CS13 Environmental Ecotoxicology
Date: Friday, June 14, 2002
Time: 10:15:00 AM
Location: Esquimalt
 
NayarS, Department of Biological Sciences, National University of Singapore, Singapore, Singapore, scip8370@nus.edu.sg
Goh, B, P, National Institute of Education, Singapore, Singapore, bgoh@nie.edu.sg
Chou, L, M, Department of Biological Sciences, National University of Singapore, Singapore, Singapore, dbsclm@nus.edu.sg
 
TOXICITY OF HEAVY METALS RESUSPENDED BY DREDGING TO PERIPHYTON IN AN IMPACTED ESTUARY IN INSITU MICROCOSMS.
image
Ponggol estuary located on the northeastern coast of Singapore is heavily impacted by anthropogenic activities such as reclamation, dredging, construction and shipping. A year round fortnightly monitoring was carried out from July 1999 to June 2000 for 6 heavy metals viz., tin, lead, zinc, nickel, cadmium and copper in the particulate and dissolved fractions besides sediments. Intensive dredging led to resuspension and bioavailability of particulate metals. Periphytic algae, being ubiquitous, and a biological component of ecological significance in an estuarine ecosystem, was used to assess toxicity of the resuspended heavy metals and metals in other fractions. Established on glass slides, they were exposed to environmentally realistic heavy metal concentrations in insitu estuarine microcosms to access the impact of the 6 heavy metal types on periphyton biomass measured in chlorophyll a. Among the metals tested, cadmium had the least effect followed by lead, zinc, nickel, tin and copper at the tested concentrations. A reduction in biomass up to 95-100% with respect to the control was seen for treatments simulating concentrations of metals in the particulates. Results from this study suggest using insitu periphyton microcosms as a tool for ecotoxicological studies.