| Popis: |
Any good conservation project should have at least basic elements of research which run parallel to the day to day conservation management. Current populations of sea. turtles in the Mediterranean are at seriously reduced levels. This is particularly the case for green turtles (Chelonia mydas) which suffered from serious over-exploitation during the last century. This exploitation has now largely ceased, with loggerhead turtles (Caretta caretta) now being the species most at risk from fisheries bycatch. I analysed 15 years of monitoring data from nesting beaches in Northern Cyprus. The major result obtained from this analysis was that, whilst the loggerhead turtle population appears.stable, the number of green turtle nests laid annually is declining. Conservation measures which have been put into place over the years, have significantly increased the clutch hatching success experienced at this location and it is hoped that these efforts will eventually counteract the apparent decline. Over a five year period we collected epibiont species present on the carapace of both green and loggerhead turtles nesting at Alagadi. The two most commonly occurring epibionts were the acorn barnacles Chelonibia testudinaria and Chelonibia caretta. For these two species we analysed their spatial distribution and found the larger. specimens of the former to be sited on the anterior portion of the carapace. I recorded five new species of sea turtle epibiont: Laomedea flexuosa, Caprella fretensis, Hyale nilssoni, Hyale schmidti, Parasinelobus chevreuxi; as part of a total of nine zoological epibionts present on 35 female green (Chelonia mydas) and 100 loggerhead (Caretta caretta) turtles nesting in Cyprus. Using nesting data, sexing of hatchlings and incubation temperatures enabled me to successfully establish the first pivotal temperatures and incubation durations for green and loggerhead turtles in Cyprus. From these findings I was able to estimate the extremely female biased hatchling sex ratio produced across the island and predict the potential catastrophic outcome for hatchlings in the face of global temperature rise. Part of my work in this thesis involved the triating of two different types of technologies. One involved placing geolocating light loggers on turtles, to indicate their locations in a Mediterranean context. An element of this study was to cakulate,-me respective errors when compared to satellite telemetry. I obtained very positive results from this study, giving an accuracy of c. 50km. The second study concerned the use of animal borne digital cameras, placed on green turtles to elucidate subsurface habitat utilisation and the possibility of feeding during the internesting period. Such analysishas established some of the criteria which may allow researchers to allocate likely behaviour based on dive profIles, and thus to examine dive data and imagery collected .over a longer time-series and to inform the determination of time-energy budgets. Due to their dependence on environmental temperatures, the Mediterranean :population of sea turtles must be considered one of the most vunerable to be impacted. by global climate change. Therefore we must develope a greater understanding of their biology, if we are to reduce current and future impacts on these species. |
