동해 독도 주변에서 관찰된 야광충에 의해 섭식된 먹이생물들

Abstract

The large heterotrophic dinoflagellate Noctiluca Scintillans is the most common “red tide” organism which is a widespread species all over the world. Around the Ulleung-Do and Dokdo in offshore waters, the unprecedented bloom of N. scintillans occurred and maintained almost over 2 weeks from April to May 2014. The Noctiluca bloom is commonly caused and supported by hydrographic and biological factors. Relatively low temperature of surface waters ranged from 9.71 to 12.83 oC and high salinity did from 33.34 to 34.12 psu when compared to traits of coastal waters. Even though the large scale bloom formation of N.scintillans has still controversial causes, long lasting occurrence of blooms could be mostly related to the prey items to the N.scintillans. Opportunistic observations were carried out on water-casted samples in the Hyunpo port of Ulleung-Do and vertical plankton net-hauls (200&micro m-mesh) in the surface waters around Dokdo in spring 2014. Food vacuoles of N.scintillans were first analyzed from the formalin preserved samples using a stereomicroscope (ZEISS Model Discovery SV8). And further analyses of prey items inside food vacuoles were conducted using a light microscope (Primo Star, ZEISS). The percentage of total prey items found inside vacuoles ranged from 3.4 to 40% from preliminary analysis. The prey items grazed by N. scintillans were diatoms, dinoflagellates, protozoans, fish egg, fish larvae and llans occurred and maintained almost over 2 weeks from April to May 2014. The Noctiluca bloom is commonly caused and supported by hydrographic and biological factors. Relatively low temperature of surface waters ranged from 9.71 to 12.83 oC and high salinity did from 33.34 to 34.12 psu when compared to traits of coastal waters. Even though the large scale bloom formation of N.scintillans has still controversial causes, long lasting occurrence of blooms could be mostly related to the prey items to the N.scintillans. Opportunistic observations were carried out on water-casted samples in the Hyunpo port of Ulleung-Do and vertical plankton net-hauls (200&micro m-mesh) in the surface waters around Dokdo in spring 2014. Food vacuoles of N.scintillans were first analyzed from the formalin preserved samples using a stereomicroscope (ZEISS Model Discovery SV8). And further analyses of prey items inside food vacuoles were conducted using a light microscope (Primo Star, ZEISS). The percentage of total prey items found inside vacuoles ranged from 3.4 to 40% from preliminary analysis. The prey items grazed by N. scintillans were diatoms, dinoflagellates, protozoans, fish egg, fish larvae and