S. Burkhardt et Jt. Lehman, PREY CONSUMPTION AND PREDATORY EFFECTS OF AN INVERTEBRATE PREDATOR (BYTHOTREPHES, CLADOCERA, CERCOPAGIDAE) BASED ON PHOSPHORUS BUDGETS, Limnology and oceanography, 39(5), 1994, pp. 1007-1019
Phosphorus excretion rates, ingestion efficiency, and P content of Byt
hotrephes at different developmental stages are used to estimate preda
tion rates indirectly from metabolic needs. A growth model is develope
d to predict P content and weight of this invertebrate planktivore thr
oughout its life. P consumption required to complete one parthenogenic
life cycle of the predator is estimated from metabolic rates and weig
ht measurements of individual instars. Based on P requirements and pre
y stoichiometry, empirical ingestion efficiency of 59%, and assimilati
on efficiency of 85%, each Bythotrephes consumes the equivalent of 14
Daphnia per day on average and can inflict mortality equal or greater
in magnitude to Daphnia recruitment rates during midsummer in offshore
waters of Lake Michigan, particularly when predator population abunda
nce exceeds 400 individuals m-2.