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Influence of biotope characteristics on the distribution of Uca annulipes (H. Milne Edwards, 1837) and U-vocans (Linnaeus, 1758) (Crustacea: Brachyura: Ocypodidae) on Pulau Hantu Besar, Singapore
Citation
Lim, S. S. L., Lee, P. S., & Diong, C. H. (2005). Influence of biotope characteristics on the distribution of Uca annulipes (H. Milne Edwards, 1837) and U-vocans (Linnaeus, 1758) (Crustacea: Brachyura: Ocypodidae) on Pulau Hantu Besar, Singapore. The Raffles Bulletin of Zoology, 53(1), 111-114. https://lkcnhm.nus.edu.sg/wp-content/uploads/sites/10/app/uploads/2017/06/53rbz111-114.pdf
Abstract
Density and distribution patterns of two species of fiddler crabs, Uca annulipes (H. Milne Edwards, 1837) and U. vocans (Linnacus, 1758) were studied on Palau [=Island] Hantu Besar, Singapore. Twenty-five and 261 m2 quadrats were sampled at the upper and lower shore levels of the lagoonal beach. Sediment samples from each quadrat were analysed for %sand, %mud and %organic content. A two-way analysis of variance (ANOVA) of crab density against species and shore level position showed the interaction term. 'Species X Shore level' to be significant (p<0.05), with Uca annulipes being more abundant on the upper shore and U. vocans preferring the lower shore. A General Linear Model for Multivariate Analysis of Variance (MANOVA) was used to further analysed the biotope-related variables (sand, mud and organic content) against crab species and shore level position. This time 'Species X Shore level' interaction was not significant (p>0.05). After this interaction term was removed from the model, only the main factor, 'Species', was significant (p<0.05). Subsequent ANOVAs showed U. annulipes was significantly (p<0.05) associated with sediments containing higher sand content regardless of shore level, and U. vocans was significantly (p<0.05) associated with sediments that had higher mud content. These results provide quantitative data to support and explain qualitative observations that U. annulipes are generally found in sandier habitats than U. vocans.
Date Issued
2005
Publisher
National University of Singapore
Journal
The Raffles Bulletin of Zoology