Monitoring Nesting Trends and Hatchling Success of the Green Turtle (Chelonia mydas) Population on Mnemba Island, Zanzibar
Tanzania: Zanzibar: Coastal Ecology and Natural Resource Management
The nesting trends and hatching success of Green sea turtles (Chelonia mydas) were studied on Mnemba Island. This study involved a continuation of data collection for the ongoing monitoring program of sea turtles on Mnemba Island. Data was collected from nesting females as well as from post hatching nest excavations. The data that has been collected over the course of ten years was then analyzed to examine trends over time as well as to assess the current status of the turtle population on Mnemba Island. Hatch success as a function of different seasons was analyzed. It has been concluded that there is a significant difference between hatching success in wet and dry seasons, but not in the different monsoon seasons. Hatch success as a function of location on the island was also explored, and trends in frequencies of nest sites in various locations were examined. Trends in nest location selection were investigated in relation to coastal erosion occurrences. The only significant preferences for nest location found was that the majority of nest sites were concentrated on the western and southwestern sides of the island. This is also related to trends in nest site selection in relation to coastal erosion, as there are no occurrences of nests on eastern side of the island, which experiences the most erosion. Furthermore, it has also been concluded that there is no difference in hatching success between years, and that hatching success has not significantly changed over time. This implies that Mnemba Island provides a stable environment for nesting green turtles, and is therefore an important area to continue to conserve. Recommendations for future studies are made.