Foraging Costs of Hypoxia Acclimation in the Swamp-Dwelling African Cyprinid, Barbus neumayeri
This study described the behavior of the swamp-dwelling African cyprinid Barbus neumayeri in response to laboratory acclimation to normoxic and hypoxic conditions to detect costs associated with hypoxia exposure. Behavioral observations were conducted every two weeks over a four-week acclimation period in both normoxic and hypoxic conditions, and feeding trials were conducted after six weeks of acclimation. Gill ventilations were shallower in normoxia-acclimated fish than in hypoxia-acclimated individuals, and gill ventilation rate declined over the hypoxia acclimation. There was no effect of hypoxia acclimation on routine activity; however, individuals acclimated to hypoxia showed a depression in feeding rate relative to normoxia acclimation. This decline in feeding activity under hypoxia acclimation may account, at least in part, for the lower condition of the hypoxia-acclimated fish. These findings suggest that hypoxia exposure does not significantly impact routine activity levels of these swamp-adapted fishes, but seems to depress higher energy activities such as feeding rate.Abstract
Bilogarithmic plot of body mass (g) versus total length (cm) for Barbus neumayeri from the Rwembaita Swamp of Uganda acclimated to six weeks of normoxia (7.4 mg l−1, ~135 mm Hg) and six weeks of hypoxia (1.2 mg l−1, ~22 mm Hg).
Contributor Notes
(LMB) Department of Zoology, University of Florida, Gainesville, Florida 32611; and (LJC) Department of Biology, McGill University, Montreal, Quebec H3A 1B1. E-mail: (LMB) lmbarrow@zoo.ufl.edu. Send reprint requests to LMB.