北海道東部の海跡湖能取湖におけるカイアシ類群集の季節変動に及ぼす水塊交替の影響

抄録

Water mass conditions in Lagoon Notoro-ko are affected by the hydrodynamics of the Okhotsk Sea out of the lagoon. In the present study, the relationship between seasonal replacement of the water masses and seasonal variation in abundance of copepods (or copepod species) was examined. During summer and fall, high saline water (>33 psu) originating from the Soya Warm Current occupied the lagoon. In winter, this water was replaced by lower saline water (<32 psu) from the East Sakhalin Current. Abundance of copepods in the lagoon was highest in May and lowest in November, and then increased again in December. Although relative abundances of cold-water and eurythermic species was comparable in May and July, the latter became dominant in August and September and the former in October and December. This indicates that seasonal change of the community structure of copepods in Lagoon Notoro-ko is strictly controlled by the seasonal water mass replacement.