Estuarine Coastal and Shelf Science最新文献

{"title":"Long-term trophic ecology of juvenile Atlantic bluefin tuna in the western mediterranean sea","authors":"Mar Pardo ,&nbsp;Fernando Á. Fernández-Álvarez ,&nbsp;José Luis Varela ,&nbsp;Joan Navarro ,&nbsp;Antonio Medina ,&nbsp;María José Gómez-Vives ,&nbsp;Valerio Sbragaglia ,&nbsp;Jose María Bellido ,&nbsp;Marta Coll ,&nbsp;Joan Giménez","doi":"10.1016/j.ecss.2025.109471","DOIUrl":"10.1016/j.ecss.2025.109471","url":null,"abstract":"<div><div>Global marine ecosystems confront increasing anthropogenic pressures, such as overfishing, pollution, habitat degradation, and climate change, leading to declining fish populations. Atlantic bluefin tuna (ABFT; <em>Thunnus thynnus</em>), an ecologically important apex predator, has historically suffered from overexploitation. Conservation efforts have been implemented to mitigate its decline, leading to a recovery of its stock in recent years. In the western Mediterranean Sea, concerns have emerged among purse seine fishers regarding the potential impact of the resurgence of ABFT on sardine (<em>Sardina pilchardus</em>) and anchovy (<em>Engraulis encrasicolus</em>) populations, crucial prey for ABFT and the fishing industry, and currently overexploited or with low population biomass levels. This study investigates the trophic ecology of juvenile ABFT in the Gulf of Valencia, western Mediterranean Sea, across three periods: 1989, 2012–2014, and 2018–2019. Through a combination of stomach content analysis and stable isotope analysis, which complement each other, we aim at achieving a comprehensive understanding of the trophic ecology. ABFT's dietary preferences are revealed as flexible and opportunistic, encompassing a diversity of prey species, including fish, cephalopods, and crustaceans. Variations in the composition of the diet of juvenile ABFT can be attributed to fluctuations in the availability of prey, mainly due to a synergistic effect of overfishing and climate change. Likely in response to declining populations of sardine and anchovy, juvenile ABFT have changed their dietary habits, decreasing their consumption of these species and increasing their ingestion of horse mackerels (<em>Trachurus</em> spp.), another pelagic predatory fish present in the western Mediterranean Sea. Our data suggest that concerns of fishers regarding the consumption of sardine and anchovy by the increasing ABFT population are not supported, at least for juvenile individuals. Understanding the trophic relationships and feeding dynamics of ABFT has wider implications, and can provide insights into ecosystem resilience, predator-prey interactions, and adaptative responses to changing environments.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"325 ","pages":"Article 109471"},"PeriodicalIF":2.6,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of salinity in shaping the early life stages of Aphanius fasciatus","authors":"Luca Altavilla ,&nbsp;Federico Surra ,&nbsp;Chiara Facca ,&nbsp;Francesco Cavraro ,&nbsp;Agostino Forlani ,&nbsp;Stefano Malavasi","doi":"10.1016/j.ecss.2025.109478","DOIUrl":"10.1016/j.ecss.2025.109478","url":null,"abstract":"<div><div>Salinity is a key environmental factor shaping the physiology, reproduction, and survival of estuarine and coastal fish species. <em>Aphanius fasciatus</em>, a euryhaline killifish inhabiting Mediterranean transitional water ecosystems, is listed in Annex II of the European Habitat Directive due to its ecological significance. Although highly tolerant to salinity fluctuations, its presence in oligohaline waters is limited. This study investigates the effects of salinity on <em>A. fasciatus</em> reproductive and early developmental stages by assessing (1) egg deposition rates, (2) hatching success across a salinity gradient, (3) egg mortality across a salinity gradient, and (4) larval survival probabilities. Results revealed that egg mortality is statistically higher and fry survival rate statistically lower in oligohaline conditions. Our findings contribute to understand how salinity influences reproductive success and early-stage survival, providing valuable insights into the species' ecological resilience. This knowledge is essential for conservation strategies in transitional waters, where salinity fluctuations are intensified by climate change. The discussion supports the use of ecological systems modelling as a valuable tool for studying and managing complex systems, such as transitional aquatic environments.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109478"},"PeriodicalIF":2.6,"publicationDate":"2025-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144764137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An experimental study of spur dike construction impacts on bed scour under bidirectional tidal currents","authors":"Chunchen Xia ,&nbsp;Huangjie Xia ,&nbsp;Zekai Zhu ,&nbsp;Lingna Zhang ,&nbsp;Chao Sun ,&nbsp;Haoyong Tian","doi":"10.1016/j.ecss.2025.109475","DOIUrl":"10.1016/j.ecss.2025.109475","url":null,"abstract":"<div><div>Spur dikes are used for bank protection in tidal rivers. During construction, the dike is extended segment by segment, and its interaction with the reversing tidal flow directly reshapes the adjacent riverbed morphology. Flume experiments were conducted to simulate this process and capture short-term bed deformation. The results revealed that tidal-induced scour holes developed in alignment with flood tide direction under flood dominance, and the secondary scour holes emerged in the ebb direction near the dike head. Under unidirectional flow, the scour hole forms along the flow direction and extends downstream in a narrow, elongated shape. For inclusion of construction-process effects (ICE), the pre-existing scour hole by the increasing dike length and newly formed scour holes after dike completion on the upstream side of the spur dike head exhibit interwoven extension patterns, while the scour holes of exclusion of construction-process effects (ECE) include a stronger primary scour hole in the flood tide direction and a smaller secondary scour hole in the opposite ebb tide direction. Scour depth of the ECE exceeds that of the ICE in the mid-to-downstream region in front of the dike head, whereas in the mid-to-upstream region of the dike head, scour depth of the ICE may surpass that of the ECE, which requires significant attention in practical construction. An empirical scour depth prediction formula for ICE was established and a parameter <span><math><mrow><mi>η</mi></mrow></math></span> was proposed to determine the maximum scour zone. The parameter <span><math><mrow><mi>η</mi></mrow></math></span> is related to a percentage <span><math><mrow><mi>β</mi></mrow></math></span>, which defines the contour of the scour area. Smaller <span><math><mrow><mi>β</mi></mrow></math></span> values indicate a wider scour zone, while larger <em>β</em> values indicate a more concentrated zone. A value of <em>β</em> = 60 % was ultimately selected as a representative threshold. This research provides scientific support for dynamic construction and protection design of tidal estuarine spur dikes.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109475"},"PeriodicalIF":2.6,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temporal dynamics of gonadal development and reproduction of wild Manila clam (Ruditapes philippinarum) in the Xiaoqing River estuary, Laizhou Bay","authors":"Lulei Liu ,&nbsp;Suyan Xue ,&nbsp;Ang Li ,&nbsp;Yushui Ren ,&nbsp;Ling Zhu ,&nbsp;Jiaqi Li ,&nbsp;Longzhen Liu ,&nbsp;Yuze Tang ,&nbsp;Yanguo Qiu ,&nbsp;Yuze Mao","doi":"10.1016/j.ecss.2025.109474","DOIUrl":"10.1016/j.ecss.2025.109474","url":null,"abstract":"<div><div>The Manila clam (<em>Ruditapes philippinarum</em>) is one of the main mudflat shellfish aquaculture species, and their wild population is widely distributed in Chinese coastal areas. However, environmental change and human activities have led to the destruction of the clam's natural habitat, resulting in a gradual decline in production. To better conserve and sustainably utilize <em>R</em>. <em>philippinarum</em> resources, the study presents the first comprehensive investigation of gonadal development and reproductive dynamics of a natural <em>R</em>. <em>philippinarum</em> population in the Xiaoqing River Estuary, Laizhou Bay, from February 2023 to January 2024. The condition index (CI) and histological examinations were used to assess the development of gametogenesis and spawning activities. The findings revealed that the CI of <em>R</em>. <em>philippinarum</em> varied seasonally, reaching its maximum at first maturation in April 2023 (22.49%) and decreasing sharply when spawning activity first appeared in May. Annual sexual changes in gonadal development were essentially the same for both males and females. Additionally, the gonads of <em>R</em>. <em>philippinarum</em> were capable of forming complete developmental stages (the proliferating, growing, maturing, spawning, and resting stages). As temperatures increased, <em>R</em>. <em>philippinarum</em> matured in successive batches, and the breeding season was observed from May to October. The RDA revealed that seawater temperature (R² = 0.7095, <em>p</em> = 0.003) and chlorophyll-a (Chl-a) (R² = 0.7293, <em>p</em> = 0.002) were the primary environmental drivers, exhibiting strong positive associations with the CI and gonadal development (growing and maturing stages). These findings provide valuable insights into the reproductive cycle of wild <em>R. philippinarum</em> and lay a foundation for exploring the mechanisms of natural seedling formation in the Xiaoqing River Estuary, Laizhou Bay. This study contributes to the conservation and sustainable utilization of this important shellfish resource in the river estuary.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109474"},"PeriodicalIF":2.6,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144738808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seagrass and macroalgae on shores: unraveling the decomposition of beach wrack on Danish coasts","authors":"Yaoru Pan,&nbsp;Marianne Holmer","doi":"10.1016/j.ecss.2025.109473","DOIUrl":"10.1016/j.ecss.2025.109473","url":null,"abstract":"<div><div>Blue Carbon Ecosystems (BCEs), characterized by highly productive habitats such as seagrass meadows and macroalgae beds, play a crucial role in the marine carbon cycle. Drifting macrophytes, exported from these ecosystems, accumulate as beach wrack onshore. Although some aspects of the fate of beach wrack, such as mineralization and offshore re-deposition, have been explored, comprehensive field-based studies are necessary to understand the dynamics of decomposition in natural settings. Hence, this study conducted an in-situ decomposition experiment of beach wrack on a Danish coast to explore the decomposition process of beach wrack in natural environments. Seagrass <em>Zostera marina</em> and macroalgae <em>Fucus vesiculosus</em> were selected as experimental materials. Two deposition scenarios (deposited above ground (AG) and buried underground (BU)) were set up for each wrack species. After around two months of decomposition, the mass loss and change in phosphorus (P) content were both significantly affected by beach wrack species and deposition scenarios. Specifically, the mass loss of <em>F. vesiculosus</em> was considerably greater than <em>Z. marina,</em> and 78 % of the mass was decomposed at AG over two months. The loss of P was largest in <em>Z. marina</em> at AG, showing a decrease of 73 %. Contrastly, carbon (C) and nitrogen (N), as well as isotopic signatures δ¹³C and δ¹⁵N, showed no significant change. The C/N ratio showed an increase in both beach wrack species after two months of decomposition, although without significant changes due to the large variation in results. This study provides insights into the decomposition dynamics of beach wrack in natural environments, contributing to a better understanding of their role in carbon and nutrient cycling within BCEs.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109473"},"PeriodicalIF":2.6,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of frequent or massive sediment supplies on sediment redox dynamics: a microcosm simulation","authors":"Corentin Guilhermic,&nbsp;Aurélia Mouret,&nbsp;Hélène Howa,&nbsp;Edouard Metzger,&nbsp;Geoffroy Couasnet,&nbsp;Maria Pia Nardelli","doi":"10.1016/j.ecss.2025.109472","DOIUrl":"10.1016/j.ecss.2025.109472","url":null,"abstract":"<div><div>Marine coastal environments are subject to depositional events generated for instance by turbidites, spring tides and estuarine floods. Biogeochemical stability in sediments was already shown to be disrupted following the deposition of a new sediment layer. The present study aims to understand the successive recovery stages of early diagenetic processes following sediment deposition events of varying intensity and frequency, using microcosms simulations. Over a five-week period with weekly sampling, high spatial resolution methods were applied to characterize the behavior of oxygen, nitrogen, manganese and iron in response to i) a single 2.7 cm sediment deposit (“one-time high volume”; OHV) and ii) a series of weekly 0.4 cm thick deposit (“frequent low volume”; FLV), compared to an undisturbed control microcosm. Results indicate that oxygen, ammonium and nitrite concentration in porewaters exhibited similar vertical distributions in FLV and control microcosms. In the OHV microcosm, oxygen penetration depth was returned to control levels after 3 weeks, whereas denitrification fronts within the newly deposited sediments reestablished within one week after disturbance. Regarding manganese and iron, both OHV and FLV treatments showed that the Mn/Fe oxide-enriched surface layer became anoxic after sediment deposition, triggering bacterial reduction of these oxides. Dissolved manganese production occurred one week before dissolved iron production, highlighting preferential organic matter remineralization pathways. These findings suggest that the transient biogeochemical response to sediment deposition can therefore be appreciated through manganese and iron cycling.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109472"},"PeriodicalIF":2.6,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Habitat suitability assessment and prediction using a physiological species distribution model based on whole-genome genotyping and microclimate data","authors":"Bing-Xian Liu ,&nbsp;Liang Zhang ,&nbsp;Zhan-Wei Zhao ,&nbsp;Lin-Xuan Ma ,&nbsp;Xiao-Nie Lin ,&nbsp;Ming-Ling Liao ,&nbsp;Yun-Wei Dong","doi":"10.1016/j.ecss.2025.109468","DOIUrl":"10.1016/j.ecss.2025.109468","url":null,"abstract":"<div><div>Microhabitat-scale thermal heterogeneity across sediment burial depths and intraspecific genetic variation are demonstrated to jointly determine habitat suitability for the Manila clam (<em>Ruditapes philippinarum</em>) under climate stress. Heat-tolerant genotypes, identified through cardiac thermal performance assays and genome-wide association analysis of four Chinese coastal populations, gain survival advantages particularly at 5 cm depth where juveniles typically burrow. Temperature simulations revealed pronounced vertical stratification in intertidal flats, with deeper burial (10 cm) providing thermal buffering against extreme heat and creating critical microrefugia. However, extreme summer temperatures reduce habitat suitability for both heat-tolerant and heat-sensitive genotypes, especially in southern China where heat stress is most severe. By integrating genome-wide genetic profiling, physiological traits, and microhabitat temperature data, a physiological species distribution model was developed that highlights the ecological importance of microhabitat variability and intraspecific diversity in coastal systems. These results establish a genotype-microhabitat matching principle governing thermal adaptation in vertically stratified sediments, with implications for sessile species across coastal ecosystems. These findings enhance predictive capacity for benthic species under climate change and inform sustainable management strategies for estuarine and coastal resources.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109468"},"PeriodicalIF":2.6,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144738805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying energy fluxes and trophic dynamics to assess artificial reef restoration success: Evidence from Bohai Bay, China","authors":"Wenshuang Yao ,&nbsp;Wei Yang ,&nbsp;Xianting Fu ,&nbsp;Xiaoxiao Li ,&nbsp;Tao Sun","doi":"10.1016/j.ecss.2025.109467","DOIUrl":"10.1016/j.ecss.2025.109467","url":null,"abstract":"<div><div>To achieve the established ecological restoration goals, habitat-based enhancement measures are commonly implemented by deploying artificial reefs, aiming to increase structure complexity and boost local production. In this study, using Juehua Island as case study, we investigated food web structure and energy fluxes to compare artificial reef habitat with natural ecosystems (seagrass bed and sediment substrate habitats surrounding). Our research revealed that seagrass beds exhibited the highest mean δ¹³C values and most complex topological properties of food web among trophic species, while artificial reefs had the largest mean δ¹⁵N values. <em>Lateolabrax japonicus</em> in seagrass beds had the highest trophic position (3.79), followed by <em>Gobiidae</em> in artificial reefs (3.45) and <em>Sebastes schlegelii</em> in sediment substrates (3.30). Species had a wide range of dietary sources, indicting the complex food web structure. Despite trophic transfer efficiency declined gradually with increasing trophic levels in artificial reefs, the presence of these reefs enhanced the <span><math><mrow><mi>P</mi><mo>/</mo><mover><mi>B</mi><mo>‾</mo></mover></mrow></math></span> (production/biomass) ratio of phytoplankton (39 times higher than macroalgae), and significantly improved primary productivity. The seagrass bed habitat showed the highest energy flow in the food web at 69.37 g m⁻² yr⁻¹, followed by artificial reefs (4.23 g m⁻² yr⁻¹) and sediment substrate habitats (1.05 g m⁻² yr⁻¹). Across three habitats, energy flow from detritus to bivalves was dominant. Bivalvia and Zooplankton accounted for nearly 90 % of consumer biomass across all habitats, acting as key intermediaries between primary producers and higher consumers. The quantitative analysis of the food web structure and energy flow in the typical ecosystems of Juehua Island provided valuable scientific data to support the assessment of ecological effects, as well as protection and restoration of offshore ecosystems.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109467"},"PeriodicalIF":2.6,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144721678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining spawning ground of cryptic mullet (Mugil cephalus) juvenile off Taiwan with otolith micro-structure and micro-chemical signal","authors":"Yu-Ling Nien ,&nbsp;Kang-Ning Shen ,&nbsp;Chuan-Hsiung Chung ,&nbsp;Chen-Feng You ,&nbsp;Chia-Hui Wang","doi":"10.1016/j.ecss.2025.109469","DOIUrl":"10.1016/j.ecss.2025.109469","url":null,"abstract":"<div><div>Grey mullet, <em>Mugil cephalus</em>, is an important fisheries resource in Taiwan, comprising three cryptic species (NWP1-3) coexisting in the Northwest Pacific. However, studies of species-specific biological characteristics remain limited. This study employed rapid screening technique to identify species and conducted otolith microstructure and microchemical analysis on juvenile mullet collected from four estuaries around Taiwan to determine their spawning grounds with focused on NWP2. Otolith daily increments showed no significant differences in NWP1 drifting durations among estuaries, whereas NWP2 exhibited significant differences in partial months, with notably shorter durations observed in the northeastern and southwestern estuaries. These findings suggest that NWP1 lacks a geographic gradient, while NWP2 exhibits a non-unidirectional geographic gradient in drifting durations, with both patterns supporting the hypothesis of multiple spawning grounds around Taiwan. Robust Linear Discriminant analysis (R-LDA) showed that the overall successful classification rate for the spawning sources of NWP2 among estuaries was 65.2 %, with higher classification rates observed between the two farthest estuaries. Cluster analysis further indicated that NWP2 may originate from five spawning sources. Spatial variability in elemental signatures of five spawning sources likely reflects the combined influence of physiological factors (e.g., species-specific sensitivity) and environmental conditions (e.g., freshwater input and water mass characteristics), providing additional evidence for the location of multiple spawning grounds. Overall, this study provides important insights into the life history and spawning behavior of different cryptic mullet species, which is crucial for effective fisheries management and conservation strategies in Taiwan.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109469"},"PeriodicalIF":2.6,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon dioxide emission and dissolved carbon transport of a large lowland river entering the Gulf of Mexico under hydrological drought","authors":"Anamika Dristi ,&nbsp;Lishan Ran ,&nbsp;Siyue Li ,&nbsp;Y. Jun Xu","doi":"10.1016/j.ecss.2025.109465","DOIUrl":"10.1016/j.ecss.2025.109465","url":null,"abstract":"<div><div>River flows have been reported to export large quantities of dissolved carbon, via both lateral transport and vertical outgassing. However, less is known about how hydrological drought years can affect transport and transformation. This study investigated dissolved carbon dynamics in North America's largest swamp river, the Atchafalaya River (AR), under the historically dry conditions during 2021–2023. Discharging on average 200 km³ of freshwater annually into the Northern Gulf of Mexico, the AR makes a substantial contribution of terrestrial carbon flux to the coastal system. From June 2021 to May 2023, we conducted river measurements and sampling in the AR at Morgan City, which included partial pressure of dissolved carbon dioxide (<em>p</em>CO₂), water temperature, dissolved oxygen, pH, chlorophyll-a, colored dissolved organic matter (cDOM), and turbidity. From this 24-month study, we found a significantly lower <em>p</em>CO₂ (850–5422 μatm) and CO₂ outgassing rates (mean: 13.06 mmol m⁻² hr⁻¹) compared to previous years of 2019–2021 (pCO₂: 1130–8650 μatm; CO₂ outgassing: 19.70 mmol m⁻² hr⁻¹). Similarly, during the 2-year dry conditions, mass export of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) to the Gulf of Mexico decreased to 4.21 Tg C yr⁻¹ and 1.78 Tg C yr⁻¹, respectively, from 6.40 Tg C yr⁻¹ and 2.40 Tg C yr⁻¹ in the previous wet years. River droughts lowered riverine carbon transport and transformation, likely due to the limited hydrological connectivity of the river channel with the floodplains. However, during both the wet and dry years, DIC concentrations were constantly higher than DOC concentrations, suggesting active organic carbon mineralization in the river water, and also in the soil organic matter.</div></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":"324 ","pages":"Article 109465"},"PeriodicalIF":2.6,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144713549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}