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Tableau 3.2 Chlorophyll a, b and carotcnoids content (% of pigment comparcd to control) and chlorophyll alb ratio in an agricultural stream phytoplankton community after a 96 hours exposure to various conccntrations of glyphosatc-based

herbicide.

Glyphosate concentrations (pg l'¹)

	Control	1	5	10	50	100	500	1000
Chi a	100	61.7*	69.3*	94.7	100.3	66.1*	29.7*	28*
	±0.8	±21	±13	±22	±18	±23	±29	±4
Chi b	100	84.2	83.8	116.2	134.3	137.4	100.6	158.4
	±0.5	±42	±17	±17	±19	±96	±113	±79
Carotenoid	100	32.9*	46.9*	56.2*	63.4*	27.4*	4.3*	l.l*
	±5	±24	±18	±24	±10	±22	±5	±2
Treatments	means from ANOVA (n=3). The			* symbol represents		significant differences from the

control treatment (p < 0.05) by the paired T-test.

3.6.4 Oxidative markers

Lipid peroxidation (MDA concentration) was significantly greater for the highest glyphosate concentration, when compared to control (figurę 3.2). Regarding antioxidant enzymes, SOD activity inereased when glyphosate concentration reached 500 pg I*¹, but was significantly lower at a concentration of 100 pg f¹. Similarly, APX and CAT activities inereased for samples treated with glyphosate concentrations of 500 and 1000 pg l’¹.

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