TP8 Biomonitoring
A105 & A106
1:20 PM - 4:40 PM, Tuesday
() Development, growth and weight of C. riparius larvae to assess heavy metal contamination of water and sediment, in field and laboratory conditions.
Faria, M1, Malcato, J1, Lopes, RJ2, Nogueira, AJA1, Soares, AMVM1, 1 Department of Biology, University of Aveiro, Portugal2 Institute of Marine Research, University of Coimbra, Portugal
ABSTRACT- Ecological assessment of water quality is essential to the management of surface waters and the protection of aquatic ecosystems. Heavy metals have the potential to affect benthic invertebrates. Here, the midge Chironomus riparius was used to study how heavy metal contamination influences ecological responses of a collector in lotic ecosystems. Bioassays using C. riparius larvae were carried out during Spring, in three consecutive years, in contaminated and reference rivers near an abandoned goldmine in northern Portugal. Simultaneously, laboratory bioassays were also performed, at 15° C and 20° C, with sediment and water from the same rivers. Endpoints were development, growth and weight. During the two last years, an ongoing process of decontamination has been reducing the concentration of heavy metals (As, Pb, Zn, Cu, Cd,) on this river system. This allowed us to perform bioassays with different heavy metal concentrations and to evaluate their performance to monitor the decontamination process. High heavy metal contamination inhibited larvae growth and weight in both laboratory and field tests. Development was not affected significantly with this contamination. During the process of decontamination a decrease of heavy metals on water and sediment was observed. This trend was also observed on the inhibition of growth and dry weight of C. riparius larvae. The laboratory tests showed that growth and dry weight were inhibited by contamination of sediment by heavy metals while only growth was also significantly inhibited by high concentration of heavy metals in water.
Key words: Chironomus riparius, Heavy metals, Bioassays, Biomonitoring