MEPS 163:37-44 (1998)  -  doi:10.3354/meps163037

Seasonal variations in biomass, growth rate and production rate of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet

Shin-ichi Uye*, Kazuhiro Sano

Faculty of Applied Biological Science, Hiroshima University, 4-4 Kagamiyama 1 Chome, Higashi-Hiroshima 739-8528, Japan

We investigated the seasonal variations in biomass, somatic growth rate and production rate of the small cyclopoid copepod Oithona davisae in Fukuyama Harbor, a eutrophic inlet of the Inland Sea of Japan. The carbon biomass of the population, excluding nauplii, was lowest in early spring and increased exponentially in early summer to a maximum of 92.2 mg m-3 in mid-June. Thereafter, it was relatively high, except for a mid-summer decline, until fall. The specific growth rates of naupliar and copepodite stages were estimated from their body weight increments and stage durations, assuming that in this highly eutrophic inlet growth is food-satiated for this species. They increased exponentially with increasing temperature, ranging from 0.088 to 0.357 d-1 for nauplii and from 0.060 to 0.446 d-1 for copepodites within the annual temperature range of 8.9 to 28.2°C. The production rate as a sum of somatic growth rate of copepodites and egg production rate of adult females varied similarly to, but showed a wider range than, the biomass variation. Annual integrated carbon production was 650 mg m-3 yr-1, or 4.88 g m-2 yr-1, 94% of which was attained between June and October. Of the production, copepodite somatic growth and female egg production comprised 75 and 25%, respectively. O. davisae contributed 26% of the annual copepod community production in Fukuyama Harbor.

Biomass · Growth · Production · Cyclopoid · Oithona · Inland Sea of Japan

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