Human impacts on global freshwater fish biodiversity

Area of Science:

• Ecology
• Ichthyology
• Conservation Biology

Background:

• Freshwater fish are vital vertebrates, providing essential ecosystem services.
• Human activities are increasingly threatening freshwater fish populations worldwide.
• Understanding biodiversity changes is crucial for effective conservation.

Purpose of the Study:

• To assess global freshwater fish biodiversity changes using a novel index.
• To identify areas and drivers of significant biodiversity alteration.
• To quantify the extent of impacted and least impacted river systems.

Main Methods:

• Development and application of the Cumulative Change in Biodiversity Facets index.
• Analysis of biodiversity across global river systems.
• Identification of key drivers such as river fragmentation and non-native species.

Main Results:

• Over 50% of global rivers show marked biodiversity changes, impacting over 40% of continental surface area.
• Less than 14% of river systems remain minimally impacted.
• Rivers are becoming more homogenous, with increased fish species diversity, morphological diversity, and evolutionary legacies.
• River fragmentation and introduced species are primary drivers in temperate zones.

Conclusions:

• Global freshwater fish biodiversity is undergoing significant, widespread alteration.
• Human impacts have homogenized river ecosystems globally.
• Targeted conservation strategies are needed to address fragmentation and invasive species, especially in temperate rivers.