Effect of Thermal Acclimation on Organ Mass, Tissue Respiration, and Allometry in Leichhardtian River PrawnsMacrobrachium tolmerum(Riek, 1951)

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The University of Chicago Press ABSTRACTChanges to an animal's abiotic environment-and consequent changes in the allometry of metabolic rate in the whole animal and its constituent parts-has considerable potential to reveal important patterns in both intraspecific and interindividual variation of metabolic rates. This study demonstrates that, after 6 wk of thermal acclimation at replicate treatments of 16Њ, 21Њ, and 25ЊC, standard metabolic rate (SMR) scales allometrically in Leichhardtian river prawns Macrobrachium tolmerum ( ) and that the scaling exponent mean scaling exponent p 0.61 and normalization constant of the relationship between SMR and body mass is not significantly different among acclimation treatments when measured at 21ЊC. There is, however, significant variation among individuals in whole-animal metabolic rate. We hypothesized that these observations may arise because of changes in the metabolic rate and allometry of metabolic rate or mass of organ tissues within the animal. To investigate this hypothesis, rates of oxygen consumption in a range of tissues (gills, gonads, hepatopancreas, chelae muscle, tail muscle) were measured at 21ЊC and related to the body mass (M) and whole-animal SMR of individual prawns. We demonstrate that thermal acclimation had no effect on organ and tissue mass, that most organ and tissue (gills, gonads, hepatopancreas) respiration rates do not change with acclimation temperature, and that residual variation in the allometry of M. tolmerum SMR is not explained by differences in organ and tissue mass and respiration rates. These results suggest that body size and ambient temperature may independently affect metabolic rate in this species. Both chelae and tail muscle, however, exhibited a reduction in respiration rate in animals acclimated to 25Њ relative to those acclimated to 16Њ and 21ЊC. This reduction in respiration rates of muscle at higher temperatures is evidence of a tissue-specific acclimation response that was not detectable at the whole-animal level.

Effects of Contingency versus Constraints on the Body-Mass Scaling of Metabolic Rate

“…Most other models focused on the differential scaling of various resource-demanding processes and tissues or organs with different metabolic rates (see e.g., [10,38,52]) have yet to consider how ambient temperature may affect metabolic scaling slopes (but see discussion of dynamic energy budget theory below). Furthermore, a recent study has shown that temperature acclimation does not affect the size and metabolic rate of various organs of the prawn Macrobrachium tolmerum [78].…”

Adapt, move or die – how will tropical coral reef fishes cope with ocean warming?

“…Accordingly, the body mass of individuals maintained at 33 °C decreased by a staggering 30% during the 27‐week trial. Energetic requirements of different organs and tissues vary according to their mass and metabolic requirements (Crnokrak & Roff, ; Darveau et al ., ; Crispin & White, ) causing tissue‐specific physiological processes to contribute differently to the animal's total energetic requirements. For example, 35% of the variation in basal metabolic expenses in some ectotherms can be attributed to differences in heart and liver masses (Garland, ).…”

Scaling of Metabolic Scaling within Physical Limits

“…Many other intraspecific studies on various kinds of aquatic and terrestrial animals have revealed negative associations between b and T [21,[94][95][96][97][98][99][100][101][102][103][104][105][106][107], but some studies have reported no significant relationship [21,89,90,[108][109][110], or more rarely positive [111], concave upward [112,113] or concave downward [114,115] relationships. Apparent exceptions to the inverse b-T pattern predicted by the MLBH may be attributed to (1) some species having metabolic rates with relatively low thermal sensitivity (leading to small changes in L and thus b); (2) temperature induced increases in activity or other energy-demanding processes and stress responses that may affect various size classes equally or unequally (leading to absent, positive or other b-T relationships, depending on the level and size-specificity of the thermally induced activity or stress); (3) thermal induction of activity and or other energy demanding processes that varies over different T ranges (leading to concave b-T patterns); and (4) insufficient acclimation to experimental temperature regimes, thus causing spurious results.…”