Effects of metazachlor and its major metabolite metazachlor OA on early life stages of marbled crayfish

Abstract

The effects of the herbicide metazachlor and its major metabolite metazachlor OA at two concentrations, including environmentally relevant concentrations of metazachlor (0.0115 µmol/l and 0.0790 µmol/l) and metazachlor OA (0.0117 µmol/l and 0.0805 µmol/l), respectively, were evaluated on early ontogeny, growth, behaviour, oxidative stress, antioxidant enzyme levels, histology, and mortality of marbled crayfish Procambarus virginalis. Both tested concentrations of metazachlor and metazachlor OA were associated with significantly lower growth and delayed ontogenetic development compared to controls. Exposure of metazachlor at 0.0115 µmol/l and metazachlor OA at 0.0117 µmol/l and 0.0805 µmol/l resulted in significantly lower activity of total superoxide dismutase (SOD), catalase (CAT), glutathione s-transferase (GST), glutathione reductase (GR), and reduced glutathione (GSH) compared with control and resulted in gill anomalies ranging from wall thinning to focal disintegration of branchial structure. Metazachlor at the environmentally relevant concentration of 0.0790 µmol/l was associated with significant alterations of crayfish distance moved and walking speed. The potential risk associated with metazachlor use in agriculture related to effects on non-target aquatic organisms.

Chronic Toxicity of Primary Metabolites of Chloroacetamide and Glyphosate to Early Life Stages of Marbled Crayfish Procambarus virginalis

“…However, in our study, crayfish’s early ontogeny did not show potential as a biomarker for monitoring AMPA and AE metabolites in the aquatic environment, as no exposure showed adverse effects on the ontogeny of marbled crayfish. This was similar to observations of chronic exposure to chloridazon residues [ 11 ] and triazine metabolites [ 91 ] on marbled crayfish. The early life stages of crayfish are more susceptible to water pollution, nutritional deprivation, and predation than adults, in both natural and cultured conditions [ 69 ].…”

“…In contrast, Levine et al [ 46 ], for 21 days of exposure to AMPA (0.75 mg/L, 1.5 mg/L, 3.0 mg/L, 6.0 mg/L, and 12), reported no effect on the growth of D. magna (NOEC 15 mg/L) or P. promelas embryos (NOEC 12 mg/L). Impacts on growth have been commonly observed in the early life stages of crayfish exposed to pesticides and their metabolites [ 11 , 41 , 83 , 84 ] as well as in the early life stages of fish [ 1 , 84 ]. These and our results imply that growth is a more sensitive parameter than mortality.…”

“…We did not find lipid peroxidation levels indicative of oxidative damage in any exposure group, suggesting that SOD and GST are the primary detoxifying antioxidants of AMPA and AE in the early life stages of crayfish, contributing to maintaining oxidative balance and preventing lipid peroxidation damage. Changes in antioxidant defence and maintenance of cell balance without effects on lipid peroxidation levels have been described in the homogenate of crayfish exposed to pesticides [ 11 , 90 , 102 ]. In other studies [ 70 , 103 , 104 , 105 , 106 ], increased TBARS levels usually indicated oxidative stress.…”

“…The behaviour of surviving juveniles was evaluated following the protocol by Velisek et al [ 11 ]. Briefly, crayfish were recorded in 50 mL of the specific bath according to experimental groups for 60 min using a digital video camera (Sony HDR-CX240, Sony, Japan) attached above arenas.…”

“…Residual pesticides and their metabolite concentration have been detected in Europe and the United States at ng/L to low µg/L [ 6 ], and greater than 10 mg/L concentrations [ 9 ] lead to ecotoxicological concerns. When chemicals occur in combination, the toxicity of their metabolites may equal or exceed that of the parent compounds [ 10 , 11 ].…”