The advent of Multicollector ICP-MS inaugurated the analysis of new metal isotope systems, the so-called “non-traditional” isotopes. They are now available tools to study geochemical and ecotoxicological aspects of marine metal contamination and hence, to push the frontiers of our knowledge. However, such applications are still in their infancy, and an accessible state-of-the-art describing main applications, obstacles, gaps, and directions for further development was missing from the literature. This paper fills this gap and aims to encourage the marine scientific community to explore the contributions of this newly available information for the fields of chemical risk assessment, biomonitoring, and trophic transfer of metal contaminants. In the current “Anthropocene” epoch, metal contamination will continue to threaten marine aquatic ecosystems, and “non-traditional” isotopes can be a valuable tool to detect human-induced changes across time-space involving metal contaminants, and their interaction with marine biota.

Biological invasions are considered one of the most important drivers of biodiversity loss. Here we use a before-after-control-impact (BACI) design to investigate the impact of Rugulopteryx okamurae on the structure of shallow-water marine benthic communities in São Miguel island, Azores. After its first appearance in 2019, R. okamurae has rapidly invaded much of the southern coast of the island, where it became the dominant algae. This was followed by significant changes in the structure of shallow-water marine benthic communities, with substantial losses of natural variability and species richness. Compared to before, there has been dramatic reductions in the abundances of articulated coralline algae, corticated algae and corticated foliose algae in invaded locations. These results highlight its highly invasive character, not seen with other, more well-known, invasive species. It remains to be investigated if its impacts persist throughout time and to quantify the functional consequences of such dramatic changes.

This study presents the fecal contamination dynamic at the two bathing sites of Aytré Bay (Charente Maritime, France). We quantified fecal indicator bacteria (FIB) abundances (Escherichia coli and enterococci) from water and sediment samples over one-year survey. Then we measured biological (bacterial abundance, chlorophyll-a), physico-chemical (dissolved nutrients and oxygen, salinity, pH …) and climatic (temperatures, rainfall and tidal coefficient) parameters. Results showed that FIB abundances were occasionally higher than the European regulatory threshold during winter, summer and fall. The “poor quality” of the bathing water was due to high enterococci abundance. We found negative significant correlations between FIB and water temperature and salinity, and positive significant correlations between FIB and rainfall, PO₄, NO₃, NO₂, and SiO₂ mainly in water. Relationships between parameters showed that during summer and spring the main environmental drivers were temperature and salinity, while in fall and winter they were rainfall and dissolved nutrients.

High sedimentation rates have well-documented, deleterious impacts on coral reefs. However, few previous studies have attempted to quantitatively describe a coral reef community across a large continuous sediment gradient. In this study distinct benthic assemblages in Fouha Bay, Guam, were identified using a Moving Window Analysis conducted along a two-order of magnitude sediment gradient, with transition boundaries that were generally consistent with sediment thresholds identified in the literature. Coral richness dropped exponentially with increasing sedimentation rate. Richness was nearly three times greater in assemblages with sedimentation rates <10 mg cm⁻² d⁻¹ compared to assemblages experiencing rates between 10 and 50 mg cm⁻² d⁻¹, and nearly 30 times greater than assemblages experiencing rates between 50 and 100 mg cm⁻² d⁻¹. No corals were found in assemblages with sedimentation rates >110 mg cm⁻² d⁻¹. Reducing sedimentation in this area could result in a shift of more diverse and abundant coral assemblages toward the head of the bay.

Heavy metals (HM) are the major proximate drivers of pollution in the mangrove ecosystem. Therefore, ecological risk (ER) due to HM distribution/concentration in core-sediment of Puzi mangrove region (Taiwan) was examined with tidal influence (TI) along with indigenous rhizospheric bacteria (IRB). The HM concentration was observed higher at active-tidal-sediment compared to partially-active-sediment. Geo-accumulation index (Igₑₒ) and contamination factor (CF) indicated the tidal-sediment was highly contaminated with arsenic (As) and moderately contaminated with Lead (Pb) and Zinc (Zn). However, the pollution loading index (PLI) and degree of contamination (Cd) exhibited ‘no pollution’ and ‘low-moderate degree of contamination’, in the studied region respectively. The isolated IRB (Priestia megaterium, Bacillus safenis, Bacillus aerius, Bacillus subtilis, Bacillus velenzenesis, Bacillus lichenoformis, Kocuria palustris, Enterobacter hormaechei, Pseudomonus fulva, and Paenibacillus favisporus; accession number OM979069-OM979078) exhibited the arsenic resistant behavior with plant-growth-promoting characters (IAA, NH₃, and P-solubilization), which can be used in mangrove reforestation and bioremediation of HM.

Phytoplankton assemblage and chlorophyll a along the salinity gradient and oxygen zonation were studied in Ulhas Estuary. Oxic condition exist in euhaline region of the estuary that receives oxygenated coastal waters, while, poly-meso-oligohaline region is hypoxic due to the accumulation of voluminous amount of pollutants from industrial effluents, domestic/sewage and agricultural discharges. Additionally, anthropogenically generated nutrients enhanced phytoplankton biomass (chlorophyll a) and their senescence also led to hypoxia. The dominance of diatoms (>70%) was observed in the euhaline-oxic region, while a tremendous decrease in their contribution (18%) was observed in the oligohaline region. Meso to oligohaline region of the estuary is governed by cyanophytes and chlorophytes due to their affinity towards low salinity and high dissolved inorganic nutrients. Carlson's Trophic State Index (TSI) further substantiated the estuary as eutrophic. Additionally, the study could identify the adaptation of cyanophytes and chlorophytes in oxygen deficient water.

This study investigated the concentration fluctuation of organotin compounds in the Turbidity Maximum Zone (TMZ) of the Yangtze Estuary within a tidal cycle. Organotin concentrations varied greatly during the tidal cycle with dissolved organotins ranged from 39 to 682 ng Sn·L⁻¹ and 40–1588 ng Sn·L⁻¹, and particulate organotins ranged from 59 to 467 ng Sn·g⁻¹ dw and 21–429 ng Sn·g⁻¹ dw in TMZ water close to Hengsha Island and Jiuduansha Island, respectively. Meanwhile, the maximum levels of organotins appeared at each period of tidal transition, suggesting the tidal-driven pulsed exposure of organotins was prevalent in the estuaries. Besides, the organic carbon-normalized partition coefficients (Kₒc) of tri-organotins between suspended particulate matter (SPM) and aqueous phase were correlated with the phase distribution of natural organic matter (NOM). The dissolved tri-organotins were also associated with the properties of dissolved organic carbon (DOC) including aromaticity, hydrophobicity, and chromophoricity. Hence, pulsed exposure on organotins in the TMZ are highly dictated by the dynamic environmental conditions (i.e., SPM and NOM) with the tidal currents, which could further provide information to assess organotin ecological risks accurately in estuaries.

In this study, density plume visualizations and statistical comparisons were made of enterococci bacteria (the main marine recreational microbial water quality indicator) densities, both before and after the upgrade of the discharge from the South Bay Ocean Outfall (SBOO) to secondary treatment level, so that the effect of this upgrade on ocean microbial water quality could be assessed. During the dry weather (bathing) season, reduction in enterococci densities was rather limited with only 2 shore stations and one kelp station showing significant reductions, and none showing increased compliance frequency. During the wet weather season, although the signature of land-based sources of bacterial pollution were evident, a majority of both shore (7 of the 11 stations) and kelp (4 of the 7 stations) stations showed statistically significant (p ≤ 0.05) reductions enterococci densities pointing to the role of the upgrade to secondary treatment in improving microbial water quality.

The pearl-farming industry depends mostly on the natural recruitment of pearl oysters. Little is known about the relative influence of different ecological processes on the natural recruitment of pearl oysters across biogeographical scales. Spatio-temporal dynamics of bivalve larvae and spats were described at Ahe and Mangareva, 1500 km apart across French Polynesia. We quantified the effect of candidate environmental predictors on the dynamics of larvae. Both lagoons showed similar temporal dynamics with twice more larvae and 6 times more spat in Ahe. Pinctada maculata spat were more abundant than for P. margaritifera at both lagoons. While the temporal dynamics in larvae abundance were best explained by a positive effect of temperature in Ahe, the dynamics in Mangareva were poorly predicted by the environmental variables, meaning bivalve early-life stages perform better in Ahe than Mangareva suggesting a mismatch between the relevant environmental forces driving larval dynamics at these two contrasting lagoons.

Oysters and clams are abundant and popularly consumed seafood in Viet Nam. These bivalves were proved to be suitable bioindicators to assess the heavy metal accumulation in the aquatic environment. The study is to investigate heavy metals such as As, Cd, Hg and Pb in the cultured oysters Saccostrea glomerata and clams Meretrix lyrata collected in VanDon - Quang Ninh, and CatBa - Hai Phong. The results showed that the metal heavy concentrations in the oysters Saccostrea glomerata and clams Meretrix lyrata presented in the order of As > Cd > Pb > Hg. The most polluted concentration with As among four heavy metals studied in six sampling sites was 2.81 ± 1.07 and 1.6 ± 0.62 mg/kg wet weight for clams and oysters, respectively. Investigated heavy metals in cultured oysters and clams indicated potential risks for human health in future by assessment of the heavy metals.