The concentration of heavy metals was determined in tissues of oyster, Saccostrea cuccullata, phytoplanktons and water samples from intertidal regions of the Chabahar bay, Oman sea. Oysters were collected from 5 stations and during spring, summer and autumn seasons. The heavy metals content in oysters, planktons and water samples showed variations depending on season, sampling station and size of the oysters. The heavy metals in water, plankton and tissue of oyster were higher in summer and the lowest metal contents were observed in autumn. The oyster tissue samples of size-class had lowest concentrations of Co, Pb, Ar and Cu. The maximum tissue levels of Ar, Cu, Ni and Zn were observed in oysters of size-class II while the values of Cd, Co and Pb had maximum levels in those of size-class III. The minimum levels of Cd and also Ni and Zn were found respectively in tissue of the oysters of size-class II and size-class III. There were significant differences in heavy metal content of oyster tissue, planktons and water samples between sampling stations. In all sampling stations and during all sampling seasons, the concentrations of heavy metals (except Cu) were almost higher in soft tissues than in hard tissues of oysters especially in oysters of size-class II and III. Seasonal analysis of tissue heavy metal content of oysters showed no significant differences between sampling stations.

The monitoring of macroalgae is required by the Water Framework Directive (WFD) to achieve good ecological status for coastal waters and specific questions arise for tropical ecosystems belonging to the outermost European regions. To assess the suitability of macroalgae as a biological quality indicator for La Réunion reef flats (France), we performed multivariate analyses linking the abundance and composition of macroalgae to water physico-chemistry. Three hydrological groups of stations were identified according to dissolved inorganic nitrogen (DIN) concentrations and DIN/PO4 ratios. Some indicator species were found at the N-enriched stations (Bryopsis pennata, Caulerpa lamourouxii, Chaetomoropha vieillardii, Derbesia sp., Blennothrix lyngbyacea, Sphacelaria tribuloides), and others at the non-impacted stations (Anabaena sp1, Blennothrix glutinosa, Codium arabicum, Neomeris vanbosseae). Another key result was the significant increase in red algal cover at the most N-enriched station. Our findings are discussed in the context of the application of the WFD in the outermost French regions.

The abundance of microplastics (MPs) in surface water and beach sediment in Southern Sri Lanka covering a distance of 91 km of coastline is reported. MPs were classified according to polymer type, geometry and color of the sites tested 60% showed MP contamination in sand and 70% in surface waters off the coast. The size range of MPs from surface waters and beaches were to 1.5–2.5 mm and 3–4.5 mm, respectively. Majority of these were identified as polyethylene (PE) and polypropylene (PP) with some polystyrene (PS) foam at a few sites. Fragments derived from larger debris appears to be the dominant type of MP at most sites and only 2 sites showed virgin pellets that accounted for 14% of the samples collected.

Though seagrass meadows are among the most productive habitats in the world, contributing substantially to long-term carbon storage, studies of the effects of critical disturbances on the fate of carbon sequestered in the sediment and biomass of these meadows are scarce. In a manipulative in situ experiment, we studied the effects of successive loss of seagrass biomass as a result of shading and simulated grazing at two intensity levels on sulphide (H2S) content and methane (CH4) emission in a tropical seagrass meadow in Zanzibar (Tanzania). In all disturbed treatments, we found a several-fold increase in both the sulphide concentration of the sediment pore-water and the methane emissions from the sediment surface (except for CH4 emissions in the low-shading treatment). This could be due to the ongoing degradation of belowground biomass shed by the seagrass plants, supporting the production of both sulphate-reducing bacteria and methanogens, possibly exacerbated by the loss of downwards oxygen transport via seagrass plants. The worldwide rapid loss of seagrass areas due to anthropogenic activities may therefore have significant effects on carbon sink-source relationships within coastal seas.

Aquatic pollution events can be detrimental to the survival of wildlife, particularly birds. To decontaminate affected birds, large quantities of fresh water are required. A recent study using seabird feathers, demonstrated that seawater wash/rinse can effectively remove oil from feathers. However to determine whether seawater was effective for live birds, we used 36 mallard ducks to replicate the oiled feather wash/rinse study. We investigated the time and volume of water used, bird water-proofing scores after daily swims and a barbule amalgamation index (BAI), for feathers collected at stages throughout the process. Results indicate that for oiled mallard ducks, the use of seawater for decontamination wash/rinse was effective. Seawater wash however, took longer and used a greater quantity of water. Time to birds being waterproof, was not significantly different between groups. The use of seawater has worldwide application for oiled wildlife response activities particularly in areas where freshwater supplies are limited.

Carbon-capture and storage is considered to be a potential mitigation option for climate change. However, accidental leaks of CO2 can occur, resulting in changes in ocean chemistry such as acidification and metal mobilization. Laboratory experiments were performed to provide data on the effects of CO2-related acidification on the chemical fractionation of metal(loid)s in marine-contaminated sediments using sequential extraction procedures. The results showed that sediments from Huelva estuary registered concentrations of arsenic, copper, lead, and zinc that surpass the probable biological effect level established by international protocols. Zinc had the greatest proportion in the most mobile fraction of the sediment. Metals in this fraction represent an environmental risk because they are weakly bound to sediment, and therefore more likely to migrate to the water column. Indeed, the concentration of this metal was lower in the most acidified scenarios when compared to control pH, indicating probable zinc mobilization from the sediment to the seawater.

Non-indigenous species (NIS) can cause substantial change in ecosystems and as marine invasives they can become a major threat to coastal and subtidal habitats. In September 2017 previously unknown and apparently NIS soft corals were detected on a shallow subtidal tropical rocky reef at Ilha Grande Bay, southeast Brazil. The present study aims to identify the species, quantify their distribution, abundance, and their interactions with native species. The most abundant NIS belonged to the recently described genus Sansibia (family Xeniidae) and the less common species was identified as Clavularia cf. viridis (family Clavulariidae). They were found along 170 m of shoreline at all depths where hard substrate was available. Sansibia sp. dominated deeper communities, associated positively with some macroalgal and negatively with the zoantharian Palythoa caribaeorum, which probably provided greater biotic resistance to invasion. Both species are of Indo-Pacific origin and typical of those ornamentals found in the aquarium trade.

The sensitivity of denitrifying community to salinity fluctuations was studied in microcosms filled with marine coastal sediments subjected to different salinity disturbances over time (sediment under frequent salinity changes vs sediment with “stable” salinity pattern). Upon short-term salinity shift, denitrification rate and denitrifiers abundance showed high resistance whatever the sediment origin is. Denitrifying community adapted to frequent salinity changes showed high resistance when salinity increases, with a dynamic nosZ relative expression level. Marine sediment denitrifying community, characterized by more stable pattern, was less resistant when salinity decreases. However, after two successive variations of salinity, it shifted toward the characteristic community of fluctuating conditions, with larger proportion of Pseudomonas-nosZ, exhibiting an increase of nosZ relative expression level. The impact of long-term salinity variation upon bacterial community was confirmed at ribosomal level with a higher percentage of Pseudomonas and lower proportion of nosZII clade genera.

Intertidal sessile organisms constitute through their life history unintended stress recorders. This study focuses on the impact of pollution on Mytilus edulis ability to cope with an additional stress. For this purpose, two acclimation stages to different temperatures were conducted before an acute stress exposure in mussels collected from a heavily polluted site. Gill proteomes were analyzed by 2DE and regulated proteins identified. Massive mortality was observed for organisms acclimated to colder temperatures. Despite this major difference, both groups shared a common response with a strong representation of proteoforms corresponding to “folding, sorting and degradation” processes. Nevertheless, surviving mussels exhibit a marked increase in protein degradation consistent with the observed decrease of cell defense proteins. Mussels acclimated to warmer temperature response is essentially characterized by an improved heat shock response. These results show the differential ability of mussels to face both pollution and acute heat stress, particularly for low-acclimated organisms.

Ailian Bay is an integrated multi-trophic aquaculture bay with approximately 60 years maricultural activities in North China. The floating raft culture of kelp and shellfish is the unique mariculture mode. In this study, the impacts of intensive mariculture activities on seasonal carbon and nutrient dynamics in Ailian Bay were systematically analysed via seasonal surveys between 2015 and 2016. The dissolved inorganic nitrogen and silicon reached the maximum concentrations during summer, which were mainly attributed to the release of shellfish metabolic by-products and their filter-feeding effects on diatoms. Dissolved organic carbon (DOC) concentrations were significantly elevated when kelps were rotting in summer and kelp seeding were occurring in winter. Meanwhile, the fluorescence intensity of humic-like chromophoric dissolved organic matter was relatively high in kelp mariculture zone. As most humic-like DOC are potentially refractory substances, we propose that kelp mariculture would contribute importantly to the increase of refractory DOC pool in oceans.