Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New invasive fish spreads through the Ebro delta

14.01.2009
A Spanish research team has researched and described for the first time in Europe the spread of the invasive dojo loach (Misgurnus anguillicaudatus) fish species.

The fish comes from East Asia and was first discovered in the Ebro delta in 2001. Since then, it has occupied various parts of the river during its lightning spread, and is now definitively established.

The researchers do not rule out that it could occupy new areas within coming years and threaten the survival of native species.

The spread of the dojo loach (Misgurnus anguillicaudatus) or weather loach, as this oriental fish from the same family as the colmilleja (Cobitis Paludica) of Spain and Portugal is commonly known, contrasts starkly with the decline of native fish in the rivers and wetlands throughout the Iberian Peninsula, where 80% of species are threatened. The introduction of species from different areas is one of the most serious threats to the preservation of biodiversity, as explained in this study published in the latest issue of Biological Invasions.

“Aquatic ecosystems on the continent are the most seriously affected by invasive species, with fish populations being particularly devastated,” Miguel Clavero, the report’s lead author and researcher at the Forest Technology Centre of Catalonia, tells SINC. Nowadays, the majority of river basins throughout the Iberian Peninsula contain more foreign species than native ones.

The dojo loach is a small yellowish fish measuring around 20cm, which was first discovered in 2001 in the Sèquia Mare, a channel draining the rice fields of the Ebro delta, located on the northern hemidelta (left side of the river), although individuals were also seen in the river itself. Within a few years, the dojo loach has come to occupy most of the hemidelta and has moved towards the southern part, where it was first found in 2005.

Clavero explains that “today, the species occupies a minimum of 31 1x1km UTM quadrants within the interior of the delta, and several thousand individuals have been caught during operations to monitor ichtyofauna carried out by the Ebro Delta National Park”. There is a high probability of the species expanding towards new areas. In fact, the researchers say that in the spring of 2007 the dojo loach was detected in the basin of the River Onyar, which is a tributary of the River Ter, in an area very close to the urban centre of Girona.

Salinity is a barrier

Despite its rapid expansion, Clavero and his team have shown that the distribution of the dojo loach “seems to be limited by salinity”, as it only occupies waters with a low salt concentration. This is one of the reasons why the fish has not invaded lagoons, swamps and other natural wetland areas in the delta.

“The presence of the dojo loach, like that of many other invasive fish species in the Ebro delta, is linked to the continuous flow of river water channelled from the Azud de Xerta reservoir to irrigate the rice fields, which cover 60% of the surface area of the delta,” the researcher points out.

Introduction of species is a threat

The researchers believe that the dojo loach population first appeared in the Ebro delta “after some individuals escaped from tropical fish maintenance and distribution facilities”. Centres that breed and maintain exotic fish pose a serious danger and are “an epicentre of the biological invasion process”.

This fish could be responsible for parasitic platelminths becoming established in the area, and could indirectly compete for resources with native species. “Each addition of a new species to an ecosystem has an impact on its other inhabitants which, in the case of fish at any rate, are always negative,” stresses the scientist. In the lower part of the Ebro, the presence of the dojo loach could threaten the survival of the freshwater blenny (Salaria fluviatilis) and the colmilleja (Cobitis paludica).

The dojo loach or weather loach is, according to Clavero, one of the most recent introductions of an invasive species in the Iberian Peninsula. With a long, somewhat flattened body, it is a fish designed to live in waters with weak currents, where it feeds on snails and insect larvae. It can survive temperatures close to freezing, and tolerates very low levels of dissolved oxygen.

Although it is not so common in Europe, it is spreading in other parts of the world such as the Philippines, United States, Central Asia, Australia and various Pacific islands, where it is used as an aquarium fish, as well as for live bait and as a food source.

SINC Team | alfa
Further information:
http://www.plataformasinc.es

More articles from Life Sciences:

nachricht Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington

nachricht The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>