Effects of human activity upon hatchlings emerging their nest
Loggerhead turtle (Caretta caretta) has been nominated to the Red Data Book as endangered species by Ministry of the Environment. Several factors for its population decline are proposed, such as bycatch death and decrease of breeding seashores. In addition, negative impacts of human activity in seashore to the emerging success rate of hatchlings is one of the important factors to consider thier population decline. Recognition of the human effects to emerging of hatchlings from the nest is required not only for the conservation purpose but also for the idea of eco-tourism.
We specified the factors preventing hatchlings emerging (Figure 1). As stepping upon the nest causes increase in density of sand upper the eggs, the heat conduction rate decreases. As a result, metabolic heat of eggs and hatchlings causes overheat inside the nest. Hatchlings activity drops as temperature increases, preventing thier emerging action outside the nest. In consequences, bacterial infections and other reasons lead to catastrophe. To prevent these consequences, seasonal sanctuarization of their nesting seashores might be indispensable.
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| Figure 1. The relationship between hatchling emerging rate and pressure integration by human stepping on |
References
- 工藤宏美・北川貴士・木村伸吾・渡辺達三．(2004) 屋久島におけるアカウミガメ孵化幼体の脱出に与える踏圧の影響．水産海洋研究，68，225-231．
- Kudo, H., Kitagawa, T. and Kimura, S. (2003) Effect of beach use and environmental conditions on emergence success of loggerhead turtles in Yakushima Island, Japan. Proc of the 3rd SEASTAR 2000 workshop, 49-52.
- Kitagawa, T., Kudo, H. and Kimura, S. (2003) Hatchling transport of loggerhead turtles in the North Pacific. Proc of the 3rd SEASTAR 2000 workshop, 39-44.