Oxygen Consumption in Anthopleura INTRODUCTION Two sympatric species of Anthopleura are found in the and local intertidal which seem to occupy different types of habitat with some overlap. Anthopleura xanthogrammica (Brandt, 1835) is generally seen lower in the intertidal and in more surf swept areas than Anthopleura elegantissima (Brandt, 1835). Suspecting this habitat difference may be correlated with metabolic differences, studies of oxygen consumption of the two species were made. Sassaman and Mangum (1972) measured the oxygen consumption for Haloclava producta and Metridium senile and found that Metridium senile from a higher oxygen environment had a higher oxygen consumption rate at the sôme oxygen concentration at (air saturation). MATERIALS AND METHODS All the animals used in this study were taken from the rocky intertidal area at Hopkins Marine Station, Pacific Grove, California. Several of each of the two species of Anthopleura were taken from three different tidal levels. Several A. xanthogrammica were taken from an exposed point where no A. elegantissima were seen. All anemones were allowed to settle for at least three days to check for trauma. During settling and between measurements the Oxygen Consumption in Anthopleura anemones were left in running sea water at 12°0. Measurements were made in a Scholander (1949) type respirometer with compensating chambers and with a Warburg respirometer. Volume compensation in the Scholander respir¬ ometer was with oxygen to maintain a constant partial pressure of oxygen. Measurements were made in a running sea water bath at 12°C. The running water current moving the chambers and the ciliary activity of the anemone provided the only mixing. Readings were taken every fifteen minutes for four hours or more. A mean volume change was calculated along with standard deviation and standard error of the mean. The b value for the log-log plot of the weight regression was calculated and tested for significance with the Student's T test. Measurements taken over prolonged periods, seventeen hours, with the Scholander respirometer revealed negligible changes in the running mean volume change from that during the first four hours. Blanks run under each set of conditions showed negligible volume changes. Both sample and compensating chambers were covered with aluminum foil for dark conditions. Uncovered glass chambers were in light at an intensity of sixty foot candles for the Scholander respirometer and forty foot candles for the Oxygen Consumption in Anthopleura Warburg respirometer. All animals were dryed for twenty four hours to a constant weight within 0.01 grams (Brafield and Chapman, 1965). RESULTS AND DISCUSSION Oxygen consumption rates in ul O/hour/gram dry wt. under four different conditions for both A. elegantissima and A. xanthogrammica are organized in Table One. Average variation for repetitive measurements for single anemones at different times at an average dark submerged oxygen consumption rate of 21.5 ul 0/hour/ gram dry wt. was + 13.8 ul O/hour/gram dry wt. The variation in the differ- ence in oxygen consumption rates under different light conditions, at different tidal levels and between the two species is as large or larger than the variation in oxygen consumption rates for a single anemone. Therefore these differences can not be established with my data. One point of interest is the increased oxygen consump¬ tion rates in dry animals vs.submerged animals by a factor of two or three. When submerged in sea water the anemone is expanded exposing a greater surface area for exchange. The partial pressure of oxygen in both air and sea water in equilibrium with each other should be the same. Since the anemones run for long periods submerged do not show a progresswe reduction in respiratory rate it is assumed that the water Oxygen Consumption in Anthopleura is maintained in approximate equilibrium. This all indicates that aquatic respiration would be more favor¬ able, but aerial respiration is consistently greater. The volume of oxygen in the air is forty times greater than in an equal volume of water and the rate of diffusion of oxygen is 324,000 times greater in air. Together these two factors make the supply of oxygen in air to respiratory tissue more effective, indicating that covering by the tide limits the anemone's metabolic rate. One advantage of the preferred habitat of A. xanthogrammica on surf swept rocks is the presence of super saturated sea water to enhance metabolic rate. The log-log plot of weight regression for A. elegantissima in Graph One reveals a good correlation between the oxygen consumption rates using the Scholander respirometer and the Warburg respirometer. The b value was calculated to consideva be 0.20 which is significantly different from the O.65 b value found for Metridium senile (Sassaman and Mangum, 1970 and the 0.75 b value found for several other intertidal invertebrates (Newell, 1970). The low b value indicates that larger anemones are not dramatically changing the morphology or physiology of the metabolizing tissue. The value above zero may be accounted for by some enlargement of individual cells in larger anemones and for burying of cells in the larger masses of tissues, thus increasing the diffusion path for oxygen. I can not account for the Oxygen Consumption in Anthopleura difference between my b value and the higher ones reported by other authors for different species of sea anemones. However a low b value for anemones seems quite expected by me. SUMMARY There is a large variation in oxygen consumption rates for both A. elegantissima and A. xanthogrammica. Aerial respiration was found to be two to three times greater than submerged respiration for both species. A b value found for A. elegantissima was calculated to be 0.20. This is quite different from b values for other anemones and other intertidal invertebrates, but seems expected. ACKNOWLEDGMENTS I would like to thank all the students, faculty and staff at Hopkins Marine Station for all their help and support, and give special thanks to Chuck Baxter for his patient guidance. Oxygen Consumption in Anthopleura LITERATURE CITED Brafield, A. E. and G. Chapman. 1967. The respiration of Pteroides griseum (Bohadsch) a pennatulid coelenterate. J. Exp. Biol., 46: 97-104. Newell, R. C., 1970. Biology of Intertidal Animals. American Elsevier Publishing Company, Inc., New York, 378 pp. Sassaman, C. and C. P. Mangum. 1972. Adaptations to environmental oxygen levels in infaunal and epifaunal sea anemones. Biol. Bull. 143: 657-678. Sassaman, C. and C. P. Mangum. 1970. Patterns of temperature adaptation in North American Atlantic coastal actinians. Mar. Biol., 7: 123-130. Oxygen Consumption in Anthopleura LEGEND Table One. Oxygen consumption rates in ul O/hour/gram dry wt. for A. xanthogrammica and A. elegantissima with standard error of the mean, Sz, in ul O/hour/gram dry wt. for each measurement and tidal level and dry weight for each anemone. Graph One. Log-log plot of the weight regression for A. elegantissima with a size range of 0.50 to 15.0 grams dry weight combining Scholander and Warburg respirometer measurements. e aa t 5 5 oOGUUU oOGO0 108 ct * o 8 pw- atatata- ataaa- CO O 5 5 1 0 9 5 8 4 8 8 H — 8U 3 — G 9 - poo o o888 ( 688 N CHAMPION LINE NO. 810-3 CROSS SECTION -10 SOUARES TO INCH I — H T ++ +t + L0G uhouemdry. + — ++ — + +++ ++ ++ + ++ +++ ++ + +++ +++ + ++ +++ ++ ++ ++ + ++ + + + ++ + + +++ +++ 11 + + + + + + + ++ ++ + ++ + + + + ++ + t + + + 0 + + + + — H —— +++ + + ++ + ++ + + ++ + + +++ H — + ++++ +++ ++ + + ++ + + + —+ + +++++ + +++ ++++ + + ++ + +++ ++ + ++ +++ + + + + + + + —+ +++ + +++ +++++ +++ ++ + +