放射能の影響下にある福島県沿岸産コノハクラゲ(ヒドロ虫綱, 軟クラゲ目)の形態

Abstract

In August, 2012 hydroids of bivalve-inhabiting hydrozoans associated with Mytilus galloprovincialis were collected at three harbors in Fukushima Prefecture, Japan, as the first occurrence records in this area affected by radioactivity, and their well-grown medusae were obtained by culture in the laboratory. From the morphology of such medusae they are determined as the northern form of Eutima japonica Uchida. It is noteworthy that most of the released medusae from hydroids were died before maturation, and a small number of individuals could be well-developed, but not ripe and their morphology is slightly odd (particularly manubrium including oral lips) except GFP pattern.

2012年8月1-2日に放射能の影響下にある福島県沿岸の3港でムラサキイガイMytilus galloprovincialis に共生するカイヤドリヒドラ類のポリプを発見し, 採集後すぐに実験室での飼育でクラゲを得た。ポリプから遊離した多数のクラゲは飼育中に死亡し, 相馬港産の少数個体のみがよく成長できた。しかし, 1個体も成熟しなかった。クラゲの形態から北日本型のコノハクラゲEutima japonica Uchidaと同定したが, よく育ったクラゲの形態は, GFPパターンを除き通常の成熟クラゲと異なり, 特に口柄や口唇の発達が悪かった。