石垣島宮良湾の裾礁礁池における塊状ハマサンゴの分布特性2000 · The spatial distribution and morphologies of massive <i>Porites</i> colonies were investigated over a large area (1100m×200m) in the sandy moat of Miyara fringing reef, Ishigaki Island, Japan. Massive <i>Porites</i> (diameter>50cm) showed a preferential distribution for deeper depths (i. e., 2 to 3m). This distribution pattern suggested that massive <i>Porites</i> colonies were transported to deeper more stable habitats, as “mobile colonies”. Twenty-three percent of the colonies were mushroom shaped, with narrow stems attached to the substratum. Significant portions of mushroom shaped colonies (69%) were dislodged and 66% of them were tilted toward the dominant direction of water flow. The mushroom morphologies appear related to the high mobility of sandy sediments around the colonies, which interferes with ordinary growth of the colony base. Mobile colonies seems important for maintaining local coral populations in sandy habitats, which are often unsuitable habitats for larval settlement. In this case, physical environmental factors, such as water movement and micro-geomorphology, influence the distribution and population structure of coral communities in the sandy shallow habitats.
The recovery process of broken Acropora branches at Mizugama,Okinawa Island,Japan2000 · Four dominants pecies ofs cleractinianc oral,A cropora gemmifera,A . digitifera,A . millepora and A. hyacinthusw erein vestigatedo n ther eef front of Mizugama reef,Ok inawa Island,Ja pan. Recoveryp rocesses involving tissue pigmentation and polyp formation were characterized for each colony. The broken surface area was smaler and ther ate of axialp olyp formation was faster forA. hyacinthus thanf or A. gemmifera. Furthermore, some branches ofA .g emmifera formed am ound-like shapei nt hec entralle siona rea, which seemedt o delayt hef ormationo f ana xialp olyp.T hem oundw as formed when sediment accumulatedo n the lesion,pr ior to tissuec overage.T his study indicates thatth e differences inp olyp formation and polypr ecovery varies amongs pecies, whichi nt urn are affectedb ye nvironmentalfa ctors buta lso inherent,sp ecies specific, constraints.
