Daily ration and predation by medusae and ctenophores in Saanich Inlet, B.C., Canada
Larson, R.J. (1987). Daily ration and predation by medusae and ctenophores in Saanich Inlet, B.C., Canada. Neth. J. Sea Res. 21(1): 35-44
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, more
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| Abstract |
The daily ration and predation impact of medusae and ctenophores in the upper 25 m of Saanich Inlet were determined using data from gut contents analyses, digestion times, and predator/prey densities. The weight-specific daily rations of the 3 major gelatinous predators (Pleurobrachia bachei, Phialidium gregarium, and Phialidium lomae) were a negative power function of their biomass. Small predators obtained a ration much in excess of maintenance needs, while the largest specimens had little excess carbon growth or reproduction. In the upper 25 m predation impact was small on the total mesozooplankton, (mostly <1%·d -1 of biomass cropped), but it was higher in the upper 5 m (5 to 10%·d -1of biomass removed). Specific predation on Euphausia pacifica eggs and nauplii was much greater, with 10 to 40% of stocks consumed by gelatinous predators per day. In Saanich Inlet, medusae and ctenophores were significant consumers of commercially important euphausiids (eggs and larvae), and are probably competitors of juvenile salmon for these same prey. |
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