Vol. 37 No. 1, 1998

Rarefaction Diversity: a Case Study of Polychaete Communities Using an Amended FORTRAN Program

Hwey-Lian Hsieh^1,* and Lung-An Li²

¹Institute of Zoology, Academia Sinica, Taipei, Taiwan 115
²Institute of Statistical Science, Academia Sinica, Taipei, Taiwan 115

Hwey-Lian Hsieh and Lung-An Li (1998) This study presents an amended Simberloff rarefaction FORTRAN program and a case study comparing the species diversities of polychaete communities using this new program. A reexamination of the rarefaction formula revealed that the Simberloff program could be simplified. The modified program requires substantially less computer memory, and concomitantly, gains greater efficiency in calculating the expected numbers of species and their variances. For the case study, the polychaete communities in 2 regions (north and south) located in the subtidal areas off the coast of Tainan County in southwestern Taiwan were examined in September 1994 and in April 1995. A total of 724 individuals of 56 polychaete species were collected from the north region and 378 individuals of 29 species were collected from the south region. The rarefaction curves of the 2 regions were well separated. The number of species expected in the north region was greater than in the south region when the abundances of the 2 regions were rarefied to the same numbers of individuals. The rarefaction curve was steeper in the north region than in the south region, indicating a more even distribution of polychaete individuals among species in the north than in the south. In addition, the rarefaction diversity and conventional Shannon diversity and evenness index were also compared to show the significant and informative strength of the employed rarefaction method.

Key words: Species diversity, Rarefaction program, Benthic communities.

*Correspondence: Fax: 886-2-27858059. E-mail: zohl@ccvax.sinica.edu.tw