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Illustrations of how P<sub>crit</sub> and metabolic reduction capacity were calculated.

By Rick J. Stoffels (754106)


<p>A, B and C: Examples of changes in </p><p></p><p></p><p></p><p></p><p><mi>M</mi><mo>˙</mo></p><p></p><p>O<mn>2</mn></p><p></p><p></p><p></p><p></p><p></p> as a function of oxygen tension for individual <i>M</i>. <i>fluviatilis</i>, <i>Hypseleotris</i> and <i>M</i>. <i>adspersa</i> (respectively), demonstrating the abrupt decline in <p></p><p></p><p></p><p></p><p><mi>M</mi><mo>˙</mo></p><p></p><p>O<mn>2</mn></p><p></p><p></p><p></p><p></p><p></p> that defines P<sub>crit</sub>. On each plot three lines are presented. The red line is the regression defining the oxyconformation zone of gradual hypoxia, while the orange line is the regression defining the oxyregulation zone during gradual hypoxia. Both the red and orange lines were determined using the algorithm of Yeager and Ultsch, and their point of intersection is one way of calculating P<sub>crit</sub> (P<sub>crit,YU</sub>). An alternative estimator of P<sub>crit</sub> (P<sub>crit,SMR</sub>) is the point of intersection of SMR (blue line) and the regression defining oxyconformation (red line). D. Reduction Capacity (RC<sub>SMR</sub> in this case), was calculated as the logarithm of the ratio of two areas (<i>ln</i>(A<sub>r</sub>/A<sub>e</sub>)), where A<sub>r</sub> is the area between the SMR and depressed metabolic rate curves, during gradual hypoxia, and A<sub>e</sub> is excess post-hypoxic oxygen consumption (EPHOC). Two points of intersection between the SMR curve and the fitted spline curve, and two points of intersection between the RMR curve and the spline, define four times critical for determination of the integrals defining A<sub>r</sub> and A<sub>e</sub>: <i>t</i><sub>startR</sub>, <i>t</i><sub>finishR</sub><i>t</i><sub>startE</sub> and <i>t</i><sub>finishE</sub> are, respectively, the times at which (a) metabolic reduction below SMR began; (b) metabolic reduction ceases; (c) EPHOC begins; (d) EPHOC finishes (see <a href="" target="_blank">Materials and Methods</a>). (Data presented in D is from a 4.67 g <i>M</i>. <i>fluviatilis</i>).<p></p

Topics: Ecology, Biological Sciences, rc, rm, inequality Melanotaenia fluviatilis, hypoxia, Static respirometry experiments, capacity, FSLC, Swimming respirometry experiments, oxygen tension, lifestyle, resilience gradient, fish community change, COTopt data, Mogurnda adspersa, species traits, Hypseleotris sp, resistance gradient
Year: 2015
DOI identifier: 10.1371/journal.pone.0130303.g001
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Provided by: FigShare
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