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CAN QUANTITY REPLACE QUALITY? FOOD CHOICE, COMPENSATORY FEEDING, AND FITNESS OF MARINE MESOGRAZERS
Author(s) -
Cruz-Rivera Edwin,
Hay Mark E.
Publication year - 2000
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2000)081[0201:cqrqfc]2.0.co;2
Subject(s) - biology , fecundity , nutrient , food quality , food choice , ecology , amphipoda , survivorship curve , zoology , food science , medicine , population , genetics , demography , pathology , cancer , crustacean , sociology
Relationships among food choice, compensatory feeding, and the consequences for consumer fitness rarely have been quantified. We created foods of varying nutritional quality and evaluated the consequences of compensatory feeding for three sympatric species of amphipods by analyzing food choices, feeding rates, and long‐term effects on fitness. Nutritional quality was manipulated by creating low‐quality diets from algae (low in protein, nitrogen, and total organic carbon), high‐quality diets from commercial fish food (high in protein, nitrogen, and total organic carbon), and intermediate‐quality diets from mixtures of those two foods. When high‐ and low‐quality diets were simultaneously offered, the more mobile, non‐tube‐building amphipods, Gammarus mucronatus and Elasmopus levis, both fed preferentially on the high‐quality diet. The more sedentary, tube‐building amphipod Ampithoe longimana did not discriminate between these foods. When confined to a single food type, all three species exhibited compensatory feeding on the low‐quality diet. Despite compensatory feeding, when Elasmopus levis were cultured on the low‐quality food, they experienced reduced survivorship, growth, and fecundity during two successive ovulations, compared to individuals feeding on more nutrient‐rich foods. Low‐nutrient foods caused similar declines in growth and female gonad size for Gammarus mucronatus. In contrast, the survivorship, growth, and fecundity of Ampithoe longimana was not affected by any of the diets tested. Thus, compensatory feeding allowed the more sedentary species, Ampithoe longimana, to completely circumvent the effects of low nutritional quality, but the same behavior was ineffective for both of the more mobile species, Gammarus mucronatus and Elasmopus levis. The ability of A. longimana to achieve equal fitness by substituting food quantity for food quality may allow this sedentary species to form longer associations with individual host plants, minimize movement among hosts, and thus lower its risk of being detected by predators.