The affect of temperature on the metabolism and behaviour of an endemic amphipod, Hyalella montezuma, from Montezuma Well, Arizona, U.S.A. |
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Authors: | GAYE OBERLIN,& DEAN BLINN |
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Affiliation: | Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011–5640, U.S.A. |
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Abstract: | 1. Hyalella montezuma is endemic to Montezuma Well, Arizona, and is exposed to minimal diel and seasonal temperature fluctuations in the pelagic zone (21 ± 4 °C). Juvenile H . montezuma feed in the pelagic zone during the day and migrate into the littoral vegetation at night, while adults remain primarily in the littoral vegetation. 2. Oxygen consumption ( V O2) of adult and juvenile H . montezuma was measured at 20, 25 and 30 °C. The V O2 of both adult and juvenile H . montezuma increased with temperature. However, the V O2 of juveniles was significantly greater than that of adults at all temperatures, with greatest divergence at 30 °C where mean juvenile V O2 (6.31 μl mg–1 dry weight (DW) h–1) was almost twice that of adults (3.60 μl mg–1 DW h–1). 3. Survivorship of juveniles was significantly lower (54%) at 30 °C than at 27.5 °C (95%) after 4 h, whereas adults showed at least a 93% survivorship at both temperatures. 4. Our data suggest that temperature may have been the proximate cue that elicited the diel horizontal migration of juvenile H . montezuma in Montezuma Well, with the behaviour maintained and enhanced by intensive invertebrate predation in the pelagic and littoral zones. |
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