Approved Abstracts

The Prochloraz chronic exposure to Daphnia magna derived in diminished growth of F0 generation daphnids and malformed F1 descendency



Author(s): Universidad Católica de Valencia San Vicente Mártir; Universitat de Valencia. UV; Universitat de Valencia. UV; Universidad Católica de Valencia San Vicente Mártir;
Presenter: Beatriz Salesa

Prochloraz is an imidazole type fungicide mainly used in agriculture due to its preventive activity, although it can also act in the cure and eradication of fungal pests. It has been reported as an endocrine disruptor with multiple modes of action on both, vertebrates and invertebrates. In Spain, several studies have revealed its presence in flowing waters at concentrations up to 486 ng/L. One of the most commonly used freshwater zooplankton organisms in Aquatic Toxicology testing is the cladoceran Daphnia magna. It has been used for many years in standard test of toxicity, because of their high sensitivity, easy handling and high reproduction rate. Classic biossays with this species include acute tests, in which the measured parameter is death, and chronic tests, in which the inhibition of normal reproduction as well as growth are the most frequently used endpoints for evaluation. Exposure to pesticides may cause serious problems for non-target organisms, leading to a number of pathological and disturbed biochemical processes, including changes in energy budgets. In general, sublethal stress induces compensatory changes in the organism‘s energy metabolism. The biomarkers of stress are potentially useful because they are sensitive to sublethal concentrations of chemicals and may provide the earliest possible warning of future adverse effects. In the present study, D. magna individuals were exposed to sublethal concentrations of Prochloraz (87, 130, 170, 230 and 380 μg/L) for 21 days according to the previous acute toxicity test. The effect of the pesticide on reproduction, survival, individual size as well as growth population rate were evaluated after 21 days of exposure. After 21 days exposure, the evaluated biochemical parameters were cholesterol, triglycerides, glucose, lactate, and LDH activity. F1 generation neonates were collected and its external morphology evaluated to estimate if the fungicide concentrations used induced effects during oogenesis and embryogenesis processes. Prochloraz EC50 values for D. magna in our experimental conditions were 9.64 and 9.23 mg/L at 24 and 48 h, respectively. At the end of the chronic exposure experiment, only F0 generation growth showed significant differences (p<0.05) compared to the controls, with a diminished individual length at all the selected Prochloraz concentrations. On the other hand, total proteins significantly increased whereas cholesterol and triglycerides remained unaltered. Glucose and the LDH enzyme levels significantly increased joint to a decreased on lactate levels. F1 alive females composed all the clutches at the collection time. However, neonates from parents exposed to 170 mg/L and higher concentrations were malformed since 16-d of exposure onward. Regardless of the concentration, all animals presented the same malformation: asymmetrical shell morphology and separated valves that did not cover the complete animal body. The results of the present work showed a direct effect of Prochloraz on D. magna individual growth, along with a mobilization of biochemical intermediate metabolism. A daphnid stress response as a result of the fungicide presence in the medium could be an explanation for the metabolic disorders found. On the other hand, the F1 malformed neonates found in the present study suggested an effect of Prochloraz among different daphnid generations and more studies would be necessary in this field.

Keywords: prochloraz; aquatic ecotoxicology; daphnia magna

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