Abstract
Digestion times and assimilation efficiencies are critical factors used in calculations of carbon and nitrogen budgets. Digestion times of natural copepod prey differed significantly among 4 genera of siphonophores (P>0.001), from a minimum of 1.6 h to a maximum of 9.6 h. Assimilation efficiencies, in contrast, were uniformly high; 87 to 94% for carbon and 90 to 96% for nitrogen. Nitrogen assimilation was consistently greater than carbon assimilation. Assimilation efficiencies calculated according to dry weight substantially underestimated assimilation of carbon and nitrogen, while calculations using ash-free dry weights and ash-free to dry weight ratios approached values for carbon assimilation. These values are appreciably higher than most of the assimilation efficiencies previously measured for a few other planktonic carnivores. These results indicate very efficient digestion of food by siphonophores in oceanic environments where prey densities are low.
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Communicated by S. K. Pierce, College Park
Contribution no. 5298 from the Woods Hole Oceanographic Institution
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Purcell, J.E. Digestion rates and assimilation efficiencies of siphonophores fed zooplankton prey. Mar. Biol. 73, 257–261 (1983). https://doi.org/10.1007/BF00392251
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DOI: https://doi.org/10.1007/BF00392251