Abstract Marine pollution threatens ocean ecosystems and human health through eutrophication, bioaccumulation, and habitat degradation. This article discusses chemical contaminants, nutrient pollution and eutrophication, marine debris, ocean noise pollution, global and regional hotspots of ocean pollution, the impact of pollution on marine biodiversity, mitigation strategies and global effects, restoration and cleanup efforts, and challenges and future outlooks in marine pollution. The excess nutrient levels disturb ecological balances, cause harmful algal blooms, and threaten biodiversity and coastal economies. While plastic pollution has received widespread attention, marine debris also includes non-plastic materials such as metal, glass, rubber, and textiles. Ocean noise pollution, primarily from shipping, seismic exploration, and military sonar, significantly disrupts marine ecosystems by interfering with the communication, navigation, and behavioral patterns of marine species. The buildup of plastic gyres such as the Great Pacific Garbage Patch is a key contributor to global ocean pollution. Remote polar regions can also show significant accumulation of pollutants due to long-distance marine and atmospheric transportation. Multi-faceted and integrated approaches, such as global regulatory frameworks, technological innovation, waste management improvement, and public engagement, are required to decrease ocean pollution. The growing awareness of marine pollution, especially for plastic debris, has fueled the pick-up trash before it disperses into the open ocean. Meanwhile, ecosystem restoration, ranging from mangrove replanting to coral reef rehabilitation, is crucial in rebuilding degraded marine habitats and promoting resilience to subsequent environmental and climatic pressures.

Abstract This study investigates the interconnections between marine resource management, local livelihoods, and governance structures at the Muni-Pomadze Ramsar Site in Ghana. Employing a mixed-methods approach guided by the Social-Ecological Systems (SES) Framework, the study combines qualitative interviews and focus group discussions with quantitative survey data from 302 respondents across three coastal communities. Findings reveal that marine resources, particularly fishing, are central to the socioeconomic fabric of these communities. Livelihood outcomes are significantly influenced by financial, natural, human, social, and physical capital, with financial capital emerging as the strongest predictor of these outcomes. However, challenges such as institutional overlaps, inadequate infrastructure, limited access to credit, and exclusion of women and youth from decision-making constrain sustainable governance. The study emphasizes the necessity for an inclusive, decentralized co-governance framework that combines traditional conservation practices with contemporary regulatory systems. Policy recommendations include the formation of a Multi-Stakeholder Lagoon Management Board, community-based monitoring, microcredit schemes, and investments in cold storage and aquaculture. These findings offer actionable pathways for enhancing ecological resilience and improving the livelihoods of coastal populations.

Abstract Tuticorin Bay (TB), a shallow semi-enclosed coastal system on the southeast coast of India, exemplifies the escalating challenges faced by urbanized tropical bays, where anthropogenic stressors interact with complex biogeochemical processes. This study investigates the spatial and seasonal variability of carbonate system dynamics and air–sea carbon dioxide (CO₂) fluxes across three hydrologically distinct periods: the southwest monsoon (SWM, August 2018), northeast monsoon (NEM, October 2018), and summer (SUM, May 2019). Surface waters exhibited a wide range of pCO₂ (380–1036 μatm), revealing spatial heterogeneity across distinct biogeochemical regimes. Elevated pCO₂ levels in most regions confirm the bay’s dominant role as a CO₂ source; however, localized undersaturation (~ 380 μatm) during the SWM indicates short-term CO₂ uptake, associated with intense biological production and high chlorophyll-a concentrations (> 50 μg L⁻ 1 ) in the nutrient-enriched north region of the bay. In contrast, the southern bay showed persistently high pCO₂, driven by elevated temperatures (> 36 °C) and enhanced respiration promoted by thermal effluent discharges. Dissolved Inorganic Carbon (DIC) exhibited non-conservative behaviour across seasons, with ΔDIC ranging from –487 to + 639 μmol kg⁻ 1 , highlighting the influence of terrestrial inputs and local metabolic processes. Peak air–sea CO₂ fluxes reached 17.23 mmol C m⁻ 2 d⁻ 1 during SUM, particularly in low-oxygen zones (< 60% saturation) of the southern bay. These findings demonstrate how seasonally shifting physical conditions and localized anthropogenic pressures govern CO₂ dynamics in a spatially confined tropical bay, underscoring the need for high-resolution assessments of such vulnerable systems to improve regional carbon budget estimates.

Abstract Coastal zones are transition zones between the land and sea, characterised by unique coastal ecosystems and natural resources, making them the focal point of human activities. Vulnerability assessments have been carried out along several coastal zones across the world. These assessments help coastal scientists, engineers, and policymakers prepare plans and devise mitigation measures to safeguard the environment and coastal population against climate change and coastal hazard impacts. The present study evaluates the vulnerability of the Kasaragod coast in Kerala, the west coast of India, due to sea-level rise. Eleven variables, viz. relative sea-level change, mean significant wave height, tidal range, geomorphology, shoreline change rate, regional elevation, coastal slope, population, road/railway networks, tourist sites and land use/land cover are considered in the estimation of the Coastal Vulnerability Index (CVI). The resulting CVI values were categorized into low, moderate, high and very high vulnerability classes. Based on this classification, 41.33% of the Kasaragod sub-district and 13.26% of the Hosdurg sub-district fall under the ‘very high’ vulnerability category. A significant decrease in vulnerability was observed along the Kasaragod sub-district when socioeconomic variables were excluded from the CVI calculation. However, in the Hosdurg sub-district exclusion of the socioeconomic variables led to increased vulnerability along the coast. The vulnerability maps developed in this study provide a crucial tool for identifying highly vulnerable coastal stretches and guiding effective strategies to safeguard the Kasaragod coast and its communities.

Blue carbon ecosystems (BCEs), such as salt marshes, are critical in climate change mitigation and biodiversity conservation and their ecosystem services. However, due to a lack of research, their carbon sequestration potential in Mexico remains poorly understood. La Ribera, Baja California Sur, exemplifies an under-researched salt marsh that provides essential benefits, including surface water for drinking, habitat, and cultural services. Besides, a recent training offered by Chinese institutions such as East China Normal University in 2024 has contributed to BCEs carbon estimation by supporting training to some researchers and practitioners from the Global South. These kinds of initiatives could enhance research capabilities and promote cost-effective conservation strategies. Although salt marshes cover less area than mangroves and seagrass meadows, their preservation is vital for climate action. Global efforts to protect these ecosystems will support carbon sequestration and safeguard other critical ecosystem services for future generations.

Marine Protected Areas (MPAs) worldwide are under increasing pressure to balance biodiversity conservation with the growing demands of tourism, often exacerbated by anthropogenic impacts on coastal ecosystems. Exogenous shocks, such as environmental or policy-driven events, can offer opportunities for shifts in natural resource governance. This longitudinal study examines how a 2016 tourism ban in Mexico Islas Marietas National Park, prompted by coral reef degradation, influenced its polycentric governance. We use a mixed-methods approach, analyzing data from 53 governance meetings held before (March 2015 to April 2016) and after (May 2016 to November 2017) the regulatory shock. We compare stakeholder participation, affiliation networks, rules, and institutions to assess changes in the polycentric governance system. Our results show an increase in stakeholder engagement and two new decision-making forums have emerged. Network analysis reveals a rise in network density and social ties, suggesting enhanced trust and collaboration among stakeholders, although individual stakeholder responses to the shock varied. The tourism ban triggered a shift towards formalizing collaboration agreements, increasing stakeholder involvement in shaping public use norms, and decentralizing revenue generation. The coastal MPA also implemented a specific regulatory framework with recalculated carrying capacity, improved monitoring, and stricter accountability for tour operators. The Islas Marietas case offers valuable insights into coastal management in the Anthropocene, emphasizing the need for adaptive polycentric governance approaches that foster collaboration, and empower stakeholders to safeguard the long-term sustainability of both marine commons and livelihoods.

The Pechora is the greatest river of the European Russian Arctic, flowing into the Barents Sea. Its estuarine area includes a vast delta, represented by extensive lowlands that are dissected by the complicated network of arms and branches. Despite the Pechora Delta is considered to be microtidal, tides with a range of 0.5–1 m during the low water period have a significant impact on the nature of currents in the main branches and the distribution of runoff among them during the tidal cycle. Tidal sea level fluctuations as well as storm surges determine the reversing pattern of currents over a significant extent of the delta branches. The modern field equipment combined with 2D hydrodynamic modeling has allowed to understand the contemporary flow features and evaluate their possible alterations under climate changes. The climate impact under considered scenarios is more pronounced during the low flow period, and this can lead to the propagation of tidal currents and an increase in water levels in the city of Naryan-Mar (100 km upstream from the mouth). From a flood risk perspective, sea level rise can be offset by a reduction in flood runoff.

The Bay of Bengal has been at the heart of human civilisation and trade for many centuries. Accordingly, this oceanic space has seen influx of people from around the world including European traders who plundered natural wealth of this region for many years. Unabated exploitation of natural resources has been the primary reason for deterioration of environment of this part of the world. To add to this, supporting a growing population through unsustainable anthropogenic activities for decades is considered a primary cause for deterioration of marine life, habitats, coastal and marine ecosystems and numerous ocean ecosystem services of this oceanic space. Since the health of the oceanic space is critical for survival of life of Earth, a detailed study of the impacts of a growing population on the coastal environment of the Bay is considered important. Unfortunately, since the anthropogenic activities causing this deterioration are numerous, they cannot be covered in one paper. Hence, only a select few critical anthropogenic activities causing coastal erosion, resource degradation, and marine pollution are being analysed here. The study shows that as a result of increasing population, terrestrial activities such as increasing built up area, industries, land use activities, fisheries and aquaculture, and construction of shore protection structures have resulted in reduced coastal vegetation and increased pollution of the ocean. As a result the coastal landscape is witnessing increased coastal erosion, coastal flooding and inundation, loss of vegetation and faunal communities especially fishes. While local initiatives and projects reflect a positive commitment to address resource degradation and to create resilient coastal ecosystems, these efforts need to be transformed into achievements by dedicated and nuanced involvement of all stakeholders, especially the public, for the desired results.

The pervasive presence of microplastics within river ecosystems has a profound and often underestimated detrimental impact. These minuscule yet persistent particles have infiltrated diverse biological habitats, making their detrimental effects on aquatic life increasingly concerning worldwide. The ability of microplastics to accumulate within aquatic organisms further exacerbates this concern. Consequently, the monitoring of microplastic pollution in surface water environments has emerged as a crucial endeavour, offering invaluable insights into the extent of this ecological threat. This study delved into the contamination levels of microplastics within two bivalve species, Perna viridis and Villorita cyprinoides, along the Chandragiri River in Kerala and Karnataka, South-West India, spanning eight distinct locations. The investigation yielded a significant discovery, with a total of 667 microplastic particles extracted from 288 individuals. On average, each individual bivalve harboured approximately 2.31 ± 0.93 microplastic items. Notably, these microplastic particles exhibited a wide range of morphological characteristics, underscoring their diverse origins and pathways into the ecosystem. Furthermore, five polymer types of microplastics were unequivocally confirmed through FTIR-ATR analysis, shedding light on the types of plastics that pose a threat to the riverine ecosystem. The findings of this study contribute to a growing body of evidence highlighting the global threat of microplastic pollution, urging international collaboration and innovative solutions to prevent further contamination and remediate existing microplastic burdens in aquatic environments.

Grain size distributions are widely used to describe sedimentary geochemistry, depositional environment, and sediment transportation. The objective of this study is to analyze grain size distributions of modern sandy beach sediments in Sri Lanka. Sediment samples (n = 90) were collected from beach berm, representing the entire coastline of Sri Lanka. Grain sizes were determined by the dry-sieving method. Statistical parameters such as mean size, sorting, skewness, and kurtosis were calculated using GRADISTATV9.1 software for all the sieved sediment samples. Grain size variations (108.2 – 609.8 µm) show that Sri Lanka mainly consists of medium sand, whereas the northeast part of the country mixes with fine sand due to the influence of Bengal fan sediments. The variations of skewness (-0.229 – 0.446) and sorting (1.305 – 2.436) indicate symmetrical distributed moderately sorted samples. These variations specify a moderate energy depositional environment/wave action around the coastline of Sri Lanka. In addition, grain size analysis confirmed relatively high and low energy deposition environments on the west and east coasts, respectively. Accordingly, the west coast is more vulnerable to coastal erosion compared to the east coast of Sri Lanka. Therefore, this study provides the baseline grain size distribution data that can be used in decision-making for coastal zone management by mitigating beach erosion.