The terrestrial biogeochemical cycle of mercury has been widely studied because, among other causes, it presents a global distribution and harmful biotic interactions. Forested ecosystems shows great concentrations from Hg and Litterfall is known as the major contributor to the fluxes at the soil/air interface, through the superficial adsorption on the leaves and by the gas exchange of the stomatal pores. The understanding of which processes control the stage of Hg cycle in these ecosystems is still not totally clear. The influences of physiological and morphological parameters were tested against the Hg concentrations in the leaves of 14 endemic species of an evergreen tropical forest in south-eastern Brazil, and an exotic species from Platanus genus. Pathways were studied through leaf areas and growing tree parameters, where maximum rate of net photosynthesis (Pnmax), transpiration rate (E), stomatal conductance (Gs) were examined. The results obtained in situ indicated a positive correlation between Pnmax and the Hg concentration; Cedrela fissilis and Croton floribundus were the most sensitive species to the accumulation of Hg and the most photosynthetically active in this study. The primary productivity from Tropical forest should be a proxy of Hg deposition from atmosphere to soil, retained there while forests stand up, representing an environmental service of sequestration of this global pollutant. Therefore, forests and trees with great photosynthetic potential should be considered in predictions, budgets and non-geological soil content regarding the global Hg cycle.

There is increasing concern that standard laboratory toxicity tests may be misleading when assessing the impact of toxicants, because they lack ecological realism. Both warming and biotic interactions have been identified to magnify the effects of toxicants. Moreover, while biotic interactions may change the impact of toxicants, toxicants may also change the impact of biotic interactions. However, studies looking at the impact of biotic interactions on the toxicity of pesticides and vice versa under warming are very scarce. Therefore, we tested how warming (+4 °C), intraspecific competition (density treatment) and exposure to the pesticide chlorpyrifos, both in isolation and in combination, affected mortality, cannibalism, growth and heat tolerance of low- and high-latitude populations of the damselfly Ischnura elegans. Moreover, we addressed whether toxicant exposure, potentially in interaction with competition and warming, increased the frequency of autotomy, a widespread antipredator mechanism. Competition increased the toxicity of chlorpyrifos and made it become lethal. Cannibalism was not affected by chlorpyrifos but increased at high density and under warming. Chlorpyrifos reduced heat tolerance but only when competition was high. This is the first demonstration that a biotic interaction can be a major determinant of ‘toxicant-induced climate change sensitivity’. Competition enhanced the impact of chlorpyrifos under warming for high-latitude larvae, leading to an increase in autotomy which reduces fitness in the long term. This points to a novel pathway how transient pesticide pulses may cause delayed effects on populations in a warming world. Our results highlight that the interplay between biotic interactions and toxicants have a strong relevance for ecological risk assessment in a warming polluted world.

The anthropogenic marine debris, especially abandoned, lost or otherwise discarded Fishing Gear (ALDFG), represents a rising concern, because of its potential harmful impact on the marine animal forests. We carried out 13 km of video recordings, by means of a remotely operated vehicle, from 10 to 210 m depth, in an anthropised area of the Tyrrhenian Sea (Mediterranean Sea). This site, for its high ecological importance and biodiversity value, has been identified for the establishment of a new marine protected area (MPA). The aim of this paper was to assess marine litter abundance and its effects on the benthic fauna. The debris density, in the study area, ranged from 0.24 to 8.01 items/100 m2, with an average of 3.49 (±0.59) items/100 m2. The derelict fishing gear, mainly fishing lines, were the main source of marine debris, contributing 77.9% to the overall litter. The impacts of debris on the benthic fauna were frequently recorded, with 28.5% of the litter entangling corals and impacting habitats of conservation concern. These impacts were exclusively caused by the derelict fishing gear (91.2% by longlines), and the highest percentage (49.1%) of ALDFG causing impacts was observed from 41 to 80 m depth, in the coralligenous biocenosis. The results of the present study will help the fulfilment of “harm” monitoring, as recommended by the Marine Strategy Framework Directive (MSFD) and the UN Environment/MAP Regional Plan on the marine litter management in the Mediterranean Sea. Regarding the actions to reduce the derelict fishing gear, preventive measures are usually preferred instead of the extensive removals based on cost-effectiveness and sustainability. The establishment of a new MPA in the area could be a good solution to reduce ALDFG, resulting in the improvement of the ecological status of this coastal area.

The Biocoenosis of Well Sorted Fine Sands (WSFS) (SFBC, Sables Fins Bien Calibrés in French) is a Mediterranean community very well delimited by bathymetry (2–25 m) and sedimentology (>90% of fine sand) occurring in zones with relatively strong hydrodynamics. In this study focused on sites located along the Algerian, French, Italian and Spanish coasts of the Western Basin of the Mediterranean Sea (WBMS) we aim to compare the structure, ecological status and diversity of the macrofauna of the WSFS and examine the effects of recent human pressures on the state of this shallow macrobenthic community. We assess the ecological status and functioning of these WSFS using three categories of benthic indices: a) five indices based on classification of species into ecological groups, AMBI, BO2A, BPOFA, IQ and IP, b) the ITI index based on classification of species in trophic groups, and c) the Shannon H’ index, and the Biological Traits Analysis (BTA), which is an alternative method to relative taxon composition analysis and integrative indices. Cluster analyses show that each zone show a particular taxonomic richness and dominant species. The seven benthic indices reveal that the macrobenthos of the WSFS of the four coastal zones show good or high Quality Status, except for one location on the Algerian coast (the Djendjen site) in 1997. BTA highlights the presence of three groups of species: 1) typical characteristic species; 2) indicator species of enrichment of fine particles and organic matter, and 3) coarse sand species which are accessorily found on fine sand. Finally, the WSFS which are naturally subject to regular natural physical perturbations show a high resilience after human pressures but are very sensitive to changes in the input of organic matter.

Many benthic communities within estuarine ecosystems are highly degraded due to the close proximity of urban and industrial contamination sources. The maintenance of recolonised, healthy ecosystems following remediation is a challenge, and better techniques are required for monitoring their progressive recovery. Rates of ecosystem recovery are influenced by the changes in the concentrations and forms of contaminants, the sensitivity of recolonising organisms to bioavailable contaminants, and a range of abiotic and biotic factors influencing the exposure of organisms to the contamination. Here we investigate the influence of bioturbation by an active amphipod (Victoriopisa australiensis) on the bioavailability of metals and hydrocarbons in highly contaminated sediments. Changes in contaminant bioavailability were evaluated by assessing sublethal effects to a smaller cohabiting amphipod (Melita plumulosa). For predominantly metal-contaminated sediments, the presence of V. australiensis generally increased survival and reproduction of M. plumulosa when compared to treatments with only M. plumulosa present (from 42 to 93% survival and from 3 to 61% reproduction). The decrease in toxic effects to M. plumulosa corresponded with lower dissolved copper and zinc concentrations in the overlying waters (14 to 9 μg Cu L−1, and 14 to 6 μg Zn L−1 for absence to presence of V. australiensis). For sediments contaminated with both hydrocarbons and metals, the increased bioturbation intensity by V. australiensis resulted in decreased reproduction of M. plumulosa, despite lower dissolved metal exposure, and indicated increased bioavailability of the hydrocarbon contaminants. Thus, the presence of a secondary active bioturbator can enhance or suppress toxicity to co-inhabiting organisms, and may depend on the contaminant class and form. The results highlight the need to consider both abiotic and biotic interactions when using laboratory studies to evaluate the ability of organisms to recolonise and reproduce within benthic environments degraded by contamination, or for more general extrapolation for sediment quality assessment purposes.

The summer of 2003 was the warmest summer in Europe since the 16th century. Its consequences on the fauna of a transitional ecosystem were studied through biodiversity, functional and ecological indicators, from summer 2002 to winter 2005. The heatwave caused considerable changes in the benthic community structure and relative composition, persisting in 2005. Animal assemblages switched from mollusc- to annelida-dominated. Biodiversity and functional indicators captured changes in community structure and composition, proving to be powerful tools to detect responses related to global warming. Ecological indicators rendered a monotonic response oscillating between bad and poor ecological status across the study period. The resilience of mollusc biocoenosis resulted limited with respect to other taxa, posing concerns about their conservation if, as predicted, the frequency of summers as hot as that of 2003 will progressively increase to become the norm at the end of this century.

Understanding the environmental context where heterogeneous ecological processes affect biotic interactions is a key aim of ecological research. However, mechanisms underlying spatial variation in trophic interactions linked to resource availability across ecosystem gradients remains unclear. We experimentally manipulated the interactive effects of predator fish and quantitative gradient of leaf detritus on macroinvertebrates and benthic algae. We found that non-linear changes in the strength of trophic cascades were strongly linked to the retention rates of experimental leaf detritus and also determined by predatory consumers. Retention rate of leaf detritus influenced the recruitment of predatory invertebrates and foraging preference of predators, accounting for largely the variations in shift of strengthening and weakening trophic cascades. Our results highlight the importance to identify joint processes of recruitment and foraging responses of functional consumer in understanding the impacts of both anthropogenic and natural alterations in subsidy on trophic interaction of coastal food webs.

Sandy shores are generally considered important sinks for marine litter and the presence of this litter may represent a serious threat to biotic communities and dune integrity mostly due to cleaning activities carried out through mechanical equipment. In spring (April–May) 2012 we sampled 153 2×2m random plots to assess the spatial distribution patterns of litter on Central Italy sandy shores. We analysed the relationship between the presence of litter and coastal dune habitats along the sea-inland gradient. Our results showed that the most frequent litter items were plastic and polystyrene. Differences of marine litter spatial distribution were found between upper beach and fore dune habitats and fixed dune habitats: embryo dune and mobile dune habitats show the highest frequency of litter, but, surprisingly, marine litter did not impact fixed dune habitats, these possibly acting as a natural barrier protecting the inner part of the coast from marine litter dispersion.

Long-term changes of nutrients, plankton and macrobenthos were studied to research the transformation of ecosystem in Jiaozhou Bay and Daya Bay in the past 30 years. Concentrations of dissolved inorganic nitrogen and phosphate increased with significant changes in nutrient compositions and ratios. Concentrations of Chl a slightly decreased in Jiaozhou Bay but increased in Daya Bay. Phytoplankton abundances increased and diatoms were dominant, however, dinoflagellate gradually had the competitive advantage under high N/P and N/Si in the two bays. Zooplankton biomass significantly increased in Jiaozhou Bay, but only increased slightly in Daya Bay over the past years. Polychaetes were dominant in macrobenthos in the bays, indicating their adaptation to the changing benthic environments. The long-time variations of biocenoses and nutrients reflected that the ecological environments have changed under the influence of anthropogenic activities in the two bays.