Permalink : http://hdl.handle.net/2115/82350

JaLCDOI : 10.14943/bull.fish.71.1.29

KEYWORDS : Respiratory flux;Active carbon flux;Copepoda;Metridia pacifica

Respiratory oxygen consumption rates (at the two temperatures of 0-50 m and 50-200 m depth strata) and day/night biomass in the top 50 m water column were determined on adult female Metridia pacifica at twelve stations in the western/ eastern subarctic Pacific and one station in the oceanic Bering Sea during summer. At each station, the respiration rates at 0-50 m depth temperatures were used to estimate ingestion rates during nighttime by assuming empirical carbon budget efficiencies, and rates at 50-200 m to estimate respiratory carbon flux during daytime. The abundance of the females in the upper 50 m at night varied between 27 and 5,422 inds. m−2 and no specimen was collected from the same layer at daytime throughout the stations. The size of the females varied regionally from 25 to 77 μg C ind.−1. As a result, diel vertical migrant biomass of the females varied greatly from one station to the next (1 and 309 mg C m−2). Weight-specific respiration rates of the females were 2.2-6.3 μl O2 mg C−1 h−1, which was a function of experiment temperatures and body mass (C) of the females. Taking into account of residence time at 0-50 m and 50-200 m in the day, daily population ingestion was estimated as 0.04-11.04 mg C m−2 day−1, which accounted for 0-2.4% of primary production at each station. Daily population respiration in the 50-200 m was calculated as 0.02-9.39 mg C m−2 day−1, which corresponds to 0-10% of the POC flux down from the euphotic zone.