Emerging threats and persistent conservation challenges for freshwater biodiversity

Area of Science:

• Freshwater ecology
• Conservation biology
• Environmental science

Background:

• The biodiversity crisis in global freshwater ecosystems (lakes, rivers, wetlands) has worsened since 2006.
• Freshwater systems, covering 2.3% of Earth's surface, host 9.5% of described animal species.
• Freshwater populations have declined by 83% (1970-2014), exceeding marine and terrestrial losses.

Purpose of the Study:

• To document 12 emerging or intensified threats to freshwater biodiversity since 2006.
• To assess the impacts of these threats on various freshwater organisms and ecosystems.
• To identify opportunities for conservation gains through novel management tools and actions.

Main Methods:

• Review and documentation of 12 emerging threats to freshwater biodiversity.
• Evidence compilation for impacts on amphibians, fishes, invertebrates, microbes, plants, turtles, and waterbirds.
• Analysis of conservation opportunities, including new management tools and actions.

Main Results:

• Twelve key threats identified: climate change, invasions, diseases, algal blooms, hydropower, contaminants, nanomaterials, microplastics, light/noise pollution, salinisation, declining calcium, and cumulative stressors.
• Observed effects across diverse freshwater taxa, with potential for ecosystem-level changes.
• Highlighted conservation successes and challenges with novel approaches like environmental DNA and dam removal.

Conclusions:

• Urgent need for hybrid conservation approaches managing fresh waters for both human life support and biodiversity.
• Significant gap exists between conservation aspirations and the accelerating rate of species endangerment.
• Reversing freshwater degradation requires bridging this gap with integrated management strategies.