PARENT SESSION

PH08 Metals in the Environment: Aquatic Biological Perspectives
Exhibit Hall
8:00 AM - Thursday

(PH075) Toxic effects of cadmium, copper, and zinc to four different marine phytoplankton quantified by PAM fluorometry.

Miao, Aijun¹, Wang, Wenxiong², Juneau, Philippe³, ¹ Biology Department of Hong Kong University of Science and Technology² Biology Department of Hong Kong Univerisity of Science and Technology³ Department of Biological Sciences-TOXEN of Université du Québec à Montréal

ABSTRACT- The toxic effects of Cd, Cu, and Zn on four different marine phytoplankton, Dunaliella tertiolecta, Prorocentrum minimum, Synechococcus spp., and Thalassiosira weissflogii were examined by comparing the cell specific growth rate, Pulse-Amplitude-Modulated (PAM) parameters _M and _M', chlorophyll a content, and cellular metal concentration, over a 96 h period. The calculated Non-Observed Effect Concentration (NOEC) and Lowest-Observed Effect Concentration (LOEC) based on both the cell specific growth rate and the PAM parameters were comparable. Thus, the PAM parameters were not more sensitive than the growth inhibition as biomarkers for trace metal toxicity to the marine phytoplankton. The cyanobacteria Synechococcus was the most sensitive species among the four algal species tested due to the highest cell surface to volume ratio. The toxicity of these three tested metals followed the following order: of Cd > Cu > Zn based on the cellular metal concentration of the four algae at the NOEC. The cellular metal bioaccumulation followed the same Freundlich isotherm for each metal regardless of the algal species, indicating that the metal accumulation was a non-metabolic process under the high ambient metal concentrations and the surface metal binding sites were comparable among the different species. For all the algae studied in our study, the bioaccumulation potentials of Cu and Zn were comparable, while the Cd bioaccumulation was much lower under the environmentally realistic metal concentration.

Key words: Cellular metal concentration, Cell specific growth rate, PAM fluorometry, Quantum yields