TUM – Technical University of Munich Menu
  • Research news

Standard toxicity analyses come up short

Waters are more polluted than tests say

Bodies of water are “sinks”, and thereby bind contaminants particularly well. If even slightly toxic concentrations in water are to be detected, the growth and swimming behavior of small crustaceans, mini-snails and copepods should be used for ecotoxicological assessments.  This was the conclusion of a scientist from the TUM, who carried out a number of studies on the subject in cooperation with the University of California in Davis. She also confirmed that it is more informative to test several substances in parallel on various aquatic species, rather than only carrying out individual toxicity tests.

If a small crustacean does not grow properly, this can affect its reproduction. And if it is no longer able to move normally, it cannot flee from predators or from changing temperatures, which eventually has a fatal outcome. In scientific research, these effects are referred to as “sublethal effects”. However, worldwide standard methods of pesticide analysis and the risk assessments associated with them only consider the lethal (deadly) effects. For the first time, three studies published in “Ecotoxicology”, “Environmental Science and Pollution Research” and “Environmental Toxicology and Chemistry” demonstrate the sublethal effects on swimming behavior and growth, caused by widely used pesticides on the animals being studied. Moreover, the results indicate that the substances influence the underwater world for weeks, even if they are no longer detectable using standard methods.

Pesticides become more toxic as a combined package

Another factor is the mix of pesticides: “We looked at the insecticides not individually, but as a mixture, in order to investigate their interaction with one another”, explains lead author Dr. Simone Hasenbein. “In addition, we observed several species in the contaminated water body, including the less standard species for these tests, such as mini-snails and copepods.”

The tests took place over a period of ten days in the laboratory and also for six months in the field. Eventually, significantly negative effects resulting from the combined pesticide pollution in the water were found for twelve of the 15 small invertebrates and ten of the 16 zooplankton species. “Another point that was considered was how long the insecticide remained detectable in water”, was Dr. Hasenbein’s explanation of the method – “thus, one of the three substances was still detectable after six weeks.”

A clear result delivered only by a combination of study series

  • Firstly, the laboratory tests provided an indication of the concentrations at which the contaminants influence the growth and swimming behavior of the organisms.
  • The field studies proved the long-term effects on an entire ecosystem, its food web and its community structures.

The negative effects on aquatic ecosystems could only be pinned down once all the results were combined. Since the microorganisms being studied can be influenced by the pesticides for much longer than these substances remain detectable, this also leads to the conclusion that bodies of water are far more polluted than all previous research had demonstrated.

Sublethal effects as alarm signals
The changes in the animals which are detectable from their swimming behavior, growth or weight, and which eventually lead to their death (sublethal), are an important indicator of this. To date, however, there is no valid scale showing the point from which, for example, a delay in growth has a fatal outcome for the animal. Therefore, study author Dr. Hasenbein is advocating this approach in particular: “Sublethal endpoints need to be integrated into the methods used in ambient water monitoring, to allow long-term negative effects on aquatic ecosystems to be detectedreliably, even when the pesticide concentrations in the water are low“, says the scientist.

“A crustacean population which is exposed to low-level contaminant pollution could be more susceptible to invasive species, changes in water temperature or different salt concentrations, because the permanent, low-level pesticide contamination increases stress on the animals.“ This is an important aspect, especially in the light of climate change, and should therefore be taken into consideration in future ecotoxicologic assessments.


Publications:

  • Hasenbein S, Lawler SP, Geist J, Connon RE.: A long-term assessment of pesticide mixture effects on aquatic invertebrate communities. Environmental Toxicology and Chemistry, 13.11.2015. DOI: 10.1002/etc.3187
  • Hasenbein S, Connon RE, Lawler SP, Geist J.: A comparison of the sublethal and lethal toxicity of four pesticides in Hyalella azteca and Chironomus dilutus, Environmental Science and Pollution Research International, 2015 Aug;22(15):11327-39. DOI: 10.1007/s11356-015-4374-1
  • Hasenbein S, Lawler SP, Geist J, Connon RE: The use of growth and behavioral endpoints to assess the effects of pesticide mixtures upon aquatic organisms. Ecotoxicology 24:746-759, 29.01.2015. DOI:10.1007/s10646-015-1420-1


Contact:
Dr. Simone Hasenbein
Technische Universität München
Chair of Aquatic Systems Biology/
University of California Davis, Dept. of Anatomy, Physiology and Cell Biology
Phone:  +1 530 752 3141
Email: shasenbein(at)ucdavis.edu


Prof. Dr. Jürgen Geist
Chair of Aquatic Systems Biology/
Department of Ecology and Ecosystem Management
Mühlenweg 22
D-85354 Freising
Germany
Phone: +49/8161/71.3947
Email: geist(at)wzw.tum.de

 

Corporate Communications Center

Technical University of Munich

Article at tum.de

Dr. Natalia P. Ivleva mit ihrem Raman-Mikroskop (Bild: U. Benz / TUM)

How dangerous is microplastic?

After early reports of microplastic pollution in our oceans and beaches sounded the alarm, the global scientific community intensified its focus into this area. Researchers have since found evidence of microplastic...

Kesslergrundeln und weitere Grundelarten aus dem Schwarzen Meer kamen ursprünglich über das Ballastwasser der Schiffe nach Bayern und sind heute vor allem in der Donau und im Main stark vertreten.  (Bild: J. Geist/ TUM)

Changing fish stocks

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...

Mit der Umwelt-DNA-Analyse werden Gewässerlebewesen nachweisbar, ohne dass sie gefangen werden müssen: Bernhard Stoeckle (re.) holt sich dafür eine Wasserflasche mit Flüssigkeit aus einem Bach. Links neben ihm Sebastian Beggel, während Prof. Jürgen Geist hinten auf die Proben wartet. (Foto: A. Heddergott/ TUM)

Species identification in the water bottle

Environmental DNA analysis makes it possible to detect water organisms without having to capture them first. For the first time, a team at the Technical University of Munich (TUM) systematically investigated the effect of...

Die Durchströmung ist für den Boden eines Gewässers entscheidend und die Chance, den Flusslauf zu verändern, dadurch entsteht Lebensraum. (Foto: TUM/J. Geist)

Preservation of floodplains is flood protection

The silting of rivers and streams leads to problems for fish, mussels, and other aquatic organisms because their habitats disappear. However, not only intensive agriculture and erosion are destroying these habitats. Now a...

Die vom Aussterben bedrohte Flussperlmuschel (Margaritifera margaritifera). Von den knapp 70 in Deutschland existierenden Beständen gab es nur in zweien innerhalb der vergangenen 50 Jahre genügend Nachwuchs, um den Fortbestand zu sichern. Die Art hat es damit nur ihrem hohen Alter – sie wird weit über 100 Jahre alt – zu verdanken, dass sie bei uns noch nicht ausgestorben ist. (Foto: TUM/ Geist)

The Status Quo on Europe’s Mussels

Mussels are the natural treatment plants of bodies of water and, therefore, just as important as bees. Unfortunately, they are equally threatened: most of the world’s mussel stocks are in decline and some species face...

Das Tarim-Becken im Nordwesten Chinas.

Last chance for oasis in China´s desert

Ten percent of the world’s cotton is produced in the Xinjiang region in northwestern China. Irrigating the cotton fields, however, is causing ecological problems. After many years of research, a team of international...

Eine Auswirkung der Schifffahrt: Uferbefestigungen schützen Fische vor dem Wellenschlag vorbeifahrender Schiffe – und bieten so neu eingewanderten Tierarten ideale Lebensbedingungen.

A fast fish with a huge impact

Globalization is breaking down barriers – also for plants and animals on the lookout for new homes. Rivers are also changing, in particular through the introduction of non-native species, often brought in by passing ships....