Jt. Lehman et Dk. Branstrator, A MODEL FOR GROWTH, DEVELOPMENT, AND DIET SELECTION BY THE INVERTEBRATE PREDATOR BYTHOTREPHES-CEDERSTROEMI, Journal of Great Lakes research, 21(4), 1995, pp. 610-619
A growth model is developed to predict C content, respiration, and rat
es of both embryonic and post-embryonic development by the invertebrat
e predator Bythotrephes. The model incorporates temperature dependent
rates of embryonic and postembryonic development as well as respiratio
n and variations in body mass. Estimated growth efficiencies indicate
that this invertebrate predator converts about 25% of its prey biomass
into predator mass, thus reducing potential resource availability to
planktivorous fish. The physiological economics of Bythotrephes with r
espect to both P and C indicate that copepods can be only a minor comp
onent of the predator's diet, owing to the high C:P composition of cop
epod tissues. Mass balance constraints dictate that field-collected po
pulations of Bythotrephes in Lake Michigan consume a prey mixture with
bulk tissue stoichiometries less than about 40:1 C:P by mass. The req
uisite stoichiometry correponds with the elemental composition of Clad
ocera, particularly Daphnia, which are the dominant Cladocera in offsh
ore regions. Thus an analysis based on conservative elemental budgets
of P and C points to Daphnia as the dominant prey of Bythotrephes in L
ake Michigan.