Public involvement in beach litter clean-ups can help tackle marine litter while providing experiential learning, raising awareness and stimulating anti-litter behaviour. Beach visitors contribute to litter generation by inappropriate discarding behaviour, and engaging them in litter removal can be beneficial. This study assessed visitors' (N = 512) stated willingness to participate in litter clean-ups at Elegushi Royal Beach, Nigeria, which is under pressure from litter problems visitors contribute to, and potentially emblematic of organised litter clean-ups. Beach visitors recognised marine litter as a global and national problem but did not perceive the case study beach as being littered. Willingness to participate in beach litter clean-ups was marginal. However, it was positively correlated with previous participation in litter clean-ups, perceived collective responsibility and the importance of policy and investments in reducing litter. These results were used to propose a framework to engage and recruit visitors in beach litter removal campaigns.

Microplastics ingested by two bivalve species Perna viridis and Meretrix meretrix collected from three estuaries viz. Ariyankuppam, Panithittu, and Chunnambar in Pondicherry, India was analysed for the first time in this research. Nile Red dye was used for microplastic detection. A survey of 50 local families was conducted to determine the frequency and quantity in which they consume mussels/clams. On an average, the number of microplastics per gram of soft tissue (wet weight) is 0.18 ± 0.04, 1.84 ± 0.61, and 1.76 ± 0.48; and the number of microplastics per bivalve is 0.50 ± 0.11, 1.75 ± 0.35, and 4.80 ± 1.39 respectively for Ariyankuppam, Panithittu, and Chunnambar. 61.02% and 77.42% of the particles belonged to the size group of <100 μm in M. meretrix and P. viridis respectively. A moderate positive correlation of r (18) = 0.6985, p < 0.05 was calculated between bivalve weight and microplastic particles. An average person belonging to the local community is likely to ingest 3917.79 ± 144.71 microplastic particles per year through mussel consumption.

Bioaccumulation of metals in ten species of green seaweeds collected along the Palk Bay was assessed in the present study. The accumulation of metals in all the ten species were in the order of Pb > Cu > Zn > Cd. Cd was recorded above the permissible level, and Pb, Cu and Zn were below the permissible level of CEQG. The metal concentration in seaweeds was above the WHO standards. The permissible levels of metals were compared with the standards of human health risk assessment, which shows that the exposure of metals from seaweeds has moderate hazard risk to humans. The result of trace element accumulation in four seasons was in the order of summer >monsoon>pre-monsoon>post monsoon. One-way ANOVA revealed that Cd and Pb show significant differences (p˂0.01) in all the species. Cu showed significant variation (p˂0.01) in all the four seasons. Zn also showed significant difference (p˂0.01) during pre-monsoon season.

China's seaborne foreign oil supply through the Malacca Strait is facing security challenges due to territorial disputes, pirate attacks, and geopolitics. To overcome these challenges, China plans to import oil through one of the corridors of the Belt and Road Initiative (BRI)—the China-Pakistan Economic Corridor (CPEC). This study estimated and compared ship emissions and their externalities associated with seaborne oil supply from the top five oil suppliers to China through the existing shipping route via the Malacca Strait and proposed route via CEPC. Ship activity-based methodology is applied to estimate the emissions of air pollutants (CO₂, NOₓ, SO₂, PM₁₀, and CO) during cruising, maneuvering, and hoteling periods. The results show that the total ship emissions of China's seaborne oil supply can be significantly reduced from 6.2 million tons to 2.1 million tons via the CPEC route. While external cost can be reduced up to 65.9% via the CPEC route.

Wastewater treatment plants (WWTPs) in coastal region play a primary role in transferring microplastics into the marine environment. Wastewater is closely related to anthropogenic activities, thus the intra-day variation of abundance of microplastics in the influent should be large and could have significant impact on their estimation of the daily mass load. In this study, a 2–hour interval sampling campaign was conducted at a secondary WWTP in Hong Kong to investigate the intra-day variations and daily loads of microplastics in influent. Results show that the average microplastic abundances increased from 7.1 ± 6.0 to 12.8 ± 5.8 particles/L over time, with predominant particle sizes ranging 1–5 mm. Approximately 80% of the microplastics in samples collected from 9:30–15:00 were polyethylene and polyester, while most samples collected at 17:00 were polypropylene and polyurethane. Microplastic loads exhibited large intra-day variations ranging 6.60 × 10⁸–1.16 × 10⁹ particles/day, indicating that calculated daily microplastic loads based on a specific sampling period may inaccurately estimate the actual daily load.

The water-soluble compounds of oil (e.g. low molecular weight PAHs) dissolve as a function of their physicochemical properties and environmental conditions, while the non-soluble compounds exist as dispersed droplets. Both the chemical and physical form of oil will affect the biological response. We present data from a mesocosm study comparing the microbial response to the water-soluble fraction (WSF), versus a water-accommodated fraction of oil (WAF), which contains both dispersed and dissolved oil components. WAF and WSF contained similar concentrations of low molecular weight PAHs, but concentrations of 4- and 5-ring PAHs were higher in WAF compared to WSF. Microbial communities were significantly different between WSF and WAF treatments, primary productivity was reduced more in WSF than in WAF, and concentrations of transparent exopolymeric particles were highest in WSF and lowest in the controls. These differences highlight the importance of dosing strategy for mesocosm and toxicity tests.

This paper presents a review around seagrass habitat in Tarawa Lagoon, Kiribati and explores the links between seagrass occurrence and the national priority issues of climate change, urban development, human health, nearshore fisheries, threatened species, ocean policy, research capacity and awareness. The contribution of healthy seagrass habitats to many aspects of these national issues is often overlooked and there is need to establish the knowledge gaps and priority actions that can enable mitigation of issues that impact on valuable seagrass resources and their management. Research data on seagrass habitats in Kiribati, and the wider Pacific Island region, is limited and this hinders informed decisions at local, national and regional levels. We present a comprehensive review on seagrass within a national context to aid prioritisation and uptake of information for resource owners, and wider stakeholders, in Kiribati while acknowledging local expertise. The paper highlights data and knowledge gaps that if addressed, will provide information useful to Kiribati nationals, communities and government stakeholders. Recommendations for actions that fill these gaps and build understanding of seagrass resources in Kiribati are provided.

Application of larvicidal oil (LO) is the most common practice in Hong Kong to control mosquitos, and hence prevent mosquito-borne diseases and protect human health. Globally, this study represented the first comprehensive assessment of toxicity and risk posed by LO to marine organisms. We found concentrations of LO ranged from 0.08 to 0.66 mg/L in coastal seawaters of Hong Kong. Waterborne exposure to water-accommodated fractions of LO resulted in growth inhibition to two microalgal species (72-h EC₅₀: 1.92–2.90 mg/L) and acute mortality to three marine animals (96-h LC₅₀: 3.41–8.10 mg/L). From these toxicity results, a concentration that considered to be hazardous to 5% of species (HC₅) was predicted at 1.45 mg/L, while the predicted no-effect concentration was determined to be 0.29 mg/L. The hazard quotient of LO exceeded 1 at 9 out of 15 sites, indicating moderate-to-high ecological risk to exposure of LO in the marine environment of Hong Kong.

The cartography of shallow water macroalgal assemblages allows the assessment of water quality in coastal water bodies through the application of CARLIT. In this study, we have applied CARLIT to assess the ecological status of Algerian coastal water bodies for the first time. The surveyed zone is still in a good ecological status since 52% have a good to a high ecological Status. CARLIT index is well correlated with anthropogenic pressures and has proved suitable for the evaluation of the ecological status of coastal waters. Comparison between EQR values and EEI-c shows a similar pattern of change. CARLIT method allowed the collection of accurate information on the distribution and abundance of shallow-water communities. We also provide a cartographic baseline of the coastal assemblages useful for further evaluations on their geographic extension and for the implementation of a monitoring project on water quality in Algerian coast.

A bacterial consortium immobilized in magnetic floating biochar gel beads is proposed to remove high-molecular-weight polycyclic aromatic hydrocarbons. The microbial consortium performed better than single strains and consisted of four strains of marine bacteria for degrading pyrene (PYR), two strains for benzo(a)pyrene (BAP), and three strains for indeno(1,2,3-cd)pyrene (INP), which were isolated from oil-contaminated seawater. The immobilized cells could biodegrade 89.8%, 66.9% and 78.2% of PYR, BAP and INP, respectively, and had better tolerance to pH, temperature and salinity than free cells. The Andrews model was used to explore the biodegradation kinetics, and when the initial concentrations of PYR, BAP, and INP were 7.80, 3.05, and 3.41 mg/L, the specific biodegradation rates reached maximum values of 0.2507, 0.1286, and 0.1930 d⁻¹, respectively. The immobilized microbial consortium had a high HMW-PAH removal ability and good floatability and magnetic properties and could be collected by an external magnetic field.