دانلود رایگان مقاله اثر آفت کش ها در ترکیب اجتماعات ماکروفون آبزی در خندق های مزرعه

Abstract

Ditches surrounding agricultural fields in the Netherlands are predominantly used for flood control, and they accommodate aquatic plant and animal species. Studies addressing the effects of pesticides in combination with abiotic and biotic factors on aquatic biota in ditches are scarce. The current study aimed to investigate the effects of pesticides along with environmental factors, presence of other biota and time on the community composition of aquatic macrofauna in ditches next to flower bulb fields and pastures. Macrofauna samples and environmental data were collected during two consecutive years. Ponds in a sandy dune area of a nature reserve next to the polders were sampled as control sites. Data was analyzed with the variance partitioning procedure based on the redundancy analysis (RDA). The total variance in macrofauna community composition was divided into the variance explained by pesticides, environmental factors (water chemistry parameters and macrophyte coverage), time (study year and the number of the month), shared variance, and unexplained variance. The total explained variance in macrofauna community reached 22.6%. The largest proportion of explained variance was attributed to environmental factors (10.1%) followed by pesticides (5.4%) and time (4.8%). When each macrofauna group was analyzed separately, presence of other biota and environmental factors explained the largest proportion of variance in most of the macrofauna groups. Results of the study indicate that environmental factors, biotic interactions and temporal variation influence freshwater macrofauna considerably along with pesticides. We suggest that environmental managers should consider the multiple stressor contexts of aquatic ecosystems.

Conclusions

The entire aquatic macrofauna community composition was highly dependent on environmental factors that made a 50% higher contribution to the total explained variance than pesticides. Based on our results we can conclude that the responses of the macrofauna community to pesticides in the field are largely dependent on environmental factors. Policy guidelines developed to protect surface water and preserve aquatic biodiversity should include multi-stressor assessments at tiered levels, taking into account abiotic factors, habitat features, biotic interactions, as well as differences in responses of distinct macrofauna groups due to their varying ecological preferences.