Marine debris is a global issue with adverse impacts on marine organisms, ecological processes, aesthetics, and economies of nations. Several studies have been conducted to quantify the plastic debris along Indian beaches. This baseline study describes the results of a survey conducted on the types of plastic litters and their quantification during January to March 2020 along Mandvi beach in Gujarat. A quadrate having 10 × 10 m size was used for sampling the plastic litter on the shoreline. A total of 10 quadrates along the shore was considered for quantification of the plastic materials based on their density, color, and weight. The plastic material observed includes gutkha pouches, food wrappers, and fragments, along with plastic straws, cutleries, and fragments of various dimensions and thickness. The major contributing factors for the debris abundance in Mandvi beach are land-based sources and recreational activities. The results suggest that similar long-term projects covering extensive areas should be undertaken for accurate quantification of available debris and their impacts on coastal habitats of Gujarat.

Understanding of the pre-development, baseline denudation rates that deliver sediment to the Great Barrier Reef (GBR) has been elusive. Cosmogenic ¹⁰Be in sediment is a useful integrator of denudation rates and sediment yields averaged over large spatial and temporal scales. This study presents ¹⁰Be data from 71 sites across 11 catchments draining to the GBR: representing 80% of the GBR catchment area and provide background sediment yields for the region. Modern, short-term, sediment yields derived from suspended load concentrations are compared to the ¹⁰Be data to calculate an Accelerated Erosion Factor (AEF) that highlights denudation “hot-spots” where sediment yields have increased over the long-term background values. The AEF results show that 58% basins have higher modern sediment yields than long-term yields. The AEF is considered a useful approach to help prioritise on-ground investments in remediation and the additional measured empirical data in this paper will help support future predictive models.

Time series were compiled of terrestrial nitrogen, phosphorus, carbon, iron, and silica fluxes to the Southern California Bight (SCB), a U.S. West Coast embayment (Sutula et al., 2021). Monitoring data and model output were used to construct a baseline of inputs from direct point source (PS) discharges of wastewater treatment (WWT) effluent (via ocean outfalls) and PS, non-point and natural sources from coastal rivers. The baseline covers 1971—2017 for large WWT plants discharging >50 million gallons per day (MGD) and 1997–2017 for small WWT plants and rivers. PS are the dominant nitrogen source, with contributions of 70% of the total annual freshwater discharge and 95% of nitrogen loads. WWT upgrades have reduced organic nitrogen loads by 73% since 1971. Inorganic nitrogen loads have generally held constant (35–40 Gg y⁻¹) for the large WWT plants. This baseline represents a period prior to extensive wastewater and stormwater recycling that is increasing in the region.

This study focuses on estimating CO₂ emissions and analysing energy efficiencies using the Energy Efficiency Operational Index (EEOI) for ferries sailing within an urban port of Taiwan and passenger-ships operating on island routes surrounding Taiwan. A comparative analysis of energy efficiency parameters showed that hybrid diesel-electric ferries had a 12% improved efficiency compared to the traditional full-diesel ferries, while high-speed passenger ships had up to 79% lower efficiency than medium-speed passenger ships. Some potential policies for reducing CO₂ emissions from in-port ferries and island passenger-ships are presented based on these results. The estimated CO₂ emissions from in-port ferries sailing within the urban port could be reduced by 10% when employing hybrid diesel-electric ferries instead of traditional full-diesel ferries. Emissions from island passenger-ships operating on island routes could be reduced by 11–26% through utilising small medium-speed passenger ships instead of small high-speed passenger ships and large passenger ships.

Effects of household post-consumer plastics and tyre rubber on a Baltic Sea copepod Limnocalanus macrurus were assessed. Fragments of commercial recycled low-density polyethylene vegetable bags and rubber originating from recycled car tyres were incubated in seawater, and the copepods were exposed to the filtrate of the water. L. macrurus experienced erratic swimming behaviour and increased mortality in the filtrate of unwashed vegetable bags, containing elevated concentrations of alcohols, organic acids and copper. Responses of the antioxidant defence system (ADS) were recorded in copepods exposed to rubber treatments containing high concentrations of zinc. Significant responses in the ADS enzymes indicate that reactive oxygen species (ROS) formation was exceeding the detoxification capacity of the ADS which may further lead to prolonged state of oxidative stress. Observed effects of exposure on the biochemical level coincide with impaired swimming activity of the copepods, indicating possible irreversible cellular responses leading to behavioural changes and mortality.

Mangroves are known to provide many ecosystem services, however there is little information on their potential role to cap and immobilise toxic levels of total petroleum hydrocarbons (TPH). Using an Australian case study, we investigated the capacity of planted mangroves (Avicennia marina) to immobilise TPH within a small embayment (Stony Creek, Victoria, Australia) subjected to minor oil spills throughout the 1980s. Mangroves were planted on the oil rich strata in 1984 to rehabilitate the site. Currently the area is covered with a dense mangrove forest. One-meter-long sediment cores revealed that mangroves have formed a thick (up to 30 cm) organic layer above the TPH-contaminated sediments, accumulating on average 6.6 mm of sediment per year. Mean TPH levels below this organic layer (30–50 cm) are extremely toxic (30,441.6 mg kg⁻¹), exceeding safety thresholds up to 220-fold which is eight times higher when compared to top layer (0–10 cm).

Little is known about the combined effect of environmental factors and contaminants on commercially important marine species, and whether this effect differs by sex. In this study, blue mussels were exposed for seven days to both single and combined stressors (i.e., +3 °C elevated temperature and two environmentally relevant concentrations of the plastic softener DEHP, 0.5 and 50 μg/l) in a factorial design. Males were observed to be more sensitive to high temperature, demonstrated by the significant increase in out-of-season spawning gonads and higher gene expression of the antioxidant catalase and the estrogen receptor genes. On the other hand, while the gametogenesis cycle in females was more resilient than in males, DEHP exposure altered the estrogen-related receptor gene expression.We show that the combined stressors DEHP and increased temperature, in environmentally relevant magnitudes, have different consequences in male and female mussels, with the potential to impact the timing and breeding season success in Mytilus spp.

The surface intertidal sediments in the Pearl River Estuary of China were analyzed from multiple perspectives, including the distribution characteristics, potential sources, and biological risks of polycyclic aromatic hydrocarbons (PAHs). The average concentration of PAHs, ranging from 73.68 ng/g to 933.25 ng/g, was 346.78 ng/g. PAHs are mainly composed of the 2- and 3-ring PAHs, with naphthalene (Nap), phenanthrene (Phe), pyrene (Pyr), benzo(g,h, i) perylene (Dib), fluoranthene (Flua), and indeno (1,2,3-c,d) pyrene (Ind) as the dominant constituents. The principal component analysis combined with multiple linear regression showed that petroleum combustion and biomass/coal combustion have contributed 52.78% and 40.53%, respectively, to the PAHs in intertidal sediments of Pearl River Estuary. The occurrence of adverse biological effects as a result of PAH contamination in the intertidal sediments of Pearl River Estuary has increased by 8% based on the mean value of the probable effect quotient.

The presence of microplastics (MPs) in the marine environment is a concerning topic due to the ecotoxicological effects and possible seafood contamination. Data is needed to evaluate human exposure and assess risks, in the context of a healthy and beneficial seafood consumption. While microplastic ingestion by wild fish has been reported since the early 70‘s, farmed fish are rarely investigated. Here, for the first time the presence of microplastics in fish cultivated in the coastal water of Tenerife (Canary Island, Spain) was evaluated. From 83 examined individuals, 65% displayed microplastics in their gastrointestinal tracts, with averages between 0.6 ± 0.8 (SD) and 2.7 ± 1.85 (SD) particles per fish. The total number of microplastics detected was 119. Fibres (81%) and fragments (12%) were the predominant shapes. FTIR analysis showed that fibres were mostly composed by Cellulose (55%) and Nylon (27%), whereas fragments by PE (25%) and PP (25%).

This study analyzed trace elements (As, Ba, Cd, Cu, Fe, Mn, Pb, Zn) and stable isotopes of carbon and nitrogen in egg yolk samples of female green turtles that nested in Rocas Atoll, Brazil, in 2017 and 2018. The trace elements concentration varied between years, with higher concentrations in 2017, suggesting that the nesting groups come from different foraging sites. The isotopic data indicated high overlap between years (73%), leading to an ambiguous interpretation on the turtles' foraging site. The Normalized Total Load presented a low association (0.01 < R² < 0.41) with the stable isotopes. The Normalized Total Load that represents the trace element load in egg yolk is a holistic approach that can be applied elsewhere to predict ecotoxicology pathways in any animal species. We recommend a continuous monitoring to verify how the trace elements load behave in the nesting green turtles on Rocas Atoll.