Glyphosate-based herbicides affect behavioural patterns of the livebearer Jenynsia multidentata.

Roundup® is one of the most widely marketed glyphosate-based herbicides in the world. There are many different formulations of this brand that differ from each other in glyphosate concentration, salts and adjuvants, including surfactants, which are labelled as "inert" compounds. Several studies have shown that these formulations are highly toxic to fish, even compared with pure glyphosate. However, mechanisms underlying this toxicity are not fully understood. In this context, this study evaluated the effects of exposure to Roundup Original® (RO), Roundup Transorb® (RT), and Roundup WG® (RWG) on the behavioural patterns of the livebearer Jenynsia multidentata. This fish naturally inhabits agricultural areas in southern Brazil and Argentina where glyphosate is used extensively. In the experiment, animals were exposed to the herbicides for 96 h, at the environmentally relevant concentration of 0.5 mg/L of glyphosate. Swimming performance, anxiety, aggressiveness, long-term memory and male sexual activity were recorded. The formulation RWG negatively affected swimming performance, thigmotaxia and long-term memory consolidation. Conversely, RT reduced the sexual performance of males. These results confirm that Roundup® formulations are extremely harmful and also that they have different targets of toxicity, affecting behaviours that are essential for fish survival.

Impacts of the biocide chlorothalonil on biomarkers of oxidative stress, genotoxicity, and sperm quality in guppy Poecilia vivipara.

Chlorothalonil is a fungicide present in antifouling paints and other formulations used in agriculture, although studies have shown this chemical to be toxic to fish species. To clarify the deleterious effects of chlorothalonil for these non-target organisms, the present study evaluated the toxic effects of this biocide for the estuarine guppy Poecilia vivipara in terms of an acute mortality test (96 h) and the analysis of biomarkers of oxidative stress, genotoxicity, and sperm quality. The LC50 calculated for P. vivipara was 40.8 µg/L of chlorothalonil. For the analysis of biomarkers, fish were exposed (96 h) to 1 and 10 µg/L of chlorothalonil. It was observed that chlorothalonil alters the levels of pro- and antioxidants towards oxidative stress. In the gills, a negative effect on total antioxidant capacity (ACAP) was detected, while there was a reduction in the activity of glutathione S-transferase (GST) in the liver. However, levels of glutathione (GSH) and the activity and glutamate-cysteine-ligase (GCL) increased in both tissues, as a possible detoxification response. Following chlorothalonil exposure, oxidative damage measured by lipoperoxidation (LPO) significantly increased at the cellular level only (red blood cells (RBCs) and sperm cells). An increase in fluidity of membranes, reactive oxygen species concentration and micronuclei (MNs) incidence were also seen in RBCs. In sperm cells, LPO increased, while membrane and mitochondrial functionality as well as sperm motility decreased. Based on these results, chlorothalonil can be considered as a toxic compound for fish, causing genotoxicity and affecting the RBCs physiology and the fertility of males of P. vivipara.

Effects of Roundup formulations on biochemical biomarkers and male sperm quality of the livebearing Jenynsia multidentata.

Roundup® formulations are the most consumed glyphosate-based herbicides in the world. When applied, they may reach water bodies and exert toxicity toward non-target species. This study evaluated and compared the effects of different variations of Roundup on biochemical biomarkers as oxidative parameters and Acethylchorinesterase (AChE) activity, and sperm quality of the livebearing Jenynsia multidentata. Fish were acutely (96 h) exposed to Roundup Original® (RO), Roundup Transorb® (RT) and Roundup WG® (RWG) at 0.0, 0.5, 1 and 5 mg L-1 of nominal glyphosate. The highest mortality (60%) was observed for fish exposed to RT at the highest concentration tested and at 0.5 mg L-1 non-mortality was observed, so this concentration was chosen for the experiments. Fish exposed to RO and RT (24 and 96 h) presented a state of oxidative imbalance, which caused lipid peroxidation (LPO) in their livers. Oxidative stress was more severe in RO treatment, which may be resulted in the highest hepathosomatic index at 96 h. However, fish exposed to RT presented a marked inhibition of AChE activity from membrane cells of muscle and brain tissues. Sperm quality was investigated in livebearing exposed (24 and 96 h) to the three formulations. Spermatozoa motility and concentration were affected by all formulations. Overall, Roundup formulations are harmful to the fish J. multidentata at 0.5 mg L-1 of glyphosate; however, mechanisms and potential of toxicity are different between formulations. The J. multidentata also represents a sensitive species and a good regional bio-monitor.