Distribution of terrestrial hermit crabs (Genus Coenobita) in Northeast seashore area of Taiwan

• Main Authors: Fu-An Tsai, 蔡富安
• Other Authors: 李培芬
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/9sc74u

碩士 === 國立臺灣大學 === 生態學與演化生物學研究所 === 105 === Terrestrial/ land hermit crabs are omnivorous scavengers, carrying, move, and change gastropods shell, which play an important role of maters, nutrient and energy cycling. Investigating ecology of land hermit crab will improve the knowledge construction to maters and energy dynamic of ecosystem. This research focus on land hermit crabs’ spatial ecology, inspect the distribution pattern in sea shore area, furthermore, mine the potential environmental factors which induce the distribution variance, explain the variance of land hermit crabs’ population distribution by landscape scale environmental factors. Distribution survey shows that, Coenobita rugosus are more dominant than Coenobita cavipes and Coenobita brevimanus, in the seashore area, side by the Provincial Highway 2 (Taiwan) from Longdong to Yanliao ,in Northeast Taiwan. Three Coenobita species have different habitat preference on the distance to sea. Estimated population size of C. rugosus are around 51810 to 228047 crabs, and C. cavipes are around 858 crabs. C. rugosus have stable population status, sex-ratio is 1:1. The Generalized linear models reveal that major type of substrate around is the most important factor that affect relative abundance, and also distance to sea, natural shore length and natural vegetation coverage are correlate to relative abundance of C. rugosus. Forenamed factors can describe the distribution variance of C. rugosus, independently without spatial auto-correlation. This research also developed a method, which can estimate all sizes of C. rugosus shield lengths, by photo-measuring each crab’s chela movable finger and second left walking leg dactyls, and some samples’ shield length. This procedure is much convenience than directly measure the shield lengths, in hence provide a referance for future land hermit crab population survey strategy, which can bring down operation difficulty, and upgrade animal welfare.