The complex mixtures known as hydrocarbons (HCs) are primarily made up of saturates, aromatics, resins, and asphaltenes, which are collectively called SARA fractions. These components, which differ based on the source, make up a significant amount of crude oil. Coastal waters are especially affected by the discharge of hydrocarbons into marine environments as a result of human-caused activities like industrial effluents, maritime traffic, and coastal tourism. The coastal area of Goa is becoming more susceptible to hydrocarbon contamination because of its ecological sensitivity and industrial pressures. In this review, the chemical, physical, and biological degradation mechanisms that control the fate of hydrocarbons in Goa's coastal waters are critically evaluated. With a focus on studies published between 2015 and 2025, a systematic literature review was done using databases like Scopus, Web of Science, and Google Scholar. According to the review, the primary natural attenuation process is microbial degradation, which is greatly impacted by temperature, salinity, oxygen concentration, and nutrient availability. TPH concentrations in Goa's coastal waters are reported to vary greatly. Significant knowledge gaps still exist, especially with regard to in-situ bioremediation trials, microbial community profiling, and site-specific monitoring data. The review emphasizes the need for focused mitigation strategies adapted to Goa's environmental and socioeconomic context, as well as the absence of integrated monitoring frameworks. The results provide a scientific foundation for better environmental management, the creation of policies, and long-term remediation techniques in coastal areas affected by hydrocarbons.

Providing robust real-time flood warnings is of paramount importance to coastal communities. Although state-of-the-art hydrodynamic models are capable of robustly predicting coastal water levels (CWL), unresolved drivers affectingwater level fluctuations are often not represented by the model governing equations. This work evaluates a novel method to improve the performance of the ADvanced CIRCulation (ADCIRC) hydrodynamic model by assimilating observations from four nadir-only satellite altimetry missions with a set of National Oceanic and Atmospheric Administration (NOAA) gauge stations located across the entire U.S. East Coast. Two different types of simulations were performed-open loop (OL) and data assimilation (DA). Five different simulations were performed in which four different satellite altimetry observations were assimilated individually and under two different scenarios-with and without considering the data quality flags. Results indicate that, despite their limited spatial coverage, merging nadir-only observations into ADCIRC from thenadir altimeter of the Surface Water and Ocean Topography (SWOT) can improve the model performance at 76% of the gauge locations, whereas Sentinel-6 improvesit at 73% of the total locations, Jason-3at 74%, and SARALat 21%. Furthermore, combining observations from SWOT-nadir, Jason-3, and Sentinel-6 can improve the ADCIRC performance at more than 80% of the gauge locations fora 107-day simulation. Nadir-only satellite altimetry observations can be useful for improving the model performance even if flagged as "poor quality" near the coast. When the flagged data are disregarded, SWOT can improve ADCIRC at 78%of the gauge locations, Sentinel-6 at 73%, Jason-3 at 53%, and SARAL at 21%. The ability to improve the model simulations largely depends on the availability of anearby satellite overpass. Therefore, model performance can be further enhanced if satellite observations are available during a storm surge event, stressing the importance of frequent satellite overpasses. RESEARCH HIGHLIGHTS: Nadir-only satellite altimetry improves storm surge model performance. Model skill increases when overpasses capture surge events. Multi-mission altimetry assimilation yields the highest overall accuracy.

The widespread application of neonicotinoid insecticides (NEOs) in urban areas has led to their transport from terrestrial ecosystems into freshwater catchments, where they undergo complex transformation processes. However, the occurrence and potential risks of NEOs and their transformation products (TPs) in urban aquatic ecosystems remain poorly understood. In this study, a comprehensive screening workflow was developed by integrating target analysis, suspect screening, and nontarget analysis through diagnostic fragment searching and molecular networking, and 104 TPs were identified for 11 NEOs in 35 coastal urban river waters from Qingdao, China. In each sample, the cumulative concentrations of NEOs and their TPs ranged from 118 to 4755 ng/L. Five NEOs and seven TPs were ranked as high-priority based on the ToxPi score, which integrated detection frequency, signal intensity, persistence, mobility, and toxicity. Notably, four NEOs (i.e., clothianidin, imidacloprid, thiacloprid, and thiamethoxam) exceeded their respective Environmental Quality Standards in 17-89% of water samples. One additional NEO (i.e., dinotefuran) and seven TPs (i.e., thiacloprid amide, TP271b, TP340b, TP201b, imidacloprid desnitro, TP247a, and TP213b) were ranked higher than clothianidin. Simultaneously, 18 TPs had a higher regulatory priority than the corresponding NEOs, highlighting that these TPs warrant equal attention. Source tracing analysis revealed that urban application and agricultural activities were the primary sources of NEOs and their TPs in urban and mixed land-use areas, respectively. Future efforts should focus on clarifying the ecological risks and major sources of neonicotinoid contamination, in terms of parent NEOs and their TPs, in coastal urban rivers to support source-control regulations for preserving freshwater and marine organisms.

Aquaculture environments in tropical coastal regions are increasingly exposed to plastic debris, creating novel microbial habitats with the potential to disseminate antibiotic resistance genes (ARGs). We deployed plastic substrates in situ for 21days at a coastal aquaculture site in Singapore, profiling substrate-attached prokaryotic communities using long-read environmental DNA sequencing. Polypropylene (PE) and polyethylene (PP) plastics supported distinct microbial assemblages that diverged over time and differed by polymer type, while seawater hosted greater overall species richness. Despite comparable alpha diversity, PE and PP biofilms demonstrated diverse taxonomic and functional gene profiles, with substrate-driven enrichment of metabolic pathways. Fifteen classes of ARGs were detected, with increased diversity and abundance on plastics, and ARG patterns were correlated with salinity, turbidity, and chlorophyll. This study provides the first long-read characterization of plastisphere biofilms and their associated ARGs in tropical aquaculture systems in Southeast Asia. These findings position aquaculture plastics as reservoirs for diverse prokaryotes and resistance genes, highlighting their ecological and food safety implications in tropical coastal systems.

Abstract Petroleum hydrocarbon contamination in coastal environments poses significant ecological and human health concerns, yet bioaccumulation dynamics in benthic organisms remain underexplored in the Niger Delta. This study investigated the spatial and temporal variation of total petroleum hydrocarbons (TPHs) in sediments and Tympanotonus fuscatus var. radula ( Tf var. radula ) across three stations in Rivers State, Nigeria, using standard analytical protocols between January and June 2023. Sediment TPHs exhibited pronounced spatial heterogeneity, with Station 2 recording the highest mean concentration (3.076 ± 0.15 mg/kg) and Station 1 the lowest (2.786 ± 0.12 mg/kg). Temporally, sediment TPHs increased from January and peaked in March (3.40 ± 0.06 mg/kg) before declining towards June (3.10 ± 0.04 mg/kg). TPH concentrations in Tf var. radula showed a narrow spatial range (1.23 ± 0.07 to 1.25 ± 0.06 mg/kg), indicating consistent but measurable accumulation in this benthic species. Bioaccumulation factor analysis revealed strong enrichment of selected compounds, notably benzene (up to 130), n-pentadecane (up to 480), and n-hexadecane (up to 520), reflecting selective uptake of individual hydrocarbon fractions. Although sediment TPH concentrations were below the EGASPIN intervention limit, the persistence of petroleum hydrocarbons and their bioaccumulation in an edible mollusc highlight the need for continuous monitoring and strengthened pollution control to safeguard sediment quality, seafood safety, and ecosystem health in coastal waters of Rivers State, Nigeria.

Monitoring Coastal Water Quality Using Remote Sensing and Machine Learning

ABSTRACTSea pens (Octocorallia: Scleralcyonacea: Pennatuloidea) are widespread but remain under‐documented in the Northwest Pacific. Using a combined molecular (MutS‐ND2‐28S rRNA) and morphological approach, we analysed sea pen samples collected from Hong Kong's urban waters. MutS sequences at a 0.3% divergence threshold and ASAP automatic delimitation resolved nine species across three families and four genera for Hong Kong specimens, consistent with phylogenies inferred from concatenated datasets (MutS‐ND2‐28S rRNA), which recovered nine species in three well‐supported clades within Pennatuloidea. Morphological examinations (colony form, zooid arrangement, axis shape, sclerite shape and size) corroborated species boundaries. We described three new species (Cavernularia solaris sp. nov., Lituaria triscleromorpha sp. nov., and Virgularia exilis sp. nov.) and updated the morphological descriptions of four previously known species. Additionally, we compared these species with sea pens reported from other regions, particularly Japan and Palau. By discovering new species and new distribution ranges, providing new DNA sequences, and clarifying phylogenetic placements for Hong Kong's sea pens, this work augments species inventories and contributes to ongoing revisions of Pennatuloidea systematics and biogeography in the Northwest Pacific.

Forecasting of Chlorophyll-a Concentrations in Coastal Waters Through Gated Recurrent Unit Neural Network Based on Time–frequency Analysis and Smoothing Filtering

Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants primarily generated from fossil fuel combustion and crude oil release. Rabigh city's coastal area, home to industries like cement, petrochemical, desalination, and power plants, faces PAH contamination. This study assesses the levels and distribution of 16 priority PAHs in surface and near-bottom waters. PAH concentrations in surface water ranged from 57.99 to 496.21ng/L, with an average of 188.95ng/L, while near-bottom waters showed values from 123.94 to 665.99ng/L, averaging 285.49ng/L. The higher levels in near-bottom waters are due to PAHs' hydrophobic nature, causing accumulation in sediments. Wind direction influenced PAH concentrations, with higher levels in the southeast and lower levels in the northwest. The highest PAH concentrations were near industrial discharge pipes. Molecular diagnostic ratios and principal component analysis indicated mixed pyrogenic and petrogenic PAH sources. Carcinogenic PAH levels ranged from 2.69-28.00ng/L in surface waters and 4.39-45.90ng/L in near-bottom waters. Toxic equivalent (TEQ) and mutagenic equivalent (MEQ) concentrations were recorded as 3.74ng TEQ/L and 2.71ng MEQ/L for surface waters, and 10.05ng TEQ/L and 7.88ng MEQ/L for near-bottom waters. Higher concentrations of certain PAHs exceeded environmental regulation limits, posing risks to marine ecosystems.

ABSTRACT Fossil bite marks provide insights into trophic and agonistic behaviors, but they can be difficult to associate with a specific actor. Finding embedded teeth, while rare, removes this ambiguity. Here we describe a tooth embedded in a mid-cervical vertebra of a subadult plesiosaur, Polycotylus latipinnis, from the Santonian/Campanian Mooreville Chalk of Green County, Alabama, U.S.A. Exposed portions of the tooth are damaged, hindering identification, so internal visualization was accomplished via computed tomographic (CT) scanning. Sectioning revealed a conical, unornamented, slightly curved tooth with a large pulp cavity. These features are inconsistent with the marine reptiles and sharks present in the Mooreville Chalk. However, they are consistent with a large, osteichthyan fish, of which only the enormous, co-occurring ichthyodectid Xiphactinus had sufficiently large gape and dentition. Preservation of the Polycotylus suggests a short residence time near the surface, before sinking into anoxic waters, limiting the window during which extensive scavenging and decomposition could have occurred. The location and depth of the bite could certainly have been fatal, severing the carotid sheath and disrupting the trachea, causing a loss of lung pressure and associated buoyancy, highlighting the vulnerability of elongate necks to predatory attack. This find joins the surprising diversity of bite marks and gut contents known from the Mooreville and contemporaneous Smoky Hill Chalks. These lines of evidence reveal a complex, dynamic trophic structure in North America’s Late Cretaceous coastal waters, with large marine reptiles and osteichthyan fish vying for position at the top of the food chain.

To elucidate water mass impacts on fish diversity in Hainan Island, bottom trawl surveys were conducted at 50 stations around the Island in December 2023 (winter) and April 2024 (spring). K-means clustering identified three water masses: Coastal Water (CW), Mixed Water (MW), and Offshore Water (OW). A total of 396 species were collected. Winter communities demonstrated clear habitat specificity, with distinct dominant species in each water mass (OW, MW, and CW). Conversely, the spring intrusion of warm, saline water facilitated the dominance of migratory species in the MW. Diversity centers shifted significantly northward and shoreward, transitioning from the MW region in winter to the CW region in spring. These findings highlight the critical influence of seasonal hydrodynamics on fish community structure, providing essential baselines for regional fisheries management and conservation.

Context The white shark (Carcharodon carcharias) is a large, highly migratory, apex predator typically found in coastal, continental shelf and pelagic environments of temperate and subtropical waters worldwide. In the western North Atlantic (WNA), white sharks have been studied for decades through catch data and other observations along the US Atlantic coast. Aims Beginning in 2012, OCEARCH has coordinated a comprehensive, long-term study of this population that includes tagging sharks with satellite-linked and acoustic tags to track their movements, understand their life history, and map their critical habitats. Methods Tagging occurred between Nova Scotia, Canada, and Jacksonville, Florida, USA, on the Atlantic coast. Four life stages (young-of-the-year, juvenile, subadult, adult) were tagged, showing the migratory cycles of this WNA population from age zero through maturity. Key results A combination of satellite-linked and acoustic tags showed all four life stages enter the Gulf of Mexico (GoM) through the Straits of Florida and use this habitat primarily during the overwintering period. Of 92 white sharks tagged, 57 (62.0%) showed activity in the GoM or the Straits of Florida, spending most of their time (91.2%) in epipelagic waters and moving mainly from the Florida Keys north along the outer West Florida Shelf. Specific areas of extensive habitat use and evidence of philopatry were identified, particularly in the Pulley Ridge area off south-western Florida. Some animals crossed into the western GoM and into Mexican coastal waters; movements along the northern coast of Cuba were also noted. Conclusions These tagging results clearly demonstrated the importance of this region as an overwintering habitat for white sharks, particularly in shelf edge waters of the eastern GoM, and indicated a more widespread and persistent use of the GoM by this recovering species than previously known. Implications Our results demonstrated the wide-ranging nature of the WNA white shark population and the faunal connectivity between Atlantic Canada and the GoM, including territorial waters of other nations. Continued monitoring of this population, fine-scale analysis of movements in critical habitats, and further research on the drivers of migration are needed for science-based policy to conserve this vulnerable species.

The Indian mackerel (Rastrelliger kanagurta) is a commercially important fish species in Bangladesh. This study was conducted by using two catch-based methods, Depletion-Based Stock Reduction Analysis (DB-SRA) and Catch-Maximum Sustainable Yield (CMSY), to determine stock status with length-based approaches to update the life-history estimates of Indian mackerel stock. Sensitivity tests and projection were also performed to find out how well the models predicted the estimates at different input parameter's value and evaluate catch strategies. The life-history parameters were estimated as L∞=33.25cm and k = 0.92 year- 1. The fishery experienced a sudden increase in its landings to the abnormally highest point in 2012, followed by a state of equilibrium. However, the current spawning potential ratio (SPR) of 17% indicated a concerning sign regarding stock spawning capacity, where over 50% of catches were observed to be below the maturity level. This study suggests an optimum length limit of 18-22cm to adjust the growth and recruitment overfishing. Hence, an annual catch limit of 1500 mt is recommended for the next 15 years under the maximum sustainable yield (MSY) reference bar (1967 mt), in convergence with the annual fishing ban, to gradually maintain the current overfished biomass of Indian mackerel approaching the BMSY level. Besides, the dynamic, transboundary nature of the Indian mackerel demands both national action and international cooperation for better management.

From wells to waves: Evaluating fecal contamination sources using FIB and MST markers along Texas coastal waters.

Effect of experimental seawater acidification on the prooxidant-antioxidant system of the Pacific oyster Magallana gigas (Thunberg, 1793) under normoxic and hypoxic conditions.

New spectral indices for identifying large plastic accumulations in coastal waters with sentinel-2 imagery.

Sunscreen-derived nano-TiO2 undermines viability and recruitment of the Mediterranean foundation alga Ericaria amentacea.

Atmospheric wet deposition acts as a critical pathway for bioavailable dissolved organic carbon in the Haizhou Bay, South Yellow Sea.

Distribution of tritium in the Changjiang estuary area, China: Transport flux and water age.

Multi-step forecasting of chlorophyll-a concentration in coastal waters through Wavelet Dense Attention Transformer model.