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(M/EH037) Different sensitivity of two microalgal groups to atrazine toxicity. González, Óscar1, Rioboo, Carmen1, Cid, Ángeles1, Herrero, Concepción1, 1 ABSTRACT- Toxicity tests are often used to measure the sensitivity of different species and to derive water quality standards aimed at protecting the natural populations of that species. Microalgae have been recognized as useful indicators of environmental water quality; simple bioassays conducted in the laboratory using microalgae can provide valuable information about the possible disruptive effects of pesticides on algal physiology. Atrazine (6-chloro-N-ethyl-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine) is one of the most widely used pesticides for controlling certain annual broadleaf weeds and grasses. As a result of its widespread use and relatively high water solubility and persistence, it has been identified as a principal contaminant of surface waters. Recent studies have indicated that different algal divisions and species apparently have different sensitivity to atrazine and that algal responses to this herbicide vary widely depending upon concentrations used and algal species tests. In the present work, two freshwater microalgal species, relevant to different kingdoms, were assayed: the green microalga Selenastrum capricornutum,a chlorophyta (Eukaryota) and the blue-green microalga Synechococcus elongatus,a cyanobacterium (Prokaryota). Both were used as tested microalgae, in order to study the differences in their sensitivity to the herbicide atrazine. The biotoxicity of the herbicide was determined as a function of the evolution of growth of the above mentioned microalgae during 96 hours of treatment with atrazine. Taking into account the results obteined, the assayed microalgal species showed different sensitivity to the herbicide, being the cyanobacterium Synechococcus elongatus more sensitive to the effect of atrazine than the chlorophyta Selenastrum capricornutum. Key words: Atrazine, Synechococcus, Selenastrum, Biassayed |
