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    Effects of salinity tolerances on survival and life history of 2 cladocerans
    (Tubitak Scientific & Technological Research Council Turkey, 2014) Gokce, Didem; Ozhan Turhan, Duygu
    Salinity alterations in freshwater ecosystems greatly affect the survival and life history of zooplankton and, therefore, have an effect on higher trophic levels. Salinity is an essential and critical factor in determining the presence, dominance, and succession of organisms. After being collected in the field, Scapholeberis mucronata and Simocephalus vetulus were brought to the laboratory in water. Under laboratory conditions (24 +/- 1 degrees C; 16:8 h photoperiod), we evaluated the effect of different salt concentrations on the neonates. The LC50 values were determined at different halotolerance levels for S. mucronata (0.375 g L-1) and S. vetulus (0.250 g L-1). Results of experiments demonstrated that S. vetulus was more sensitive than S. mucronata, which has hyponeustonic behavior. Morphometrics of the body in salinity stress were measured for S. mucronata. In the measurements of body length, body width, and spine lengths, there were significant differences determined by post hoc analysis between the control, 0.250, and 0.375 g L-1 dose groups and the 0.500 and 0.625 g L-1 dose groups. However, no clear relation between ovum size and salinity concentration was found. This study demonstrated how an increase in salinity significantly affects survival and life history properties, which can cause changes in the zooplankton community structure.
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    Evaluation of teratogenic and toxic effects of enrofloxacin-based antibiotic on zebrafish (Danio rerio) larvae with biochemical and developmental markers
    (Taylor & Francis Ltd, 2021) Ozhan Turhan, Duygu
    In this study, the effects of enrofloxacin-based antibiotic (EBA) used as a drug in veterinary medicine were evaluated on zebrafish embryos and larvae. The embryos were exposed to 17.56-300 mg L--(1) EBA for 96 h and survival rates and body malformations were evaluated under a stereo-microscope. In addition, 10-days larvae were exposed to LC50/4, LC50/2 and LC50 concentrations of antibiotic for 72 h and activities of glutathione S-transferase (GST), glutathione reductase, carboxylesterase, acetylcholinesterase, lactate dehydrogenase (LDH) and aspartate aminotransferases (AST) were measured. LC50 and EC50 values and the teratogenic index (TI) were calculated as 150.1 and 124.8 mg L--(1) and 1.2, respectively. EBA was teratogen for zebrafish embryos according to calculated TI. Spinal curvature, tail malformation, pericardial oedema and yolk sac oedema were determined in embryos exposed to 88.8 mg L--(1) and higher EBA concentrations. Furthermore, significant growth inhibitions were determined in larvae exposed to 59.26 mg L--(1) and above EBA concentrations. Also, 75 and 150 mg L--(1) concentrations of EBA caused a significant increase in GST, LDH and AST activities in zebrafish larvae. These results show that EBA causes adverse effects on zebrafish development and may adversely affect the aquatic ecosystem if it enters the aquatic environment.