This proposal requests funds for the purchase of an open-flow microcalorimetry-respirometry system. This instrumentation will enable analytical capabilities not presently available and will foster the expansion and enhancement of existing programs directed by five primary and three secondary users. It will support research on (l) mechanistic analyses of hypometabolic states in invertebrates, (2) regulation of glucoeogenesis in skeletal muscle, (3) metabolic adaptations of planktonic invertebrates, (4) physiological basis for flood-tolerance among congeneric plant species, and (5) nitrophenol-based metabolism of soil microbes. In addition to quantifying total metabolic rates of the respective tissues/organisms, the microcalorimetry- respirometry system will allow anaerobic components, monitoring of metabolic compensation during entry and exist from stressful environmental conditions, and analysis of the relative contributions of different substrates to total metabolic rate.