The aim of this study was to evaluate the regeneration of nutrients from the sediments to the water column in varying salinities, with an innovative experiment that closely simulates real environment. In vitro experiments were carried out simulating six scenarios with two sediment types (low carbonate and high carbonate). Local water and sediments were added to microcosms where circulation was forced. Results showed nitrogen release from low carbonate sediment in the lagoon, mixed and seawater (1.69, 4.68 and 7.36 μmol m⁻² day⁻¹, respectively). Phosphate diffusive fluxes were positive in lagoon water and low carbonate sediment (2.24 μmol m⁻² day⁻¹), negative with mixed water (−0.30 μmol m⁻² day⁻¹) and seawater (−0.51 μmol m⁻² day⁻¹). A phosphate release surge was observed in the low-carbonate sediment with overlying mixed water and seawater that, in the natural environment, may boost primary production.

Organophosphate ester (OPE) flame retardants and plasticizers in surficial sediments were collected in Liao River estuarine wetland during the dry, flood, and level periods to understand the seasonal variation, potential sources, and environmental risks. The concentrations of ∑₁₃OPEs ranged from 19.5 to 67.0 ng g⁻¹ dry weight (dw), with an average concentration of 30.6 ng g⁻¹ dw. OPEs pollution displayed a seasonal variation, the concentrations of OPEs in dry period > level period > flood period. Tributyl-n-phosphate was the predominant OPEs, which accounts for 29.7% of ∑₁₃OPEs. Principal component analysis and positive matrix factorization suggested that the pollution sources of OPEs also varied seasonally. The ecological risk of OPEs to aquatic organisms was low, and the non-carcinogenic and carcinogenic risks to human beings were also far below the acceptable level. 2-Ethylhexyl diphenyl phosphate was the major compound causing ecological and non-carcinogenic risk, while tris-(2-chloroethyl) phosphate had the highest carcinogenic risk.

As sites of floating marine material deposition, sandy beaches accumulate marine litter. While research and assessment on beach litter is increasing and involves various actors (scientists, society and NGOs), there is the need to assess current and future dominant trends, directions and priorities in that research. As such, a textural co-occurrence analysis was applied to published scientific literature. Words were considered both singly and as part of compound terms related to concepts relevant to sandy beach ecology: morphodynamic state; Littoral Active Zone; indicator fauna. Litter as a compound term was also included. The main co-occurrences were found within compounds, with scarce interaction of “morphodynamic state” with the others, indicating the need for further integration of beach ecology paradigms into beached plastics studies. Three approaches are proposed to overcome the research limits highlighted: the unequivocation of terms, the consideration of adequate scales, and the attention to dynamics rather than just patterns.

The present study is aimed at investigation of surface water quality of Gulf of Kachchh (GoK), Gujarat. The main objective of this study was to convert complex dataset of water quality parameters from GoK into comprehensive, simple and interpretable observations. Hence, physico-chemical parameters and nutrients of surface water from GoK were analyzed. Chemometric results indicated that oxygen, salinity, dissolved solids, nutrient and natural conditions were the factors that affected surface water quality. The water quality index was calculated to identify water quality classes to evaluate the spatio-seasonal trend in the study area. The results revealed that water quality was moderate in summer, worst in pre-monsoon and best in post-monsoon. The study also highlighted that Marine National Park (Central GoK) was observed to be comparatively in good condition with abundant marine biodiversity. Thus, the results of chemometric study of water quality parameters can be a valuable tool for government authorities for sustainable development of GoK.

Karankadu mangrove situated along the Southeast coast of India is known for its unique and extreme species diversity and richness. Ecological functions of this mangrove comprise of nutrient cycling, coastal protection, fish fauna production and carbon sequestration besides providing livelihood to nearby coastal communities. The current study having assessed seasonal fluctuations of various Physico-chemical factors viz., rainfall, pH, surface water temperature, salinity, dissolved nutrients in the water and sediments, primary productivity and plant pigments (chlorophylls a,b,c) during the study period from July 2018 to June 2019, recorded a total of 29 species of zooplankton, 26 species of phytoplankton, and 19 species of fish with observed maximum density at summer and pre-monsoon period of the year. Relationship between the biotic and abiotic components of the ecosystem from the baseline data collected, was established through the statistical analysis performed.

Anthropogenic litter negatively impacts the marine environment and threatens biodiversity. At the same time, it represents a suitable substrate for the settlement of sessile species, thus potentially altering composition and structure of soft bottom benthic assemblages. By using a Remotely Operated Vehicle (ROV), we hereby investigated patterns of abundance, distribution, and origin of benthic litter in three subtidal habitats of a heavily urbanized area and tested whether litter distribution related to patterns of fish and mega- and macro-benthic diversity. Litter accumulation mostly occurred on soft bottoms, while rocky substrata were the least affected, albeit being particularly threatened by sea-based pollution. As expected, the highest biodiversity was observed on rocky bottoms, hosting notable biogenic formations (Cladocora caespitosa, Leptogorgia sarmentosa) despite the area is historically affected by anthropogenic activities. No correlation was found between biota and marine litter, suggesting that litter does not apparently influence biodiversity and distribution of the investigated assemblages.

Short term stress experiments with dissolved inorganic phosphorus (DIP) and tripolyphosphate (TPP) have been carried out on the staghorn coral Acropora intermedia, collected from Heron Island in the southern Great Barrier Reef, at low and elevated seawater temperatures. Zooxanthellae, chlorophyll a, intracellular and tissue dimethylsulfoniopropionate (DMSP), and extracellular DMSP production were measured to assess the level of stress on A. intermedia at different winter and summer seasons from 2001 to 2003. Whilst no significant changes were measured in these stress indicators in 2001 and 2003, significant changes occurred in winter 2002, reflecting natural stresses on A. intermedia in the field, and stress from added DIP and TPP at high seawater temperatures. These stresses caused corals to bleach, whilst extracellular DMSP, intracellular and tissue DMSP concentrations increased, reflecting the antioxidant role of DMSP in the coral zooxanthellae and coral host to combat stress. These results have important implications for future research in the GBR.

Contamination by metals is among the most pervasive anthropogenic threats to the environment. Despite the ecological importance of marine apex predators, the potential negative impacts of metal bioaccumulation and biomagnification on the health of higher trophic level species remains unclear. To date, most toxicology studies in sharks have focused on measuring metal concentrations in muscle tissues associating human consumption and food safety, without further investigating potential impacts on shark health. To help address this knowledge gap, the present study evaluated metal concentrations in the gills, muscle, liver and rectal gland of coastal sharks opportunistically sampled from Brazilian waters and tested for potential relationships between metal bioaccumulation and general shark health and homeostatic balance metrics. Results revealed high metal concentrations in all four tissue types, with levels varying in relation to size, sex, and life-stage. Metal concentrations were also associated with serum biomarkers (urea, lactate, ALT, triglycerides, alkaline phosphatase, and phosphorus) and body condition, suggesting potential negative impacts on organismal health.

Face masks are playing an essential role in preventing the spread of COVID-19. Face masks such as N95, and surgical masks, contain a considerable portion of non-recyclable plastic material. Marine plastic pollution is likely to increase due to the rapid use and improper dispensing of face masks, but until now, no extensive quantitative estimation exists for coastal regions. Linking behaviour dataset on face mask usage and solid waste management dataset, this study estimates annual face mask utilization and plastic pollution from mismanaged face masks in coastal regions of 46 countries. It is estimated that approximately 0.15 million tons to 0.39 million tons of plastic debris could end up in global oceans within a year. With lower waste management facilities, the number of plastic debris entering the ocean will rise. Significant investments are required from global communities in improving the waste management facilities for better disposal of masks and solid waste.