Estuaries and Coasts最新文献

Seagrasses are marine angiosperms that function as ecosystem engineers, forming complex structure that enhance nearshore environments. Globally, seagrass habitats are threatened by intensifying impacts from climate change, which exacerbate non-climatic stressors such as coastal development, invasive species, and overfishing. Advances in the methodological efficacy of active seagrass restoration efforts have sought to mitigate substantial anthropogenic-induced losses. Restoration efforts along the U.S. West Coast have primarily focused on Zostera marina (common eelgrass) in shallow, sheltered estuarine environments, where most coastal development occurs. However, within the Southern California Bight, Zostera spp. also occurs along the exposed coastlines of the California Channel Islands archipelago. Despite their unique location and the ecosystem services they provide, a paucity of information persists on open-coast seagrass systems and restoration efforts. In this study, we conducted a novel transplant of Z. marina on Catalina Island and tracked temporal and spatial performance metrics (i.e., areal coverage, morphometrics, and fish assemblages) at the restoration site and seven extant Z. marina reference beds on the island from 2021 to 2024. The transplant activities successfully established over 0.18 hectares of Z. marina habitat. The transplant site paralleled or exceeded extant reference beds morphometrically (shoot density and blade length) and functionally (fish composition and fish diversity), while concomitantly providing habitat for the occupancy of, and utilization by, federally listed endangered and managed species. Our results provide a model for broadening the scope of, and augmenting strategies for, seagrass habitat recovery beyond conventional restoration spaces by underscoring the role of open-coast seagrasses in enhancing nearshore ecosystem function and resilience.

Supplementary information: The online version contains supplementary material available at 10.1007/s12237-025-01609-x.

It is well known that publications with collaborators from external institutions increase citations. This effect scales with spatial distance. There are also many barriers to long-distance collaborations, including linguistic differences, funding constraints, and the incremental costs of remote collaboration. This paper uses the Gulf of Mexico as a case study to examine long-distance research collaboration because it consists of three countries with diverse development levels and two prominent diplomatic languages, within a singular regional ecosystem of tremendous natural and economic value. This paper uses bibliometric network analysis to examine scientific research article co-authorship in the Gulf of Mexico from 2000 to 2018. The results reveal that, although inter-organizational co-authorship has increased, significant fragmentation exists between the U.S.A, Mexico, and Cuba. Large differences in technological and organizational proximity as well as research capacity between US and Mexican states in the Gulf of Mexico may make collaboration more difficult compared to other transboundary settings, such as the US-Canadian border. Centrally located organizations in the network, such as NOAA, have played a prominent role in cross-institutional research, suggesting a capacity to bridge political entities in the Gulf of Mexico.

Zooplankton play a key role in the cycling of carbon in aquatic ecosystems, yet their production of carbon-rich fecal pellets, which sink to depth and can fuel benthic community metabolism, is rarely quantified in estuaries. We measured fecal pellet carbon (FPC) production by the whole near-surface mesozooplankton community in the York River sub-estuary of Chesapeake Bay. Zooplankton biomass and taxonomic composition were measured with monthly paired day/night net tows. Live animal experiments were used to quantify FPC production rates of the whole community and dominant individual taxa. Zooplankton biomass increased in surface waters at night (2- to 29-fold) due to diel vertical migration, especially by Acartia spp. copepods. Biomass and diversity were seasonally low in the winter and high in the summer and often dominated by Acartia copepods. Whole community FPC production rates were higher (3- to 65-fold) at night than during the day, with the 0.5-1 mm size class contributing 2-26% to FPC production in the day versus 40-70% at night. An increase in the relative contribution of larger size fractions to total FPC production occurred at night due to diel vertical migration of larger animals into surface waters. Community FPC production was highest in fall due to increased diversity and abundance of larger animals producing larger fecal pellets, and lowest in summer likely due to top-down control of abundant crustacean taxa by gelatinous predators. This study indicates that zooplankton FPC production in estuaries can surpass that in oceanic systems and suggests that fecal pellet export is important in benthic-pelagic coupling in estuaries.

Supplementary information: The online version contains supplementary material available at 10.1007/s12237-024-01442-8.

In well-mixed estuaries, the up-estuary salt flux is often dominated by tidal dispersion mechanisms, including tidal trapping. Tidal trapping involves volumes of water being temporarily trapped in dead zones or side channels adjacent to the main channel and released later in the tidal cycle, which causes an additional up-estuary salt flux. Tidal trapping can result from a diffusive exchange between a channel and a trap, or from filling and emptying of the trap by a tidal flow that is ahead in phase compared to the flow in the main channel (advective out-of-phase exchange). This study revisits the dispersive contribution from tidal trapping in a single dead-end side channel using an idealized numerical model. The results indicate that advective out-of-phase exchange yields the largest additional salt flux for the largest realistic velocity phase difference of 90 $_{}^{\circ }$ . Mixing of the trapped salinity field enhances the dispersive effect for small velocity phase differences. A continuous diffusive channel-trap exchange also enhances the dispersive trap effect when the velocity phase difference is small, but can dampen it when the phase difference is large. We demonstrate that the effect of a trap is twofold: firstly, channel-trap exchange alters the salinity field and introduces an additional salt flux in the main channel over a distance equal to the tidal excursion length; secondly, the altered salinity gradients are advected in both up- and down-estuary direction, influencing the tidal salt flux over twice the excursion length.

Subtropical estuaries worldwide are facing increasing pressure from human population growth, development, and climate change. Carbon is a useful currency for understanding how estuaries respond to these pressures and yet relatively little is known about carbon cycling in subtropical estuaries. Here we compute gross primary production (GPP), ecosystem respiration (ER), and net ecosystem production (NEP) from the diurnal cycle in dissolved oxygen measured during 38 week-long individual deployments over three years in two estuaries in the southeastern United States, Biscayne Bay and Tampa Bay. On average for both estuaries, GPP and ER nearly balance, with NEP about an order of magnitude smaller. Even though production in Tampa Bay and Biscayne Bay is dominated by different primary producers and limiting nutrients, mean GPP was the same, about 190 mmol O₂ m^-2 d^-1 (570 g C m^-2 y^-1). Our GPP estimates for Biscayne Bay are more than an order of magnitude greater than the only other productivity estimates available for this system, which are planktonic net primary productivity measurements from the late 1970s. GPP was strongly correlated with water temperature in Biscayne Bay (r = 0.60) but had the strongest correlation with salinity in Tampa Bay (r = 0.39). These findings highlight the importance of more frequent production measurements in these complex estuaries, especially in the face of a changing climate.

Supplementary information: The online version contains supplementary material available at 10.1007/s12237-025-01597-y.

Variations in estuarine carbonate chemistry can have critical impacts on marine calcifying organisms, yet the drivers of this variability are difficult to quantify from observations alone, due to the strong spatiotemporal variability of these systems. Terrestrial runoff and wetland processes vary year to year based on local precipitation, and estuarine processes are often strongly modulated by tides. In this study, a 3D-coupled hydrodynamic-biogeochemical model is used to quantify the controls on the carbonate system of a coastal plain estuary, specifically the York River estuary. Experiments were conducted both with and without tidal wetlands. Results show that on average, wetlands account for 20–30% of total alkalinity (TA) and dissolved inorganic carbon (DIC) fluxes into the estuary, and double-estuarine CO₂ outgassing. Strong quasi-monthly variability is driven by the tides and causes fluctuations between net heterotrophy and net autotrophy. On longer time scales, model results show that in wetter years, lower light availability decreases primary production relative to biological respiration (i.e., greater net heterotrophy) resulting in substantial increases in CO₂ outgassing. Additionally, in wetter years, advective exports of DIC and TA to the Chesapeake Bay increase by a factor of three to four, resulting in lower concentrations of DIC and TA within the estuary. Quantifying the impacts of these complex drivers is not only essential for a better understanding of coastal carbon and alkalinity cycling, but also leads to an improved assessment of the health and functioning of coastal ecosystems both in the present day and under future climate change.

Seagrass beds are composed of foundation species, providing essential nursery grounds, feeding areas, and refuge for various marine life. Several species of fish and invertebrates utilize seagrasses as essential habitat. The Dwarf Seahorse (Hippocampus zosterae) is an understudied species in Texas, and little is known about its density, distribution, and habitat associations in this area of their range. Physicochemical water parameters, nekton community data, habitat data, and Dwarf Seahorse catch data were collected at 80 sites in Texas. The highest catch per unit effort (CPUE) of the target species was in Aransas Bay (0.038/m²). There was a positive relationship between the presence and percent cover of turtle grass (Thalassia testudinum) and the presence and CPUE of Dwarf Seahorses. Dwarf Seahorses were detected more often and at a higher CPUE in locations with a higher seagrass community diversity and richness. The nekton community at sites where Dwarf Seahorses were detected was also more abundant, diverse, and species rich. This is the first comprehensive study of the distribution of the Dwarf Seahorse along the Texas coast. Dwarf Seahorses were generally found in higher abundances in association with mature, stable, and diverse seagrass beds. Recommended conservation strategy to protect Dwarf Seahorses should prioritize the protection of established and mature seagrass beds. Continued directed monitoring of this species is recommended to better understand their distribution and population status.

Major storms can cause significant changes to coastal and wetland environments. A series of storm events in 2020 resulted in closure of the historically open estuary at Cabbage Tree Basin, Port Hacking, New South Wales (NSW), Australia. Prolonged tidal impoundment (3 months) led to substantial changes in hydrological and sedimentological processes, resulting in widespread mangrove dieback. This study aimed to quantify the degree of impact and recovery for mangroves, identify factors contributing to dieback, and consider the implications for carbon sequestration. This was achieved using remotely piloted aircraft structure-from-motion approaches, aerial photography, and field-based assessments of vegetation health and above-ground biomass (AGB). Mangroves were classified as ‘dead’, ‘partially dead’, and ‘live’. In October 2019, there was 10.8 ha of live mangroves, with this reduced to 6.6 ha by August 2022. Digital surface models (DSMs) were intersected with classified mangroves to assess the vertical distribution of each zone. All mangroves classified as ‘dead’ were distributed at elevations < 0.4 m with respect to the Australian Height Datum (AHD), suggesting these regions were persistently inundated, which was confirmed by water level loggers (inundated during logger deployment). Field data confirmed substrate elevation related to dieback with the proportion of ‘live’ mangroves greatest at elevations > 0.6 m AHD. Substrate elevation and distance to the estuary mouth were significantly correlated with species, with Avicennia marina located at lower tidal positions and closer to the entrance compared to Aegiceras corniculatum. The dieback event equated to a loss of 81.5 ± 48 Mg of above-ground biomass, 38.1 ± 22.5 Mg C, or 140 ± 82 Mg CO₂ equivalence (CO₂e). This study provides an important baseline for monitoring dieback events. Continued monitoring is crucial to assess recovery and to tailor management strategies.

Small crustaceans, such as the mysid Neomysis americana (S.I. Smith 1873), are a central component of coastal food webs and, while generally tolerant of a wide-range of environmental conditions, can be negatively affected by poor water quality. In this study, daily growth rates (GR_D) and clutch size metrics of N. americana collected during the early and late summer of 2018–2019 were evaluated for the Choptank and Patuxent rivers, major tributaries of Chesapeake Bay known to exhibit different oxygenation regimes. Genetic variation in the mitochondrial CO1 locus was assessed to evaluate the potential intraspecific genetic structure within Chesapeake Bay. CO1 haplotype network analysis, phylogenetic analysis, and analysis of molecular variance revealed no genetic differences between Choptank and Patuxent river populations, with all Chesapeake Bay individuals belonging to a single genetic lineage (lineage C), of the N. americana cryptic species complex. Total and size-specific clutch size were approximately 18% and 53% higher, respectively, in the normoxic Choptank River during the early summer. Embryos within the marsupium, corrected for clutch size and female length, were consistently larger in the Choptank River during later larval development stages. Size-specific clutch size showed correlations with bottom water dissolved oxygen concentration (positive) and water temperature (negative). GR_D did not differ between rivers or seasonally but juveniles grew twice as fast as adults. Given that all individuals genotyped from both rivers belonged to lineage C of the N. americana cryptic species complex, it is hypothesized that bottom water hypoxia (rather than genetic differentiation) is responsible for reduced clutch size in the Patuxent River. Our findings build on other recent work by providing evidence of a direct, negative relationship between hypoxia and local population dynamics of N. americana, a key ecological component of Chesapeake Bay’s food web.

Most living shoreline site selection and design decision support tools are based upon existing environmental conditions. We developed a web-based, geospatial tool called Future Shorelines that integrates high-resolution landscape elevation data and a matrix of locally derived NOAA Interagency Sea Level Rise Scenarios to characterize future conditions of submergence and shoreline translation induced by sea level rise. Once the practitioner selects a location of interest, sea level rise scenario (e.g., high), and target year (e.g., 2050), the tool will generate plan view and cross-sectional informational graphics specific to their choices. This information can then be paired with other menu options, like parcel ownership, to facilitate the planning and construction of nature-based shoreline stabilization solutions that (1) are located where opportunities for horizontal migration are optimized, (2) remain accessible for monitoring and maintenance, and (3) perform as intended over the design life of the installation. The tool’s menu options and the user interface were informed by project partner input solicited during numerous workshops convened over the duration of the 2-year project. This coproduction created a product that was familiar to the end user and therefore increased the likelihood that it would be utilized by them during the planning and design of living shoreline projects. Although developed for use in the Indian River Lagoon, located along the east-central Florida coast, it can be seamlessly replicated for application in other coastal regions of the USA where the requisite data are available.