Chemical composition and metabolic rates of gelatinous zooplankton from midwater and benthic boundary layer environments off Cape Hatteras, North Carolina, USA

Quantitative determinations of chemical composition and oxygen consumption rates were made for 7 species of gelatinous zooplankton (ctenophores and medusae) from midwater and benthic boundary layer habitats off Cape Hatteras, North Carolina, USA. Although there were no apparent trends in chemical composition with depth of occurrence, midwater species were generally less robust, in terms of protein and lipid content, than those from benthopelagic depths. These differences in chemical compositions between midwater and benthopelagic species are probably related to factors associated with swimming behaviors required for prey capture and predator avoidance. Measurements of carbon specific metabolic rates (0.59 to 17.9 μl O2 mg−1 C h−1) indicated that minimum daily rations required by mesopelagic gelatinous zooplankton can impact carbon cycling and energy transfer in deep-water ecosystems. These data are consistent with a growing inventory of metabolic measurements undertaken with submersible platforms and strongly implicate gelatinous zooplankton as ecologically important components of pelagic communities.