Threats Facing Freshwater Species

Threatened species – that’s orangutans, pandas and tigers, right? Yes, but also so many more. Did you know that around one-fifth of reptiles are threatened with extinction, as well as 40% of amphibians, 12% of birds, and a staggering 71% of cycads? A lot of what we know about extinction risk of species has been focused on terrestrial systems, and this information has formed the basis for conservation prioritization and action. Until now.  

After over 20 years of work by more than 1,000 experts from around the world (including the Freshwater Conservation Coordinator at the Global Center for Species Survival at the Indianapolis Zoo), the Global Freshwater Fauna Assessment was published today in the journal Nature, showing that a quarter of freshwater animals are at risk of extinction. 

Included in the assessment were 23,496 species from select freshwater groups: freshwater fish, dragonflies, damselflies, freshwater crabs, crayfish and freshwater shrimps. The greatest number of threatened freshwater species are found in Lake Victoria, Lake Titicaca, Sri Lanka’s Wet Zone and the Western Ghats of India, according to the study. These areas are home to some of the richest freshwater biodiversity in the world, including many species found nowhere else on Earth.  

Underground water systems have been found to contain more threatened species than expected, and these can be found right here in the United States. For example, the U.S. is home to many threatened crayfish species, such as the daisy burrowing crayfish (Fallicambarus jeanae) in Arkansas, which is Vulnerable on the IUCN Red List. Lakes, oases and springs are also hotspots for extinction. In 2020, 15 fish species from Lake Lanao in the Philippines were declared Extinct on the IUCN Red List! 

What causes the high level of threat we see in freshwater systems? Pollution, mainly from agriculture and forestry, impacts over half of all threatened freshwater animals. Additional threats stem from land conversion for agricultural use, water extraction and the construction of dams, which also block fish migration routes. Overfishing and the introduction of invasive alien species have had a particularly strong role in driving extinctions.  

Since freshwater animals generally face different threats than terrestrial species, conservation actions need to be specifically targeted for freshwater species, so simply extrapolating actions from what we see in terrestrial systems is not enough to safeguard freshwater biodiversity. Similarly, other indicators previously used to locate threatened freshwater biodiversity, such as water stress and eutrophication, do not perform as well at indicating areas of threatened freshwater species. 

“It is essential that freshwater species data are actively included in conservation strategies and water use planning and management, to ensure their practices support healthy freshwater ecosystems,” says Dr. Topiltzin Contreras Macbeath, Co-Chair of the IUCN SSC Freshwater Conservation Committee. 

The Global Center for Species Survival at the Indianapolis Zoo actively supports the work of the IUCN SSC Freshwater Conservation Committee (FCC) as well as all other IUCN Species Survival Commission Specialist Groups that represent freshwater species, from freshwater animals to freshwater plants and aquatic fungi. Recent years have seen the publication of our Fantastic Freshwater report to highlight specific species stories from the freshwater realm (in collaboration with the IUCN SSC FCC and our partners at Shoal) and supporting, if from afar, the efforts of FCC member Dr. Kay van Damme to protect Socotra’s unique freshwater species.. 

While this new study shines a light on the levels of threat in freshwater animals, several knowledge gaps remain: freshwater plants remain largely unassessed, and aquatic fungi have only recently entered the conservation arena, with assessments not yet underway! In addition, several animal groups lag behind in assessment and conservation efforts, like freshwater molluscs! The United States represents a hotspot for freshwater mussel biodiversity, and while we know a lot about threat of freshwater mussels here in North America, very little is known in other parts of the world. Yet freshwater mussels are highly threatened here in our backyard. The Indianapolis Zoo, through the Global Center for Species Survival, is involved in setting up a plan under the Association of Zoos and Aquariums Saving Animals From Extinction (AZA SAFE) program to support freshwater mussel conservation in North America. We also support a mussel rearing facility with the Muncie Bureau of Water Quality to improve mussel conservation efforts right here in Indiana. to improve mussel conservation efforts right here in Indiana. 

In addition, through the Indianapolis Zoo’s Saving Species Challenge, we have supported the creation of several action plans to improve the status of freshwater species: from the humpbacked mahseer in India to Extinct in the Wild freshwater fish in Mexico. Now is the time to turn these plans into action. 

But what can we all do to help freshwater species in Indiana? From supporting local laws and ordinances benefiting freshwater systems, to reducing or eliminating herbicides, pesticides and fertilizers in your yard and making sure you use water mindfully, there is plenty we all can do. You can also find great materials about Indiana wetlands on the Indiana Department of Natural Resources website. And of course, spread the word about freshwater species, their importance in keeping our freshwater systems healthy for all, and that freshwater conservation needs all of us to make a difference.  

This blog was a collaboration between experts at the Global Center for Species Survival, including Freshwater Conservation Coordinator Dr. Monika Böhm. 

Title image showing tilapa fish is courtesy of Dr. Topiltzin Contreras Macbeath.

Published January 8, 2025