Preface: Emerging trends in aquatic ecology III

Humans have never faced such major threats to their homes as they are experiencing now. Despite several global initiatives to ameliorate environmental problems, to preserve biodiversity and to alleviate poverty, these major threats are far from being resolved. According to a recent survey conducted by Ripple et al. (2017) and signed by 15,364 scientists of 184 countries, several indicators of environmental health are still worsening significantly. For example, along with the continuing increase of atmospheric CO2 and global temperatures (the threats best known by the general public as ‘‘climate change’’), there are still steep increases in atmospheric concentrations of methane and nitrous oxide, in ocean acidification and in the number of regions affected by dead zones, all at global scales, to cite only some examples. Aquatic (both marine and freshwater) and terrestrial ecosystems and their biodiversity are also declining at a planetary scale, with no signs of imminent recovery, ever since extensive surveys started back in the 1970s (WWF, 2018).