Effects of different concentrations of the herbicide, Butachlor, on the growth of the green alga, Chlorella sp.

Date

10-2003

Degree

Bachelor of Science in Biology

Major Course

Major in Cell Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Milagrosa, R. Martinez-Goss

Abstract

LATORRE, KAREN B 2003 Effects of different concentrations of the herbicide, butachlor, on the growth of the green alga Morella sp. University of the Philippines Los Banos B.S. Biology major in Cell Biology

Major Adviser. Dr. Milagrosa R Martinez-Goss

ABSTRACT

The effect of the herbicide, butachlor, on the growth of the unialgal culture of ChimeIla sp. was determined using different concentrations, as: 0.001-. 0.01-, 0.1-, 1-,5-, 10-, and 20 ppm in Bold's Basal inorganic medium. Growth was measured colorimetrically (absorbance at 513 nm) and by determining chlorophyll a concentration. Toxicity test was done over a period of 96 h at 24 h intervals starting at 0 time. Mean culture densities (absorbance at 513 nm) at 96 h were relatively higher in the control and in those under lower concentrations of butachlor, such as 0.23, 0.22, 0.22 and 0.21 at 513 nm for 0-, 0.001-, 0.01-, and 0.1 ppm respectively while the mean culture densities at higher concentrations of butachlor (1-,5-,10-, and 20 ppm) ranged from 0.04 to 0.09 absorbance at 513 nm. Data obtained at 96 h was used to calculate the 96 h EC50 (Effective lethal concentration inhibiting 50% of the algal population) through non-linear regression and was found to have a value of 0.2938 ppm. The 9611 NOEC (No Observable Effect Concentration) was determined by Least Significant Difference test (LSD) at 0.05 level of significance and was found to be 0.1 ppm. The order of toxicity among the higher treatment levels in terms of percent reduction in growth rate proceeds as 20 ppm>10 ppm=5 ppm=lppm>0.1ppm=0.01ppm=0.001ppm=0 ppm. Reduction in growth rate among the lower treatments was not significantly different from the control. Chlorophyll a analysis showed the same trend as colorimetric analysis wherein there was an inverse relationship between the amount of butachlor to the chlorophyll a concentration of the algal cultures. The order of toxicity of treatment levels in terms of percent reduction in growth rate proceeds as 1 Oppm=20ppm>1 ppm=5ppm>0.1 ppm=0.001ppm=0.01ppm=0 ppm. Reduction in growth rate among the lower treatments was not significantly different from the control. Highest mean chlorophyll a concentrations were observed in 0,0.001-, and 0.01 ppm, respectively while the lowest values were observed in 20- and 10 ppm, respectively. Chlorella .sp. could be used as an indicator of the amount of butachlor, an herbicide, in the aquatic ecosystem because its growth was significantly inhibited at concentrations from 1- up to 20 ppm after 96 h exposure while the growth of the green alga was not inhibited at low concentrations from 0.001- to 0.1 ppm and its growth was found not significantly different from the control (0 ppm).

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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