Fungicides are unbalancing aquatic ecosystems

Bruno Castro, from the Center for Molecular and Environmental Biology (CBMA), is investigating the impact of pesticides on reservoirs and lakes.

Lagoons and reservoirs are the working place of Bruno Castro, Researcher at CBMA (Centro de Biologia Molecular e Ambiental | Centre of Molecular and Environmental Biology) of the School of Sciences of University of Minho. In his research, Bruno is trying to demonstrate that man-induced application of chemicals is originating a negative impact on water lines, such as lagoons, reservoirs and relevant ecosystems. Basing his research in the boundary between ecology and toxicology – mainly focusing environmental stressors in freshwaters -, he combines lab and field approaches to evaluate how communities cope with man-induced environmental changes.

Having as reference small crustaceans existing in lagoons which have a central role in trophic chains and water transparencies, the researcher refers that “we are interested in the natural enemies of these small organisms, in particular a fungus that invades the body mass of these crustaceans, causing them damage and reducing their life expectation.” Focusing his work on this host-parasite dynamics, the research team assesses the effect of chemical agents, such as fungicides, that get to the aquatic systems and change this mutual relationship. “What we are observing is that some fungicides are extremely detrimental for the parasite, thus suppressing the transmission of the disease,” reveals the biologist. The work carried out in the lab, simulating relationships in experimental models, allows us to “establish a causal relationship”, says Bruno Castro.

Although there is a negative perception associated with parasites, Bruno Castro argues that “from the ecological point of view, human activities interfering in the transmission of diseases in natural populations has nothing of positive to it.” The researcher at the Centre of Molecular and Environmental Biology (CBMA) warns that “microorganisms, specially fungi, play a key role in ecosystems, acting as decomposers or living associated with other organisms” (VIDEO).

Due to these factors, Bruno Castro has the same opinion as those who defend that “less chemical agents should be used and the application of pesticides should be more sustainable,” something which is being regulated by law. The truth is that the extensive use of pesticides in agricultural crops, namely in vineyards, leads contaminated sediments by streams and rainwater seepage into the aquatic systems. The organisms living there, as crustaceans, insect larvae, amphibians, or fish species are particularly sensitive to the biological effects of these chemical agents.

Regulatory scientific contribution

This research has special significance within the scope of the Framework for Communitarian Action and for the National Action Plan in what concerns the sustainable use of pesticides. Both aim to raise awareness of the population in general to the potential risks of these substances and that their application within the European scenario should be reduced. The undertaken scientific work will allow this group of the CBMA to conclude which are the most selective and the most harmful agents for aquatic organisms.

The conclusions and the acquired knowledge will help to take sustained decisions with view to the legal regulation on the use of chemicals and a list of the relevant chemical agents used in agriculture. Among the studied substances, tebuconazole stands out: a triazole fungicide used agriculturally to treat plant pathogenic fungi, with an action like some anti-fungal medications used in humans and revealing “a very radical effect in the suppression of the infection of the fungal micro parasite we are dealing with, even in quite short exposures,” says the researcher.

After a few conclusions already disclosed in scientific papers, the research group is preparing “a report for the competent authorities, although it is known that the European Union already produces a list of the authorized fungicides, as well as a team carrying out research which, according to scientific evidence, keeps the list updated and eliminates those compounds representing greater ecological risk,” says Bruno Castro. At this stage, the investigation is broadening the biological models under study, “going beyond the host-parasite model, and carrying out similar studies concerning the decomposition process, where aquatic fungi have quite a critical role.”



NOS – Uminho