Biological invasions and continued salinization of freshwater are two global issues with largely serious ecological consequences. Increasing salinity in freshwater systems, as an environmental stressor, may negatively affect normal life activities in fish. It has been documented that salinity limits the invasive success of alien species by mediating physiological and life-history performances, however, there are few studies on how salinity affects its invasive process via altered behaviors. Using wild-caught invasive western mosquitofish (Gambusia affinis) as animal model, in this study, we asked whether gradual increasing salinity affects behaviors (personality and mate choice decision here), life-history traits, as well as the correlation between them by exposing G. affinis to three levels salinity (freshwater, 10 and 20‰). Results showed that, with increased salinity, male tended to be shyer, less active, less sociable, and reduced desire to mate, and female tended to be shyer, less active and lost preferences for the larger male. Furthermore, across salinity treatments, male exhibited reduced body fat content and rising reproduction allocation, however, pregnant female revealed diametrically opposed trends. In addition, the correlation between life-history traits and behaviors was only identified in pregnant female. It seems that either salinity or life-history traits directly affects mosquitofish behaviors. In summary, our results partially emphasize the harmful consequences of salinity on both life-history traits and behavioral performances. These findings provide a novel perspective on how salinity potentially affect fish fitness via altering personalities, mate choice decisions, as well as body condition, and hence supports the idea that salinity could affect the spread of invasive mosquitofish.

Freshwater ecosystems are negatively impacted by various pollutants, from agricultural, urban and industrial wastewater, with metals being one of the largest concerns. Moreover, freshwater ecosystems are often affected by alien species introductions that can modify habitats and trophic relationships. Accordingly, the threat posed by metals interacts with those by alien species, since the latter can accumulate and transfer these substances across the food web to higher trophic levels. How metals transfer within such communities is little studied. We analysed the concentration of 14 metals/metalloids (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Se, Zn, hereafter ‘metal(s)’) of eight fish and three crustacean species co-existing in the Arno River (Central Italy), most of which were alien. To assess the pathway of contaminants within the community, we coupled metal analysis with carbon and nitrogen stable isotope analysis derived from the same specimens. Crustaceans showed higher metal concentration than fish, except for Cd, Hg and Se that were higher in fish. We found evidence of trophic transfer for six metals (Cd, Cr, Hg, Mg, Se, Zn). Additionally, ontogenetic differences and differences among various fish tissues (muscle, liver, and gills) were found in metals concentration. Considerable biomagnification along the trophic chain was found for Hg, while other metals were found to biodilute. Using stable isotopes and Hg as a third diet tracer, we refined the estimations of consumed preys in the diet previously reconstructed with stable isotope mixing models. Alien species reach high biomass and can both survive to and accumulate high pollutants concentrations, potentially posing a risk for their predators and humans. A combined effect of environmental filtering and increased competition may potentially contribute to the disappearance of native species with lower tolerances.

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.

Ecosystems modified by human activities are generally predicted to be biologically impoverished. However, much pollution impact theory stems from laboratory or small-scale field studies, and few studies replicate at the level of estuary. Furthermore, assessments are often based on sediment contamination and infauna, and impacts to epibiota (sessile invertebrates and algae) are seldom considered. We surveyed epibiota in six estuaries in south-east Australia. Half the estuaries were relatively pristine, and half were subject to internationally high levels of contamination, urbanisation, and industrialisation. Contrary to predictions, epibiota in modified estuaries had greater coverage and were similarly diverse as those in unmodified estuaries. Change in epibiota community structure was linearly correlated with sediment-bound copper, and the tubeworm Hydroides elegans showed a strong positive correlation with sediment metals. Stressors such as metal contamination can reduce biodiversity and productivity, but others such as nutrient enrichment and resource provision may obscure signals of impact.

With increasing urbanization the importance of cities for biodiversity conservation grows. This paper reviews the ways in which biodiversity is affected by urbanization and discusses the consequences of different conservation approaches. Cities can be richer in plant species, including in native species, than rural areas. Alien species can lead to both homogenization and differentiation among urban regions. Urban habitats can harbor self-sustaining populations of rare and endangered native species, but cannot replace the complete functionality of (semi-)natural remnants. While many conservation approaches tend to focus on such relict habitats and native species in urban settings, this paper argues for a paradigm shift towards considering the whole range of urban ecosystems. Although conservation attitudes may be challenged by the novelty of some urban ecosystems, which are often linked to high numbers of nonnative species, it is promising to consider their associated ecosystem services, social benefits, and possible contribution to biodiversity conservation.

Global urbanization and plastic pollution has increased the availability and variety of substrates for sessile organisms, and are intensively used by invasive species for settlement. Despite extensive literature describing the strong association between artificial structures and invasive species, little effort has been directed towards identifying the larval traits that favor this selection. Larval selection and settlement are crucial as larvae actively search and interpret environmental cues to identify suitable habitats to settle. The aim of this research was to investigate if invertebrate larvae have a preference for a particular anthropogenic substrate, and how pre-settlement behaviors vary when encountering different substrates. We used two invasive bryozoan species, Bugula flabellata and Bugula neritina, which are commonly found in urbanized areas around the world. Energy expenditure during planktonic and benthonic stages, pre-settlement swimming/exploring behaviors, settlement and larval selectivity were quantified under laboratory conditions on different substrates (concrete, wood, polystyrene, polyvinyl chloride, polyethylene terephthalate and polycarbonate). The energy expenditure measured was higher in planktonic larvae than in early settled larvae. Larvae of both species swam less and explored more when exposed to plastic surfaces, suggesting a preference for this substrate and resulting in lower energy expenditures associated with searching for habitat. Larvae actively chose to settle on plastics rather than on wood or concrete substrates. The results suggest that for Bugula larvae, the likelihood of colonizing plastic surfaces is higher than other materials commonly found in urbanized coastal areas. The more quickly they adhere to artificial substrates the lower the energy expenditure, contributing to higher fitness in these individuals. The strong preference of invertebrate larvae for plastics can potentially extend the distribution range of many invasive marine species as they are able to travel long distances attached to floating debris. This phenomenon will likely exacerbate the introduction of exotic species into novel habitats.

Throughout 90-day biodegradation under microaerobic conditions, invasive to Lithuania species boxelder maple (Acer negundo) leaves lost 1.5-fold more biomass than that of autochthonous black alder (Alnus glutinosa), releasing higher contents of Ntot, ammonium and generating higher BOD7. Boxelder maple leaf leachates were characterized by higher total bacterial numbers and colony numbers of heterotrophic and cellulose-decomposing bacteria than those of black alder. The higher toxicity of A. negundo aqueous extracts and leachates to charophyte cell (Nitellopsis obtusa), the inhabitant of clean lakes, were manifested at mortality and membrane depolarization levels, while the effect on H+-ATPase activity in membrane preparations from the same algae was stronger in case of A. glutinosa. Duckweed (Lemna minor), a bioindicator of eutrophic waters, was more sensitive to leaf leachates of A. glutinosa. Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter water body, affect differently microbial biodestruction and aquatic vegetation in freshwater systems.

Tropospheric ozone is a secondary pollutant whose primary sources are volatile organic compounds and nitrogen oxides. The national standard is exceeded on a third of summer days in some areas of the Chilean Metropolitan Region (MR). This study reports normalized springtime experimental emissions factors (EF) for biogenic volatile organic compounds from tree species corresponding to approximately 31% of urban trees in the MR. A Photochemical Ozone Creation Index (POCI) was calculated using Photochemical Ozone Creation Potential of quantified terpenes. Ten species, natives and exotics, were analysed using static enclosure technique. Terpene quantification was performed using GC-FID, thermal desorption, cryogenic concentration and automatic injection. Observed EF and POCI values for terpenes from exotic species were 78 times greater than native values; within the same family, exotic EF and POCI values were 28 and 26 times greater than natives. These results support reforestation with native species for improved urban pollution management.

It can be suggested that the combined stress of pesticide pollution and suboptimal temperature influences the sensitivity of life stages of aquatic invertebrates differently.The embryo, juvenile, half- and full-life-cycle toxicity tests performed with the snail Physella acuta at different concentrations (0.06–0.5 or 1.0 mg L−1) of the model fungicide pyrimethanil at 15, 20 and 25 °C revealed, that pyrimethanil caused concentration-dependent effects at all test temperatures. Interestingly, the ecotoxicity of pyrimethanil was higher at lower (suboptimal) temperature for embryo hatching and F1 reproduction, but its ecotoxicity for juvenile growth and F0 reproduction increased with increasing temperature.The life-stage specific temperature-dependent ecotoxicity of pyrimethanil and the high fungicide susceptibility of the invasive snail clearly demonstrate the complexity of pesticide–temperature interactions and the challenge to draw conclusions for the risk of pesticides under the impact of global climate change.