A quinquennial seasonal study (2015–2019) has been conducted to evaluate the bioaccumulation pattern of trace metals in Meretrix meretrix. The concentration of trace metals in the clam was observed as Cr > Cu > Ni > Zn > Pb > Cd > Hg, (Body> Mantle > Gills), similar to sediments. Contamination Factor of Cu and Cr in sediments showed strong association with the corresponding metal concentration in the body (r = 0.687, r = 0.962), mantle (r = 0.880, r = 0.956) and gills (r = 0.937, r = 0.863). Bioconcentration Factor was high for Cr followed by Ni. Mean Metal Concentration Rate (MMCR) of Cr was high and Hg was low (Body>Mantle>Gills). Our study establishes that the trace metal intake by Meretrix meretrix is associated with seasonal variation, physicochemical factors, sediment texture, chemical speciation and the metabolic stress created within the species induced from increased demand for protein synthesis. The latter resulted in the augmented rate of accumulation of Cu and Cr.

An overview of dinoflagellates cysts assemblage is presented as a trophic index for three monsoon-influenced estuarine and marine ports along the Indian coast. The cyst distribution (including harmful species) showed a trend of highest abundance and species number in highly eutrophicated estuarine (Cochin-south) followed by medium (New-Mangalore-central) and low (Kandla-north) levels of eutrophicated marine ports. The investigation revealed four new species in the region (Bitectatodinium spongium, Gonyaulax elongatum, Brigantedinium sp. and potential harmful species Blixaea quinquecornis-cyst similar to planktonic). Autotrophs dominance in the highly productive Cochin and New-Mangalore ports reveals that, in eutrophic systems, heterotrophs need not always be dominant. The indicator taxa (Polykrikos, Protoperidnium, and Lingulodinium) presence in high density indicated a eutrophic system. This study concludes cyst (species numbers/Fisher-α index/indicator species) as potential eutrophication proxies and emphasizes greater harmful-algal-bloom risks in the high trophic-index ports (Cochin and New-Mangalore).

The emergence of the COVID-19 pandemic has caused worldwide health constraints. This study was conducted to establish a baseline monitoring survey to describe the distribution of PPE litters during the COVID-19 pandemic in the province of Palawan, Philippines. A total of 386 COVID-19-related PPE items were present in 83 % of coastal sampling sites with over a cumulative area of 48,200 m², with a density of 8 × 10⁻³ items m⁻². The facemask (98 %; n = 377) was the primary type of PPE, followed by face shield (2 %; n = 9). Meanwhile, the daily density of PPE litters in San Manuel, Puerto Princesa ranged from 0 to 9.9 × 10⁻² items m⁻², with a mean density of 8 × 10⁻³ items m⁻². The accumulation rates of PPE items ranged from 3.27 × 10⁻¹ items to 1.143 items d⁻¹, with an average rate of 7.29 × 10⁻¹ items d⁻¹.

Twenty beaches located around the island of Cyprus, in the eastern Mediterranean, were identified as monitoring sites. They were monitored over four monitoring sessions from January to September 2021 to assess marine litter amounts, categories, and spatiotemporal distribution. A total of 42,499 marine litter items were collected. The average marine litter density was 0.19 items/m². Most of the collected items were plastics, with single-use plastics being ubiquitous. Plastic fragments >2.5 cm made a significant proportion of the plastic litter collected, particularly in the northern coasts of the island. Cigarette butts were abundant on touristic beaches, especially in the tourism period. The study identifies significant temporal and spatial variations in the abundance and distribution of marine litter, as well as variations related to waste management or lack thereof.

Trindade is a remote island far from 1170 km of the Brazilian coast in the Atlantic Ocean, between South America and South Africa. The island has great biodiversity and scientific studies on the fauna and flora of Trindade are still scarce. Accordingly, since crustacean species of the island are also little known, this research features an unprecedented data set, which provides information on the level of potential toxic elements in two crab species: the Grapsus grapsus (herbivore) and the endemic species Gecarcinus lagostoma (omnivorous) which is in threatened status. Although Trindade has experienced contamination from human activities, mainly plastic debris, the element levels found in the samples suggest that there are no relevant inorganic sources into the island. Since minor and trace elements accumulated by marine invertebrates does not present a pattern behavior, our results can support other studies focused on the impact of global warming to the marine ecosystem.

Heavy metal concentrations in surface waters and sediments of Shanghai port were measured to analyze the spatial distribution characteristics, sources and pollution degrees. The southern Shanghai port was heavily polluted by Cd, Pb, Cr and Cu in water, and the concentrations of Pb, Hg and Zn in sediments exceeded Effects Range Low. Cu, Pb, Cd and Cr in water were positively correlated in group, and they probably derived from industrial and domestic sewage, fossil fuel burning and vehicular pollution and represented 82.47 % of the contribution. Zn, Hg and As contaminations represented industrial and agricultural effluent sources and accounted for the remaining 17.53 %. Heavy metal pollution of Yangshan Port water was at high pollution, and the remaining sites were at low pollution. Most of the sampling sites were at moderate ecological risk in sediments, and the pollution of Cd, Hg and Zn were serious.

The increased use of disinfectants due to the spread of the novel coronavirus infection (e.g. COVID-19) has caused burden in the environment but knowledge on its ecotoxicological impact on the estuary environment is limited. Here we report in vivo and molecular endpoints that we used to assess the effects of chloroxylenol (PCMX) and benzalkonium chloride (BAC), which are ingredients in liquid handwash, dish soap products, and sanitizers used by consumers and healthcare workers on the estuarine rotifer Brachionus koreanus. PCMX and BAC significantly affected the life table parameters of B. koreanus. These chemicals modulated the activities of antioxidant enzymes such as superoxide dismutase and catalase and increased reactive oxygen species even at low concentrations. Also, PCMX and BAC caused alterations in the swimming speed and rotation rate of B. koreanus. Furthermore, an RNA-seq-based ingenuity pathway analysis showed that PCMX affected several signaling pathways, allowing us to predict that a low concentration of PCMX will have deleterious effects on B. koreanus. The neurotoxic and mitochondrial dysfunction event scenario induced by PCMX reflects the underlying molecular mechanisms by which PCMX produces outcomes deleterious to aquatic organisms.

Brackish areas are where freshwater and seawater meet and possess high geographical and biological importance. However, no unified evaluation method exists for brackish sediments. Therefore, this study applies both the fresh water-sediment quality guidelines (F-SQGs) and the marine-sediment quality guidelines (M-SQGs) to evaluate metal contamination in brackish areas of Korea. The predicted reliability was examined using a receiver operation characteristic (ROC) curve. In the threshold effect level (TEL) evaluation of F-SQGs and M-SQGs, some metals (Cu, Zn, Hg, and Cd) showed significant differences according to guideline characteristics. The ROC curve showed that the predicted reliability of F-SQGs was 97.8 %, which was higher than M-SQGs (91.7 %). From the results of TEL evaluation and ROC curve prediction, F-SQGs are more suitable for the evaluation of brackish sediments in South Korea than M-SQGs.

Coral diseases acting synergistically with other environmental stressors are a growing problem for Caribbean reefs. Hard coral cover, coral traits, and coral diseases were examined from 1999 to 2021 for Akumal reef, located in the Northern Mexican Caribbean. The 45 recorded coral species were classified into life-history strategies: competitive, stress-tolerant, and weedy, associated with different framework-building capacities. Results indicate that cumulative impacts of coral diseases outbreaks in the last two decades, in synergy with the effects of coastal development and thermal stressors, have decreased significantly cover and abundance of major reef-building corals, shifting the dominance of the coral assemblage to species belonging to non-framework weedy life history strategy, corresponding to a low Reef Functional Index. Due to the relevant role of coral diseases in shaping coral assemblages, addressing current, and preventing future coral disease outbreaks through integrated management strategies, will be paramount to preserving physical functionality in Caribbean reefs.

Environmental impacts of the first submersible salmonid culture cage, which was launched in the deep-sea of the Yellow Sea Cold Water Mass, were investigated. The temporal and spatial variations of several physicochemical parameters were observed in both the bottom and sediment pore water. Aquaculture activities decreased bacterial richness in the sediment. The dominant phyla Proteobacteria, Desulfobacterota and Acidobacteriota, accounted for 30.42 % of the total bacteria community. Principal component analysis indicated that the bacterial composition in December was different from that in the other three months, and the aquaculture activity affected the distribution of the sediment microbial community in June, August and April. Planctomycetes was selected as biomarkers in the aquaculture area by linear discriminant analysis effect size. Redundancy analysis showed that the biomarkers were positively correlated with temperature and the concentration of nitrite in June, and negatively correlated with the dissolved oxygen in August and April.