resumo
Urbanization and industrial activities have contributed to widespread contamination by metals and polycyclic aromatic hydrocarbons, but the combined effects of these toxics on aquatic biota and processes are poorly understood. We examined the effects of cadmium (Cd) and phenanthrene on the activity and diversity of fungi associated with decomposing leaf litter in streams. Leaves of Alnus glutinosa were immersed for 10 days in an unpolluted low-order stream in northwest Portugal to allow microbial colonization. Leaves were then exposed in microcosms for 14 days to Cd (0.06-4.5 mg L(-1)) and phenanthrene (0.2 mg L(-1)) either alone or in mixture. A total of 19 aquatic hyphomycete species were found sporulating on leaves during the whole study. The dominant species was Articulospora tetracladia, followed by Alatospora pulchella, Clavatospora longibrachiata, and Tetrachaetum elegans. Exposure to Cd and phenanthrene decreased the contribution of A. tetracladia to the total conidial production, whereas it increased that of A. pulchella. Fungal diversity, assessed as denaturing gradient gel electrophoresis fingerprinting or conidial morphology, was decreased by the exposure to Cd and/or phenanthrene. Moreover, increased Cd concentrations decreased leaf decomposition and fungal reproduction but did not inhibit fungal biomass production. Exposure to phenanthrene potentiated the negative effects of Cd on fungal diversity and activity, suggesting that the co-occurrence of these stressors may pose additional risk to aquatic biodiversity and stream ecosystem functioning.
palavras-chave
POLYCYCLIC AROMATIC-HYDROCARBONS; EEL ANGUILLA-ANGUILLA; PLANT LITTER; HEAVY-METALS; PLEUROTUS-OSTREATUS; POLLUTED RIVER; MINE DRAINAGE; STREAMS; ZINC; DEGRADATION
categoria
Environmental Sciences & Ecology; Toxicology
autores
Moreirinha, C; Duarte, S; Pascoal, C; Cassio, F
nossos autores
Catarina Moreirinha
Bolseiro de pós-Doutoramentoagradecimentos
The Portuguese Foundation for the Science and Technology supported this work (POCI/MAR/56964/2004) and S. Duarte (SFRH/BPD/47574/2008) as well.