初夏のオホーツク海における深海におよぶ優占大型カイアシ類の鉛直分布および個体群構造

• Main Authors: 柊, 萌乃, 山口, 篤
• Format: Article in Journal/Newspaper
• Language: Japanese
• Published: 北海道大学大学院水産科学研究院
• Subjects: Calanoid copepods; Neocalanus; Eucalanus; Metridia; Paraeuchaeta; Heterorhabdus; Heterostylites; Sex ratio; Lipid accumulation; Gonad maturation; 660; Okhotsk; okhotsk sea; Copepods
• Online Access: http://hdl.handle.net/2115/76383; https://doi.org/10.14943/bull.fish.69.2.83

Vertical distribution and population structure of large dominant planktonic copepods (Neocalanus cristatus, N. flemingeri, N. plumchrus, Eucalanus bungii, Metridia okhotensis, M. pacifica, Paraeuchaeta elongata, P. birostrata, P. rubra, Heterorhabdus tanneri, and Heterostylites major) were studied down to greater depths in the Okhotsk Sea during early summer. For suspensionfeeders (Neocalanus spp., Eucalanus bungii, and Metridia spp.), their vertical distributions were well separated within 0-250m depths. For carnivores (Paraeuchaeta spp. and Heterorhabdidae), vertical partitioning within the genus and family was also the cases throughout the 0-3,000 m water column. The vertical partitioning within the same feeding pattern copepods may have a function to reduce competition on similar food items. Population structures of the most suspension feeders were dominated by middle- to late-copepodids with low-lipid accumulation. This may reflection of their life cycle seasonal phenomena. For most of the copepods treated in this study, the sex ratio was skewed for females. It caused by the degeneration of feeding appendages (Eucalanus bungii and Paraeuchaeta spp.) and the vertical distribution behaviors (Metridia spp. : stay deep-layer where food-limited throughout the day) of adult males. Since adult females may perform massive feeding in adult females, their body sizes were much larger than the males.