Threats to the running water ecosystems of the world

Abstract

Running waters are perhaps the most impacted ecosystem on the planet as they have been the focus for human settlement and are heavily exploited for water supplies, irrigation, electricity generation, and waste disposal. Lotic systems also have an intimate contact with their catchments and so land-use alterations affect them directly. Here long-term trends in the factors that currently impact running waters are reviewed with the aim of predicting what the main threats to rivers will be in the year 2025. The main ultimate factors forcing change in running waters (ecosystem destruction, physical habitat and water chemistry alteration, and the direct addition or removal of species) stem from proximate influences from urbanization, industry, land-use change and water-course alterations. Any one river is likely to be subjected to several types of impact, and the management of impacts on lotic systems is complicated by numerous links between different forms of anthropogenic effect. Long-term trends for different impacts vary. Concentrations of chemical pollutants such as toxins and nutrients have increased in rivers in developed countries over the past century, with recent reductions for some pollutants (e.g. metals, organic toxicants, acidification), and continued increases in others (e.g. nutrients); there are no long-term chemical data for developing countries. Dam construction increased rapidly during the twentieth century, peaking in the 1970s, and the number of reservoirs has stabilized since this time, whereas the transfer of exotic species between lotic systems continues to increase. Hence, there have been some success stories in the attempts to reduce the impacts from anthropogenic impacts in developed nations. Improvements in the pH status of running waters should continue with lower sulphurous emissions, although emissions of nitrous oxides are set to continue under current legislation and will continue to contribute to acidification and nutrient loadings. Climate change also will impact running waters through alterations in hydrology and thermal regimes, although precise predictions are problematic; effects are likely to vary between regions and to operate alongside rather than override those from other impacts. Effects from climate change may be more extreme over longer time scales (>50 years). The overriding pressure on running water ecosystems up to 2025 will stem from the predicted increase in the human population, with concomitant increases in urban development, industry, agricultural activities and water abstraction, diversion and damming. Future degradation could be substantial and rapid (c. 10 years) and will be concentrated in those areas of the world where resources for conservation are most limited and knowledge of lotic ecosystems most incomplete; damage will centre on lowland rivers, which are also relatively poorly studied. Changes in management practices and public awareness do appear to be benefiting running water ecosystems in developed countries, and could underpin conservation strategies in developing countries if they were implemented in a relevant way.

Conservation of freshwater bivalves at the global scale: diversity, threats and research needs

“…Increasing anthropogenic pressure worldwide results in habitat loss, habitat modification and fragmentation, overexploitation of natural resources (including water), pollution, introduction of invasive alien species (IAS) and climate change (Malmqvist & Rundle, 2002;Strayer & Dudgeon, 2010). Biodiversity crisis is one of the major consequences of steeply rising human demands, and among the animals with high extinction rates are freshwater bivalves (FB) (Strayer et al, 2004;Lydeard et al, 2004;Régnier et al, 2009;Lopes-Lima et al, 2014, 2017a.…”

Budget and Fate of Phosphorus and Trace Metals in a Heavily Loaded Shallow Reservoir (Shahe, Beijing City)

“…Drinking water production requires increasingly laborious and expensive techniques, and surface water ecosystems are under great threat with respect to biodiversity and ambient quality [3][4][5]. Rivers in urban areas are particularly vulnerable due to the lack of sufficient sewage treatment facilities and increasing overexploitation of their headwaters [6,7]. In addition, dams and floodgates constructed for water storage, irrigation, and flood control destroyed their lateral and longitudinal connectivity, thus impairing self-purification [8,9].…”

Patterns of earthworm communities and species traits in relation to the perturbation gradient of a restored floodplain

“…Floodplains are among the most threatened ecosystems worldwide (Malmqvist and Rundle, 2002;Tockner and Stanford, 2002). In the last decades, a paradigm shift has taken place in river management, the dominant view shifting from controlling rivers to restoring their natural states and functions.…”