New research has produced a global threat map outlining the risks to freshwater biodiversity, a response to alarming declines in wildlife populations that are decreasing more rapidly than terrestrial or marine species. The study, published in the journal Science, aims to provide insights into the geographic distribution of threats affecting more than 2,100 freshwater species identified on the International Union for Conservation of Nature’s (IUCN) “red list,” which indicates that approximately one-quarter of these species are at risk of extinction.
Christophe Brabant, a PhD candidate at McGill University and lead author of the research, emphasized the need for a clearer understanding of where these threats occur. “We generally know pretty well which threats are impacting freshwater species, but we don’t know where those threats are happening across the world,” he said.
The research identified five groups of threatened freshwater fauna, including amphibians, reptiles, fish, mammals, and odonates (dragonflies and damselflies). The team developed a color-coded map illustrating threat intensity by region, coupled with an index that links specific threats to declines in freshwater species. Brabant explained that the mapping method takes into account how different threats impact various species, rather than assuming a uniform effect.
In Canada, leading threats to freshwater species include natural system modifications such as dams and diversions, as well as biological resource use, agriculture, development, pollution, energy production, and mining. Globally, agriculture and aquaculture stand out as the primary threats, particularly in the Global South, followed by pollution and biological resource uses prevalent in regions like northern latitudes, including Canada.
The research highlights the diversity of threats faced by freshwater species. Brabant noted the significant accumulation of threats in areas such as northwestern Africa, Europe, the lower Himalayas, and the Missouri River basin. The study found that regions with a high proportion of species nearing extinction often experienced more intense threats.
Climate Change Impact
While the map showcases various threats, it indicates that climate change is a lesser driver of species decline in Canada compared to other factors. Brabant mentioned that this might reflect limitations in how climate change is currently assessed within the IUCN criteria.
The Experimental Lakes Area in northwestern Ontario has provided valuable data on how human activity impacts freshwater systems. Research there has shown a rise in air temperatures and a decrease in winter ice cover, correlating with changes in the sizes of local fish populations.
Frederik Noack, the Canada Research Chair in environmental economics, acknowledged the complexity in applying findings from the threat map to conservation strategies, emphasizing that understanding where to allocate resources is essential for effective biodiversity preservation.
Brabant hopes this research will elevate the urgency of freshwater conservation efforts, guiding decision-makers to focus on the most critical areas for intervention.
