Abstract
Skeletal growth parameters (extension rate, density and calcification rate) were determined for annual growth bands in skeletal slabs and tips of the zoothanthellate scleractinian (hermatypic) coral Dipsastraea speciosa (Dana, 1846) [= Favia speciosa (Dana, 1846)] at Iriomote Island in the southwestern part of the Ryukyus (24°25′N, 123°47′E) and at Fukue, Wakamatsu, Iki and Tsushima islands in the northwestern part of Kyushu (32°39′N – 34°24′N, 128°39′E – 129°40′E), Japan. Relationships among these three parameters along a latitudinal gradient in annual mean sea surface temperatures (SSTs) were also examined. Annual mean density and calcification rate in D. speciosa of Iriomote Island located in a subtropical region (Iriomote Is.) were higher than those of the other islands in temperate regions, although there was no significant difference in the extension rates between the two regions. These results agreed well with those of Porites astreoides Lamarck, 1816 in the Atrantic rather than those of the Atlantic Orbicella (= Montastraea) and the Pacifc Porites species. Both Dipsastraea speciosa and Porites astreoides are geographically widespread species, and they have lower extension and calcification rates than other neighboring genera/species. Of the three growth parameters of D. speciosa, the calcification rate showed the highest significant correlation with the annual mean SSTs. It suggests that while D. speciosa distributed in the Japanese islands could keep their calcification rates stable for each site, they change their extension rates and densities in response to the latitudinal gradient in annual mean SSTs.
