The successful protection and management of marine ecosystems depend on understanding the capability of biota for recovering after stressor mitigation actions are taken. Here we present long-term changes (1984–2012) in degraded subtidal assemblages following the implementation of the sewerage scheme for the metropolitan area of Bilbao (1 million inhabitants). Qualitative and quantitative species composition of disturbed vegetation shifted over time, making it more similar to that of the reference assemblages considered. Species density in the disturbed habitats increased, which is also a positive sign of recovery. However, eleven years after the clean-up was completed, canopy-forming macrophytes showed no signs of recovery. We argue that the ecological resilience of the ecosystem may have been eroded after a long-standing pollution perturbation and that underlying climate change could be influencing the recovery trajectory of the degraded assemblages. The implications of these conclusions for the implementation of European marine environmental legislation are discussed.

Anthropogenic nitrogen (N) discharges has caused eutrophication in coastal zones. Ammonia-oxidizing bacteria (AOB) convert ammonia to nitrite and play important roles in N transformation. Here, we used pyrosequencing based on the amoA gene to investigate the response of the sediment AOB community to an N pollution gradient in the East China Sea. The results showed that AOB assemblages were primarily affiliated with Nitrosospira-like lineages, and only 0.4% of those belonged to Nitrosomonas-like lineage. The Nitrosospira-like lineage was separated into four clusters that were most similar to the sediment AOB communities detected in adjacent marine regions. Additionally, one clade was out grouped from the AOB lineages, which shared the high similarities with pmoA gene. The AOB community structures substantially changed along the pollution gradient, which were primarily shaped by NH4+–N, NO3−–N, SO42−–S, TP and Eh. These results demonstrated that coastal pollution could dramatically influence AOB communities, which, in turn, may change ecosystem function.

The ecological relevance of polychaetes coupled with their easy culture and maintenance in the laboratory, has led them to become increasingly used in marine ecotoxicological studies, raising the need to validate frequently applied monitoring tools at various biological levels. The present study was aimed to characterize the cholinesterases (ChE) activity in the polychaete Capitella teleta, using three substrates (acetylthiocholine iodide, propionylthiocholine iodide, and S-butyrylthiocholine iodide) and four known inhibitors (eserine hemisulfate, BW284c51, iso-OMPA and chlorpyrifos-oxon). Results showed that most of the measured cholinesterase activity was acetylcholinesterase (AChE). Inhibition of enzyme kinetic experiments denoted that sensitivity of C. teleta’s ChE to the organophosphorous metabolite chlorpyrifos-oxon (IC50=60.72nM) was analogous to some fish species. This study highlights the relevance of ChE characterization before its use as a biomarker in ecotoxicology and biomonitoring studies.

Sediments, clams Scrobicularia plana and worms Hediste diversicolor from the Guadalquivir estuary were collected ten years after the Aznalcóllar mine spill and analyzed for metals. Significant seasonal and spatial effects were detected for most elements, so data from different sampling periods and locations were treated separately. Overall, the most polluted sites were found upstream, although Zn and Cu tended to accumulate at the estuary mouth. A significant decline of Zn in sediments and clams was observed compared to levels reported following the spill, so the estuarine ecosystem has recovered. However, the concentrations of some elements in S. plana were still higher than those of heavily contaminated regions. In this mollusk, Pb and As levels were higher in 2008 than in previous years, suggesting a new source entering into the estuary. Metals in sediments presented low bioavailability for biota, so other sources must account for the concentrations observed in these species.

Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN. Metallothionein, copper and zinc in Franciscana were assessed in two geographic groups; one inhabits La Plata River estuary, anthropogenically impacted, and the other inhabits marine coastal ecosystems, with negligible pollution. Despite the environment, hepatic and renal MT concentrations were similar, but there was a declining trend from early to later developmental stages. Metallothionein K/L, Cu and Zn levels corresponded to normal reported ranges. MT was not related with Cd. Fetal concentrations were higher than its mother. These results and the health status of dolphins are suggesting that MT correspond to physiological ranges for the species, and they are closely to homeostasis of Zn and Cu, according to its ontogenetic changes. The information constitutes the first MT information on Franciscana dolphin and can be considered as baseline for the species conservation.

Alexandrium catenella (group IV) and Alexandrium tamarense (group III) (Dinophyceae) are two cryptic invasive phytoplankton species belonging to the A. tamarense species complex. Their worldwide spread is favored by the human activities, transportation and climate change. In order to describe their diversity in the Mediterranean Sea and understand their settlements and maintenances in this area, new microsatellite markers were developed based on Thau lagoon (France) samples of A. catenella and A. tamarense strains. In this study twelve new microsatellite markers are proposed. Five of these microsatellite markers show amplifications on A. tamarense and ten on A. catenella. Three of these 12 microsatellite markers allowed amplifications on both cryptic species. Finally, the haplotypic diversity ranged from 0.000 to 0.791 and 0.000 to 0.942 for A. catenella and A. tamarense respectively.

The tolerance and physiological responses of the larvae of two congeneric gastropods, the intertidal Nassarius festivus and subtidal Nassarius conoidalis, to the combined effects of ocean acidification (pCO2 at 380, 950, 1250ppm), temperature (15, 30°C) and salinity (10, 30psu) were compared. Results of three-way ANOVA on cumulative mortality after 72-h exposure showed significant interactive effects in which mortality increased with pCO2 and temperature, but reduced at higher salinity for both species, with higher mortality being obtained for N. conoidalis. Similarly, respiration rate of the larvae increased with temperature and pCO2 level for both species, with a larger percentage increase for N. conoidalis. Larval swimming speed increased with temperature and salinity for both species whereas higher pCO2 reduced swimming speed in N. conoidalis but not N. festivus. The present findings indicated that subtidal congeneric species are more sensitive than their intertidal counterparts to the combined effects of these stressors.

Grey seals as top-predators bioaccumulate contaminants and can be considered as sentinels of eco-system health. Pups are weaned after a short nursing period, characterised by an enormous lipid transfer and exposure to contaminants. This study established molecular biomarkers of the xenobiotic metabolism and immune system to help assess health and immune status. mRNA transcription of AHR, ARNT, PPARα and cytokine IL-2 and heat-shock-protein HSP70 was measured in blood of grey seal pups and adults in rehabilitation and permanent care using RT-qPCR and compared to rehabilitating harbour seal pups and haematology values. In pups highest levels at admission in xenobiotic biomarker, HSP70 and cytokine transcription may show contaminant exposure via lactation, stress during abandonment and dehydration. The significant decrease may be linked to diet, health improvement and adaptation. Adults showed higher levels and more variation in biomarker transcription and clear species-specific differences between harbour and grey seal pups were found.

Extreme heating (up to 43°C measured from five-year temperature records) occurs in shallow coastal seagrass meadows of the Great Barrier Reef at low tide. We measured effective quantum yield (ϕPSII), growth, senescence and mortality in four tropical seagrasses to experimental short-duration (2.5h) spikes in water temperature to 35°C, 40°C and 43°C, for 6 days followed by one day at ambient temperature. Increasing temperature to 35°C had positive effects on ϕPSII (the magnitude varied between days and was highly correlated with PPFD), with no effects on growth or mortality. 40°C represented a critical threshold as there were strong species differences and there was a large impact on growth and mortality. At 43°C there was complete mortality after 2–3days. These findings indicate that increasing duration (more days in a row) of thermal events above 40°C is likely to affect the ecological function of tropical seagrass meadows.

PCB levels in plankton were investigated in the Bay of Marseille, Western Mediterranean Sea, between September 2010 and October 2011. Concentrations of PCB congeners (CB 18, CB 52, CB 101, CB 118, CB 138, CB 153, CB 180) were determined in three plankton size-classes (60–200, 200–500 and 500–1000 μm) together with different parameters: chlorophyll content, plankton dry-weight biomass, carbon and nitrogen stable isotope ratios and plankton-community structure. The ∑PCB7 concentrations ranged between 14.2 and 88.1 ng g−1 d.w., for all size classes and all sampling periods. The results do not show the biomass dilution effect and indicate moderate but significant biomagnification with plankton trophic position estimated by δ15N signatures. Equilibrium with water phase may notably contribute in controlling the PCB levels in the plankton. More generally, presented results imply that PCB accumulation in the plankton is an effect of abiotic and trophic complex interactions in the Bay of Marseille.