Fish populations in two rivers in the US and China respond similarly to human-led changes in environmental conditions, a paper has said.

The study, led by researchers at the Michigan State University and Chinese Academy of Sciences and published in the journal Water Biology and Security, analysed the traits of over 120 species in the Mississippi and Yangtze rivers, such as their feeding habits, reproductive strategies, migratory behaviour, and habitat preferences.

Despite differences in species, the behaviour of fish populations in the two rivers was very similar, according to the study.

Feeding habits and habitat preferences had the most significant influence on their responses to changes in environmental conditions, including those linked to extensive agricultural production and human population growth.

“This information may prove particularly useful in supporting efforts to derive shared management strategies that could help to safeguard against the loss of ecological functions,” said the study.

The researchers said their study aimed to bridge the existing knowledge gap of fish species’ behaviour across large river-related ecosystems, and inform waterway conservation efforts.

“By combining traits with environmental data, including factors like climate, land use, and water quality, we gain a better understanding of why biodiversity loss is occurring,” said lead author Kyle Brumm, a researcher at the Department of Fisheries and Wildlife at Michigan State University.

“Traits provide details about what a species needs to survive, grow, and reproduce, so this type of analysis tells us whether biodiversity loss is associated with changes in food availability, habitat complexity, or water temperature, to name a few examples.”

According to WWF’s Living Planet Index, freshwater biodiversity is the most threatened on Earth, facing an 83% decline in the global population compared to 1970.

Migratory fish populations, in particular, have fallen by 81% between 1970 and 2020, mainly due to habitat loss and degradation, including fragmentation of rivers by dams and other barriers.

Human activity in the past century has dramatically altered freshwater flows, jeopardising their capacity to regulate vital ecological and climatic processes.

In May, a paper revealed that the extent of land affected by global warming or the construction of dams and irrigation systems almost doubled compared to pre-industrial conditions.

By Sergio Colombo – sergio@carbon-pulse.com

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