. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 180 R. J. ULBRICHT AND A. W. PRITCHARD fragile urchins, respectively). Resulting sea water volumes ranged from to liters. A magnetic stirring bar was placed at the bottom of each con- tainer, and a slow stirring rate, created by an immersible magnetic stirrer (Tri-R Instrument Co.) was used in all studies to provide for uniform temperature and oxygen tension values. A Beckman oxygen macro-electrode was used in con- junction with a physiological gas analyzer (Beckman Spinco model 160) to determine the oxygen tension
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 180 R. J. ULBRICHT AND A. W. PRITCHARD fragile urchins, respectively). Resulting sea water volumes ranged from to liters. A magnetic stirring bar was placed at the bottom of each con- tainer, and a slow stirring rate, created by an immersible magnetic stirrer (Tri-R Instrument Co.) was used in all studies to provide for uniform temperature and oxygen tension values. A Beckman oxygen macro-electrode was used in con- junction with a physiological gas analyzer (Beckman Spinco model 160) to determine the oxygen tension. Appropriate shields restrained the urchins from interfering with the operation of the stirring bar and the oxygen macro-electrode. The arrangement is pictured in Figure 1. < cc 30 20 10 X o O one urchin A a second urchin. high UflJLQ low I tide high low tide high I 1 ijl e low i tide hill ELAPSED TIME FIGURE 2. Relationship between oxygen consumption rate and elapsed time for Strongylocentrotus purpuratus. The temperature range used was 6° to 24°, with measurements made at 3° intervals. Temperature was maintained with a Bronwill thermoregulator combined with a portable cooling unit (Precision Scientific Company). Urchins were placed in the containers about 5 hrs for equilibration in aerated sea water at 6°, the initial test temperature. The container was sealed and oxygen tension recorded at 10-20 min intervals. In this manner from 3 to 6 measurements of oxygen uptake were obtained. The temperature was then changed to the next level while the respiratory container was aerated. After reaching the new tem- perature, a one hour period of equilibration was allowed before measurements of oxygen uptake were made. Oxygen tension of the sea water in the container at no time fell below 75 mm Hg, and runs at any one temperature were usually terminated at considerably higher oxygen levels. Measurements of chamber water pH were made from samples taken before urchins were placed in
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
