中海の環境条件が異なる3地点で，表層と底層に垂下したネットにサルボウガイを入れ，2008年5月から2009年5月まで飼育し，成長，生残，肥満度を比較した。また，これと同時に中海に生息する天然個体との比較も行った。その結果，夏季は表層で成長が大きく，冬季は底層で成長が大きかった。夏季の成層期では，DO がサルボウガイの成長・生残を制限する一因であり，冬季の循環期では，水温が成長を制限する一因であった。表層で垂下飼育したサルボウガイは天然個体に比べ成長が速く，肥満度も明らかに高かった。閉鎖性の高い中海では，サルボウガイは潜砂しなくても成長し，夏季は表層に垂下し，冬季は底層に垂下することで，年間を通して高い成長率が見込めることがわかった。

抄録全体を表示

On April 14, 1997, the inner part of Isahaya Bay was isolated from the Ariake Sea by a dike for reclamation. Thereafter, red tides and episodes of hypoxia began to occur frequently in the Ariake Sea. The government introduced seawater inside of the dike from April 24 to May 20, 2002, but the reclamation project was continued and finally completed on November 20, 2007. We periodically monitored the grain-size of bottom sediments and the benthic macrofauna using sediment samples collected from (1) 32–50 fixed stations around the inner part of the Ariake Sea in June or November every year from June, 1997, to June, 2007, and (2) 88 fixed stations throughout the entire Ariake Sea in June of 1997, 2002, and 2007. During the decade between 1997 and 2007, the median particle diameter of the bottom sediment decreased at many stations around Isahaya Bay and also in some stations around the mouth of the Ariake Sea. As for the benthic macrofauna, a total of 38,221 individuals were collected from the 88 fixed stations in June, 1997, and the most dominant taxa were polychaetes, gammaridean amphipods, and bivalves. In June of 2002, 74,273 individuals of benthic animals were collected from the same stations, but in June of 2007, just 12,386 individuals. Some opportunistic species such as Modiolus (M.) comptus and Corophium spp., those inhabit fine sediment around the mouth of Isahaya Bay, became abundant in June, 2002, but most of them disappeared by June, 2007 because of hypoxia and a change in the composition of the bottom sediments.

抄録全体を表示