Cadmium toxicity and bioaccumulation in freshwater biofilms.
A microcosm study was undertaken to examine the effects of dissolved cadmium at various concentrations (0, 10, and 100 microg . L(-1)) on biofilm accumulation and diatom assemblages. A natural biofilm sampled from the Riou-Mort River (Southwest France) was inoculated into three experimental systems, where biofilm settled on glass slides. Samples collected after 1, 2, 4, and 6 weeks of colonization were analyzed for metal accumulation (total metal content and intracellular metal content in the biofilm), biomass (as measured through dry weight and ash-free dry matter), and quantitative as well as qualitative analysis of diatom assemblages. There was a positive correlation between cadmium accumulation and dissolved cadmium concentrations and duration of exposure: a linear relationship was found between concentration factors (CFs) of growing biofilms and time (CFs/day = 0.25 and 0.38 under contaminations of 10 and 100 microgCd . L(-1), respectively). Biofilm settlement, more than photosynthetic activity, was affected by high cadmium concentrations: we observed for all stages of settlement a drastic and significant (p < 0.05) reduction in biofilm biomass and in diatom densities in the highest cadmium contamination, compared to control and low cadmium concentration units.
Morin
Soizic
S
Cemagref, UR REQE, 50 av. de Verdun, Cestas Cedex, France, soizic.morin@bordeaux.cemagref.fr
Duong
Thi Thuy
TT
Herlory
Olivier
O
Feurtet-Mazel
Agnès
A
Coste
Michel
M
D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D017377:Diatoms / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
D014874:Water Pollutants, Chemical; D002104:Cadmium