Freshwater crisis: One in four species faces extinction

Freshwater ecosystems, though they occupy less than 1% of Earth’s surface, are incredibly rich in biodiversity. They provide habitats for more than 10% of all known species, making them critical to global ecological balance.

Despite their small size, these ecosystems support a rich variety of species, including fish, dragonflies, crabs, and shrimp – many of which are crucial for maintaining ecological balance.

However, a recent study has sounded an alarm, revealing that nearly 25% of species reliant on freshwater habitats face a high risk of extinction.

This troubling statistic comes from an analysis featured in the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species, which assesses the extinction risks of thousands of species worldwide.

These findings highlight an escalating crisis that threatens biodiversity, ecosystem services, and the countless communities that depend on freshwater resources.

Freshwater species at risk

A global assessment of 23,496 freshwater species – including fish, dragonflies, crabs, and shrimp – has exposed a critical biodiversity crisis. The study found that 24% of these species – approximately 4,294 – are at high risk of extinction.

Of the groups studied, crabs, crayfish, and shrimp are the most at risk – with 30% classified as endangered. Freshwater fish face a similarly dire situation, with 26% threatened, while 16% of dragonflies and damselflies are also in danger.

The key factors behind these alarming trends include pollution from agriculture and urban runoff; habitat loss caused by land conversion, dam construction, water extraction; and the spread of invasive species that prey on or outcompete native populations.

The findings highlight the urgent need for conservation efforts to address these threats and protect the vital biodiversity of freshwater ecosystems.

Threats to freshwater ecosystems

The threats facing freshwater ecosystems arise from multiple human activities, each significantly impacting biodiversity.

Freshwater pollution

Over half of the threats to freshwater species come from pollutants released by agriculture and forestry. Agricultural runoff containing pesticides, fertilizers, and sediments pollutes water bodies, while forestry operations contribute to soil erosion and chemical contamination.

Habitat alteration

Human-driven changes to landscapes, such as converting natural habitats into agricultural or urban areas, severely disrupt ecosystems. Water extraction for irrigation and industrial use reduces water availability, while dams block fish migration routes and alter natural water flow.

Invasive species

Non-native species introduced to freshwater ecosystems often outcompete native species for resources or prey on them directly. This disrupts the ecological balance, pushing many native species toward extinction.

Overfishing

Unsustainable fishing practices, such as overharvesting or using destructive fishing techniques, deplete freshwater species populations. This not only impacts biodiversity but also jeopardizes food security for communities relying on these resources.

Global hotspots of threatened species

The study highlights regions with the highest number of endangered freshwater species, including parts of Africa, South America, and India.

Lake Victoria (Africa)

As Africa’s largest lake, Lake Victoria is a biodiversity-rich ecosystem supporting numerous unique species.

However, it is under immense pressure from pollution, overfishing, invasive species, and habitat degradation – threatening the survival of its aquatic life.

Lake Titicaca (South America)

Straddling Peru and Bolivia, Lake Titicaca is home to many vulnerable freshwater species. Habitat loss, pollution, and invasive species pose significant risks to its unique biodiversity.

Sri Lanka’s Wet Zone

This region, characterized by its lush freshwater habitats, supports an incredible diversity of aquatic life. However, land conversion, pollution, and human encroachment are endangering this once-thriving haven for freshwater biodiversity.

Western Ghats (India)

Recognized as a global biodiversity hotspot, the Western Ghats are home to a vast array of freshwater species.

Despite its ecological significance, the region faces mounting pressures from deforestation, agricultural expansion, pollution, and dam construction, threatening its rich biodiversity.

These regions highlight the urgent need for targeted conservation efforts to protect their unique and endangered freshwater ecosystems.

Broader impact of wetland loss

Between 1970 and 2015, the world experienced the loss of 35% of its wetlands. This staggering rate of decline is three times faster than the loss of forests during the same period.

Wetlands, which include marshes, swamps, and bogs, are vital ecosystems that provide habitat for diverse species, regulate water cycles, and offer flood control.

Simultaneously, many of the world’s major rivers, such as the Amazon in South America and the Ganges in South Asia, have been significantly altered. These rivers, once free-flowing, now face disruptions due to dams, water extraction, and other human activities.

The loss of natural flow patterns in these rivers further threatens aquatic ecosystems by fragmenting habitats, altering water quality, and disrupting the life cycles of fish and other species dependent on uninterrupted water systems.

This combined loss of wetlands and free-flowing rivers has profound implications for biodiversity, water security, and the health of ecosystems globally.

Saving freshwater ecosystems from extinction

Catherine Sayer, lead author of the study, emphasized the urgent need for conservation and restoration efforts.
“Freshwater landscapes are home to 10% of all known species on Earth and key for billions of people’s safe drinking water, livelihoods, flood control, and climate change mitigation, and must be protected for nature and people alike,” said Sayer.

The loss of freshwater biodiversity is not just a conservation crisis – it’s a threat to humanity. By protecting these vital ecosystems, we safeguard the future for countless species and the billions of people who depend on them.

The study is published in the journal Nature.

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