PARENT SESSION
3B General and multipurpose analysis
9:00 AM to 7:00 PM, Tuesday, 08 May 2001

(T/EH122) Comparative study of the effects of metals on Gonium pectorale Müller and Selenastrum capricornutum Printz.

Pereira, Mário¹, Váu, Sílvia¹, Bom, Joana¹, Santos, Conceição¹, Gonçalves, Fernando ¹, Soares, Amadeu M.¹, ¹

ABSTRACT- Pseudokirchneriella subcapitata (Korshikov) Hindak (syn. Selenastrum capricornutum Printz) is widely used in ecotoxicology. Gonium pectorale Müller is a flagellate species. The relative sensitivity of both these species to three metals was investigated. Our results demonstrate that P. subcapitata shows higher levels of 96h IC₅₀ than Gonium pectorale, that copper is the most toxic metal and nickel the least toxic, revealing for both species the following rank order: Cu (II) > Cr (II) > Ni (II). The levels of toxicity for the flagellate species are below 0.6 mg L^-1. Assays with other metals, using G. pectorale as test organism, have shown the following order of toxicity: Hg (II) > Cd (II) > Cu (II) > Cr (II) > Ni (II) > Zn (II) > Cr₂O₇^2- > Cs (I) > Pb (II). This species is most appropriate to be used in static tests because its mobility avoids problems of algae sedimentation and the growth behaviour leads it to occupy the whole tested volume, including the interface water-air, an ecological niche that has not received much attention in ecotoxicology.

Key words: Metals, Gonium, Selenastrum, Growth