. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. C. N. AIRRIESS AND J. J. CHILDRESS Animals were allowed to recover at normal environ- mental pressure until the ' beat frequency stabilized and the scaphognathin .;egan to alternate between pe- riods of continuou .nig and inactivity in the fashion typical of nonstrc:>..:J decapod crustaceans (McMahon and Wilkens, 1972). Animals that did not regain typical, stable readings of heart and scaphognathite activity within 2 h of instrumentation were not used in subse- quent experiments. Experimental protocol Once the crab
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. C. N. AIRRIESS AND J. J. CHILDRESS Animals were allowed to recover at normal environ- mental pressure until the ' beat frequency stabilized and the scaphognathin .;egan to alternate between pe- riods of continuou .nig and inactivity in the fashion typical of nonstrc:>..:J decapod crustaceans (McMahon and Wilkens, 1972). Animals that did not regain typical, stable readings of heart and scaphognathite activity within 2 h of instrumentation were not used in subse- quent experiments. Experimental protocol Once the crabs appeared to have recovered, the chart speed was increased to allow resolution of individual con- tractions of the ventricle. Heart beat frequency was ob- tained by counting the waveform peaks over a 30-s period. Ventricular contraction pattern was quantified by cal- culating the standard deviation of 10 successive interbeat intervals. Immediately after this control recording, the pressure inside the experimental chamber was increased from 28 to 31 MPa. The animals were allowed 10 min to adjust, then the chart speed was increased for determi- nation of ventricular contraction frequency and pattern before the pressure was raised to 34 MPa. This protocol continued, with pressure increasing in 3-MPa steps, until the maximum pressure tested (62 MPa) was reached. After 30 min, the vessel pressure was gradually lowered to 28 MPa. Data were obtained 30 min after return to the orig- inal pressure, and the chamber was subsequently depres- surized for removal of the crabs. The effects of pressure and temperature on heart beat frequency and contraction pattern were estimated using analysis of variance with repeated measures (ANOVAR). ANOVARs significant at the level were further an- alyzed using Tukey's HSD multiple-comparison test. In addition, Spearman rank correlation was used to deter- mine the relationship between pressure and heart beat frequency at each temperature. All value
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
