Distribution of the Japanese sea cucumber Apostichopus japonicus in the intertidal zone of Hirao Bay, eastern Yamaguchi pref., Japan: Suitable environmental factors for juvenile habitats
2006
Yamana, Y.(National Fisheries Univ., Shimonoseki, Yamaguchi (Japan)) | ; Hamano, T. | ; Miki, K.
To reveal the distribution of Apostichopus japonicus in the intertidal zone of Hirao Bay, eastern Yamaguchi Pref., 1-4 line-transect surveys were carried out at 8 stations during 24-27 April 2005. At St. D-1 (Mizuba, Hirao Town) , a number of juveniles of about 10-50 mm Le (estimated anesthetized body length, the standard body length of A. japonicus) were observed, and the habitat was considered to be suitable for juveniles of A. japonicus. However, at St. D-2, 3, and 4, which were only about 50 m apart from St. D-1, A. japonicus were rare and 5 individuals in total (O.1 inds./square m) were observed, while 133 individuals (6.7 inds./square m) were observed at St. D-1. Here environmental conditions suitable for the growth of A. japonicus were described from differences in both habitats as follows: in +0.4 m at tide level and rocky bottom favorable for Sargassum; eutrophicated moderately with clusters of Ulva; protected from environmental fluctuation in low tide.
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