This study proposes a pro-active approach for evaluations of methylmercury (MeHg), total mercury (THg), arsenic (As), cadmium (Cd) and lead (Pb) in situ bioaccumulation in fish (Atherinella brasiliensis) muscles, using specimens from the external sector of Guanabara Bay as a study case. This approach included an hierarchical sequence: analysis of the pollutants concentrations and their comparison to safety criteria; correlations between specimens concentrations vs length (as a proxy of exposure time); projections of concentrations in key lengths (sexual maturation, asymptotic, length limits for fishing and median of fish population) through polynomial regressions, dose-response analysis (Probit), decreasing curves and incorporation rates (using only three length intervals). The incorporation rates were ascending for MeHg and THg (continued bioaccumulation) and descending for As, Pb and Cd (possible biological dilution). The projections were satisfactory, evidencing their use for an improvement on the risks monitoring of fishing and fish consumption by humans in coastal environments.

The distribution of 14 ARGs, intI1, and 16S rDNA were analysed in 4 wastewater treatment plants (WWTPs), 2 effluent receiving areas (ERAs), and Hangzhou Bay (HZB). The results showed that each integrated WWTP (IWWTP) received higher abundance of ARGs than pharmaceutical WWTPs (PWWTPs), and IWWTPs removed ARGs more efficiently than PWWTPs. The WWTP effluents greatly contributed to the ARGs pollution in the water environments of the ERAs and HZB, and the total abundance of the ARGs displayed a distance decay pattern. In coastal sediments, more ARGs were accumulated in remote sites. The correlation analysis showed that the occurrence of ARGs was more related to 16S rDNA and intI1 in the WWTPs. Three macrolides resistance genes (ermB, mphA, and vatB) had strong correlations with 16S rDNA and intI1 in all the sample groups. Our study clearly reveals the link between land WWTPs discharge and emerging pollution of ARGs in coastal environments.

The interaction between bottom-up and top-down processes in coastal ecosystems has been scarcely studied so far. Temporal changes in trophic interactions of Zostera marina along the Swedish west coast are relatively well studied, with the exception of epifaunal communities. Epifauna was used as a model study to explore resource (bottom-up) or predator (top-down) regulated in a vegetated ecosystem. We conducted a 21-year comparative study (1997 and 2018) using epifauna of 19 Zostera marina meadows along the Swedish Skagerrak coast. Large changes were observed in the composition of small (0.2–1 mm) and large (>1 mm) epifauna. In the small-sized epifauna, the nematode Southernia zosterae and harpacticoids showed an increase of 90% and a decrease of 50% of their abundances, respectively. In the large-sized epifauna, the polychaete Platynereis dumerilii and chironomid larvae were absent in 1997 but thrived in 2018 (>2000 ind. m⁻²). Mesoherbivores (Idoteids and gammarids) were locally very abundant in 1997 but disappeared in 2018. An 83% decline of mytilids settling in Zostera marina leaves was observed. Our results showed that epifauna is predominantly top-down regulated. An integrative framework of the study area is outlined to shed light on the causes and consequences of the environmental shifts reported in Zostera meadows from the northern Skagerrak area throughout the last three decades.

In this study, we derived the predicted no-effect concentrations (PNEC) for triphenyl (octadecylamine) boron (TPB-18) and investigated the occurrence of triphenylboranes (TPBs), including TPB-18, for ecological risk assessment in the Seto Inland Sea, Japan. We tested algal growth inhibition, crustacean immobilization, and reproductive toxicity and performed toxicity tests in fish to assess acute and chronic toxicity and generate the PNEC for TPB-18. The minimum toxicity value was 0.30 μg/L, as determined by the 72-h no-observed-effect concentration (NOEC) for the alga Chaetoceros gracilis. The 5th-percentile of hazardous concentration (HC₅), derived from NOECs using the species sensitivity distributions approach, was 0.059 μg/L, which indicated the PNEC of 0.0059 μg/L. In comparison, the highest concentration in seawater sampled from the Seto Inland Sea was 0.00034 μg/L, suggesting that the ecological risks posed by TPB-18 are currently low.

The spatial distribution of phthalate acid esters (PAEs) in sediments of the Jiaozhou Bay and its relationships with anthropogenic activities and environmental variables were investigated in this work. Thirteen PAEs were prevalent in sediments and the total PAE concentrations ranged from 462.1 to 15,133.2 μg/kg. The PAE concentrations increased northeastward and northwestward from the bay mouth in saddle shapes and the highest concentrations were located in the northeastern region according to the spatial distribution patterns generated by geographic information systems. The rivers were the main routes for transporting pollutants into the bay and terrigenous PAEs diluted offshore, so the PAE distribution in sediments was originated from anthropogenic activity intensity. There were strong positive correlations among PAEs with each other, except for di-n-octyl phthalate, and the average residence time (ART) exerted a significant positive impact on the PAE concentrations by Pearson correlation and redundancy analysis. The dibutyl phthalate and di-(2-ethylhexyl) phthalate had high risks to organisms in the northeast and west regions according to the environmental risk limits and risk quotients. The results might provide new insights into the PAE researches and supply information for environmental management and remediation.

Understanding which drivers cause diversity patterns is a key issue in conservation. Here we applied a spatially explicit model to predict marine benthic diversity patterns according to environmental factors in the NW Mediterranean Sea. While most conservation-oriented diversity studies consider species richness only and neglect equitability, we measured separately species richness, equitability, and ‘overall’ diversity (i.e., the Shannon-Wiener H′ function) on a dataset of 890 benthic species × 209 samples. Diversity values were predicted by means of Random Forest regression, on the basis of 10 factors: depth, distance from the coast, distance from the shelf break, latitude, sea-floor slope, sediment grain size, sediment sorting, distance from harbours and marinas, distance from rivers, and sampling gear. Predictions by Random Forests were accurate, the main predictors being latitude, sediment grain size, depth and distance from the coast. Based on predicted values, diversity hotspots were identified as those localities where indices were in the 15% top segment of ranked values. Only a minority of the diversity hotspots was included within the boundaries of the protection institutes established in the region. Marine protected areas are often created in sites harbouring important coastal habitats, which risks neglecting the diversity hidden in the sedimentary seafloor. We suggest that marine protected areas should accommodate portions of sedimentary habitat within their boundaries to improve diversity conservation.

We assessed seasonal and spatial variability of seawater quality and bacterial pollution in two sewage-impacted and two reference rocky shores in the area of Comodoro Rivadavia, the largest city in central Patagonia. Samples taken from winter 2015 to autumn 2017 at different intertidal levels showed that the impacted sites experienced a decrease of salinity—more pronounced towards the autumn—, a slightly higher turbidity, the lowest values of dissolved oxygen, and significantly higher concentrations of nitrates throughout the year. They also were up to ten times above the legal limit of fecal indicator bacteria (FIB) for recreation and fishing areas. Enterococci increased particularly during winter. All bacteriological indicators decreased markedly during spring. Principal component analysis arranged the reference sites mostly by their higher salinity, and the impacted sites by concentration of FIB, nitrates and phosphates. Impacted and reference sites overlapped towards lower levels, where the explicative variables were more stable.

The southern Yellow Sea (SYS) is a significant repository of sedimentary organic matter (SOM) and has been impacted by green tides since 2007; however, data on the distribution and quantitative contributions of different SOM sources has been scarce. TOC, TN and their δ¹³C and δ¹⁵N values were determined in 38 surface sediments. TOC and TN were high in central mud area and low in sand area. TOC was positively correlated with the abundance of fine-grained sediments, indicating that controlling factors of SOM were the sediment types and circulation system. The SOM included marine and terrestrial organic matter and anthropogenic nutrient inputs according to TOC/TN (5.8–14.3), δ¹³C (−25.1‰ to −21.0‰) and δ¹⁵N (2.6‰–6.4‰). High terrestrial contributions in northern and western parts of SYS, were influenced by terrestrial materials and eroded substances of the abandoned Yellow River delta, respectively. In the central mud area of SYS, marine organic matter was dominant.

Heatwaves are an increasing threat to organisms across the globe. Marine and atmospheric heatwaves are predicted to impact sessile intertidal marine organisms, especially when exposed at low tide and unable to seek refuge. The study aimed to determine whether a simulated atmospheric heatwave will alter the survival of selectively bred families of Sydney rock oysters (Saccostrea glomerata), and whether survival is dependent on morphological and physiological traits. The survival of S. glomerata families to a simulated atmospheric heatwave varied from 25 to 60% and was not correlated with morphology or physiology. Survival may depend on the presence of genotypes that translate into molecular defenses such as heat-shock proteins and inhibitor of apoptosis proteins that provide oysters with resilience. Understanding the responses among families of oysters to heatwaves is critical if we are to restore the ecological services of oyster reefs and sustain oyster aquaculture.

The nitrogen uptake kinetics and physiological growth of Karenia mikimotoi and Skeletonema costatum sensu lato grown on different N substrates and concentrations were compared in the laboratory. In the presence of three N substrates, both species preferred to take up NH₄⁺. K. mikimotoi and S. costatum s.l. showed the highest substrate affinities for urea and NO₃⁻, respectively. Both species grew well on three N substrates, and the growth parameters were comparable among the different N substrates. However, K. mikimotoi assimilated urea more efficiently than it assimilated either NO₃⁻ or NH₄⁺. Different with S. costatum s.l., K. mikimotoi grew slowly and steady and the physiological and growth activities in N-depleted conditions were higher than those in N-replete conditions. Our results suggested that K. mikimotoi shows a greater readiness for uptake and assimilation of urea, and that this species is more competitive in an N-depleted environment when compared with S. costatum s.l.