Caloric content of Daphnia magna as reflect of propanil stress during a short-term exposure and its relationship to long-term responses.

The present study investigates energy stores changes in the aquatic invertebrate Daphnia magna following a 5-d exposure to propanil. Juveniles of D. magna were exposed to sublethal propanil concentrations (0.07, 0.10, 0.21 and 0.55 mgl(-1)) which were used previously to test their effect on reproduction, growth and survival (21 days test) of D. magna. Glycogen, total lipids, proteins, and dry weight were determined in control and exposed daphnids at 24, 48, 72, 96 and 120 h. Data were used to calculate caloric content as biomarker of propanil exposure. Results showed a depletion of energy reserves in D. magna exposed to the herbicide. At 120 h of exposure to the highest propanil concentration (0.5 mgl(-1)), the reduction in daphnid reserves were glycogen (28%), proteins (28%) and lipids (31%), and caloric content was reduced in 27%. On the other hand, we found a positive correlation between caloric content and the chronic parameters intrinsic rate of natural increase and offspring per female when daphnids were exposed for 120 h to the herbicide.

Physiological effects of tricyclazole on zebrafish (Danio rerio) and post-exposure recovery.

Short-term effects of tricyclazole on male zebrafish (Danio rerio) physiology were examined joint to the degree of recovery after exposure. Fish were exposed to 142 microg/L (1/100 LC(50)-96 h) of tricyclazole for 7 (Exp.1) and 14 days (Exp.2) and then allowed to recover for 7 or 14 more days, respectively. Whole-body triglycerides, cholesterol, glucose, lactate and total proteins were measured as well as the aspartate aminotransferase (AAT), alanine aminotransferase (AlAT), alkaline phosphatase (AP) and lactate dehydrogenase (LDH) activities as biomarkers of intermediary metabolism; gamma-glutamyl transpeptidase (gammaGT) as biomarker of oxidative detoxification processes and vitellogenin (Vtg) concentration as endpoint for endocrine disruptor effect were also determined. Corpulence factor (k) was calculated. Fungicide exposure in zebrafish resulted in an increased of triglycerides, cholesterol, glucose and lactate levels, however the total protein content did not change. LDH, AlAT and AAT enhanced while AP activity decreased. Corpulence factor (k) also decreased. At the end of the recovery periods cholesterol and glucose levels recovered whereas triglycerides and lactate continued to elevate. Induced disorders on the selected enzymes remained and did not recover at the end of experiments. Fish exhibited significant increases of Vtg during the overall experimental times as a consequence of the fungicide exposure. These findings are of importance in the assessment of the potential risk of new fungicides as tricyclazole on aquatic ecosystems.