발전소 취수구 막힘 현상 규명을 위한 동해에서의 난바다 곤쟁이의 이동 연구

Abstract

Large amounts of euphausiids have often clogged the drum screens of the cooling-water supply unit to cause temporal interruptions of electric power production at Uljin Nuclear Power Plant. While surface swarms for breeding of the euphausiids might be responsible for the malfunction, little is known about its ecology focused to relationships with the regional environment. Its distributional characteristics, especially related to diel rhythm and ontogenic migration is being investigated. We came in pursuit of zooplankter's distributional modes and migration using a ecosounder with 200 kHz transducer and sets of multiple towing nets from Oct 2002. High density demersal layers of a euphausiid, Euphausia pacifica, have been detected in the channel (the depth approximately 200 m) near extension of the Hupo Bank during the fall and winter. In the late spring in 2003, huge amounts of eggs and larvae of the euphausiids were collected from the waters nearer to the coast where the depth was approximately 100 m. The adults and larvae of euphausiids in all investigations have performed active diel vertical migration. Euphausiids were also significantly important food source to the mesopelagic and demersal fishes examined, arabesque greenling, Pleurogrammus azonus, and spinyhead sculpin, Dasycottus steiger. These observation of abundances, diel and ontogenic migration of the euphausiids may explain its high production attributed to the near waters off Uljin Nuclear Power Plant and clogging the cooling water supply screen.