However, the mechanisms of its impact are still poorly known, particularly in the aquatic environment. At Cemagref, two researchers, who have been analysing the freshwater fish community over the two last decades, have observed profound changes that are more intense and long-lasting than predicted.
Global warming, whose impacts have been demonstrated since the 1980s and 1990s, influences the functioning of the world’s ecosystems as well as the structure and the diversity of animal and plant communities. The GIEC’s (International group of experts on global warming) latest report in September 2007 states that the global temperature should increase by 1.4–5.8°C between now and the year 2100. This phenomenon is an added pressure on the environment that will become increasingly intense over time and should be taken into account in planning sustainable resource and ecosystem management. However, its impact and the possible influence of the effects of other non-climate factors still remain difficult to determine.
- Towards reduced stream biodiversity?
Two Cemagref researchers, Martin Daufresne and Philippe Boet, have studied the effects of this phenomenon on aquatic environments and particularly on the fish communities residing in French streams. Changes in the number, size and representativeness of fished species have been observed for approximately 20 years. Fishermen believe that the fish caught today are no longer the same as before. New species living in warm or Southern waters, such as spirlin and the common bitterling, are gradually replacing the traditionally fished species.
With a large-scale analysis, combining data collected on several streams and several sites for 15–25 years, these researchers have shown a substantial impact of global warming on the structure of fish communities. It appears that the proportion of South-living and warm-water fish in French rivers has increased from 20% and 40%, respectively, to 50% between 1979 and 2004. Whereas large numbers of these small fish tend to become predominant within the communities, large fish, more sensitive to the temperature increase, tend to disappear little by little. However, this change is accompanied by a global drop in biodiversity. The large number of fish observed is distributed within an increasingly limited number of species.
- Distinguishing the impacts of global warming from those of other factors
In large rivers, fish can also be subjected to non-climatic factors such as water development programmes, dams or nuclear power stations, which may influence the vast changes identified within aquatic communities. According to the data collected at this scale, the impact from these sources appears to be quite low on the trends observed. On the other hand, since dams act as natural barriers, they hinder the Southern species in their migration towards the North. In a context of increasing climate warming, the lack of a fish flow from the South, as has been observed on these sites, could be harmful to the current process of species renewal and subsequently intensify the threat weighing on the biodiversity of large rivers. Current research on a finer, individual scale, continues in a partnership with EDF (French electricity company) in order to better assess the real impacts of these developments on fish and most particularly their physiology. In the long run, this research has shown itself to be a requirement for a better understanding of these slowly progressing phenomena.
Marie Signoret | alfa
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
23.04.2018 | Physics and Astronomy
23.04.2018 | Physics and Astronomy
23.04.2018 | Trade Fair News