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Secondary metabolites often function as antipredator defenses, but when bioactive at low concentrations, their off-target effects on other organisms may be overlooked. Candidate "keystone molecules" are proposed to affect community structure and ecosystem functions, generally originating as defenses of primary producers; the broader effects of animal chemistry remain largely unexplored, however. Here, we characterize five previously unreported polyketides (alderenes A to E) biosynthesized by sea slugs reaching exceptional densities (up to 9000 slugs per square meter) in Northern Hemisphere estuaries. Alderenes comprise only 0.1% of slug wet weight, yet rendered live slugs or dead flesh unpalatable to three co-occurring consumers, making a potential food resource unavailable and redirecting energy flow in critical nursery habitat. Alderenes also displaced infauna from the upper sediment of the mudflat but attracted ovipositing snails. By altering communities, such compounds may have unexpected cascading effects on processes ranging from bioturbation to reproduction of species not obviously connected to the producing organisms, warranting greater attention by ecologists. [ABSTRACT FROM AUTHOR]

Estuaries are essential habitats for recreational and commercial fish that are shaped by both natural and anthropogenic processes. In Louisiana a combination of climate change and planned coastal restoration actions is predicted to increase freshwater introduction to coastal estuaries. As such there is a need to quantify the relationships between estuarine fish ecology and salinity to aid in predicting how species will respond to shifts in salinity. We investigated the relative abundance and dietary niches of adult (24.5 ± 5.4 cm standard length) spotted seatrout Cynoscion nebulosus across varying salinity regimes (oligohaline, mesohaline, and polyhaline) within Barataria Bay, Louisiana, using a combination of net sampling and gut content and stable isotopes analysis. We found that the relative abundance of C. nebulosus was lowest at the oligohaline site, translating to approximately five fewer fish captured for every single psu decrease in a site's average annual salinity. In contrast, we found that diets and, to a lesser extent, isotopic niches had a high degree of overlap across sites with differing salinity regimes. Fish and penaeid shrimp were the most common and important prey taxa recovered from guts at all sites. The small isotopic differences found among sites were likely due to spatial variation in hydrogeochemical baselines, and the observed isotopic overlap provides support for the idea that C. nebulosus move between adjacent salinity regimes and forage throughout Barataria Bay. Our results contribute to a greater understanding of the salinity preference and trophic ecology of C. nebulosus that can aid in predicting their responses to future salinity and habitat changes within Barataria Bay associated with predicted climate change and planned coastal restoration actions. [ABSTRACT FROM AUTHOR]

Continuous measurements of dissolved oxygen (DO) are useful for quantifying ecosystem metabolism, which is critical for understanding estuarine biogeochemistry and ecology, but current methods applied to these data may lead to estimates that are physically impossible and poorly constrained errors. Here, we present a new approach for estimating estuarine metabolism: Estuarine BAyesian Single‐station Estimation (EBASE). EBASE applies a Bayesian framework to a simple process‐based model and DO observations, allowing the estimation of critical model parameters, specifically light efficiency and respiration, as informed by a set of prior distributions. EBASE improves upon the stream‐based model from which it was derived by accommodating missing DO data and allowing the user to set the time period over which parameters are estimated. We demonstrate that EBASE can recover known metabolic parameters from a synthetic time series, even in the presence of noise (e.g., due to tidal advection) and when prior distributions are uninformed. Optimization periods of 7 and 30 d are more preferable than 1 d. A comparison with the more‐conventional method of Odum reveals the ability of EBASE to avoid unphysical results (such as negative photosynthesis and respiration) and improves when the DO data are detided. EBASE is available using open‐source software (R) and can be readily applied to multiple years of long‐term monitoring data that are available in many estuaries. Overall, EBASE provides an accessible method to parameterize a simple metabolic model appropriate for estuarine systems and will provide additional understanding of processes that influence ecosystem status and condition. [ABSTRACT FROM AUTHOR]

Jobos Bay National Estuarine Research Reserve (JBNERR) has flora and fauna adapted to a tropical climate. Within the reserve lies the Aguirre Power Plant Complex, which produces a great deal of noise that could place significant stress on marine life and cover a significant area. To test this hypothesis, underwater sound frequencies were recorded at several points of different proximity to the power plant using a hand-held sound recorder with a hydrophone attachment. Each recording was two minutes in duration and positioned one meter above the ocean floor. Results revealed anthropogenic noise from the power plant is strongly present in the 0.01-200 Hz frequency range in an area up to 1.5 km from the power plant. However, because sound waves travel further in water than in air, this distance could be even greater. Acoustic frequencies from the power plant were not detected across a mangrove barrier located approximately 1.0 kilometers from the power plant. This implies that mangroves may have an unreported noise reduction function which, in this case, mitigates and completely blocks off acoustic frequencies from the power plant. [ABSTRACT FROM AUTHOR]

Variations in primary production in relation to selected physicochemical and biological parameters of the Oum Er Rbia River estuary were measured monthly from November 2018 to January 2020 at two stations using the clear and dark bottle method. Gross primary production (GPP) ranged from 9.28 to 467.07 mg C/m3/h; net primary production (NPP) ranged from 3.09 to 248.13 mg C/m3/h; and respiration (R) ranged from 4.03 to 262.73 mg C/m3/h. GPP, NPP and R are lowest in summer, increasing to peak in spring. In summer and winter, significantly positive correlations were observed between GPP and NPP on the one hand, and phaeopigments on the other. In summer, there is also a significant positive correlation between respiration and dissolved oxygen concentration. In winter, significant negative correlations were found between conductivity and salinity, on the one hand, and GPP, and in summer and winter, on the other, with NPP. Spatial and seasonal variations in productivity depend on the environmental and meteorological conditions at each station, including water temperature, salinity, conductivity, nutrient inputs and light availability. [ABSTRACT FROM AUTHOR]

Blue crab (Callinectes sapidus) supports lucrative Mid‐Atlantic crustacean fisheries and plays an important role in estuarine ecology, so their larval transport and recruitment dynamics in the Maryland Coastal Bays system were investigated using simulated and observed surface drifters. Relative contributions of winds, tides, density gradients, and waves to larval recruitment success were identified during the spawning season, particularly under hurricane conditions in 2014. Based on temperature (e.g., 19–29°C) and salinity conditions (e.g., 23–33 PSU), particles representing virtual blue crab larvae were released into the model domain from early June to late October 2014. During the spawning season, variations in the larval recruitment success caused by wind speed and direction, tides (e.g., affecting through inlets), density gradients (e.g., salinity variations), and surface gravity waves were 17%, 4%, −9%, and 17%, respectively. During Hurricane Arthur (2014), variability of self‐recruitment success caused by density gradients are negligible while by other three factors are comparable at 3%–4%. Surface drifter experiments support the modeling results that larval recruitment success is strongly associated with the coastal circulation. The high (low) self‐recruitment success in the Assawoman and Chincoteague Bays (Sinepuxent Bay) is related to the locally weak (strong) circulation; released larvae escape from inlets are likely recruited to southern Fenwick and northern Assateague Islands, and the coastal regions outside the Chincoteague Inlet. Understanding physical factors influencing larval recruitment success helps resource managers make informed decisions about habitat restoration and harvest regulations, in addition to seafood‐related food security. Plain Language Summary: Blue crab supports lucrative Mid‐Atlantic fisheries and plays an important role in the estuarine and coastal ecosystems. Its larval movement and recruitment in the Maryland Coastal Bays system were studied using computational visualizations and surface floating drifters. Given environmentally relevant water conditions, virtual particles that mimic blue crab larvae were released into a model domain from early June to late October 2014. During the spawning season, variations in the larval recruitment success caused by winds, tides, salinities, and waves are large, while they are relatively small but non‐ignorable during Hurricane Arthur (2014). Surface drifter experiments support the computer simulations that larval recruitment success is strongly associated with the background water movement. The high (low) self‐recruitment success in the bay is related to the locally weak (strong) circulation; released larvae escape from inlets are likely recruited around nearby islands and coasts. Presented is a successful application of coastal oceanography in fisheries oceanography. Understanding physical factors influencing larval recruitment is beneficial to habitat restoration, harvest regulations, seafood‐related food security. Key Points: A particle‐tracking model was successfully applied to investigate blue crab larval dynamics in a shallow lagoon‐inlet‐coastal ocean systemWind, tide, density gradient, and wave affect larval recruitment success in the Maryland Coastal Bays system during spawning seasonA unique data set of surface drifters confirms model simulations and provide additional insights into larval recruitment dynamics [ABSTRACT FROM AUTHOR]

Natural environmental change, anthropogenic development, and inter-annual variability can affect the ecology of estuarine fish and invertebrates. Yaquina Bay, Oregon, a well-studied estuary, has undergone intense development, as well as deep-draft dredging during the latter half of the 20th century, resulting in the alteration of ~45% of the lower estuary's natural shoreline. In 1967, the United States Environmental Protection Agency (USEPA) conducted a 21-month survey of Yaquina Bay to characterize the demersal fishes and epibenthic crustaceans that occupy the bay. From 2003 to 2005, we conducted a 25-month survey to replicate that work and provide a comparative snapshot of the demersal fish and epibenthic crustacean community in the bay. A comparison of the trawl survey datasets reveals a 91% decline in total catch per unit effort (CPUE) between surveys, as well as a decline in multiple measures of biodiversity. Furthermore, the fishes and crustaceans of Yaquina Bay have experienced a shift in species dominance from demersal fishes in the late 1960s to epibenthic crustaceans in the 2000s, marked most notably by a nine-fold increase in the Dungeness crab CPUE. While this work does not establish a causal relationship between changes in the demersal communities of this West Coast estuary and human or natural events, it does document substantial changes in both the diversity and total abundance of animals in that community over a three-plus decade period of development and environmental variability. Hence, this forms a second baseline for continued long-term monitoring. [ABSTRACT FROM AUTHOR]

One-third of all elasmobranchs (sharks and rays) are threatened with extinction. Euryhaline and estuarine generalist elasmobranchs are a group of 29 species that occupy non-marine environments during particular life-stages. These species are poorly known and disproportionately threatened, with 72.4% at risk of extinction or Data Deficient. A detailed knowledge of a species' life history characteristics, movement ecology, habitat use, and population structure are required for the implementation of appropriate management and conservation measures. To date, research on euryhaline and estuarine species has lagged behind marine species. Here, a literature review and gap analysis of the euryhaline and estuarine species was conducted to identify gaps in 14 key parameters required for management. Of the 29 species, only the Bull Shark (Carcharhinus leucas) and the Largetooth Sawfish (Pristis pristis) had detailed information on a majority of parameters assessed. Nine species lack information on most parameters, while the Broadnose Wedgefish (Rhynchobatus springeri) lacks information on all but one of the parameters investigated. There is a high level of understanding of age- and size-at-maturity, size-at-birth, and growth for only five species, while nine species have estimates of natural mortality. Comprehensive reproductive biology data is unavailable for six species. Both short- and long-term movement ecology is well-understood for only two species, and habitat use for six species. Population structure has been studied in only eight species. Data on key life history parameters, population structure, and habitat requirements of the euryhaline and estuarine elasmobranchs are urgently required to develop appropriate management strategies and to secure populations. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis of contaminant transport in estuarine environments, focusing on the impact of tidal creeks and flats. The research employs advanced hydrodynamic models with irregular grid systems and conducts a detailed residual current analysis to explore how these physical features influence the movement and dispersion of contaminants. The methodology involves simulating residual currents and Lagrangian particle trajectories in both 'Creek' and 'No Creek' cases, under varying tidal conditions. The results indicate that tidal creeks significantly affect particle retention and transport, with notable differences observed in the dispersion patterns between the two scenarios. The 'Creek' case demonstrates enhanced material retention along the creek pathways, while the 'No Creek' case shows broader dispersion, potentially leading to increased sedimentation in open sea areas. The discussion highlights the implications of these findings for sediment dynamics, contaminant transport, and estuarine ecology, emphasizing the role of tidal creeks in modulating flow and material transport. The research underlines the necessity of incorporating detailed environmental features in estuarine models for accurate contaminant transport prediction and effective estuarine management. This study contributes to a deeper understanding of estuarine hydrodynamics and offers valuable insights for environmental policy and management in coastal regions. [ABSTRACT FROM AUTHOR]

Objective: The Atlantic blue crab Callinectes sapidus (hereafter, "blue crab") is an ecologically and economically important species that supports one of the highest valued commercial fisheries in coastal South Carolina, USA. Researchers at the South Carolina Department of Natural Resources conduct multiple surveys to monitor the status of the blue crab by using a variety of gear configurations. Demographic characterizations can often be influenced by sampling gear‐related biases. Methods: We compared blue crab sex ratios between passive, pot‐based sampling and active, trawl‐based sampling in the fall across three estuaries and for year‐round sampling in a single estuary (Ashley River, South Carolina). Result: During the fall, there was a difference of 20.1% between the percentage of males collected in pot‐based sampling (73.5%) and the percentage of males in trawl‐based sampling (53.4%). Furthermore, an overall male bias of 23.0% was observed for year‐round sampling in the Ashley River; however, this bias was only significant in certain months. Conclusion: Our findings suggest that although particular sampling gears may have specific advantages, such as greater suitability to effectively sample certain habitats, the resulting characterizations of blue crab population demographics can differ among gear types. Recognizing gear‐related biases is important for ensuring that field surveys are representative of population demographics, particularly when sex‐specific modeling approaches are used as part of stock assessments to determine population status. Impact statementIn this study, we found that fisheries‐independent, pot‐based sampling produced blue crab catches that in many cases were significantly biased toward males when compared to catches from trawl‐based sampling. This finding has implications for sex‐specific stock assessments of blue crabs using fisheries‐independent data. [ABSTRACT FROM AUTHOR]

River flow is an important component of estuarine ecology, delivering the freshwater and nutrients that drive physical characteristics and productivity of the ecosystem. Extreme events (droughts and high rainfall) can have profound effects on estuarine nekton communities. In the present study, we used a 19-year fisheries-independent monitoring time series (2001–2019) in combination with data on river flow to examine long-term patterns in nekton community structure in Apalachicola Bay and investigate the effects of Apalachicola River flow rate on observed changes in community structure. Analyses included lagged effects at 1-, 3-, 6-, and 12-month intervals. Results suggested episodic shifts in relative abundances of numerically dominant taxa with a relatively stable group of species occurring through time, however there was some evidence of serial change in community structure. Correlations of community structure with time revealed regular seasonality of species assemblages in the Apalachicola Bay system, which was strongly correlated with water temperature. Spatial structure (zones within the system) in nekton communities was correlated with salinity, water clarity, and depth. River flow rates affected community structure at 6- and 12-month time lags, but the magnitude of effects varied among gear types and spatial zones within the system. The most significant shifts in fish community structure occurred during drought years. Results suggest that long-term changes in flow regimes strong enough to alter spatial salinity patterns and distribution of habitat types could affect community structure of nekton in the Apalachicola Bay system. [ABSTRACT FROM AUTHOR]

Cluster 5 picocyanobacteria significantly contribute to primary productivity in aquatic ecosystems. Estuarine populations are highly diverse and consist of many co‐occurring strains, but their physiology remains largely understudied. In this study, we characterized 17 novel estuarine picocyanobacterial strains. Phylogenetic analysis of the 16S rRNA and pigment genes (cpcB and cpeBA) uncovered multiple estuarine and freshwater‐related clusters and pigment types. Assays with five representative strains (three phycocyanin rich and two phycoerythrin rich) under temperature (10–30°C), light (10–190 μmol photons m−2 s−1), and salinity (2–14 PSU) gradients revealed distinct growth optima and tolerance, indicating that genetic variability was accompanied by physiological diversity. Adaptability to environmental conditions was associated with differential pigment content and photosynthetic performance. Amplicon sequence variants at a coastal and an offshore station linked population dynamics with phylogenetic clusters, supporting that strains isolated in this study represent key ecotypes within the Baltic Sea picocyanobacterial community. The functional diversity found within strains with the same pigment type suggests that understanding estuarine picocyanobacterial ecology requires analysis beyond the phycocyanin and phycoerythrin divide. This new knowledge of the environmental preferences in estuarine picocyanobacteria is important for understanding and evaluating productivity in current and future ecosystems. [ABSTRACT FROM AUTHOR]

Objective: Seaward migration and early marine residence are periods of high mortality in the lifecycle of Pacific salmon Oncorhynchus spp. The conservation of these species requires knowledge of habitat use patterns during early life to address survival bottlenecks. Using new miniaturized transmitters (V3 307‐kHz tag; Innovasea Systems), we investigated the association between biological and environmental factors and the residence behavior of subyearling Chinook Salmon Oncorhynchus tshawytscha in a fjord estuary in British Columbia. Methods: Tagged wild subyearling Chinook Salmon (n = 49; 67–95 mm) were experimentally released into an estuary. Using time‐to‐event analysis and model selection, we evaluated the association between biological (size, growth, day of release) and environmental (temperature, salinity, depth, discharge, tide direction) factors and estuary residence patterns. Result: Of the 49 fish released, 36 were inferred to have exited the estuary successfully. In this sample of subyearling Chinook Salmon, the median residence duration was estimated to be 11.2 days (95% CI = 6.5–15.5). We found tide direction and salinity to be important factors influencing the probability of a fish leaving the estuary. Fish were 75% more likely to leave the estuary on an ebb tide. Higher salinity also increased the probability of a fish leaving the estuary. Fish successful in leaving the estuary displayed either direct or indirect movement patterns in the estuary, with most fish (71%) being indirect movers that made multiple trips upstream and downstream. Within the estuary, most movements occurred at night (76%), regardless of tide direction. Conclusion: This study provides the first direct measure of estuary residence duration in wild subyearling Chinook Salmon and a valuable description of movement ecology in this age‐class of fish. While this was a small study in a single year, our results indicate this estuary is likely a stopover habitat for larger subyearlings. Studies indicating the use of habitats by specific populations, as presented here, are integral to the design of habitat‐based conservation measures for mobile species. Impact statementAcoustic telemetry reveals estuary residence patterns in subyearling Chinook Salmon to be diverse and largely influenced by tide (current) direction. This study supports calls for habitat connectivity along the entire migration corridor of juvenile salmonids. [ABSTRACT FROM AUTHOR]

Mud plays a pivotal role in estuarine ecology and morphology. However, field data on the lateral and vertical depositional record of mud are rare. Furthermore, numerical morphodynamic models often ignore mud due to long computational times and simplifications of mixed depositional processes. This study aims to understand the spatial distribution, formative conditions and preservation of mud deposits in the intertidal zone of bars in high‐energy sand‐dominated estuaries, and to elucidate the effects of mud on morphology, ecology and stratigraphic architecture. To meet these objectives, field data (historic bathymetry, bio‐morphological maps and sediment cores of the shoal of Walsoorden, Western Scheldt estuary, the Netherlands) were combined with complementary hydro‐morphodynamic numerical modelling (Delft3D). Based on the field observations, two types of mud deposits were distinguished: (1) mudflat deposits, which are thick (>10 cm) mud beds at the surface associated with high elevations and low accumulation rates; and (2) mud drapes, which are thin (millimetre to centimetre) buried laminae that form and preserve at a wide range of elevations and energy conditions. Model results show that deposition on mudflats occurs just after high‐tide slack water in areas shielded from high flood velocities, suggesting that mud accumulation is mostly controlled by elevation, flow velocity and flow direction. Mud accumulation increases shoal elevation, sometimes to supratidal levels. This reduces flow over the shoal, which in turn reduces chute channel formation, stabilises bar morphology and decreases local tidal prism. These effects further promote mud deposition and vegetation settling. Although observations show that mud cover at the surface is relatively high (20%–40% of the intertidal area), mud constitutes only a small percentage of the total estuary volume (ca 5%) revealing that only a small fraction is preserved in the stratigraphy. Due to this mismatch between surface and subsurface expression of mud, interpretations of estuarine stratigraphy risk underestimating the influence of mud at the surface on morphodynamics and habitats. [ABSTRACT FROM AUTHOR]

The present study intended to find out the variations in fish composition and CPUE (Catch Per Unit Effort) (November 2017 -- March 2018) of bottom trawl fishery at three stations viz., Parangipettai, Cuddalore and Pazhayar. Out of 16 sampling from these three stations, the highest CPUE was recorded from Parangipettai (70 kg/hr) and Cuddalore (51.4 kg/hr) between January and February 2018. Altogether, 67 finfish and shellfish species were identified from the trawl catches, of which Trichiurus lepturus, Leiognathus equula, Nemipterus furcosus, Rastrelliger kanagurta, Nibea maculata, Deveximentum insidiator, Nemipterus randalli, Terapon theraps, Eubleekeria splendens, Loligo vulgaris, Nemipterus japonicus, Sepia officinalis, and Leiognathus berbis were found as commercially important fishes. Additionally, Loligo vulgaris (165 kg) and Leiognathus berbis (35 kg) were found dominantly in the total catches from January to March 2018. The present investigation revealed that amid three study areas investigated, Parangipettai and Cuddalore exhibited higher total catch, CPUE, and fish diversity, which is also highlighted in the PCA (Principal Component Analysis). The high catch noticed in these areas might be due to increased productivity in the post-monsoon season supported by corresponding monsoonal nutrient influx, as Parangipettai and Cuddalore coastal waters experience high estuarine influx. Further, it was also evidenced by the observed higher values of essential nutrients such as nitrate (Cuddalore: 7.66 µM; Parangipettai: 8.17 µM) and silicate (Cuddalore: 6.68 µM; Parangipettai: 8.48 µM), and chlorophyll-a concentration (Cuddalore: 1.43 µg/l; Parangipettai: 2.09 µg/l) at both the stations. [ABSTRACT FROM AUTHOR]

Oyster farming may impact the estuarine tidal circulation with a series of effects on environmental conditions and cultures' growth. Hydrodynamic numerical models set up in estuaries integrated the presence of oyster structures by simply increasing the bottom friction coefficient over farming areas. However, for elevated oyster tables in tidal environments, such default calibration ignored the temporal variations of the friction coefficient between the conditions of submerged or unsubmerged structures. Thus, an original formulation of the Chézy coefficient was here proposed to integrate these modulations. Assessed against measured and predicted vertical velocity profiles on a 1/2 scaled model, this formulation was implemented in a simulation of the tidal circulation within the Aber Wrac'h estuary (Brittany, France). Particular attention was dedicated to the changes induced on the current magnitudes and sediment transport. Oyster tables were found to impact current magnitudes in the vicinity of elevated structures, with major differences at times of local peak flood and ebb. These modifications were characterised by (i) a reduction of current magnitudes over oyster farming areas and (ii) a tidal-flow acceleration on both sides of these structures. Increased sediment transport was, therefore, expected in the vicinity of these cultures, with potential implications on seabed morphology and water quality. [ABSTRACT FROM AUTHOR]

Hydrobioid gastropods are abundant in coastal systems and ecologically important for ecosystem functioning. We aimed to unravel the relationship between usual and stress-related population attributes of the dominant macrofaunal species Heleobia australis with indicators of environmental quality and coastal pollution. Using Guanabara Bay (GB, Brazil) as a model of a multi-impacted coastal system, our hypothesis is that increased amounts of rainfall during the warm season reduce the bay's environmental quality and induce shifts in snail population attributes. A suite of environmental variables, population attributes, and sediment quality descriptors was assessed by combining field and laboratory evaluations with literature compilation. Results indicate high organic pollution levels with environmental degradation and reinforce GB status as a severely contaminated system. Some environmental conditions can be applied as seasonal predictors of changes in warm-rainy (rainfall and salinity), intermediate (silicate), and cold-dry seasons (nitrite and nitrate). Three selected usual population attributes (snail density, fecundity, and recruitment) were not affected by changes in environmental conditions, but significant effects were detected on two stress-related attributes (relative penis length index and shell deformity). For the first time, shell deformity was recorded in H. australis snails. Low variation in usual population attributes highlight the high tolerance of H. australis to shifts in environmental conditions. [ABSTRACT FROM AUTHOR]

The vegetation history of the Texas Gulf Coastal Plain in the Holocene is considered according to pollen evidence from three coring sites where both terrestrial and marine ecology are reconstructed. These pollen sites record oscillations in the limit of the Southeastern US Forest zone in relation to climate changes, with a major, southward migration of the forest limit and expansion of the range limit of Betula nigra being recorded in the 6th millennium BP and a northward migration in the 4th millennium BP. The appearance of Rhizophora pollen also indicates increased tropical influence in the Middle Holocene. Moreover, changes in the salinity profiles of estuaries are reconstructed in relation to broader coastal environmental changes, such as sea-level oscillations and the formation of barrier islands, with a major sea-level transgression phase being recorded in the 4th millennium BP and still-stand conditions after the 3rd millennium BP. These vegetation changes are finally compared to occupational evidence of prehistoric humans in the Central Texas Gulf Coastal Plain region in relation to ecological factors. Here, human occupation of the coastal zone is correlated with afforestation, the proliferation of pecan and the emergence of low-salinity estuaries. [ABSTRACT FROM AUTHOR]

Estuarine systems often have degraded ecology and functioning due to the multiple interacting stressors that they face. While conventional management might address such a situation with narrow focus, ecosystem based management provides a more holistic and adaptive option allowing for multiple objectives and values. Such an approach has some commonality with that of the Indigenous Māori of New Zealand, who have holistic, interconnected and intergenerational aspirations. In this study we utilised Te-Rerenga-Parāoa, Whangārei Harbour, Aotearoa New Zealand as a case study to explore how ecological and Māori knowledge systems and approaches may align to address complex multi-stressor and multi-value scenarios common to estuarine systems. To achieve this we co-developed a Bayesian network heuristic modelling tool which provided a probabilistic framework to consider the relationship between stressors and the outcome states for ecological function and cultural values. The process of model development itself was a rewarding exercise of joint learning. For example, this process illustrated that while western ecological values can focus on endpoints such as abundance, cultural values were more diverse, experiential in nature, with value often centred on a cultural practise being enabled, not just the ecological component the value was connected to. Once the model was developed we considered three specific scenarios relating to harbour dredging, environmental degradation from land use changes, and fishery extraction. Model predictions for these scenarios generally matched expectations, but were generic in nature and could therefore benefit from more specificity relating to aspects such as spatial scale and context around cultural interpretation. Overall, the model demonstrated generic utility as an interactive educational tool for resource managers considering the broader impacts (on ecology and cultural values) of major societal challenges. [ABSTRACT FROM AUTHOR]

IntroductionSediment and nutrients flow into estuary with runoff, and then influence the estuary ecosystem. Much work has been done for investigating the response of water quality and species group (eg. phytoplankton or zooplankton) to the runoff from upstream, while few research has been taken to evaluate the response of the whole ecosystem.MethodsFood webs of different seasons and regions were established based on stable isotope analysis and Bayesian mixing model. The influences of upstream runoff and sediment transport on the estuarine food webs were analyzed.ResultsFood web in estuary had highly spatial-temporal variability. The stable isotope values of organisms were higher on the northern shore than that on the southern shore. The area with high-turbidity freshwater inflow nurtured more terrestrial- organic- matter (TOM) relying species. And the contribution of TOM to food web was higher in flood season than that in non-flood season. The trophic levels of major consumers in the non-flood season were generally higher than that in the flood season. Significant differences in the average TP of species between two shores appeared during the non-flood season (P < 0.05). Expect for the C value, all of the topological indexes of food webs on the northern shore were higher than those on the southern shore, and they were higher in the flood period.DiscussionThe input and diffusion of sediment and nutrients carried by runoff led to the changes in the dietary structure of estuarine organisms and the decrease in trophic levels of major consumers. At the same time, flow pulse with high sediment also aggravated the spatial differences of the structure of food webs. The higher contribution of TOM to consumers increased the link density of food web on the southern shore, making it a more robust system. However, the high diversity of food sources and aquatic species made the food web more complex on the northern shore.

This work assesses the effectiveness of sample preservation techniques for measurements of pHT (total scale), total dissolved inorganic carbon (DICT), and total alkalinity (AT) in organic-rich estuarine waters. Using HgCl2-treated and untreated water samples, measurements of these carbonate system parameters were examined over a period of three months. Over this duration, continued respiration of dissolved organic matter (DOM) in untreated samples created large discrepancies in DICT concentrations, while DICT was effectively constant in treated samples. Changes in AT were observed for both treated and untreated samples, with treated samples showing the greatest variation. In response to changing AT / DICT ratios, pHT changes were observed in both treated and untreated samples but were relatively small in treated samples. Improved accuracy of results in organic-rich estuarine waters that reflect the in situ carbonate system characteristics of the samples at the time of collection can be achieved when samples obtained for DICT and AT analysis are collected and stored separately. Accurate analyses of DICT can be obtained by filtration and preservation with HgCl2. Accuracy of AT analyses can be improved by filtration and storage in polypropylene bottles at 4 °C without adding HgCl2. Quality of pHT measurements can be improved by prompt analysis in the field and, if this cannot be accomplished, then samples can be preserved with HgCl2 and measured in the laboratory within one week. [ABSTRACT FROM AUTHOR]

Several organisms serve as biological indicators for assessing various ecosystems’ health. Different chemical compounds found in the environment such as copper, chloroform, and adrenaline can induce to the crustaceans an adaptive response by producing more Crustacean Hyperglycemic Hormone (CHH) by the X organ and sinus gland (XO-SG) complex located in the eyestalks. Even though the above-mentioned chemical compounds provoke stress in the species organism, the abiotic factors have the same effects too. They both can increase the hemolymph glucose level, affect the total hemocyte count (THC), and the differential hemocyte count (DHC), and cause the destabilization of the lysosome membrane (decrease of NRRT, p<0.05). In the long-term, stressors will adversely impact the C. aestuarii health, compromise reproduction, and the general population health of this species. The Crustacean Hyperglycemic Hormone (CHH) is a proteinic hormone that intermediates the whole physiological process at the molecular level. It represents an open reading frame sequence of 429 base pairs, responsible for the coding of a 142-aminoacid protein with a signaling peptide of 26 amino acids, followed by a peptide attached to the CHH precursor of 40 amino-acids, and the mature peptide of 72 amino acids and it results by the first determination based on a high similarity (98.6%) with the CHH peptide from C. maenas compared with CHHs from Brachyura infraorder. [ABSTRACT FROM AUTHOR]

Marine heat waves (MHWs) have been associated with extensive harmful algal blooms (HABs) in the northeast Pacific Ocean, but the degree to which these large-scale oceanographic events are mirrored in nearshore environments has not been well established. We compared phytoplankton assemblages in the Lower Columbia River Estuary (LCRE) during two Pacific MHWs that took place in 2015 and 2019, with observations from 2017, a year with no MHW. These data were paired with environmental data from the summers of 2015–2019 to characterize differences in estuarine conditions during MHWs that promote phytoplankton assemblage transitions and identify HAB-conducive conditions. Bloom densities of HAB taxa, Pseudo-nitzschia spp. (4.16 × 106 cells L−1) and Gymnodinium catenatum (5.66 × 106 cells L−1), were noted in the estuary during 2015 and 2019, respectively, 2 years where Pacific MHWs occurred during the summer months. These blooms coincided with estuary temperatures that were 1–2 ℃ above and river discharge volumes 46–48% lower than decadal daily averages. We identified patterns in the densities of several algal taxa associated with MHW-mediated low discharge in the LCRE, such as declines in tychopelagic diatoms and increasing abundance of pelagic marine taxa. We conclude that low river discharge, through extension of saline habitat area and longer residence times, likely contributed to the development of the observed marine HABs in the estuary. MHWs and associated declines in discharge are projected to become more common in the Pacific Northwest with climate change, which may alter late summer phytoplankton assemblages in the LCRE. [ABSTRACT FROM AUTHOR]

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Estuarine eutrophication due to the nutrient run-off from the agricultural fields encourages the establishment of several opportunistic seaweeds. These fast-growing seaweeds, considered an untapped resource, with a circular economy approach, can be employed as soil plant fertilizer. In agriculture, there is a global trend toward shifting from chemical-based conventional farming to sustainable agriculture. In this context, this study aimed to understand the biostimulant potential of the aqueous extracts from seaweeds harvested in Mondego estuary located on the Atlantic coast of Portugal, namely Ulva lactuca (Sea lettuce), Fucus ceranoides (Estuary Wrack) and Gracilaria gracilis (Slender Wart Weed), in kale (Brassica oleracea L.) seed germination and seedling development. The results showed that Gracilaria gracilis extract enhanced kale seed germination, presenting a higher seedlings weight (0.076 ± 0.004 g) and length (15.48 ± 0.59 cm), when compared with seedlings obtained in distilled water used as a control (weight = 0.059 ± 0.002 g; length = 13.10 ± 0.54 cm). Fucus ceranoides showed the lowest influence on seedling development (weight = 0.062 ± 0.002 g; length = 12.97 ± 0.59 cm). However, these results demonstrated that seaweed aqueous extracts can indeed enhance seed germination and seedling development. [ABSTRACT FROM AUTHOR]

Differential metal accumulation in fractionated sediments within highly urbanized land-sea ecosystems is significant, often due to an imbalance between sluggish hydrodynamics and over dumping of contaminants. Here, an initial constraint on differential metal enrichment in fractionated sediments is highlighted along the estuary, creek, and nearshore regions of one of India's highly urbanized regions, Mumbai. Sediments were segregated into four fractions (A: < 25 µm; fine, B: 25 - 63 µm; moderate, C > 63 µm; coarse, and D: bulk) using the wet-sieving technique and were analysed for 23 metals. The results indicated that bulk sediment (D) constituted a moderate enrichment of transition metals Cr, Co, Ni, Cu, Hg, and Tl. The Distribution Factor (DF) indicated that metals such as Cr, Co, Ni, Cu, and Zn frequently showed DF > 1 in fraction C. The reason for higher concentration of these metals in fraction C is indicative to weak tidal influence, that resist the flow of the higher density fraction and increases its residence time in the anthropogenically stressed region. Grain size showed a notable dominance of silt (> 80 %), mainly transported from the mudflats. Turbulence caused by activities such as periodic deepening, high-frequency vessel movement, and other modernization activities provoked the transport of fine particles. Considering that weak dynamic sediment transportation is mainly conducive to man-made changes, the associationdissociation of metals in size-specific sediment particles will significantly impact their further transport and cycling. [ABSTRACT FROM AUTHOR]

Biodiversity is important for communities to be resilient to a changing world, but patterns of diversity fluctuate naturally over time. Understanding these shifts — and the species driving community dynamics — is crucial for informing future ecological research and conservation management plans. We investigated the impacts of seasonality, small-scale changes in seagrass cover, and small-scale spatial location on the epifaunal communities occupying a temperate seagrass bed in the South Island of New Zealand. By sampling epifaunal communities using a fine-mesh push net two to three times per season for 1 year, and using a combination of multivariate and hierarchical diversity analyses, we discovered that season, seagrass cover, and the location within the bay, and their interactions, explained 88.5% of the variation in community composition. Community composition and abundances, but not numbers, of species changed over seasons. The most common taxa were commercially important Caridean shrimp and juvenile flounder (Rhombosolea spp.), and both decreased in abundance in summer (shrimp: 1.40/m2 in winter to 0.80/m2 in summer; flounder: 0.15/m2 in winter to 0.01/m2 in summer). Other commercially important species were captured as juveniles, including blue cod (Parapercis colias), kahawai (Arripis trutta), and whitebait (Galaxias spp.). The only adult fish captured in the study were two pipefish species (Stigmatopora nigra and Leptonotus elevatus), which had distinctly seasonal breeding patterns, with reproductively active adults most likely to be found in the spring and fall. Our study highlights the importance of estimating biodiversity parameters based on sampling throughout the year, as some species will be overlooked. We demonstrate that the temperate estuarine seagrass-affiliated animal communities differ in response to season and fine-scale local environments, causing fluctuations in biodiversity throughout the year. [ABSTRACT FROM AUTHOR]

Estuaries are ecologically sensitive areas influenced by river regulation. Knowledge of how marine megabenthos responds to river regulation and artificial flooding events remains limited. The study aims to provide a comprehensive understanding of the impacts of river regulation on marine megabenthic fauna. The oceanographic investigations were conducted at the Yellow River Estuary and its adjacent area during three distinct periods of river discharge, that is, spring low-flow (IA), summer low-flow (IB), and artificial flood (IC) periods. Samples of megabenthos and 14 mainly environmental parameters were investigated during different periods. The comprehensive indices of biodiversity ( C-diversity ), phylogeny ( C-phyl ), and stability ( C-stability ) were synthesized from 24 basic indices to characterize the overall traits of megabenthos faunas. All 210 species were collected during three periods, belonging to 16 classes and 51 orders. The typical estuarine communities were mainly distributed in the key area within 30 km of the estuary during the low-flow periods. The estuarine community presented with low biodiversity ( C-diversity  = 0.15) but high stability ( C-stability  = 0.64) during the IA period, followed by an increase in biodiversity during the IB period ( C-diversity  = 0.35, C-phyl  = 0.69). The community underwent dramatic changes during the IC period, which bifurcated into distinct northern and southern groups. The northern community maintained high biodiversity and homeostasis ( C-stability  = 0.60), whereas the southern stability decreased sharply (0.11). On the whole, the artificial flood reshaped the geographical distribution of megabenthic fauna in the estuarine area within 20 days, mainly as a result of the dramatic changes in seawater salinity and nutrient structure caused by flow pulse. An eco-friendly discharge management of the Yellow River is needed to mitigate the impact., Competing Interests: The authors declare no conflicts of interest., (© 2025 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

Uncertainties associated with wild harvests of seed and adult oysters due to unknown oceanographic oscillations are a major challenge in oyster fisheries and aquaculture development. In contribution to addressing this challenge, we proffer clarity on the spatiotemporal variations in spatfall (number of spat/m2) of the mangrove oyster Crassostrea tulipa (Lamarck, 1819) in four estuaries along the Gulf of Guinea coast. By monthly deployment of artificial substrates affixed to bamboo racks over 12 months, we find significant differences in spatfall among and within the brackish systems, and across months and seasons. Spatfall regimes were unique in each ecosystem albeit with an overall preponderance of dry season availability of spat. Locations with reef oysters had superior spatfall to mangrove root-adapted-oyster areas. Narkwa, a relatively small lagoon with reef oysters had the highest annual mean spatfall, which was 1.3, 2.5, and 9.8 folds the spatfall in Densu Delta, Benya Lagoon and Whin Estuary, respectively. Spatfall varied significantly by depth as the more frequently exposed top collectors harvested much less spat than submerged collectors. There was a year-round availability of spat, confirming continuous spawning in C. tulipa. Spatfall variability was significantly driven by fluctuations in prevailing dissolved oxygen and salinity. Prevailing dissolved oxygen and salinity levels in the estuaries for optimal spat settlement were 1.68 – 3.40 mg L-1 and 11.00 – 29.33 ppt (parts per thousand), respectively. The findings of this study are recommended as empirical reference points for sustainable seed procurement for aquaculture production and management of C. tulipa fishery in the region of the study.

Coastal lagoons and other estuarine habitats are increasingly exposed to the negative effects of growing human populations with associated intensifications in nutrient loading, harmful algal blooms, pollution, and habitat degradation. We examined population dynamics of Gulf pipefish Syngnathus scovelli in estuarine waters of the Indian River Lagoon, on the Atlantic coast of Florida. Substantial declines in abundance of this sentinel species were concurrent with significant losses of seagrass habitat associated with ongoing harmful algal blooms, and other perturbations during the study period spanning from 1998 to 2018. Moderate declines in S. scovelli were observed with early downward trends in seagrasses ahead of the onset of the precipitous seagrass reductions observed. The massive decline of seagrass habitats in the Indian River Lagoon in recent years had negative influences and was directly linked to population declines we observed in the S. scovelli population. Lack of seagrass habitat essential to this and related syngnathid species may reduce optimum seagrass-associated prey, increase predation by lack of appropriate cover, and increase energetic costs which may be realized through reduced growth rates and potential reproductive impairment. Identification and monitoring of population trends of S. scovelli and related sentinel fish species allow for early implementation of management actions that reduce the impact of anthropogenic pressures on the services that estuarine systems provide to the fishes and fisheries they support. [ABSTRACT FROM AUTHOR]

A crucial aspect of sustainable resource management is understanding the trophic interactions amongst fish in the estuarine ecosystem. The goal of this study was to look into the food preferences, feeding strategies, trophic partitioning, as well as dietary overlap among four omnivorous species that live in the Cochin Estuary: Mugil cephalus (n = 73), Planiliza parsia (n = 35), Planiliza planiceps (n = 65) and Chanos chanos (n = 55) through the analyses of gut-content. Index of relative importance demonstrated that prey items in Mugil cephalus and Planiliza planiceps guts were dominated by Bacillariophyceae whereas in Planiliza parsia and Chanos chanos guts were dominated by Myxophyceae. The highest diet value (7.5) was recorded in Chanos chanos, while the lowest was recorded in Mugil cephalus (5.69). The highest niche breadth value (0.77) was recorded in Planiliza planiceps while the lowest value was recorded in Planiliza parsia (0.52). Pianka's overlap, evaluated with the help of null models structured by Ecosim 7.0, showed remarkable niche overlap between Mugil cephalus and Planiliza planiceps (0–0.92, P < 0.001), between Planiliza planiceps and Planiliza parsia (0–0.77, P < 0.05) and between Mugil cephalus and Planiliza parsia (0–0.7, P < 0.05). The fish's trophic niche width, along with prey-specific abundance confirmed that they are generalist feeders. The present results differed from the general hypothesis related to the omnivorous species and concluded that these four omnivorous species live in the same niche zones of the Cochin Estuary with no interspecific conflict. This work provides the first information about feeding habits, trophic ecology and trophic interactions of all examined species(Planiliza parsia, Planiliza planiceps, Mugil cephalus and Chanos chanos) from Cochin Estuary. The result of this work differs from the hypothesis related to omnivorous fishes and concludes that these four omnivorous species live in the same niche zones of the Cochin Estuary with no interspecific conflict. This work will help to give light to the trophic interaction of this species and helps to formulate sustainable resource management. [ABSTRACT FROM AUTHOR]

This study explores the differences of fish assemblages in three macrotidal estuaries of Man-gyeong River Estuary (MRE), Geum River Estuary (GRE), and Han River Esturay (HRE) with similar ranges of seasonal water temperature that are diked with different levels of disconnection from freshwater discharge. The distribution of major species in the three estuaries could generally be grouped into three distinctive patterns based on their cumulative distribution with respect to the salinity gradient. The MRE was geographically closer to the GRE than to the HRE, but the fish community of the MRE more closely resembled that of the HRE. Increased freshness of the water inside the dike and the limit of coastal fish to the river may have led to this result. The results provide clues to how enclosure patterns of estuarine waters could affect fish communities over a long-term period. In addition, the information may provide guidance for how a fish community may return once environmental conditions are restored. [ABSTRACT FROM AUTHOR]

Vibrio cholerae is a potential human pathogen that inhabits aquatic environments, although its presence and abundance have been associated with increased water temperature, little research has been done on its ecology in tropical estuarine environments, where salinity changes tend to be more important. The present study evaluated the distribution of V. cholerae in the Ciénaga Grande de Santa Marta and its relationship with temperature and salinity; For this, between 2016 and 2018 this microorganism was quantified bimonthly in surface water samples, using TCBS agar and biochemical tests. V. cholerae was detected in 57 of 198 samples (28.8 %), varying in density between 5 CFU / 100 mL and 54,800 CFU / 100 mL. Between January and September 2016 there was a high average monthly salinity (= 28.7 °C) and a low detection of the bacteria (0.01 %). Average salinity dropped drastically in November 2016 (9.6), coinciding with a proliferation of V. cholerae (geometric average 36.4 CFU / 100 mL). During 2017 and 2018, the average salinity remained below 15.2 and the detection of V. cholerae was higher (39.4 %) than in 2016, with higher densities in the months with lower salinity. At the BVA and NVE stations, where palaphytic populations are located, the highest average (geometric) densities were recorded, 25.3 CFU / 100mL and 15.4 CFU / 100mL, respectively. The results of this study show that salinity plays a determining role in the occurrence and abundance of V. cholerae in this tropical lagoon. [ABSTRACT FROM AUTHOR]

Accounts are provided of the examination of two adjacent crannogs in the Clyde at Erskine and Old Kilpatrick. The first is based on the planning of the surface remains, a more detailed examination of some of the timbers and an assessment of the limited finds recovered; the second on collating the scattered antiquarian records of an 'excavation' undertaken in 1906 and a detailed examination of the surviving finds. The two sites are contextualised within current understanding of the chronology, character and function of estuarine crannogs in the western lowlands of Scotland [ABSTRACT FROM AUTHOR]

The eastern oyster Crassostrea virginica contributes important ecological and structural elements to estuarine ecosystems worldwide. Oyster reef persistence requires regular recruitment as well as growth by existing individuals. Saltmarsh tidal creek oyster population age structure and growth rales directly influence local benthic-pelagic coupling and biogenic habitat formation. Recruitment monitoring, substrate deployments (2017-2020), and field surveys (2018) were conducted in North Inlet Estuary, SC, to quantitatively describe oyster age-shell height relationships, population age structure, daily growth rates, and survivorship. Multiple recruitment events resulted in three to four cohorts each year. Oysters exhibited rapid shell growth but most died by the end of their second growth season after attaining shell heights of less than 100 mm. Daily growth rates immediately after recruitment (approximately 0.07-0.29 mm [day.sup.-1]) and within the first 2 y (0.1-0.4 mm [day.sup.-1]) allow maximum shell heights of 50-55 mm after to 6-8 mo, 80 mm within 1 y, and 140 mm within 1.6 y. Recruitment timing strongly influenced shell heights after 1 y. with July recruits approximately 33% larger than May recruits within the same year. The North Inlet oyster population age structure was dominated by oysters in their first (55%) or second (45%) growth season, with individuals less than 100 mm shell height composing approximately 99% of the population. Oyster survivorship beyond 2 y appears to be unusual. The opportunistic life history strategy used by North Inlet oysters incorporates multiple large recruitment events each year and rapid growth rates to offset short life spans so as to maintain reef populations and related ecosystem services. KEY WORDS: oyster, Crassostrea virginica, recruitment, life history strategy, life expectancy, population dynamics, saltmarsh tidal creek, INTRODUCTION Eastern oysters (Crassostrea virginica) contribute fundamental ecosystem services to estuarine and coastal habitats worldwide (Ulanowicz & Tuttle 1992, Coen & Luckenbach 2000, Gutierrez et al. 2003, Coen et al. [...]

In this study, we numerically investigate the effect of the Earth's rotation on the salt dynamics in an idealized convergent partially mixed estuary. The effect of the Coriolis force on salt transport is shown to vary in different parts of the estuary. Near the estuary mouth and in the upper estuary, compared with nonrotating environments, the Coriolis force weakens the longitudinal estuarine circulation and salinity stratification, thus decreasing the landward salt transport induced by the steady shear. On the other hand, the Coriolis force increases the magnitudes of the tidal variations of current and salinity, and decreases the phase shift between these two variables, resulting in enhanced landward transport of salt by the tidal oscillatory. In the middle estuary, the Coriolis force has less effect on the steady shear and tidal oscillatory transport. The Coriolis force decreases the salinity along the channel bottom by decreasing the vertical advection and increasing the vertical mixing, which results in a decreased salt intrusion. Sensitivity experiments show that in partially mixed estuaries with landward salt transport dominated by steady shear, the effect of the Coriolis force is proportional to the Coriolis parameter, and is more prominent for moderate tidal mixing and higher river discharge scenarios. However, when the tidal mixing is further increased and the estuary transits into a state of well‐mixed with landward salt transport dominated by tidal dispersion, the Coriolis force is shown to increase the stratification and estuarine circulation, and consequently enhances the salt intrusion. Plain Language Summary: Salt dynamics are important for estuarine physics, and also essential to freshwater supply in many estuaries around the world. This study specifically examines the effect of Coriolis force in convergent partially mixed estuaries. We note that the Coriolis force decreases the salt intrusion length in partially mixed estuaries. The Coriolis force increases the development of landward residual flow on the right side of the channel (looking into the estuary in the Northern Hemisphere) and seaward residual flow on the left side of the channel. It redistributes salinity in the cross‐section by decreasing salinity near the bottom and on the left side of the channel, but increasing salinity at the upper part and on the right side of the channel, therefore enhancing the vertical mixing. In this way, the Coriolis force decreases the salt intrusion in the estuary. This study also examines the dependency of the Coriolis' effect on the Coriolis parameter, river discharge, and tidal mixing. We find that a larger Coriolis parameter, a higher river discharge, and a stronger tidal mixing generate stronger impacts on the salt intrusion. However, when the tidal mixing is further increased and the estuary changes into a well‐mixed one, the Coriolis force enhances the salt intrusion. Key Points: The Coriolis force decreases salt intrusion length in convergent partially mixed estuariesThe Coriolis force weakens the longitudinal estuarine circulation and salinity stratificationThe effect of the Coriolis force depends on the Coriolis parameter, river discharge and tidal mixing, and the status of the estuary [ABSTRACT FROM AUTHOR]

Mumbai's dumping grounds, located on the city's estuarine edge, are sites where garbage and marsh are turned into salable land. This process of translating waste into land depends on keeping matter, beings, and landscapes separate and on limiting their interactions. Yet waste and the marsh interact and transform in ways that escape managerial discourse, revealing a haze of category and control errors that complicate knowledge, agency, and responsibility. While developers translate waste to land in relation to developmental goals, fishing communities, scientists, and activists translate it differently: scientists translate it in relation to chemical properties, interactions, and timelines; marine‐life activists draw attention to its coastal ecologies; and fisher communities look for productive possibilities on a polluted shore. These translations attend to the inseparability of waste substances from the coast and its futures. They articulate a politics that acknowledges waste's sociopolitics, material agency, temporalities, and multispecies ethics. [coast, waste, development, pollution, marine life, ecology, chemistry, Mumbai] [ABSTRACT FROM AUTHOR]

Fisheries and urban marine ecology meet within the world's densely populated estuaries and coasts, where the imperative of dredging, construction and catchment modification occurs alongside the socio-economic characteristics of urban communities. Estuarine fisheries in urban areas have often shifted away from commercial harvest towards recreational fishing, fuelled by a diverse range of motivational factors. These systems are thus often dominated by recreational and subsistence fisheries, with the fisheries system variously impacted by eutrophication, contamination and pollution, altered trophic structure, habitat loss and hard structure. Urban marine ecosystems may be distinguished by the absence of spawning by exploited finfish, coupled with the gradual loss of environmental signals for recruitment, reduced larval supply and loss of nursery habitats for juveniles, but alongside an abundance of hard structure habitats for adults. The shift from commercial fishing to preferential harvest of more predatory "sportfish" means that the historical trophic structure has shifted towards lower trophic levels (e.g. prawns, detritivores, planktivores). We outline urban estuarine fisheries ecology as a developing paradigm defined by the unique ecological attributes of urbanised estuaries, the socio-economic objectives of fishers therein, and bottlenecks to productivity of the species they exploit. We identify goals for future research and management and illustrate these concepts through discussion of stock enhancement with a large estuarine predatory fish. [ABSTRACT FROM AUTHOR]

Coastal upwelling caused by winds seasonally occurs in summer in the Northern South China Sea. The alongshore prevailing southwest winds, induced by East Asia Summer Monsoon, exert a uniform Coriolis force to drive the surface water offshore, which in turn pushes the deeper coastal water upward. The common view is that coastal upwelling brings up nutrients from deep water. The presence of a buoyance layer such as the riverine or estuarine plumes damps the Ekman effect and hence upwelling. However, the semi-quantitative analysis of reduced upwelled nitrate amount due to plume (barrier) effect during this interactive process is rare. To examine the dynamics of water masses and nutrient upward transport process in the coastal waters in summer, vertical profiles of temperature, salinity, and nitrate were taken along the transects from the Pearl River estuary to 150 km offshore in July cruise of 2002 in the northern South China Sea. The results show a three-layer structure resulting from the three water masses under the impact of a large buoyant plume: high-nutrient plume water in the surface layer, undetectablenutrient offshore surface water in the middle layer, and low-nutrient deep water in the bottom layer. This structure indicates that this middle layer was the offshore surface water entrained underneath the estuarine plume and hence, weakened the intensity of upwelling. Upwelled nitrate amount is reduced by ∼30%–35% from the deep water to the surface layer due to the middle layer based on our estimate. The finding suggests that the presence of estuarine plumes plays an important role as a barrier to weaken upwelling of deep water and subsequently reduce the upward transport of nutrients by wind-induced coastal upwelling and therefore, such the barrier effect should be considered in estimating budgets of nutrients and subsequent carbon fixation in coastal waters. [ABSTRACT FROM AUTHOR]