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
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Materials Sciences
27.10.2016 | Physics and Astronomy
27.10.2016 | Life Sciences