Invasive Riverine Fish Starts to Dominate US Rivers and Other Parts of the World, Poses Threat to Native Species [Study]

Invasive riverine fish are starting to take over American rivers and other similar bodies of water worldwide, threatening native species and their aquatic ecosystems. This comes after scientists found that the increasing number of invasive fish species has contributed to the increase of diversity of riverine fish across the globe over the decades. These new findings are based on a new study led by researchers in the United Kingdom and the United States.

The growing threat of non-native species can disturb the ecological balance of a particular riverine, which includes rivers, streams, tributaries, creeks, and canals. In previous studies, evidence shows that local fish and other native aquatic animal populations face serious competition for food and other resources against invasive species. Furthermore, indigenous riverine fish can also be directly killed by non-native fish.

There are several reported reasons why Earth's riverine environments have been visited or dominated by invasive fish species, which the new research paper revealed in late January 2024. Aside from natural factors, human activities that harm aquatic habitats have paved the way for the introduction of non-native species, either intentionally or by accident. This anthropogenic threat impacts freshwater systems.

Invasive Riverine Fish Increases

Findings about the global increase of invasive riverine fish, including on US rivers, was published in the journal Nature Ecology & Evolution on January 30, with the paper entitled 'Past and recent anthropogenic pressures drive rapid changes in riverine fish communities.' Authors of the study are from the University of Sheffield in the UK, the University of Tennessee, University of Washington, and Illinois State University.

The US and UK research team found a significant spike in the population and diversity of riverine species across the planet over the past 30 years. Another finding pertains to the increase in fish species living in rivers, which are concentrated in most degraded areas. Although the team found positive trends in riverine fish communities, the threat posed by invasive fish on non-native species is still a growing concern.

Native Fish at Risk

In a news release earlier in February, the University of Sheffield implies that native fish are at risk due to the surprising trends in the "abundance and species richness" of riverine fish in related freshwater systems across the globe. Based on their conclusion, the researchers uncovered an average increase in fish community abundance of 13% per decade, while noting a 7% increase in species richness.

The findings contradict the ongoing thought or common scientific belief that increases in species richness and abundance in such systems were due to recent improvements in water quality in industrialized regions. However, academics from the US and UK universities stressed that the increase in river fish biodiversity is not because of ecosystem recovery, which was previously thought. Instead, the phenomenon is the result of the growing dominance of non-native species.