Nav: Home

Decline in native fish species -- Invasive species on the increase

October 01, 2018

The majority of Bavaria's watercourses are in poor ecological condition. A team from the Technical University of Munich (TUM) has now conducted the first systematic analysis of long-term data on fish stocks in the Upper Danube, Elbe and Main rivers. The team concluded that native fish species are on the verge of extinction, while the populations of some invasive species are increasing.

On behalf of the Bavarian State Office for the Environment and financed by the Bavarian Ministry of the Environment, the scientists analyzed all available fish data sets for the Bavarian catchment areas of the Danube, Elbe and Main rivers over a period of more than 30 years. They compared the current status with the historically derived reference status of the originally occurring species at the respective locations.

The study, published in the October issue of the journal Biological Conservation, shows that native character species such as grayling, after which a river region was named, have suffered massive losses in terms of both area and numbers compared to their historical reference status.

A similar picture emerges for other specialized fish species whose habitats are severely affected by siltation, higher water temperatures and dammed water bodies. Many of the particularly endangered species have complex lifecycles and are dependent on special conditions during different life phases. "If these special conditions no longer exist, or if the animals cannot migrate between sub-habitats, then they will have problems," says Dr. Melanie Müller from the Department of Aquatic Systems Biology at the Technical University of Munich and author of the study.

Formerly widespread species are strongly declining today.

A new result of the study is also that species such as the "common dace", which were previously regarded as widespread, are also declining compared to the historical reference status. In contrast, those species known as generalists, which demand very little from their habitat, are now propagating even more. Notable among these species are many non-native fish which were either deliberately imported to Central Europe, such as the rainbow trout or the topmouth gudgeon, or which arrived unintentionally via the ballast water of ships, such as the Pontocaspian goby species.

"In the future, we will have to be prepared to encounter increasing numbers of water bodies with new biological communities consisting of a mixture of species that would never naturally meet," says Prof. Jürgen Geist, professor at the Department of Aquatic Systems Biology and head of the study.

For this reason, systematic long-term analyses of the distribution and abundance of aquatic species are important: "The conservation of species and biodiversity must not stop at the water surface and should be based on scientific results," says Prof. Geist.
-end-
Publication:

Mueller, M., Pander, J., Geist, J.: Comprehensive analysis of > 30 years of data on stream fish population trends and conservation status in Bavaria, Biological Conservation 226; 311-320, 2018. DOI: https://doi.org/10.1016/j.biocon.2018.08.006

Contact:

Prof. Dr. Jürgen Geist
Technical University of Munich (TUM)
Chair of Aquatic Systems Biology
Tel: +49 (8161) 71 - 3767
E-Mail: geist@wzw.tum.de

Technical University of Munich (TUM)

Related Invasive Species Articles:

Charismatic invasive species have an easier time settling into new habitats
An international study, in which the University of Cordoba participated, assessed the influence of charisma in the handling of invasive species and concluded that the perception people have of them can hinder our control over these species and condition their spread
Invasive species with charisma have it easier
It's the outside that counts: Their charisma has an impact on the introduction and image of alien species and can even hinder their control.
Invasive species that threaten biodiversity on the Antarctic Peninsula are identified
Mediterranean mussels, seaweed and some species of land plants and invertebrates are among the 13 species that are most likely to damage the ecosystems on the Antarctic Peninsula.
Research networks can help BRICS countries combat invasive species
BRICS countries need more networks of researchers dedicated to invasion science if they wish to curb the spread of invasive species within and outside of their borders.
Look out, invasive species: The robots are coming
Researchers published the first experiments to gauge whether biomimetic robotic fish can induce fear-related changes in mosquitofish, aiming to discover whether the highly invasive species might be controlled without toxicants or trapping methods harmful to wildlife.
Monster tumbleweed: Invasive new species is here to stay
A new species of gigantic tumbleweed once predicted to go extinct is not only here to stay -- it's likely to expand its territory.
DNA tests of UK waters could help catch invasive species early
A team of scientists led by the University of Southampton have discovered several artificially introduced species in the coastal waters of southern England, using a technique that could help the early detection of non-native species if adopted more widely.
For certain invasive species, catching infestation early pays off
An international research team led by invasion ecologist Bethany Bradley at UMass Amherst has conducted the first global meta-analysis of the characteristics and size of invasive alien species' impacts on native species as invaders become more abundant.
Study offers insight into biological changes among invasive species
A remote island in the Caribbean could offer clues as to how invasive species are able to colonise new territories and then thrive in them, a new study by the University of Plymouth suggests.
The invasive species are likely to spread to a community not adapted to climate change
Laboratory experiment to indicate how invasive species are to spread new areas.
More Invasive Species News and Invasive Species Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

TED Radio Wow-er
School's out, but many kids–and their parents–are still stuck at home. Let's keep learning together. Special guest Guy Raz joins Manoush for an hour packed with TED science lessons for everyone.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.