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 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.
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. http://link.springer.com/article/10.1007%2Fs11356-015-4374-1
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
Dr. Simone Hasenbein
Technical University of Munich
Chair of Aquatic Systems Biology/
University of California Davis, Dept. of Anatomy, Physiology and Cell Biology
Tel: +1 530 752 3141
Prof. Dr. Jürgen Geist
Chair of Aquatic Systems Biology
Department of Ecology and Ecosystem Management
Dr. Ulrich Marsch | Technische Universität München
Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt
Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction