Quantitative calculation of the supply ratio of nutrients by different water masses suggests that the intrusion of Kuroshio subsurface water (KSSW) may indeed be an important factor in the formation of harmful algal blooms (HABs) in the Min-Zhe coastal area. This region in China has a complex hydrographic structure as well as a high incidence of HABs. The results of the calculations of the dissolved neodymium and its isotopes show that KSSW is an important provider of dissolved inorganic nitrogen (30–90 %) and phosphates (80–100 %) compared to the cases of the Taiwan Warm Current and the Changjiang Diluted Water. Sensitivity analysis results indicate that the percent contribution of KSSW in volume increased to 50–60 % in June, supplying favorable conditions for the growth of harmful algae. Our study implies that the invasion of the Kuroshio is likely to be a driving factor of HABs and, accordingly, a key factor in predicting HABs.

Understanding the relationship between mercury in seafood and the distribution of oceanic methylmercury is key to understand human mercury exposure. Here, we determined mercury concentrations in muscle and blood of bigeye and yellowfin tunas from the Western and Central Pacific. Results showed similar latitudinal patterns in tuna blood and muscle, indicating that both tissues are good candidates for mercury monitoring. Complementary tuna species analyses indicated species- and tissue- specific mercury patterns, highlighting differences in physiologic processes of mercury uptake and accumulation associated with tuna vertical habitat. Tuna mercury content was correlated to ambient seawater methylmercury concentrations, with blood being enriched at a higher rate than muscle with increasing habitat depth. The consideration of a significant uptake of dissolved methylmercury from seawater in tuna, in addition to assimilation from food, might be interesting to test in models to represent the spatiotemporal evolutions of mercury in tuna under different mercury emission scenarios.

Plastic pollution in the ocean primarily originates from the land-derived mismanaged plastic waste that is transported by rivers. This study aimed to estimate the plastic litter generation in the surface water in Jakarta and Indonesia. A field survey was conducted at six riverine sampling points (upstream to downstream) and three holding facilities of the litter in Jakarta during the rainy season. The Jakarta Open Data database was used to estimate the tonnage of plastic litter. By mass, plastic comprised approximately 74 % of the anthropogenic litter in rivers and 87 % in holding facilities. The riverine plastic proportion slightly increased downstream. Approximately 9.9 g/person/day of plastic litter was discharged into Jakarta's surface water during rainy season and recovered by floating booms. To reduce plastic pollution and its severe impacts on aquatic ecosystems and human health, further field investigation is necessary to design an effective clean-up system and litter-prevention strategy.

To evaluate the prospects of using Baikal endemic sponges as bioindicators of chemical elements pollution, the elemental composition of sponges, water and substrate samples, collected in two areas with different levels of anthropogenic loading of the Baikal Lake, was determined using two analytical techniques. The content of Cl, Ca, V, Zn, As, Se, Ba, Cd, and Cu in the sponges collected in Listvennichny Bay was significantly higher than in Bolshye Koty Bay. The values of the pollution indices point at the slight to moderate pollution of the substrates. According to the bioaccumulation factor values, sponges accumulate mainly Cd, Cu and Br from the substrate, and the main part of the elements from water. The distribution of elements longwise the sponges and their intraspecific variation were evaluated. It was shown that Lubomirskia baikalensis sponges were suitable bioindicators to assess the pollution of Lake Baikal.

Continuous input of plastic litter in ocean and coastal environments achieved alarming levels that are exposing new settings in natural systems. While novel plastic debris pollution, with rock-like appearance, has been reported worldwide, fundamentally geological analyses are still lacking. We surveyed the first occurrence of multiple associated plastic debris on a single outcrop located in a remote site (Trindade Island, SE Atlantic Ocean). Even though all plastic debris forms consisted of polypropylene and polyethylene, through a sedimentary approach (cross section, macro, and micro analyses) distinct types were identified. We detected plastiglomerates, geogenic analogous to conglomerates, divided into in situ and clastic types, and formed over beach sediment. We identified plastistones as a new type with homogeneous composition (lacking incorporated materials), geogenic-looking igneous rocks, divided into in situ and clastic types, and formed over rock surfaces. We linked pyroplastics, geogenic analogous to clasts, to clastic plastiglomerates/plastistones, therefore representing clastic types of plastic debris forms. This association was correlated in a depositional system model, which suggests that plastic debris forms are rock synthetic equivalents in which humans act as depositional and post-depositional agents.

In coastal productive zones, phytoplankton activity may influence trace metal speciation and partitioning at short temporal scale. We coupled hourly in situ voltammetry quantification of the lead (Pb), cadmium (Cd), and copper (Cu) potentially bioavailable fractions, using an innovative submersible sensing probe (the TracMetal), to surface water sampling for the quantification of the targeted trace metals in the dissolved <0.2 μm and <0.02 μm fractions, suspended particles, and phytoplankton nets in the Gironde Estuary mouth. The in situ TracMetal monitoring reflected real-time dynamic Cd and Cu regeneration related to algal cells under post-bloom conditions as well as Pb remobilization due to photoreduction of colloids. The potentially bioavailable fraction consisted in 30, 30–50 and <10 % of the total dissolved fraction for Pb, Cd, and Cu, respectively, representing crucial ecotoxicological information. Metal bioconcentration factors using the dynamic fraction concentrations showed levels up to 10⁷ for Cu in phytoplankton.

Understanding ecological impacts of bottom-based clam aquaculture can improve its management. In this study, taxonomic and functional macrofaunal assemblage were evaluated for two clam farms located in Laizhou Bay, China. Beta diversity and factors potentially regulating the dissimilarity of macrofauna were estimated. Both taxonomic and functional composition of macrofauna showed large differences between the clam farm and the control area. Functional dissimilarity within the clam farms was found to be nestedness and negatively correlated to local clam abundance. Additionally, the cultured clam enhanced the functional richness but made the macrofaunal assemblage more fragile against species or function loss. This effect would increase with clam abundance, which highlights the importance of identifying optimal clam culture intensity in developing a bottom-based clam aquaculture program.

Sea ice loss is opening shipping routes in Canada's Northwest Passage, increasing the risk of an oil spill. Harnessing the capabilities of endemic microorganisms to degrade oil may be an effective remediation strategy for contaminated shorelines; however, limited data exists along Canada's Northwest Passage. In this study, hydrocarbon biodegradation potential of microbial communities from eight high Arctic beaches was assessed. Across high Arctic beaches, community composition was distinct, potential hydrocarbon-degrading genera were detected and microbial communities were able to degrade hydrocarbons (hexadecane, naphthalene, and alkanes) at low temperature (4 °C). Hexadecane and naphthalene biodegradation were stimulated by nutrients, but nutrients had little effect on Ultra Low Sulfur Fuel Oil biodegradation. Oiled microcosms showed a significant enrichment of Pseudomonas and Rhodococcus. Nutrient-amended microcosms showed increased abundances of key hydrocarbon biodegradation genes (alkB and CYP153). Ultimately, this work provides insight into hydrocarbon biodegradation on Arctic shorelines and oil-spill remediation in Canada's Northwest Passage.

This study provides the first assessment of the impact of the worst oil spill ever faced by Brazilian sandy beaches by analyzing changes in the community structure of intertidal macroinfauna. Four sandy beaches were sampled three times after the oil spill, and the results were compared with previous data. The first sampling, conducted 15 days after the oil spill (October 2019), showed higher abundance of macroinfauna, which decreased in subsequent sampling conducted 60 and 120 days later, but never reached a lower level than in previous sampling. Of the macroinfauna species, Scolelepis sp. was most abundant in October 2019, while Donax gemmula was predominant during the other time periods. Changes observed in macroinfauna were due to natural fluctuations rather than a response to this disturbance. Characteristics of both the oil spill and macroinfauna contributed to the lack of acute impacts.

The Yellow Sea Bottom Cold Water zone (YSBCW) is a unique seasonal phenomenon in the Yellow Sea, where sea-floor cold water formed in winter is maintained until summer. This survey was conducted at 36 sites from 2018 to 2020. We identified 130 species of polychaetes, with an average density of 275 individuals/m². The number of species and density were different outside and inside of the YSBCW, and the outside was generally high. The remaining dominant species were all deposit feeders, although differences were observed in the surface or subsurface (burrowers). Correlations between polychaete community and environmental variables strongly correlated with depth, temperature, gravel, and sand. This study investigated polychaete community distribution, environmental characteristics, and feeding guilds in the YSBCW and can be used as a basic database for comprehensive research related to the Yellow Sea in the future.