Selection characteristics and utilization of nesting grounds by green sea turtles on Xisha Islands, South China Sea

Abstract

Effective species management and conservation require an understanding of geographical distribution patterns and reasons for species dispersal in a larger environment. The Xisha Islands are currently the largest green sea turtle nesting grounds in China, and green sea turtles breeding there belong to an independent geographic population with irreplaceable conservation value. In this study, field surveys and remote sensing satellite image mapping were used to investigate the use of green sea turtle nesting sites on 15 islands in the Xisha Islands and to analyze the effects of island morphology and human disturbances on nesting ground selection. The results revealed that green sea turtle nesting grounds were distributed throughout 10 islands with a total area of 0.1062 km2. The average beaches utilization rate by green sea turtle for nesting was 32.46 %, with the North Island of Qilianyu having the biggest nesting ground area (0.0436 km2) and the highest beach utilization rate (70.75 %). The next highest utilization rates were found on Ganquan Island, South Island, Jinqing Island, and South Sand. Generalized linear model (GLM) indicated that the effect of beach width on nest density was significant, building density and sand particle size affected nest density. Therefore, green sea turtles prefer to nest in islands with wider beaches, higher proportion of coarse and medium sand, and lower human activity. These areas should be prioritized for protection and management.

Keywords

• Green sea turtle
• Nesting ground
• Morphological characteristics
• Utilization rate