Aquatic Sciences Meeting, Albuquerque 2001

CS37 Zooplankton

Date: Wednesday, February 14, 2001, Time: 3:00:00 PM

Location: Aztec

Uye, S, , Faculty of Applied Biological Science, Hiroshima University, Higashi-Hiroshima, Japan, suye@hiroshima-u.ac.jp

Aoto, I, , Saga Prefectural Office, Saga, Japan,

Onbe, T, , Professor emeritus, Hiroshima University, Higashi-Hiroshima, Japan,

SEASONAL POPULATION DYNAMICS AND PRODUCTION OF MICROSETELLA NORVEGICA, A WIDELY-DISTRIBUTED BUT LITTLE-STUDIED MARINE PLANKTONIC HARPACTICOID COPEPOD

Microsetella norvegica is a widely-distributed marine planktonic harpacticoid copepod, but there has been few studies on its biology/ecology. We investigated the seasonal population dynamics and production of M. norvegica in the Inland Sea of Japan. It occurred throughout the year with a numerical peak in October, whilst its reproduction was confined to the warm seasons between May and November. The composition of ovigerous females which carry a single egg sac was highest (53.6%) in October. Their brood size attained maximum (mean: 15.8 eggs per sac) in July and August. Duration time from egg lay to moulting to adulthood was temperature-dependent; it was 31.9 and 14.3 days at 20 and 27 C, respectively, under excess food in the laboratory. The most of annual population production rate was attained in October, when the population biomass was also highest. Nauplii and copepodites disappeared in December, and the overwintering population was consisted of adults, mainly large-sized females. Associations of M. norvegica with marine snow aggregates, which have been often found in oligotrophic waters, were not observed in food-rich Inland Sea of Japan.

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Aquatic Sciences Meeting, Albuquerque 2001

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