentatus) and great black-backed gull (Larus marinus) nests at three colonies in the northeast United States that varied in their degree of urbanization: Jamaica Bay (JB) in New York City, Youngs Island (YI) on Long Island, New York, and Tuckernuck Island (TN) in Massachusetts. Nests in urban colonies contained a higher proportion of microplastics than those in the more remote colony. Our results link urbanization with microplastic accumulation in coastal environments and suggest that assessing microplastics in seabird nests could provide a means of evaluating microplastics encountered by seabirds and other coastal marine animals.

Correction to: Impacts of climate change on hurricane flood hazards in Jamaica Bay, New York

Correction to: Impacts of climate change on hurricane flood hazards in Jamaica Bay, New York

Dynamics of Marsh‐Derived Sediments in Lagoon‐Type Estuaries

AbstractSalt marshes are valuable ecosystems that must trap sediments and accrete in order to counteract the deleterious effect of sea level rise. Previous studies have shown that the capacity of marshes to build up vertically depends on both autogenous and exogenous processes including ecogeomorphic feedbacks and sediment supply from in‐land and coastal ocean. There have been numerous efforts to quantify the role played by the sediments coming from marsh edge erosion on the resistance of salt marshes to sea level rise. However, the majority of existing studies investigating the interplay between lateral and vertical dynamics use simplified modeling approaches, and they do not consider that marsh retreat can affect the regional‐scale hydrodynamics and sediment retention in back‐barrier basins. In this study, we evaluated the fate of the sediments originating from marsh lateral loss by using high‐resolution numerical model simulations of Jamaica Bay, a small lagoonal estuary located in New York City. Our findings show that up to 42% of the sediment released during marsh edge erosion deposits on the shallow areas of the basin and over the vegetated marsh platforms, contributing positively to the sediment budget of the remaining salt marshes. Furthermore, we demonstrate that with the present‐day sediment supply from the ocean, the system cannot keep pace with sea level rise even accounting for the sediment liberated in the bay through marsh degradation. Our study highlights the relevance of multiple sediment sources for the maintenance of the marsh complex.

Impacts of climate change on hurricane flood hazards in Jamaica Bay, New York

Sea level rise (SLR) and tropical cyclone (TC) climatology change could impact future flood hazards in Jamaica Bay—an urbanized back-barrier bay in New York—yet their compound impacts are not well understood. This study estimates the compound effects of SLR and TC climatology change on flood hazards in Jamaica Bay from a historical period in the late twentieth century (1980–2000) to future periods in the mid- and late-twenty-first century (2030–2050 and 2080–2100, under RCP8.5 greenhouse gas concentration scenario). Flood return periods are estimated based on probabilistic projections of SLR and peak storm tides simulated by a hydrodynamic model for large numbers of synthetic TCs. We find a substantial increase in the future flood hazards, e.g., the historical 100-year flood level would become a 9- and 1-year flood level in the mid- and late-twenty-first century and the 500-year flood level would become a 143- and 4-year flood level. These increases are mainly induced by SLR. However, TC climatology change would considerably contribute to the future increase in low-probability, high-consequence flood levels (with a return period greater than 100 year), likely due to an increase in the probability of occurrence of slow-moving but intense TCs by the end of twenty-first century. We further conduct high-resolution coastal flood simulations for a series of SLR and TC scenarios. Due to the SLR projected with a 5% exceedance probability, 125- and 1300-year flood events in the late-twentieth century would become 74- and 515-year flood events, respectively, in the late-twenty-first century, and the spatial extent of flooding over coastal floodplains of Jamaica Bay would increase by nearly 10 and 4 times, respectively. In addition, SLR leads to larger surface waves induced by TCs in the bay, suggesting a potential increase in hazards associated with wave runup, erosion, and damage to coastal infrastructure.

Identifying opportunities for local assisted expansion of coastal upland vegetation in an urban estuary

Resilience planning requires an understanding of the potential impact of accelerated sea level rise on the narrow coastal habitats between the sea and the built environment in urban estuaries. Preliminary work suggests that facilitating expansion of coastal upland vegetation (grasslands and maritime shrubland/successional maritime forest) may improve resilience. We created a GIS model for Jamaica Bay, New York to identify areas of inland salt marsh migration induced by sea level rise and map potential locations for expansion of coastal upland vegetation through plantings of local provenance given land use, soil type, and adjacency to predicted future salt marshes. We predicted that regularly flooded salt marshes (low marsh) will comprise the large majority of salt marsh area (89% up from 68% currently) in the coming century due to daily tides covering areas currently categorized as irregularly flooded salt marsh (high marsh), brackish marsh and coastal upland vegetation. Considering land use, 16% of the area suitable for coastal upland vegetation within the coastal buffer zone could be considered possible sites for local assisted coastal upland vegetation expansion with about a fifth of those areas adjacent to predicted new sea level rise induced inland salt marsh areas. Parks and recreational facilities (43%) and open space (32%) were the dominant land uses available for local assisted coastal upland vegetation expansion adjacent to predicted new sea level rise induced inland salt marsh areas. Potential sites for local assisted coastal upland vegetation expansion were considerably more numerous on sandy soils than on loamy sand soils. Maintained lawn and shrubs and the borders of roads and railroads provided available space in areas disjunct from the predicted new salt marsh areas. Our study of opportunities for local assisted expansion of coastal upland vegetation fills a gap within existing models and informs land managers of predicted future inland salt marsh migration locations, regions of existing vegetation to support, and areas where restoration plantings may help sustain coastal upland vegetative communities and their many ecological services.