Sp. Jiang et Dl. Claussen, THERMAL INFLUENCE ON METABOLIC RATES AND A BIOENERGETIC BUDGET FOR NOTOPHTHALMUS-VIRIDESCENS FROM SOUTHWESTERN MASSACHUSETTS, Comparative biochemistry and physiology. Part A, Physiology, 109(4), 1994, pp. 1059-1065
Notophthalmus viridescens has been reported to overwinter on land in s
outhwestern Massachusetts, whereas these newts hibernate in water in s
outhern Ohio. Aquatic and terrestrial metabolic rates of newts from Ma
ssachusetts were measured at different exercise speeds and acclimation
temperatures in order to better understand their seasonal energetic b
udgets. Oxygen uptake at 25 degrees C increased with increased swimmin
g and walking speeds and reached a plateau at speeds of 60 and 90 cm/m
in, whereas at 5 degrees C, oxygen consumption linearly increased with
swimming speeds. Aerobic transport costs of the newts thus decreased
with increased locomotor speeds at 25 degrees C but remained unchanged
when the newts were exercised in water at 5 degrees C. Anserobic meta
bolic rates of the newts on land were little affected by acclimation t
emperature but also increased linearly with walking speeds at both 5 d
egrees C and 25 degrees C. Anaerobiosis contributed most of the energy
for the locomotion of the newts. These newts stored an average of 12
mg lipd/g body mass, which could apparntly support their survival at 5
degrees C for 46 days without food on land but only for 18 days in wa
ter. These calculations, based on measured metabolic rates and energy
reserves, support field observations of red-spotted newts hibernating
on land in Massachusetts.