PARENT SESSION
MP8a Site-Specific Ecological Risk Assessment.
3:00 PM to 4:00 PM, Monday, 07 May 2001
Session Chair: Lorraine Maltby
Room 8

(136) A weight-of-evidence approach for assessing effects of metals exposure to fish fauna in a Brazilian rain forest reserve.

Moraes, Rosana¹, Gerhard, Pedro², Andersson, Linda³, Rauch, Sebastian¹, Sturve, Joachim³, Molander, Sverker¹, ^{1 2 3}

ABSTRACT- The Parque Estadual Turistico do Alto Ribeira (PETAR) is a preserved area of Atlantic rain forest in Brazil. Lead-silver mining has been an important activity in the region. At some sites, piles of waste rock with high concentrations of heavy metals have been left when mining stopped. Some streams of PETAR (e.g., Furnas) flow close to one of the abandoned mines. The objective of this study was to identify possible effects on fish fauna due to exposure to heavy metals originating from the mine using a weight-of-evidence approach. Concentrations of metals in sediment and fish (muscles and liver) were analyzed from samples taken from the Furnas stream and two non-exposed rivers in January 2000. ALAD activity in two species of siluriform catfishes, one herbivore (Isbrueckerichthys sp., Fam. Loricariidae) and one insectivorous (Rhamdioglanis frenatus, Fam. Pimelodidae) was measured. In addition, the entire fish community was sampled using electro-fishing and analyzed for biomass, diversity, abundance, trophic composition and condition factor. Results showed that fish community in the stream was exposed to high levels of lead, cadmium, zinc and silver. Concentrations of these metals were higher than toxicologically effective concentration for both fish and fish prey. Residual concentrations in tissue are high enough to indicate a reduced growth and survival of fish. ALAD activity and condition factor of Isbrueckerichthy sp. from the Furnas stream were lower than from other non-contaminated sites. Fish specimens showing deformities were observed near the mine. The fish community from that stream was less diverse, had lower density and biomass, and presented a higher percentage of prey generalists compared to similar streams. The integration of data using a weight-of-evidence approach provided a strong argument that fish fauna from the Furnas stream has been affected by exposure to metals from the abandoned mine.

Key words: biomarker, ecological risk assessment, fish community, weight-of-evidence