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Sublethal toxicity of the Diazinon insecticide on the growth, survival, antioxidant and digestive enzymes activity of Fairy shrimp (Phallocryptus spinosa)
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Behrooz Atashbar Kangarloei1   , Mojtaba Pourahad Anzabi2 , Raman Amini2 |
1- Department of Ecology and Resources Management, Artemia and Aquaculture Institute, University of Urmia, Urmia, Iran
2- Department of Fisheries, Faculty of Natural Resources, University of Urmia, Urmia, Iran |
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Abstract: (27 Views) |
Introduction
Population growth and limited production inputs have forced farmers to use pesticides (Zand et al., 2002), and aquatic ecosystems are consistently exposed to these pollutants (Mansingh and Wilson, 1995). Pesticide contamination in aquatic ecosystems poses a serious threat to the foundation of the food chain (Aydın and Köprücü, 2005; De Prado et al., 2012). Pesticides at the chronic level led to destructive effects in various physiological functions (Varo et al., 2002; Koprucu and Koprucu, 2006). Additionally, organophosphorus pesticides have been shown to induce oxidative stress, alter growth rates, and disrupt reproductive indices in the larvae of the shrimp Streptocephalus dichotomus (Arun Kumar and Javahar, 2014). Diazinon is one of the most important organophosphorus pesticides. As a persistent pesticide, it is highly toxic to fish and aquatic invertebrates (Coupe et al., 2000; Samadi et al., 2019). This chemical is easily washed away after use, entering aquatic environments in significant quantities (Aydın & Köprücü, 2005). Many species of large branchiopods occur in temporary habitats surrounding agricultural areas and farmlands, which serve as locations where Phallocryptus spinosa can be found (Atashbar et al., 2014). Phallocryptus spinosa inhabits temporary freshwater to brackish water bodies, the hydroregime patterns of which are highly unpredictable. These habitats typically fill in early spring and dry out by summer (Atashbar et al., 2014). Environmental pollution from diazinon-one of the most widely used agricultural pesticides-affects the life cycle of zooplankton, such as fairy shrimp, and threatens their populations. Thus, understanding the impact of such substances on the environment, particularly aquatic ecosystems, is essential. Therefore, this study aimed to investigate the effects of diazinon insecticide toxicity on the growth, survival, and activity of antioxidant and digestive enzymes in P. spinosa larvae.
Methodology
This study was conducted at the Artemia and Aquaculture Research Institute of Urmia University. P. spinosa shrimp cyst hatching was performed following the method recommended by Atashbar et al. (2012). To determine the 24-hour LC50 of diazinon, a preliminary range-finding test was first conducted using 30 shrimp larvae (in triplicate) (Lan and Lin, 2005). Based on these results, three experimental treatments (Table 1) were selected to investigate the effects of sublethal diazinon concentrations on shrimp rearing conditions. Survival and growth rates were assessed on days 1, 3, 5, and 7 using the methods of Rahimi and Nejatkhah Manavi (2011) and Agh et al. (2008). The activities of SOD, CAT and GPX enzymes were measured according to Yazdanparast et al. (2008). Malondialdehyde (MDA) activity was determined based on thiobarbituric acid inhibition by MDA in the crude enzyme extract (Ledwożyw et al., 1986). Digestive enzyme activities were measured as follows: Alkaline protease: Garcia-Carreno and Haard (1993), Lipase: Iijima et al. (1998), Alpha-amylase: Bernfeld (1955). Data were analyzed using one-way ANOVA in SPSS (version 21), with a significance level (Type I error) set at α = 0.05.
Results
The comparison of mean survival percentages (Table 3) revealed a significant decrease due to diazinon exposure (p < 0.05 Day 3: a significant difference (p<0.05) was observed between treatment 1 (control) and treatment 4 (100% diazinon). Day 5: significant differences (p<0.05) were detected between treatment 1 and treatments 2 (25% diazinon), 3 (50% diazinon), and 4. Also, treatments 2 and 3 vs. treatment 4. Day 7: significant differences (p<0.05) occurred between treatment 1 and treatments 2, 3, and 4 and between the treatment 2 and treatments 3 and 4. The highest survival rate was recorded in treatment 1, while the lowest was in treatment 4 (100% diazinon) (p<0.05). Comparison of mean growth indices (Table 4) revealed a significant decrease due to diazinon exposure (p<0.05). The significant differences were observed as follows: day 3: treatment 1 (control) vs. treatments 3 (50% diazinon) and 4 (100% diazinon), day 5: treatment 1 vs. treatments 3 and 4; treatment 2 (25% diazinon) vs. treatment 4; day 7: treatment 1 vs. treatments 2, 3, and 4; treatment 2 vs. treatments 3 and 4; treatment 3 vs. treatment 4. The highest growth rate was observed in treatment 1 (control), while the lowest occurred in treatment 4 (100% diazinon) (p< 0.05). The results for whole-body antioxidant enzyme activity and malondialdehyde (MDA) levels (Figure 1) showed significant increases due to diazinon exposure (p<0.05). Significant differences were observed in: SOD activity: treatment 1 (control) vs. treatments 2 (25% diazinon), 3 (50% diazinon), and 4 (100% diazinon); CAT activity: treatment 1 vs. treatments 3 and 4; GPX activity: treatment 1 vs. treatments 2, 3, and 4; treatment 3 vs. treatments 2 and 4; MDA content: treatment 1 vs. treatments 2, 3, and 4; treatment 4 vs. treatments 2 and 3. The results of whole-body digestive enzyme activity (Figure 2) showed significant increases due to diazinon exposure (p<0.05). Alkaline protease, lipase, and α-amylase in treatment 1 (control) showed significant differences compared to treatments 2 (25% diazinon), 3 (50% diazinon), and 4 (100% diazinon) (p<0.05). The α-Amylase in treatment 4 differed significantly from treatments 2 and 3 (p<0.05). The lowest and highest levels of alkaline protease activity were observed in treatments 1 and 4, respectively, and the lowest and highest activity of lipase and alpha-amylase enzymes were observed in treatments 1 and 3, respectively (p<0.05).
Discussion and conclusion
The results of this study demonstrated that shrimp larval survival decreased with increasing diazinon concentration. This aligns with findings by Taylor et al. (1998), where pollutant exposure affected vital functions in zooplankton, leading to population density reduction, decreased oxygen consumption, and nutritional limitations that ultimately impact survival rates. Additionally, shrimp larval growth declined at higher diazinon concentrations. Asadpour et al. (2012) attributed such growth reduction to disturbances in feeding behavior and alterations in biochemical and physiological responses to pollutants.
Toxins reduce growth through absorption and organ damage (Cong et al., 2009; Rudnicki et al., 2009; Aggarwal et al., 2013). Our results demonstrated elevated levels of SOD, CAT, GPX, and MDA following diazinon exposure. The increased SOD and CAT enzyme levels reflect stimulated free radical elimination (Rumley and Paterson, 1998), while elevated GPX activity indicates an enhanced antioxidant defense capacity against radical chain reactions in P. spinosa (Schneider et al., 2005). The rise in MDA content suggests diazinon-induced lipid peroxidation (Jafari et al., 2012). We also observed increased digestive enzyme activity at various diazinon concentrations. This may result from toxin-induced stress altering feeding behavior and subsequent digestive enzyme secretion (Suzer et al., 2006). In summary, diazinon exposure at different concentrations: (1) reduced survival and growth rates, (2) disrupted vital physiological functions in P. spinosa larvae.
Conflict of interest
The authors declare no conflict of interests.
Acknowledgment
We extend our heartfelt thanks to the Office of Vice Chancellor for Research and Artemia and Aquaculture Research Institute of Urmia University for enabling this research. |
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| Keywords: Diazinon, Growth, Survival, Antioxidant enzymes, Digestive enzymes, Phallocryptus spinosa |
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Full-Text [PDF 914 kb]
(10 Downloads)
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Type of Study: Research |
Subject:
فيزيولوژي آبزيان
Received: 2025/02/20 | Accepted: 2025/08/1
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