Dams exacerbate the consequences of climate change on river fish

September 14, 2020

A potential response of river fish to environmental changes is to colonize new habitats. But what happens when dams and weirs restrict their movement? And are native and alien species similarly affected? Researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and the Spanish University of Girona (UdG) have addressed these questions in a recent study.

River ecosystems are frequently fragmented by dams and weirs. As a result, native fish are often restricted in their movement along the river course and are unable to colonize new habitats. Thus, barriers impede native species from adjusting their distributions in response to the effects of climate change such as changes in water temperature and quality.

On the other hand, river fragmentation might also limit the further spread of invasive alien species. Using the Ebro River in Spain as an example, the research team has investigated how habitats of native and alien fish species change under different climate scenarios and how dams mediate habitat accessibility.

"The Ebro River is particularly vulnerable and threatened by climate change and species invasions. In addition, the Ebro River is fragmented by over 300 dams and many smaller barriers, which makes it even worse for the native fish species", said Emili García-Berthou, Professor at the University of Girona and co-author of the study.

By applying a spatial modelling framework, the authors showed that losses of native species and gains of alien species and consequentially most pronounced biodiversity changes are particularly expected in the lower and mid reaches of larger Ebro River tributaries. According to their results, the majority of species are projected to shift their range in upstream direction with alien species such as eastern mosquitofish, wels catfish and common carp showing especially large habitat gains.

"The Ebro River system is home to several endemic species that exclusively occur on the Iberian Peninsula. These species are particularly imperilled by barriers that limit movements in response to climate change. Whether dams can effectively prevent the spread of alien species is questionable. In fact, the establishment of alien fishes is often facilitated by the changed flow and habitat conditions that result from damming rivers", said IGB researcher Johannes Radinger, lead author of the study.

The results clearly show that fish communities in highly fragmented rivers affected by climate change will be particularly affected by biodiversity changes and species loss in the future. "Effective conservation of fishes should focus on the restoration of habitats and the natural flow regime, improvements of connectivity for native species and the control of alien species, particularly the prevention of further introductions", concluded the authors.

Forschungsverbund Berlin

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.