Hatchling sex ratios of loggerhead sea turtles (Caretta caretta) were estimated on two main nesting beaches (Dalyan Beach and G€ oksu Delta) in Turkey using three methods: nest temperature, incubation period and gonad histology. The electronic temperature recorders were placed in 35 selected nests. The mean nest temperature in the middle third of the incubation period was calculated as 29.5 C on Dalyan Beach and as 31 C on G€ oksu Delta. Incubation periods on Dalyan Beach and G€ oksu Delta were found as 52.9 days and 50.4 days, respectively. Gonad histology method was used only on Dalyan Beach and it was determined that 235 (55.6%) hatchlings were female out of 423 histologically examined hatchlings. Using nest temperatures and incubation periods, sex ratios on Dalyan Beach were estimated as 61% and 69.3%, and on G€ oksu Delta as 81% and 73.1%, respectively. In light of our sex ratio results, Dalyan Beach has a relatively high proportion of male hatchlings possibly due to its relatively western location. Our findings indicate that Dalyan Beach is an important nesting beach for loggerhead sea turtles in the eastern Mediterranean not only in terms of nest numbers and hatching success but also for its high proportion of male hatchlings. As for the methods used in this study, for further studies, we can suggest that nest temperature method provides the most accurate sex ratio result compared with incubation period and gonad histology methods, if temperature-recorded nests are selected in a manner of representing temporal distribution of the total nests on study beach.
In this study, five new heterocyclic disazo dyes containing pyrazole and pyrazolone were synthesised (3a-3e). The synthesised disazo dyes were characterised by elemental analysis and Fourier Transform-infrared and proton nuclear magnetic resonance spectroscopy. The effects of two different solvents upon the absorption ability of the dyes substituted with electron-withdrawing and electron-donating groups were examined in detail. In addition, the acute toxicity of each synthesised azo dye was evaluated using a short-term bioassay with Gammarus roeseli (Crustacea: Amphipoda) for 48 hours. According to the evaluations, the dyes 3a, 3b and 3d were categorised as slightly toxic, and the dyes 3c and 3e as practically non-toxic. Considering the toxicity of the dye 3a, it was determined that the substitution of the electron-withdrawing group in the azo dye resulted in more toxicity, while the substitution of the electrondonating group resulted in less toxicity. It was also found that the presence of the strongly electron-withdrawing group resulted in the azo dye becoming more toxic in comparison with the presence of the weakly electron-withdrawing group, but that the presence of the strongly electron-donating group resulted in the azo dye becoming less toxic in comparison with the presence of the weakly electron-donating group. It is contended that this study is novel and of great importance in terms of synthesising new azo dyes, investigating their absorption properties and assessing their acute toxicities.
The sex of neonatal sea turtles is difficult to determine, because neonates lack heteromorphic sex chromosomes and dimorphic external characteristics; internal dimorphic morphology is defined at hatching. We used histochemical staining and made measurements in the gonads and paramesonephric ducts (PD) of both sexes to determine structural differences in female and male loggerhead sea turtle (Caretta caretta) hatchlings. We detected differences in the gonads and PD between the sexes including the amounts of mucopolysaccharides, collagen and elastic fibers. We determined that the thickness of the gonadal cortex and the diameter of the PD lumen are reliable sex-specific characteristics. We also assessed immunolocalization of aromatase, an enzyme complex that converts androgens to estrogens, and found differences in the localization and intensity of aromatase immunostaining in the gonads and PD of female and male hatchlings. Comprehensive studies of the sexual differences of sea turtles are important for conservation programs.
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