Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Endangered giants: large freshwater species most threatened with extinction on the planet

13.03.2017

Freshwater megafauna such as river dolphins, crocodilians and sturgeons play vital roles in their respective ecosystems. In a recent scientific publication, researchers of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin have teamed up with international colleagues to illustrate the factors that currently threaten these large vertebrates. The authors also call for a more comprehensive assessment on these large freshwater animals and for a more targeted conservation plan. Also, a wider range of freshwater species and freshwater ecosystems suffering from biodiversity decrease have the potential to benefit from such megafauna-based actions.

Many large aquatic vertebrates, referred to as freshwater megafauna, cover long distances between their breeding and feeding grounds. To ensure their safe passage, they are dependent on free-flowing waters. However, this makes them vulnerable to the increasing fragmentation of river catchments caused by damming.


The Yangtze Finless Porpoise is listed as critically endangered on the IUCN Red List of Threatened Species.

Photo: Huigong Yu


These animals are threatened by incidental catch, vessel collision, pollution, and habitat degradation.

Photo: Huigong Yu

The Russian sturgeon, for example, has lost 70 per cent of its spawning grounds in the Caspian Sea basin and its entire Black Sea basin spawning grounds over the last 60 years due to dam construction. The boom in dam construction also affects many other species, such as the Amazonian manatee, the Ganges river dolphin and the Mekong giant catfish – these species are now classified as threatened. “The fragmentation of habitats is one of the central threats to freshwater megafauna, as well as overexploitation” explained Fengzhi He.

The IGB researcher is the lead author of the study on the disappearance of large vertebrates from rivers and lakes, published recently in WIREs Water. According to The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, more than half of the world’s large-bodied vertebrates weighing more than 30 kg that live in freshwater ecosystems are threatened.

Yet, freshwater megafauna species play key roles in their respective ecosystems: owing to their size, most are at the top of the food chain, meaning that a large proportion of creatures in the local ecosystem would be affected by their extinction.

The mode of life of the Eurasian beaver and the North American beaver, for example, induces them to shape entire river courses, affecting not only biochemical and hydrological processes, but also in-stream and riparian assemblages; in the Everglades, the American alligator creates and maintains small ponds, providing habitats for a large number of plants and smaller animals.

“The importance of freshwater megafauna for biodiversity and humans cannot be overstated,” stressed Fengzhi He. Together with colleagues from IUCN, the University of Tübingen and Queen Mary University of London, Fengzhi He describes in this publication which factors pose threats to freshwater megafauna. Besides the obstruction and fragmentation of water bodies following dam construction, these factors include overexploitation, environmental pollution, habitat destruction, species invasion and the changes associated with climate change.

According to the authors, megafauna species are highly susceptible to external factors owing to their long lifespan, large body size, late maturity and low fecundity. Despite the fact that many megafauna species are under great threat, they have been largely neglected in previous research and conservation actions.

Fengzhi He and his co-authors call for research focusing on the distribution patterns, life history and population dynamics of freshwater megafauna. Freshwaters are among the most endangered ecosystems on the planet, where biodiversity is declining faster than in marine and terrestrial realms. For this reason, it is all the more important to develop sustainable nature conservation strategies for freshwater ecosystems and their megafauna.

Link to study

http://onlinelibrary.wiley.com/doi/10.1002/wat2.1208/full

He, F., Zarfl, C., Bremerich, V., Henshaw, A., Darwall, W., Tockner, K. and Jähnig, S. C. (2017), Disappearing giants: a review of threats to freshwater megafauna. WIREs Water, e1208. doi:10.1002/wat2.1208

Contacts

Fengzhi He
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB)
Müggelseedamm 310, 12587 Berlin
fengzhi.he@igb-berlin.de

Dr. Sonja Jähnig
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB)
Justus-von-Liebig-Str. 7, 12489 Berlin
sonja.jaehnig@igb-berlin.de
+49 (0)30 6392 4085

About IGB:

http://www.igb-berlin.de

Work at IGB combines basic research with preventive research as a basis for the sustainable management of freshwaters. In the process, IGB explores the structure and function of aquatic ecosystems under near-natural conditions and under the effect of multiple stressors. Its key research activities include the long-term development of lakes, rivers and wetlands under rapidly changing global, regional and local environmental conditions, the development of coupled ecological and socio-economic models, the renaturation of ecosystems, and the biodiversity of aquatic habitats. Work is conducted in close cooperation with universities and research institutions from the Berlin/Brandenburg region as well as worldwide. IGB is a member of the Forschungsverbund Berlin e.V., an association of eight research institutes of natural sciences, life sciences and environmental sciences in Berlin. The institutes are members of the Leibniz Association.

Angelina Tittmann | idw - Informationsdienst Wissenschaft

Further reports about: IGB aquatic ecology fragmentation freshwater freshwater species

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>