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Abstract

Toxicity testing of four heavy metals (Cd, Cu, Mn and As) using four species of tropical marine phytoplankton, Chaetoceros calcitrans, Isochrysis galbana, Tetraselmis tetrahele and Tetraselmis sp., was carried out in multiwell plates with test volumes of 2 mL and the results compared to those of standard, large volume, shake-flasks. IC50 values (concentrations of metals estimated to inhibit 50% growth relative to the control) were determined after 96 hours based on automated O.D. readings measured in Elisa microplates by a Multiskan spectrophotometer. Good agreement was achieved between O.D. readings and cell counts indicating that this new method is a simple, economical, practical and rapid technique for toxicity testing, and provides good reproducibility of IC50 values. Results of the toxicity tests indicate that Cu was the most toxic metal (average IC50 values ranging from 0.04 to 0.37 mg L(-1)), followed by Cd (0.06-5.7 mg L(-1)), Mn (7.2-21.4 mg L(-1)) and As (33.9-319.3 mg L(-1)). Test species had different degrees of sensitivity to the metals tested, with I. galbana and C. calcitrans the most sensitive to Cu, Cd and Mn. Based on these findings it is recommended that the existing Malaysian Interim Standards for Marine Water Quality for Cd and Cu be reviewed.

Copper and Cadmium Toxicity to Marine Phytoplankton, <i>Chaetoceros gracilis</i> and <i>Isochrysis</i> sp.

“…have been reported by several authors: Cu 110-1000 μg/L [29]; Cu 30-410 μg/L [30]; Cu 910 μg/L [16]; Cu 4200 μg/L [8]. Comparing the values of Table 4 with those cited, this study shows lower IC 50 values for Cu.…”

Single and combined effects of microplastics and copper on the population growth of the marine microalgae Tetraselmis chuii

“…Levy et al, 2008Ismail et al, 2002Yap et al, 2004Levy et al, 2007 Levy et al, 2008 Franklin et al, 2002Ismail et al, 2002 Levy et al, 2008 …”

The Use of the Marine Microalga Tisochrysis lutea (T-iso) in Standard Toxicity Tests; Comparative Sensitivity With Other Test Species

“…The recommended test format is glass Erlenmeyer flasks and polycarbonate for tests with metals. The comparability of toxicity responses between tests in microplates and standard flask has been the subject of discussion (Ismail et al, 2002;Eisentraeger et al, 2003;Blaise and Vasseur, 2005;Pavlic et al, 2006). Microplate tests have advantages such as reduction of the volume of sample needed and the possibility to perform high throughput analyses, reducing also costs in glassware and reagents.…”

“…Many authors discuss this issue and several other endpoints are suggested (see Table 3). Growth rate may also be assessed through chlorophyll content, and has also been applied to microscale assay using microplates (Ismail et al, 2002;Satoh et al, 2005). Pérez et al (2010a) found fluorescence more suitable for assays with fuel but Othman et al (2012) found greater sensibility in the population density endpoint at 72 h (absorbance at 650 nm) than the photosynthetic endpoint at 24 h (fluorescence of chlorophyll at 450 and 680 nm) for benz(a)anthracene and fluoranthene.…”