Ova production by hydromedusae from the NE Pacific

Gonads of hydromedusae had a dry wt of 18 of wet wt, with carbonand nitrogen compos ition equalling 40 and 10 of dry wt, respectively.These values are 4 times higher than for whole specimens. Gonadsof mature medusae represented 2–15 of total wet wt (10–50of total dry wt). For Phialidium gregarium (the most numeroushydromedusa in surface waters of Saanich Inlet, BC), gonadsvaried in size seasonally and were largest in May when foodwas most abundant and when daily rations were maximum. Diametersof ova ranged from 70 to 200 µm; estimated dry wts equalled0.03–0.8 µg and estimated carbon weights were 0.01–0.3µg. Medusae released up to > 10 000 ova/female/day.This rep resented 0.1–4 of total dry wt/day (1–16of carbon). Egg production was dependent on nutritional stateand on female biomass; ova size, on the other hand, was independentof female biomass both within and among species. For the hydromedusaein Saanich Inlet, carbon flux of ova was estimated to equalonly about 50 of metabolic carbon losses because reproductiveindividuals represented only a small part of the total hydromedusapopulation.