Copepods mainly plays a role of the secondary producers, who transfers energy and materials from the phytoplankton such as diatoms to higher trophic levels. Copepod feeding contributes to transferring them. Feeding experiments of dominant copepods Pseudocalanus newmani and Neocalanus plumchrus collected from the coastal area of the southwestern Okhotsk Sea on large phytoplankton were done by using the food removal method. Feeding rates of P. newmani were higher than those of N. plumchrus when Chl-a concentrations was same level. Our results suggest that P. newmani plays potentially an important role for linking between large phytoplankton and higher trophic organisms during highest phytoplankton production period in the coastal area of the southwestern Okhotsk Sea.

References

[1]    Asami, H., Shimada, H., Sawada, M., Sato, H., Miyhakoshi, Y., Ando, D., Fujiwara, M. & Nagata, M. (2007). Influence of physical parameters on zooplankton variability during early ocean life of juvenile chum salmon in the coastal waters of eastern Hokkaido, Okhotsk Sea. North Pacific Anadromous Fish Commision Bulletin, 4, 211-221.

[2]    Båmstedt, U., Gifford, D. J., Irigoien, X., Atkinson, A. & Roman, M. (2000). Feeding. In: Harris, R., Wiebe, P., Lenz, J., Skjoldal, H. R. & Huntley, M. (eds.). ICES Zooplankton Methodology Manual. London: Academic Press.

[3]    Bradford, M. J. (1995). Comparative review of Pacific salmon survival rates. Canadian Journal of Fisheries and Aquatic Sciences, 52, 1327-1338.

[4]    Corkett, C. J. & McLaren, I. A. (1978). The biology of Pseudocalanus. Advances in Marine Biology, 15, 1-231.

[5]    Dagg, M., Strom, S. & Liu, H. (2009). High feeding rates on large particles by Neocalanus flemingeri and N. plumchrus, and consequences for phytoplankton community structure in the subarctic Pacific Ocean. Deep-Sea Research I, 56, 716-726.

[6]    Ducklow, H. W., Steinberg D. K. & Buesseler, K.O. (2001). Upper ocean carbon export and the biological pump. Oceanography, 14, 50-58.

[7]    Frost, B. W. (1972). Effects of size and concentration of food particles on the feeding behavior of the marine planktonic copepod Calanus pacificus. Limnology and Oceanography, 6, 805-815.

[8]    Hardy, A. (1965). The Open Sea: Its Natural History, Part 1: The World of Plankton. Cambridge: Riverside Press.

[9]    Lalli, M. C. & Parsons, T. R. (1993). Biological Oceanography: An Introduction. Oxford: Butterworth-Heinemann.

[10]  Longhurst, A. R. (1985). The structure and evolution of plankton communities. Progress in Oceanography, 15, 1-35.

[11]  Nagata, M., Miyakoshi, Y., Ando, D., Fujiwara, M., Sawada, M., Shimada, H. & Asami, H. (2007). Influence of coastal seawater temperature on the distribution and growth of juvenile chum salmon, with recommendations for altered release strategies. North Pacific Anadromous Fish Commision Bulletin, 4, 223-235.

[12]  Nakagawa, Y., Ichikawa, H., Kitamura, M., Nishino, Y. & Taniguchi, A. (2015). Copepod community succession during warm season in Lagoon Notoro-ko, northeastern Hokkaido, Japan. Polar Science, 9, 249-257.

[13]  Nakagawa, Y., Kitamura, M., Nishino, Y. & Shiomoto, A. (2016). Community structure of copepods associated with water mass replacement in the coastal area of the southwestern Okhotsk Sea during ice-free period. Bulletin of the Society of Sea Water Science, Japan, 70, 49-50.

[14]  Nishino, Y., Sato, T. & Taniguchi, A. (2014). Lower trophic levels of coastal marine ecosystem in Lagoon Notoroko on the coastal Okhotsk Sea. Journal of Agriculture Science, Tokyo University of Agriculture, 59(1), 11-20.

[15]  Paffenhöfer, G. A. & Harris, R. P. (1976). Feeding, growth and reproduction of the marine planktonic copepod Pseudocalanus elongatus Boeck. Journal of the Marine Biological Association of the United Kingdom, 56, 327-344.

[16]  Radchenko, V. I., Dulepova, E. P., Figurkin, A. L., Katugin, O. N., Ohshima, K., Nishioka, J., McKinnell, S. M. & Tsoy, A. T. (2010). Status and trends of the Sea of Okhotsk region, 2003-2008. In: MckKinnell, S. M. & Dagg, M. J. (eds.). Marine Ecosystems of the North Pacific Ocean, 2003-2008. PICES Special Publication 4.

[17]  Runge, J. A. (1985). Relationship of egg production of Calanus pacificus to seasonal changes in phytoplankton availability in Pugest Sound, Washington. Limnology and Oceanography, 30, 382-396.

[18]  Ryther, J. H. (1969). Photosynthesis and fish production in the sea. Science, 166, 72-76.

[19]  Shiomoto, A. (2011). Phytoplankton biomass and production in the coastal area of the Shiretoko Peninsula during late spring to early autumn: Comparison between the Okhotsk Sea and the Nemuro Straight. Bulletin on Coastal Oceanography, 49, 37-48 (In Japanese with English abstract).

[20]  Sorokin, Y. I. & Sorokin, P. Y. (1999). Production in the Sea of Okhotsk. Journal of Plankton Research, 21, 201-230.

[21]  Taguchi, S. & Saino. T. (1998). Net zooplankton and the biological pump off Sanriku, Japan. Journal of Oceanography, 54, 573-582.

[22]  Thompson, A. M., Durbin, E. G. & Durbin, A. G. (1994). Seasonal changes in maximum digestion rate of Acartia tonsa in Narragansett Bay, Rhode Island, USA. Marine Ecology Progress Series, 108, 91-105.

[23]  Welschmeyer, N. A. (1994). Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and pheopigments. Limnology and Oceanography, 39, 1985-1992.