Passive acoustic recorders were deployed over two years (February 2018–March 2020) in the Salish Sea to monitor the underwater soundscape. Seasonal cycles and differences between the open Strait of Juan de Fuca and protected inner waterways were pervasive during this period. A comparison between natural and human-derived noise demonstrated the impact of anthropogenic activities on the sound field. Elevated ambient noise levels during winter resulted predominantly from greater sea states and storm events. Abiotic additions were defined through correlations to wind speed, wave and precipitation measures. Vessel noise was a pervasive anthropogenic addition; commercial vessel noise was consistently present, whereas smaller vessels showed weekly and diurnal patterns, especially during the summer when their presence increased. A better understanding of the different soundscape constituents, and when each dominates, is crucial to understanding the human impact on underwater ecosystems and the organisms within them, leading to more effective mitigation measures.

The awareness of impact of microplastics has led stakeholders to define strategies for the reduction of plastic emission and for their removal from aquatic environments. Glitter includes a wide range of shapes, chemical types of plastics covered by a metallic layer and color addition that confer them the typical ‘sparkling’ aspect. Here we focus on critical aspects that make glitter a product with a potential of significant environmental impact suggesting the need to take effective measures to limit emissions. Glitter is used here as a paradigm for all emergent plastic pollutants which calls for a deeper rethinking of our concept of sustainability. We are only at the beginning of the studies on glitter in the aquatic environment but on the basis of their potential impacts now is the time to take decisions taking the sparkle off the sparkling time.

In aquatic environments, assessment of microplastic concentrations is increasing worldwide but environments from developing countries remain under-evaluated. Due to disparities of facilities, financial resources and human resources between countries, protocols of sampling, analysis and observations used in developed countries cannot be fully adapted in developing ones, and required specific adaptations. In Viet Nam, an adapted methodology was developed and commonly adopted by local researchers to implement a microplastic monitoring in sediments and surface waters of 21 environments (rivers, lakes, bays, beaches) of eight cities or provinces. Microplastic concentrations in surface waters varied from 0.35 to 2522 items m-3, with the lowest concentrations recorded in the bays and the highest in the rivers. Fibers dominated over fragments in most environments (from 47% to 97%). The microplastic concentrations were related to the anthropogenic pressure on the environment, pointing out the necessity in a near future to identify the local sources of microplastics.

Although seagrass ecosystems provide various ecosystem services, the implications in correspondence with temporal changes of the meadows is lacking. In this study, we analyzed two-decade changes of the seagrass area with the organic carbon storage and the sources at Libong island in Thailand. The seagrass area covered 841 ha in 2019, after two decades of decline (3.2 and 0.6% yr⁻¹ between 2004 and 2009 and 2009–2019, respectively). Although δ¹³C was not significant between depth layers (p > 0.05), the general trend suggested that the terrestrial source of carbon is dominating bottom depth layer (31.7–37.2%), mixture of terrestrial (19.7–30.3%), seagrass (22.9–29.6%), mangrove (16.8–43.0%) and CPOM (11.2–25.4%) in the middle, and mangroves and seagrasses are dominating surface layer (28.3–66.2 and 29.3–36.5%, respectively). These trends approximately correspond to the areal changes of the meadows, as well as changes of urban area and water quality, providing detailed information on the meadow changes and possible causes.

We investigated a sediment core collected from the Geum Estuary through sedimentological and geochemical analyses. Three lithological units were classified based on sedimentological characteristics. Unit 1 and Unit 3 were geochemically distinct, while Unit 2 was the transitional phase between them. The geochemical results suggest that the contribution of terrestrial organic carbon (OC) to the sedimentary OC pool in the coarse-grained Unit 1 was lesser than that of fine-grained Unit 3. The excess activity (²¹⁰Pbₑₓ) and the sedimentation rate indicate that Unit 1 corresponded to 1977 Common Era (CE). Since the first dam construction on the Geum River began in 1975 CE, the deposition of Unit 1 in the Geum Estuary is likely associated with river impoundments, which reduce the delivery of fine-grained sediment and terrestrial OC to the estuary. This study highlights the role of river impoundments in altering the sedimentary OC and thus the sedimentary environment in the estuary.

The fluctuating asymmetry values of the two otolith parameters: length and width of Engraulis australis, recovered from the food of gannet, which inhabit colonies in islands at Hauraki Gulf, New Zealand was calculated in this study. The dissimilarity value of the otolith width was higher than that of the otolith length. An inclination of upsurge in the dissimilarity values with the fish length was noted for the otolith sizes studied. The dissimilarity value in the two otolith sizes was the lowest for fish having total length of 115–154 mm, and the highest for fish with length of 151–160 mm. The conceivable reason of the dissimilarity obtained could be related to diverse contaminants and their presence in the study location.

Zn, Pb, Cr, Cu, Ni, Cd concentration and ecological risk were studied in three bays to evaluate the heavy metal (HM) contamination of seagrasses. Seasonal HM accumulation varied according to locations, seagrass species and tissues. Halophila beccarii had much higher HM concentrations except for Cr in Zhelin Bay, however, bioconcentration factors (BCF) of Cu, Ni, Pb, Zn were higher in Liusha than Zhelin Bay. Cr was much enriched in Thalassia hemperichii and Enhalus acoroides than Halophila beccarii and Halophila ovalis. Cr, Cu, Ni, Pb were easy to accumulate in belowground tissues in Halophila ovalis. In contrast, almost all HM were more enriched in aboveground tissues in other species. Generally, BCF exceeding 1 and high metal pollution index suggested HM had potential ecological risk on seagrasses. The results provide the reference for managing and protecting seagrass ecosystem in South China, and are significant to expand the global seagrass detection network.

Millions of tons of plastic enter the environment every year, where much of it concentrates in environmental sinks such as tidal marshes. With prior studies documenting harm to marine fauna caused by this plastic pollution, the need to understand how this novel type of pollution affects estuarine fauna is great. Yet, research on the fate and uptake of plastic pollutants in estuarine ecosystems is sparse. Therefore, we quantified plastic prevalence and ingestion by two species of resident marsh bird, Clapper Rails (Rallus crepitans) and Seaside Sparrows (Ammospiza maritima), in coastal marsh ecosystems within Mississippi. We detected microplastics (plastics smaller than 5 mm) in 64% of marsh sediment samples, 83% of Clapper Rail and 69% of Seaside Sparrow proventriculus samples. Dominant types of microplastics detected in sediment and bird samples were fibers. This study provides the first evidence of microplastic ingestion by marsh birds and its distribution in coastal marshes within Mississippi.

The present study aimed to assess corocoro grunt use as bioindicator of Hg contamination in coastal marine systems by testing environmental (seasons) and biological effects (sexual maturity, size and weight) on THg accumulation and assessing human health risk. Fish was captured in winter and summer seasons at Vermelha Beach, Rio de Janeiro, Southeast Brazil. Adult O. ruber showed significantly higher THg than juveniles, and THg concentrations were positively correlated to fish length and weight. Fish THg concentrations did not differ between seasons and were below the accepted limit for human consumption. Human exposure risk by fish consumption was 0.31 μg MeHg kg⁻¹ week⁻¹ and the hazard quotient was 0.44 (0.11–1.84). Our results confirm the applied use of O. ruber as sentinel species for Hg contamination monitoring and highlight concern for its consumption, especially for local fishermen populations that highly consume this fish and may be more susceptible to Hg adverse effects.

Mercury (Hg) is a contaminant of global concern in marine ecosystems, notably due to its ability to accumulate and concentrate in food webs. Concentrations of total mercury (THg), methylmercury (MeHg) and inorganic mercury (IHg) were assessed and compared in different tissues (liver, muscle, and gonads) of three common fish species (hake Merluccius merluccius, red mullet Mullus surmuletus, and sole Solea solea) from the continental shelf from the southern part of the Bay of Biscay. Several studies investigated Hg concentration in fish muscle, but few assessed concentrations in other organs, despite the importance of such data to understand contaminant organotropism and metabolization. Results showed that trophic position and feeding habitat are required to understand the variability of Hg concentration in muscle between fish species. In addition, high MeHg/THg ratio in muscle could be explained by the predatory behavior of the studied fish species and the biomagnification of this Hg species within the food web, MeHg. Despite differences between species, Hg concentration was always higher in muscle (from 118 ± 64 to 338 ± 101 ng g⁻¹ w.w.) and liver (from 122 ± 108 to 271 ± 95 ng g⁻¹ w.w.). These results can be related to physiological processes especially the MeHg detoxification strategies.