The rapid expansion of aquaculture in fjords and channels has raised concerns about the accumulation of marine plastic pollution. These environments are particularly vulnerable to plastic accumulation. This study assessed the composition, distribution, and abundance of aquaculture-derived plastics in fjords, archipelagos, and channels of the Los Lagos and Aysén regions in Chile. Vessel-based photographic surveys across 136 observation sites (≈718km of coastline) recorded 918 large plastic items, mainly aquaculture buoys and floating structures, concentrated in 32 coastal sectors. Most marine plastic pollution (89%) was observed in Los Lagos, where in situ observations were located near aquaculture centres (within a 1km radius), whereas this spatial association was not observed in Aysén. Hydrodynamic modelling was used to identify potential accumulation zones of marine plastic pollution. A positive but non-significant relationship was found between modelled accumulation probability and observed plastic densities; however, spatial accumulation patterns were broadly consistent across datasets. These results highlight both the challenges of predicting marine plastic pollution in complex fjord systems and the value of integrating field observations with modelling as a complementary approach for monitoring and managing aquaculture-related plastic pollution.

Abstract Climate change‐induced wave energy enhancement and reduced sediment supply are driving surface sediment coarsening on tidal flats in the Yellow Sea coastal zone, which constitutes our hypothesis. However, large‐scale, long‐term empirical evidence supporting this hypothesis has been lacking. Here, we present the first comprehensive spatiotemporal analysis of tidal flat sediment coarsening across approximately 950 km of coastline from 2005 to 2024, based on a combination of numerical simulations, Landsat‐based remote sensing, and in situ data from 1,170 surface sediment samples. Using mean grain size as a quantitative metric, we document spatially heterogeneous but regionally widespread sediment coarsening trends across the study’s coastal transects. The analysis reveals significant correlations among the coarsening rate of surface sediments on tidal flats, the rate of change in surface suspended sediment concentration in marine waters, and the rate of topographic change on tidal flats. Our findings provide the first large‐scale, long‐term empirical validation of climate‐driven tidal flat coarsening and elucidate its underlying drivers. Given the pervasive intensification of wave energy and widespread reduction in riverine sediment supply across coastal systems, such tidal flat surface sediment coarsening likely represents a previously underrecognized regional coastal phenomenon with broader potential implications for global tidal flat systems.

Abstract Abiotic, biotic, and spatial processes shape patterns of biodiversity in coastal ecosystems. In this study, we test how these processes influence eelgrass‐associated invertebrate diversity in a subarctic seascape. We sampled invertebrate assemblages in 12 meadows along 300 km of coastline in James Bay, Canada, and tested the relative contributions of abiotic conditions, spatial arrangement, and meadow attributes in explaining variation in invertebrate community composition, abundance, and diversity within and among meadows. We found that eelgrass meadows in James Bay support diverse invertebrate communities comprising at least 72 taxa. Greater invertebrate abundance was associated with higher epiphyte load and clearer water (lower turbidity). Invertebrate diversity increased with aboveground eelgrass biomass and epiphyte loads, and species richness increased in clearer water. Invertebrate communities in very salty and very fresh waters contributed the most to regional beta diversity. Variation in taxonomic composition across the seascape was notable; no species was observed at every site, and most taxa were observed at 3–5 sites. The most widely distributed taxa were the arctic amphipod Gammarus setosus and the bivalves Mytilus trossulus and Macoma balthica , each observed at 11 of the 12 sites. Variation in taxonomic composition among meadows was partially explained by meadow spatial arrangement and local abiotic conditions (salinity, fetch, temperature, and turbidity) but not meadow attributes such as eelgrass biomass or shoot size. We conclude that both local conditions and regional ecological processes such as spatially structured population dynamics and species interactions may be important for regional‐scale biodiversity patterns on this coastline.

A large quantity of archaeological remains has been collected over several decades along more than 15 km of coastline around Centinela del Mar (Buenos Aires province). These remains consist mainly of refined earthenware fragments, bone cutlery handles, and artifacts of nautical origin. The coverage of these findings in public media prompted an archaeological evaluation, which included interviews with collectors, a general analysis of the collections, and a coastal survey. The study of the assemblages and their distribution, combined with historical information, supports the hypothesis that the remains correspond to a commercial cargo lost in a shipping mishap between the early and mid-19th century while en route to a Pacific harbor. Several lines of investigation are proposed to further evaluate this interpretation. Both natural and anthropogenic site formation processes in coastal environments are considered, along with the challenges associated with their management. Finally, the study provides insights into the social practices surrounding maritime cultural heritage.

Marine species with high fecundity and larvae with long-distance dispersal potential can have complex population genetic patterns. Characterizing population structure in these species is important for understanding their ecology and life history and designing management strategies. The eastern oyster (Crassostrea virginica) is both ecologically and economically important but has experienced recent population declines. Characterizing genetic variation in regional C. virginica populations will contribute to conservation and restoration practices. We used 20 nuclear microsatellite loci to examine genetic diversity, population structure, and kinship within and among wild oyster populations in coastal Georgia. Oysters were sampled from multiple fringe reefs within a single tidal creek and from four estuarine creeks spanning approximately 115 km of coastline. Genetic diversity was high across all sites, but modest yet significant population structure was detected at both local and regional scales. Within a single creek, significant genetic differentiation was observed among reefs separated by only a few kilometers. Kinship analyses revealed significantly higher relatedness within reefs and within creeks than among locations relative to random expectations. These results indicate that regional coastal dynamics, kin aggregation, local retention, and sweepstakes reproductive success contribute to fine-scale genetic structure despite high dispersal potential. Our findings suggest that accounting for local retention is important when designing oyster restoration, broodstock selection, and management strategies in dynamic estuarine and coastal environments.

Predicting how species will respond to global change requires understanding how environmental drivers shape both neutral and adaptive genetic variation across space. The kelp Eisenia arborea is a thermally tolerant foundation species spanning more than 3000 km of coastline and a broad latitudinal temperature gradient in the Northeast Pacific, yet how environmental and demographic processes influence genomic and population structure remain unclear. We used genome-wide ddRAD sequencing to investigate patterns of genetic diversity, connectivity and local adaptation in E. arborea across two depths and ~2700 km of coastline. We detected strong genetic differentiation between northern (British Columbia, Canada) and southern (Baja California, Mexico) populations, indicating limited gene flow across the species' broad range. Southern populations also had the lowest genetic diversity and highest inbreeding, broadly consistent with expectations for populations occupying environmentally marginal portions of a species' range. However, the two southernmost populations (~200 km apart) were highly similar and well connected, whereas mid-range sites were more differentiated, indicating that the geographic range edge population was not genetically isolated as is often hypothesised. Environmental association analyses identified SNPs correlated with both sea surface temperature and depth, revealing signals of local adaptation to broad climatic gradients and fine-scale habitat variation. The combination of high inbreeding, restricted connectivity and local adaptation highlights both the vulnerability and potential conservation value of distinct genetic units, especially warm-adapted southern populations, for maintaining the resilience of these Eisenia forests under ocean warming.

A synthesis on the spread of the tailing plumes resulting from the Fundão dam collapse along the Brazilian coast: Integrating evidence from multiple sources.

Human activities are increasingly driving the co‐occurrence of multiple ecological stressors, resulting in interactive and cumulative impacts that can reshape ecosystem dynamics and accelerate population declines of climate‐sensitive species. Here, we use over two decades of rocky intertidal monitoring data from 17 sites spanning over 1200 km of coastline to assess how two unprecedented stressors—a multiyear marine heatwave and the disease‐driven loss of a keystone predator (Pisaster ochraceus)—impacted populations of the canopy‐forming intertidal kelp Postelsia palmaeformis. We show that Postelsia experienced rapid and severe declines during the 2014–2016 northeast Pacific marine heatwave, with an average population decline of 50%, multiple site‐level extirpations, and particularly striking losses in the southern portion of the species' geographic range. Concurrently, Pisaster declines triggered mussel bed expansion into habitats previously occupied by Postelsia, further inhibiting kelp recoveries. Our findings reveal how converging stressors can drive persistent, broad‐scale ecological shifts through both direct and indirect pathways. These results also highlight the critical role of long‐term, spatially extensive monitoring in detecting and understanding global change impacts and provide a foundation for guiding Postelsia conservation and restoration efforts.

The seaweed aquaculture has become the highest growing sector of global aquaculture, which presents a sustainable route to fulfilling the increasing resource demands whilst alleviating the strain on terrestrial agriculture and marine life. The review is based on synthesizing world and national data on seaweed production, trade and policies based on international agencies such as FAO, UNCTAD, and the World Bank and national sources such as ICAR-CMFRI and the Department of Fisheries, which refer to the last 20 years (2000-2022). The world seaweed harvested in the year 2021 was 35.2 million tons, of which more than 98 percent was produced in Asian countries, mainly China and Indonesia. The global market is estimated at about USD 17 billion in 2021 but will rise to close to USD 85 billion by 2026 because of the increasing demand of renewable, bio-based and environmentally sustainable products. Although this has been increased, commercial cultivation continues to be highly concentrated with eight dominant species predominantly Laminaria japonica and Eucheuma spp. producing 93.7% volume of the world output. The seaweed segment is now broadening out of the food and hydrocolloid market into high-value market segments like bio-stimulants, methane-reducing livestock feed additives, bioplastics, alternative protein, nutraceuticals and biofuels. Bio-stimulants made out of seaweed in and of themselves form USD 1 billion market, which is expected to grow to USD 1.87 billion by year 2030. Nevertheless, international and national development is progressively limited by climate-related stressors such as increasing sea temperatures, reduced growing season, and diminished output. The sector has been underutilized in India, even though it has 7517km of coastline, 844 reported seaweed species, and 317 of the possible sites of cultivation occupying 23970 hectares. The national production dropped by almost 20 percent, 34,922 tons in 2009 and 27,937 tons in 2018, as a result of mass mortality of farmed Kappaphycus alvarezii after 2013 and overharvesting of natural agarophyte stocks. As a result, processing industries in the country are running at a low level and India is mainly importing sodium alginate mainly the Chinese industries which are also supplying about 92 percent of the total imports. To curb this situation, the Government of India has put in place ₹640 crore in the Pradhan Mantri Matsya Sampada Yojana (PMMSY) with a production goal of 1.12 million tons by 2025. To reach this target, the development of large-scale mariculture as an alternative to the wild harvest and the financial assistance of research in the field of the diversification of their species and the creation of strains with high yields is mandatory. The fortification of the seaweed industry will not only increase industrial independence and livelihood in the coast but also lead directly to the UN Sustainable Development Goals via climate change and carbon capture, coastal cleanup and the larger-scale transformation of the sea. Seaweed farming can be described as a bio engine of the green economy, which can sustainably address the needs of the environment and the economy at the same time.

Global documentation of coral spawning has been increasing, yet remains restricted to corals and reefs for which established patterns have largely been identified, being overwhelmingly associated with periods of darkness after sunset. With this increase in geographic representation has come a growing number of spawning observations that skew or directly challenge previously established trends. After multiple incidental observations of daytime spawning of Pavona corals in the Gulf of Thailand, we aimed to establish spawning patterns for Pavona in the region using non-invasive surveys. Here we document synchronous daytime coral spawning for the species Pavona explanulata and P. varians across over 450 km of coastline along the Eastern Gulf of Thailand and Cambodia. Data collected via observation-only SCUBA surveys over a five-year period identified contrasting patterns of spawning timing of these corals from most other taxa for which data is available in the Gulf of Thailand, based on time of the year, proximity to the lunar peak and hours after sunrise. Based on a null-dataset of reef surveys with an absence of spawning, we were able to add credence to a restricted spawning period of these corals to being typically between September and December in the Gulf, with a sequential spawning of P. explanulata after P. varians with minimal overlap. We identified a consistently predictable onset of gamete release approximately between 6-8 hours after sunrise for P. varians and 7-9.5 hours for P. explanulata. We therefore conducted a review of spawning timing and patterns for Pavona corals across the globe identifying considerable variation across taxa and regions with support for high synchronicity within biogeographic regions. Finally, our dataset also incidentally documented additional cases of synchronised daytime gamete release from Cycloseris and Porites corals highlighting the need for further study on the dynamics of daytime gamete release.

With about 750 km of coastline along the southern Caspian Sea, Iran holds substantial potential for coastal aquaculture. Overfishing and other anthropogenic pressures have caused a sharp decline in valuable fish stocks, prompting the government to explore cage fish farming as an alternative to reduce pressure on wild populations, ensure food security, and support local livelihoods. This review synthesizes national efforts, policies, and scientific studies on cage aquaculture in the southern Caspian Sea, highlighting the key factors behind its limited progress. Between 2018 and 2023, cage aquaculture in the southern Caspian produced nearly 1,940 tonnes, with 1,850 tonnes recorded across central coastal counties (Mazandaran) in the 2023–2024 period, while provincial and national datasets show a wider but uneven distribution of production. These figures suggest that less than half of the region`s estimated carrying capacity is currently utilized. Environmental concerns, economic instability, stakeholder conflicts, and insufficient legal and technical frameworks continue to constrain sustainable growth. Nevertheless, targeted adoption of eco-friendly technologies, strengthened governance, and community-based management could unlock substantial capacity and lead to resilient development of cage aquaculture in Iran`s Caspian region. This review integrates ecological, socio-economic, and policy perspectives to provide a forward-looking framework for sustainable aquaculture planning in the southern Caspian Sea.

Knowledge of the genetic structure of commercially exploited marine species populations is crucial to gaining insights into stock dynamics and population connectivity. This information is essential for effective fisheries management. Economically important benthic fishery species include brachyuran crabs, with the hairy crab Romaleon setosum being an important resource in Chile and Peru. The exploitation is uneven along the Chilean coast, with two areas accounting for 67% of the total biomass caught per year. The genetic structure of the R. setosum population along the Chilean coast was analysed based on the variability of thousands of single-nucleotide polymorphisms (SNPs) in individuals from 10 areas covering 2700 km of coastline. After data filtering, 256 individuals and 2,383 SNPs remained. There was no evidence of genetic population structure within the studied area, suggesting that there is only one genetic population of R. setosum along the coast of Chile. Therefore, among Cancridae species, R. setosum has the largest geographic distribution of a single population described worldwide to date. Finally, the analysis of gene flow showed that the zone with the highest fishery also provided the highest proportion of migrants to the other zones. This study emphasises the urgency of local management of source populations in conjunction with the use of size and sex for fisheries control of R. setosum along the Chilean coast.

ABSTRACT The widenose guitarfish ( Glaucostegus obtusus ) is a Critically Endangered shark‐like ray in the Northern Indian Ocean. They aggregate in shallow waters where they may be threatened by nearshore fisheries, tourism and coastal development, yet their use of these spaces is not well documented. Understanding their population sizes and seasonal use of these nearshore waters is crucial in developing effective conservation strategies. We estimated the abundance of juvenile widenose guitarfish across 10 beaches in South Goa, India, and their variation with seasonal, environmental and anthropogenic factors. We walked transects along the wave line (< 30 cm deep) from September 2023 to March 2024 to record guitarfish counts, sizes and distribution. The total juvenile guitarfish abundance was estimated through N‐mixture modelling as 538 individuals over 25 km of coastline. Galgibaga Beach had significantly higher juvenile abundances (205 individuals, 95% CI: 191–217), indicating the presence of a nursery ground, and has been identified as an Important Shark and Ray Area (ISRA) based on our work. November showed the highest relative abundance of juveniles (35.14 ± 38.47), suggesting that this month is a potential pupping season. We provide first estimates for the population of this species in India and new insights into their ecology, highlighting critical habitats and seasons where conservation efforts, like spatiotemporal restrictions or live release measures, could be directed.

Millennial-scale societal shifts drive the widespread loss of oyster reefs in East Asia.

Objective: This study aims to estimate the sediment budget of the shoreline (SL) in the municipalities of Ilhéus, Una, and Uruçuca, located along the Cocoa Coast in Bahia, Brazil, between 2018 and 2024, allowing the identification of annual trends in erosion and accretion as well as the most susceptible beaches. Theoretical Framework: The SL is an extremely dynamic feature, and engineering works, such as port construction, can alter its natural morphodynamics. Method: The adopted methodology involved the analysis of the mean high-water line along approximately 90 km of coastline, using monthly PlanetScope satellite images (Dove and SuperDove) with 3-meter resolution as a viable alternative for large-scale monitoring. Annual shoreline variations were estimated using the Digital Shoreline Analysis System (DSAS), applying the statistical metrics Net Shoreline Movement (NSM), End Point Rate (EPR), and Linear Regression Rate (LRR). Results and Discussion: Nearly all years analyzed (2019 to 2024) showed average erosion rates according to the LRR, indicating a general trend of shoreline retreat. The year 2020 was the most critical, recording the highest negative average sediment budget (NSM of –12.41 m and EPR of –13.67 ± 0.91 m/year). Research Implications: The results highlight the increasing vulnerability of beaches to erosion, corroborating the emergency decrees issued by the Ilhéus city government. The findings provide support for coastal management, urban planning, and public policy aimed at risk mitigation. Originality/Value: This research stands out for its use of satellite imagery in sediment monitoring, contributing to the identification of the most vulnerable beaches and enabling the definition of locations for more detailed monitoring efforts.

Panama, with nearly 3000 km of coastline and half its population living in coastal zones, faces high vulnerability to sea level rise, flooding, and extreme events. The most vulnerable areas include low-lying coastal provinces such as Panama, Colón, and Chiriquí. This review explores the use of sustainable concrete to address the effects of climate change in Panama towards coastal resilience. The methodology combined a bibliometric analysis using VOSviewer, a systematic literature review (2015–2025) of 99 sources including regulations and technical standards, and a socioeconomic SWOT analysis to assess adoption drivers and barriers. A 2050 permanent inundation map was examined to identify vulnerable areas, and an inventory of concrete-based protection structures was developed. The results highlight that concrete is already used in Panama for coastal resilience through structures such as breakwaters, dolos, and Xbloc units. However, as the country still needs to expand its coastal protection infrastructure, there is a crucial opportunity to implement lower-impact, sustainable concrete alternatives that minimize environmental burdens while ensuring long-term durability and performance. Sustainable options, including supplementary cementitious materials (SCMs), recycled aggregates, and CO2 injection technologies, demonstrate strong mitigation potential, with national initiatives such as Vertua, Greentec, and Argos pozzolan offering early pathways. The conclusions emphasize the need to expand sustainable concrete applications, integrate nature-based solutions, and strengthen Panama’s regulatory and technical capacity to achieve resilient, low-carbon coastal infrastructure.

IntroductionDue to its vulnerability to climate-driven floods and storms, Mozambique faces significant challenges in coastal planning due to limited reliable data. In this context, studying mangrove cover and dynamics could provide valuable insights to enhance coastal area management.MethodsThis study introduces an innovative framework that assesses mangrove extent and coastal vulnerability by integrating the Mangrove Vegetation Index (MVI) with the InVEST Coastal Vulnerability model to accurately identify areas of highest priority for intervention. Using MVI applied to Landsat-8 (30 m) and Sentinel-2 (2023, resampled from 10 m to 30 m) imagery, we mapped mangrove cover for 2013 and 2023, refining accuracy by excluding pixels beyond 1.2 km inland and above 10 m elevation. A cloud-based workflow leveraging Google Earth Engine and QGIS enabled scalable, efficient analysis.ResultsThe mangrove area declined from 2,116 km2 in 2013 to 1,739 km2 in 2023—a 18% loss, equivalent to 1.8% annually. The results of the Coastal Vulnerability Model, applied to the entire coast of Mozambique, produced an Exposure Index (EI) for flooding and erosion events. Each point along the coast was classified with values from 1 to 5 at a distance of 100 m from each other: the highest values indicating greater exposure. It emerged that 16.2% of the 11,768.11 km of coastline were classified with an EI as ‘Very Low’, 42% as ‘Low’, 32% as ‘Intermediate’, 9.4% as ‘High’ and 0.1% as ‘Very High’. Considering the points classified with a ‘High’ and ‘Very High’ EI, approximately 1,117.97 km of coastline is highly vulnerable and in need of intervention. Analysis of the impact of Cyclone Idai (2018–2019) on the Púnguè and Buzi River delta revealed a 69% reduction in mangrove cover, from 76 km2 to 23 km2.DiscussionThese findings underscore the urgent need for targeted interventions, prioritizing Sofala and Zambezia for mangrove restoration and nature-based solutions to bolster coastal resilience. This scalable approach advances global mangrove monitoring and supports data-driven coastal management in climate-vulnerable regions.

Abstract Argentina has around 5,000 km of coastline and one of the world's largest continental shelves. Its enormous marine wealth supports a thriving large-scale industrial fishery. In contrast, the artisanal fishing sector remains far less developed. Its origins trace back to the late 1800s, when European immigrants introduced it in Buenos Aires province, primarily in the ports of Mar del Plata and Bahía Blanca. These fisheries peaked in the 1960s but saw limited expansion in the rest of the country. Today, the artisanal fishing landscape has shifted: traditional fishing ports have very small artisanal fleets, while the activity has expanded in other regions such as Patagonia. Additionally, new commercial operations using semi-rigid boats and kayaks have gained prominence in Buenos Aires. By combining the limited available statistics with interviews from key informants, we identified 60 fishery units along the coast, encompassing 15 distinct metiers and employing nearly 1,000 vessels and around 3,000 fishers in extractive activities. Using a Factor Analysis of Mixed Data on 13 variables —including vessel and gear characteristics, fishing operation, and catch utilisation—we categorised these units into three groups: Strictly Small-Scale Fisheries, Medium Small-Scale Fisheries, and Semi-industrial fisheries. These clusters exhibit varying levels of informality and management intensity. We compare Argentina’s artisanal marine sector with those of other developing and developed nations, analysing its evolution in recent decades and discussing key challenges and priorities for its sustainable management.

Geospatial analysis of shoreline dynamics and drivers in the Sundarbans Biosphere Reserve (1990-2020): Integrating natural and anthropogenic influences for coastal resilience.

Banyuwangi Regency has 282 km of coastline with high coastal potential to be developed, such as tourism, fisheries, and ports. This study aimed to analyze the suitability of the Tanjung Wangi Port location based on tidal and ocean current data. Tidal data were obtained from the Indonesian Hydrographic Data Center (IHDC), and ocean current data were obtained from AVISO Satellite Altimetry. The data were processed using Microsoft Excel and ArcGIS using the inverse distance weighted (IDW) method to create ocean current maps. The results showed that Tanjung Wangi Port has a double-dominant mixed tidal type. The highest water level was recorded at 5.207 m, and the lowest water level was 0.809 m, with a Mean Sea Level (MSL) of 3.048 m. The sea current speed ranged from 0.023 m/s to 1.414 m/s from the Southeast and Southwest Indian Ocean, with the direction of the sea current towards the Banyuwangi Regency. Stable tidal conditions and low ocean currents make the Tanjung Wangi Port ideal for safe harbor and navigation activities and contribute positively to the effectiveness of port activities. Further research should involve direct field surveys and seasonal variability analyses to improve the accuracy of port planning.