Estuaries In England Research Articles

Haplosporidium nelsoni and Perkinsus marinus occurrence in waters of Great Bay Estuary, New Hampshire.

In Great Bay Estuary, New Hampshire, USA, Haplosporidium nelsoni and Perkinsus marinus are 2 active pathogens of the eastern oyster Crassostrea virginica (Gmelin), that cause MSX (multinucleated sphere with unknown affinity 'X') and dermo mortalities, respectively. Whereas studies have quantified infection intensities in oyster populations and determined whether these parasites exist in certain planktonic organisms, no studies thus far have examined both infectious agents simultaneously in water associated with areas that do and do not have oyster populations. As in other estuaries, both organisms are present in estuarine waters throughout the Bay, especially during June through November, when oysters are most active. Waters associated with oyster habitats had higher, more variable DNA concentrations from these pathogenic organisms than waters at a non-oyster site. This finding allows for enhanced understanding of disease-causing organisms in New England estuaries, where oyster restoration is a priority.

Larval presence and settlement of the American lobster (Homarus americanus) in a changing southern New England estuary

During the late 1980s and early 1990s, the American lobster (Homarus americanus) fishery boomed in southern New England, but starting in the early 2000s lobsters declined in the nearshore regions and the fishery retracted. While previous research has focused on the causes for the declining numbers of adult lobsters in the region as well as lobster settlement, lobster larvae were not sampled in Rhode Island waters. Additionally research was mixed on the origin of lobster larvae found inshore. To examine larval presence in coastal Rhode Island, weekly net tows were conducted at the mouth of Narragansett Bay during summer from 2019 to 2021, and light traps were deployed in 2020 and 2021. Time series segmentation and generalized linear models assessed trends and connections between lobsters caught in trawl surveys, commercial landings data, lobster settlement data, bottom water temperatures, and climate indices. Larval supply to Narragansett Bay is very low and mostly concentrated in the East Passage where ocean water flows into the bay, suggesting that a failure in larval supply from offshore sources is harming local population levels. Time series segmentation and models indicate that declines in lobster settlement followed the decline in adult lobsters in coastal Rhode Island, not Narragansett Bay. Altogether, the data suggest that larval lobster are transported inshore from spawning stock outside the bay. Present circulation patterns combined with the movement of lobsters into deeper waters has made the transport of larvae to Narragansett Bay unlikely.

A baseline for microplastic occurrence in three New England estuaries

Although microplastics (MP) have been documented in estuarine habitats, limited published data exist for New Hampshire and northern Massachusetts hampering meaningful, regional comparison with other geographies. Here we synthesize previously unpublished data from several independent baseline studies spanning three estuarine systems including Great Bay Estuary (GBE), Hampton-Seabrook Estuary (HSE), and Great Marsh Estuary (GME) to compare geographic data for MP to other published regional studies. Data include water column in GBE (n = 179 from 7 sites), surface waters and salt marsh sediment cores from HSE (n = 72 water samples from 12 sites and n = 77 sediment cores from 8 sites), and surface waters from GME (n = 42 water samples at 10 sites). Samples were analyzed for MP characteristics initially via either automated confocal microscopy or light microscopy, allowing initial estimation of the number and size distribution of putative MP. Particles from representative samples were analyzed using laser direct infrared spectrometry (LDIR) to determine elemental analysis. MP were found in > 98% of samples collected including surface waters, water column, and marine sediments. Counts ranged from 1 to 144,000 MP particles m-3 and mean MP differed significantly among regions, sites within regions, and across years. In the GBE water column, MP tended to peak during June-August in 4 of the 5 years studied. Most MP were roughly circular and ~50 μm in diameter. LDIR confirmed that many types of plastics are in these estuarine waters and also revealed that despite the digestion processes, biogenic materials often remained, predominantly chitin, rubber, wood, and coal. These data allow us to address the realistic levels of risk that estuarine MP pose in NH and northern MA estuaries and can be used to populate existing hydrodynamic models that will predict the tributary sources, movements, and fate of MP within these aquatic habitats.

Simulating Hypoxia in a New England Estuary: WASP8 Advanced Eutrophication Module (Narragansett Bay, RI, USA).

Anthropogenic sources of nutrients cause eutrophication in coastal waters. Narraganset Bay (USA), the largest estuary in New England, has large seasonal zones of hypoxia. In response, management strategies have been implemented to reduce nutrient loadings. In this study, a mechanistic, mass balance fate and transport modeling framework was developed and applied to Narragansett Bay to improve our understanding of the processes governing hypoxia. Discrete and continuous observations were used for model comparison and evaluation. Simulations captured the general trends and patterns in dissolved oxygen (DO) with depth and space. Simulations were unable to capture the wide diurnal range of observed continuous DO and phytoplankton concentrations, potentially suggesting the need for improved understanding of processes at this time scale. Mechanistic modelling scenarios were performed to investigate how different sources of nutrients affect DO. Results suggest tributary sources of nitrogen affected upper layers of DO, while sediment oxygen demand and nutrient fluxes affected deeper waters. This work highlights the importance of understanding and simulating the legacy effects of historic nutrient loading to estuary systems to understand the magnitude and timing of long-term recovery due to reductions in nutrient loadings.

Habitat and trophic niche overlap among juvenile black sea bass, tautog, and cunner: interspecific interactions amid a species geographic range expansion

Juvenile black sea bass Centropristis striata populations are increasing in southern New England estuaries of the northeastern USA with possible trophodynamic effects on labrid species: tautog Tautoga onitis and cunner Tautogolabrus adspersus. In this study, we examined the abundance, size-structure, and feeding ecology of juvenile sea bass and labrids in Narragansett Bay (Rhode Island, USA) from June to October in 2018 and 2019 and evaluated potential interspecific competition using habitat, diet, and isotopic niche overlap indices. Juveniles (age-0+) of each fish species spatiotemporally co-occurred in shallow, polyhaline habitats throughout the estuary. Age-0 cohorts were numerically dominant across species and initially recruited to the study area in July (minimum total length, TL = 15-20 mm), reached peak abundances in mid- to late summer (maximum abundances = 12-140 fish 100 m-2), and emigrated from field sites in October (maximum TL = 85-96 mm). Stomach content and stable isotope (δ15N and δ13C) analyses determined that focal fishes were generalist carnivores that foraged in bentho-pelagic food webs. Fishes also overlapped in their respective ambit and core isotopic niche space, but interspecific dietary overlap was size-dependent. Dietary overlap was most pronounced between sea bass ≤49 mm TL and labrids ≤59 mm TL due to their mutual reliance on gammarid and caprellid amphipods. Ontogenetic dietary shifts then resulted in food niche segregation, such that sea bass 50-139 mm TL consumed decapod crustaceans and fish, whereas labrids 60-181 mm TL mainly fed on amphipods, worms, bivalves, and turf-associated biota, i.e. bryozoans, hydroids, and seaweeds. Habitat and trophic niche overlap between early juvenile sea bass and labrids purportedly have not caused opposite population trajectories or food resource limitation in Narragansett Bay, indicating an absence of exploitative competition. Alternatively, realized competition between species may be too spatiotemporally restricted to alter their population dynamics. Continuous monitoring of the sea bass’s bio-ecological effects in southern New England estuaries is warranted, however, given their recent range expansion and increasing abundances at northern latitudes.

Large-scale historic habitat loss in estuaries and its implications for commercial and recreational fin fisheries

AbstractEstuaries provide important nursery and feeding habitat for numerous commercially and ecologically important fish, however, have been historically subject to substantial habitat alteration/degradation via environmental fluctuations, sea level rise, human activity on intertidal habitats, and adjacent land management. This review has summarized estuarine habitat use for 12 economically important finfish in the United Kingdom, of which seven were found to utilize estuarine habitats e.g. saltmarsh during their life cycle. This review reveals that ∼2500 km2 of intertidal habitat has been lost from estuaries in England and Wales since 1843. The implications of this large-scale habitat loss and continued anthropogenic disturbance within estuaries for a variety of fish species is discussed, in particular the requirement of finfish for particular habitats to be accessible and in a suitable condition. As a result of the high economic and social value of commercial and recreational fisheries, it is suggested that further research attention should investigate the spatial ecology of fish. Holistic fisheries management policies should also be considered, which would both sustainably manage fisheries landings but also account for the habitat requirements of the fisheries species.

Simulating Hypoxia in a New England Estuary: Wasp8 Advanced Eutrophication Module (Narragansett Bay, Us)

Simulating Hypoxia in a New England Estuary: Wasp8 Advanced Eutrophication Module (Narragansett Bay, Us)

Assessing drivers of winter abundance change in Eurasian Curlews Numenius arquata in England and Wales

ABSTRACT Capsule We assessed annual changes in Eurasian Curlew Numenius arquata wintering numbers at estuaries in England and Wales over 40 years against local and broadscale factors. Long-term trends likely reflect the cessation of hunting, but potentially also distributional changes associated with milder winters and changes in breeding success. Aims To investigate whether local or broadscale factors might affect site-level annual abundance changes in Curlews in England and Wales. Methods Relationships between Wetland Bird Survey (WeBS) counts from 46 estuaries from 1974/75 to 2016/17 and environmental data were assessed using Generalized Linear Mixed Models. Results The winter abundance trend of Curlews in England and Wales closely matched the decline of breeding populations since the mid-1990s. However, there are clear differences in the trends prior to this. Our analysis suggests that winter counts were influenced by the cessation of hunting and by weather, with abundance decreasing during cold winters and increasing the following winter. The influence of severe weather was less pronounced in the immediate aftermath of the hunting ban. An increase in numbers in the east of the UK also occurred during this period. No effects were detected for other environmental variables, but this may reflect the fact that only static variation between sites was tested for these variables rather than change. Conclusion The increase in wintering Curlew numbers in the UK during the 1980s and early 1990s likely reflects a positive response to the cessation of hunting, but also a wider redistribution associated with milder winters across the European wintering range. Winter temperatures influenced annual abundance changes at individual sites, although impacts on detectability are difficult to disentangle from impacts on survival using WeBS counts alone. Factors operating during the breeding season are likely to be the main drivers of the current population decline.

Evaluating connections between nitrogen cycling and the macrofauna in native oyster beds in a New England estuary.

Recent efforts to quantify biogeochemical and ecological processes in oyster habitats have focused on provision of habitat and regulation of the nitrogen cycle. However, it is unclear how these two processes may interact. In this study, seasonal patterns of habitat use and nitrogen removal from natural oyster beds were quantified for comparison with nearby bare sediment in Green Hill Pond, a temperate coastal lagoon in Rhode Island USA. Relationships were tested between benthic macrofaunal abundance and nitrogen removal via denitrification and burial in sediments. Nitrogen removal by oyster bio-assimilation was quantified and compared with nearby oyster aquaculture. Despite limited differences in habitat use by macrofauna, there were fewer non-oyster benthic organisms (e.g., filter-feeders, detritivores) where oysters were present, possibly due to competition for resources. Additionally, low rugosity of the native oyster beds provided little refuge value for prey. There was a shift from net N removal via denitrification in bare sediments to nitrogen fixation beneath oysters, though this change was not statistically significant (t(96) = 1.201; p = 0.233). Sediments contained low concentrations of N, however sediments beneath oysters contained almost twice as much N (0.07%) as bare sediments (0.04%; p < 0.001). There was no difference in tissue N content between wild oysters and those raised in aquaculture nearby, though caged oysters had more tissue per shell mass and length, and therefore removed more N on a shell length basis. These oyster beds lacked the complex structure of 3-dimensional oyster reefs which may have diminished their ability to provide habitat for refugia, foraging sites for macrofauna, and conditions known to stimulate denitrification.

Salt marsh sediments act as sinks for microplastics and reveal effects of current and historical land use changes

Microplastic particles are widespread in marine sediments and the abundance of the different types of particles vary widely. In this paper we demonstrate that salt marshes effectively capture microplastics in their sediments, and that microplastic accumulations increase with the level of urbanization of the land surrounding estuarine areas. We extracted microplastics from sediment cores in salt marshes of SE New England estuaries at different degrees of urbanization and land use intensity. Microplastics were present everywhere, but their abundances increased markedly with the degree of urbanization of the land. Microplastic fragment counts were linked to nearby urbanization and their abundances seemed to be linked to more local, within-watershed inputs. The number of fibers was similar across all sites suggesting that fiber accumulation in these sediments is likely influenced by effective long-distance transport from large-scale areas. The sedimentary record confirmed that microplastics have been accumulating in these estuaries since the early 1950s, and their abundances have increased greatly in more recent years in response to the progressive urbanization of the watersheds and intensification of land uses. Our results highlight the role of salt marsh sediments as sinks for microplastics in the marine environment.

American Lobster, Homarus americanus, Reproduction and Recruitment in a New England Estuary

While egg-bearing (ovigerous) American lobsters are found in estuaries, it is not known if they are present when their eggs hatch. The major goal of this study was to test the hypothesis that a portion of the larvae that serve as new recruits to the Great Bay Estuary lobster population originate from females that are year-around residents. First, a total of nine ovigerous lobsters were fitted with acoustic transmitters and tracked from October through the following spring-to-early summer. We found that all lobsters overwintered in the estuary and were located again within 1 km of their fall positions the following May–June, when their eggs likely hatched. Second, sea sampling surveys carried out in the spring revealed that ovigerous lobsters in the estuary were carrying more developed eggs than their coastal counterparts. Third, through a series of laboratory-based studies, we calculated the putative hatch dates of egg clutches carried by estuarine and coastal lobsters and show that estuarine lobster eggs likely hatch 2–3 weeks earlier than eggs carried by coastal females. Finally, plankton tow surveys in the estuary revealed that stage I larval lobsters (zoeae) were present in the estuary from May to July, which encompasses the predicted hatching period for both estuarine and coastal eggs. Therefore, new recruits to the Great Bay Estuary lobster population likely come from both resident estuarine lobsters and coastal females.

Comparable short-term morphodynamics of three estuarine–coastal systems in the southwest coastal region of England, UK

Here, we describe and compare the changes in low tide channel position and the morphology of the three estuaries in southwest England from an analysis of contemporary (2008–2016) topographic surveys. The Hayle, Gannel, and Camel estuaries and their adjacent open-coast shorelines were subject of various studies in the past principally in terms of mining impacts on estuarine sediments and sedimentation, but no regional synthesis of the contemporary behaviour has yet been attempted. Light Detection and Ranging (LiDAR) data for the north coast of Cornwall are analysed for planform morphological changes of the systems. At the annual scale, intertidal bars and sandwaves migrate across the foreshore and into the inlet region, where flood-oriented and wave-forced movement is evident. This is evidenced at all the estuarine systems considered here. However, the steep upstream slope of the Hayle is almost devoid of bedforms, while the shallower upstream slope of the Gannel comprises similar scaled bedforms to the whole flood delta, and the megaripples of Camel flood delta are smaller on the backslope. Over the short-term covered by the LiDAR data considered here, there was no significant storm surges, and a relatively consistent wave climate. The occurrence of strong onshore wave conditions are possibly the drivers of contemporary behaviour, and with the inner estuary intertidal currents, for the movements of sediments within the estuarine environment, thereby causing the re-organisation of sediments and the shifting of channel position.

Evaluating Summer Flounder Spatial Sex‐Segregation in a Southern New England Estuary

AbstractMarine fish species can exhibit sex‐specific differences in their biological traits. Not accounting for these characteristics in the stock assessment or management of a species can lead to misunderstanding its population dynamics and result in ineffective regulatory strategies. Summer Flounder Paralichthys dentatus, a flatfish that supports significant commercial and recreational fisheries along the northeastern U.S. shelf, expresses variation in several traits between the sexes, including growth and habitat preference. To further understand these patterns, 1,302 Summer Flounder were collected and sexed in 2016 and 2017 from fisheries‐independent surveys conducted in Rhode Island state waters. Female flounder were more prevalent in shallow waters (≤15 m) through all months, but males had a greater presence in deeper waters (&gt;15 m) from May through September. The probability of a collected flounder being female was evaluated with generalized linear models and covariates representing depth, temperature, month, year, and TL. Summer Flounder were more likely to be female at larger sizes, in shallower waters, and late in the season. When compared with landings data in the recreational fishery over the sampling period, the results suggest that nearly all flounder harvested in the sector were female. This work provides further evidence for and characterization of Summer Flounder sex‐segregation and highlights, for management purposes, the importance of considering fine‐scale spatial dynamics in addition to broader distribution patterns. The fitted model represents an effective first step toward understanding the implications of an aggregated fishing effort for disproportionate removals of male or female flounder and for exploring resulting consequences for regional spawning stock biomass and stock resiliency.

Tidal erosion and upstream sediment trapping modulate records of land-use change in a formerly glaciated New England estuary

Land clearing, river impoundments, and other human modifications to the upland landscape and within estuarine systems can drive coastal change at local to regional scales. However, as compared with mid-latitude coasts, the impacts of human modifications along sediment-starved formerly glaciated coastal landscapes are relatively understudied. To address this gap, we present a late-Holocene record of changing sediment accumulation rates and sediment sources from sediment cores collected across a tidal flat in the Merrimack River estuary (Mass., USA). We pair sedimentology, geochronology, bulk- and stable-isotope organic geochemistry, and hydrodynamic simulations with historical data to evaluate human and natural impacts on coastal sediment fluxes. During the 17th to 19th centuries, accumulation rates increased by an order of magnitude in the central tidal flat, likely in response to enhanced delivery of terrestrial sediment resulting from upland deforestation. However, the overall increase in accumulation (0.56–2.6 mm/year) within the estuary is subtle and spatially variable across the tidal flats because of coincident anthropogenic land clearing and dam building, upland sediment storage, and estuarine hydrodynamics. This study provides insight into the response of formerly glaciated fluvialcoastal systems to human modifications, and underscores the role of estuarine environmental conditions in modifying upland signals of land-use change.

Correction to: An Experimental Evaluation of Dock Shading Impacts on Salt Marsh Vegetation in a New England Estuary

In the original article there was an error in the reported quadrat size. Sample quadrats were described as 1/16 m2 when they should have been reported as 1/32 m2 in the text of page 16 and in the figure legend for Figs. 6 and 7.

Salt Marsh Aboveground Production in New England Estuaries in Relation to Nitrogen Loading and Environmental Factors

Aboveground production responses of Spartina alterniflora and S. patens in estuaries in Massachusetts, USA were assessed in relation to temporal (date) and physical (elevation and distance from creek edge) factors as well as nitrogen loading using stem δ15N, water column dissolved inorganic nitrogen (DIN), and upland nitrogen loading as nitrogen input proxies. All nitrogen input proxies had negative relationships with S. alterniflora stem density while stem height and biomass increased or were unaffected. Nitrogen content of S. alterniflora increased with stem δ15N but was not related to DIN or upland nitrogen loading proxies. For S. patens, stem density, biomass, and height all increased with stem δ15N while nitrogen content decreased. Stem density and biomass also varied with elevation. For S. alterniflora, this relationship was parabolic for stem density and declined linearly for biomass. Both stem density and biomass increased linearly for S. patens. Across the growing season, S. alterniflora stem density decreased, S. patens biomass increased, and nitrogen content declined for both Spartina species. S. alterniflora stem height also decreased with distance from the creek edge. Results show different responses for Spartina species to upland and water column nitrogen inputs and provide complementary information to results from controlled fertilization experiments.

Six decades of change in pollution and benthic invertebrate biodiversity in a southern New England estuary

Pollution has led to a decline of benthic invertebrate biodiversity of Narragansett Bay, raising questions about effects on ecosystem functions and services including shellfish production, energy flow to fishes, and biogeochemical cycles. Changes in community composition and taxonomic distinctness (biodiversity) were calculated from the 1950s—when quantitative benthic invertebrate data first became available—to 2015. Change in community composition of the bay was correlated with changes in dissolved inorganic nitrogen, dissolved oxygen, and sediment contaminants. A mid-bay reference site showed moderate changes in community composition but no change in biodiversity. In contrast, a more impacted site in the upper bay showed substantial differences in community composition over time and a decline in taxonomic distinctness. Bay-wide, as inputs of some stressors such as nutrients and sediment contaminants have declined, there are signs of recovery of benthic biodiversity but other stressors such as temperature and watershed development are increasing.

Historical Trends of Benthic Invertebrate Biodiversity Spanning 182 Years in a Southern New England Estuary

Benthic invertebrates support numerous ecosystem functions and services including shellfish production, energy flow to fishes, and biogeochemical cycles. The decline of marine biodiversity worldwide has raised concerns about effects on ecosystems. To examine biodiversity trends of Narragansett Bay over time, a list was compiled of all benthic invertebrate species collected from the bay since 1834. The list covers 104 studies spanning 182 years and currently holds 1214 unique taxa from 21 phyla, the majority of all animal phyla on Earth. A permuted estimator of number of species suggested there are about 300 more yet to be discovered. Widely varying sampling gear and sieve mesh sizes precluded the use of abundance data. Instead, multidimensional scaling and taxonomic distinctness were used with presence-absence data to examine biodiversity trends. The changes in community composition and decline of benthic biodiversity (p < 0.01) since 1855 are what would be expected of a community that gradually deteriorated in the face of increasing anthropogenic stressors. Taxonomic distinctness had negative correlations (p < 0.05) with human population in the watershed, total nitrogen inputs, and inputs of metals. This loss of benthic biodiversity has implications for ecosystem functions and services. As some of the stressors waned in the last two or three decades, following passage of environmental legislation in the 1970s, biodiversity appeared to show a partial recovery. An inventory of species, how it has changed over time, and understanding what caused those changes are important for assessing whether remediation programs are achieving improved water quality and ecosystem health.

Macroalgal composition and accumulation in New England estuaries

New England estuaries provide essential feeding grounds and nursery habitat for important recreational and commercial species. However, these functions are being altered by a recent shift in estuarine plant dominance from rooted plants to opportunistic drift macroalgae that can form dense accumulations. We hypothesize that formation of these macroalgal accumulations is controlled by the level of nutrient enrichment and the low hydrodynamic energy regime present in many estuarine basins. To test this hypothesis, we conducted temporal macroalgae surveys in eight s.e. Massachusetts estuaries to quantify the level of accumulation within basins with varying levels of nitrogen enrichment and bottom currents. Our results indicate that opportunistic Ulva spp. dominated the macroalgal community in both estuaries with temporal surveys, Green and Great Ponds. Measurements of tidal transport revealed a net import of macrophyte material but with no import or export of Ulva. Within each estuary, occurrence of opportunistic macroalgae was positively related to levels of water column total nitrogen (R2 = 0.76) and growth rate of Ulva spp. directly related to total nitrogen + light level (R2 = 0.92), while bottom coverage was >20% at TN levels >0.48 mgL−1. We conclude that opportunistic species accumulate in response to nutrient enrichment with in situ processes controlling growth and decay, while import and tidal transport play relatively minor roles in the distribution of opportunistic drift macroalgae in these shallow estuaries.

Spatial and temporal distribution of juvenile Cyclopterus lumpus (lumpfish) in a New England estuary

Lumpfish (Cyclopterus lumpus) is a semi-pelagic species that is broadly distributed in the temperate regions of the North Atlantic. Little is known about the distribution of juveniles, therefore this study was the first attempt to determine juvenile lumpfish distribution in near-coastal and estuarine locations, as represented by the Great Bay Estuary, NH. Sampling took place in 2015 and 2016 from June through September at four different locations along the Piscataqua River and Great Bay. Juveniles were caught using dipnets, from macroalgae growing on floating docks in all four months and all locations, except for the site furthest (∼25 km) up the estuary (Great Bay site (JEL). Water temperatures ranged from 8.6 –22.3 °C and salinities ranged from 21.9 –33.95 where lumpfish were found. Juvenile lumpfish were never captured at the Great Bay sampling site, therefore it is still unclear whether or not they are using the upper portions of the Bay as a nursery ground. With the changing climate, it is important to fully investigate the abiotic factors that influence the temporal and spatial distribution of juvenile lumpfish.