Pond biodiversity, management and pollution
Most ponds are located in areas that are under heavy influence by human activities, such as agricultural areas, roads and urbanized zones. The biota in ponds is therefore very prone to pollution by a variety of chemical substances, such as pesticides and heavy metals. Because of their potentially high impact on freshwater biota, MANSCAPE mainly focused on the measurement of triazine pesticides (atrazine, simazine and their metabolites) and heavy metals in a large number of ponds and yielded a rather static picture of a limited number of polluting agents. PONDSCAPE will add a complementary contribution to this, because it will extend the number of investigated pesticides and it will study the temporal dynamics of pesticides in relation to application schemes in the agricultural sector. This work will be complemented with in vitro and in vivo estrogenicity tests that will allow the detection of steroid-mimicking pollutants (pesticides and several chlorophenyl compounds), which may induce reproductive dysfunctions in aquatic organisms. The evaluation of estrogenic activity will be confirmed by an integrative approach of stress responses of selected sentinel organisms (fish and amphibians). The MANSCAPE project revealed the presence of several heavy metals (Cu, Sn, Zn, Cd, Pb and Hg) in Belgian ponds. It is not clear what effects the management techniques will have on the dynamics and bioavailability of these toxic substances. Measures such as deepening or re-profiling may create re-suspension of sediments and thereby increase heavy metal loads in the water column and their bioavailability to aquatic organisms. However, physical removal of sediments may also result in a strong decrease of their concentrations. We will evaluate the effect of typical management techniques on heavy metal concentrations and use specific methods to address their bioavailability. Furthermore, we will assess whether fish and amphibians show a change in indicators to pollution stress before and after pond management.