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Optimal foraging theory as a predictor of chemically mediated food selection by suspension‐feeding copepods
Author(s) -
DeMott William R.
Publication year - 1989
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1989.34.1.0140
Subject(s) - algae , biology , digestion (alchemy) , optimal foraging theory , particle (ecology) , green algae , food science , foraging , botany , ecology , chemistry , chromatography
Chemically mediated food selection was studied by offering copepods pairs of particles which differed in nutritional quality or size. Eudiaptomus spp. fed in varying concentrations of algae and polystyrene spheres, high#x2010;quality algae of different sizes, toxic and nontoxic algae, digestible and digestion#x2010;resistant algae, live and dead algae, and dead algae with and without attached bacteria. Experiments with polystyrene spheres showed that the rejection of nonfood particles did not interfere with feeding on relatively scarce algae. Particle selection in mixtures of algae exhibited good agreement with predictions of optimal foraging theory. Selectivity did not change with food concentration for mixtures of high#x2010;quality algae or mixtures of toxic and nontoxic algae. Copepods showed a weak but consistent preference for the larger of a pair of high#x2010;quality algae, whereas a toxic blue#x2010;green bacterium was eaten at a very low rate whether offered alone or in combination with an edible alga. Selection against low#x2010;quality nontoxic particles (e.g. digestion#x2010;resistant algae), however, was sensitive to food concentration. Discrimination against low#x2010;quality particles was strong when high#x2010;quality food was abundant and weak when high#x2010;quality food was scarce. In agreement with theory, diet selection by Eudiaptomus spp. is strongly influenced by both particle quality and the abundance of alternative foods.