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No.13 (1970/06) >

 
Title :Calcification in a Solitary Coral, Fungia scutaria Lamarck in Relation to Environmental Factors
Authors :Yamazato, Kiyoshi
Issue Date :30-Jun-1970
Abstract :With the ultimate purpose of clarifying the role of zooxanthellae in calcification in corals, a study was conducted (1) to analyze the effects of some environmental factors on the rate of calcium uptake by Fungia scutaria Lamarck and (2) to obtain a clear picture of the uptake and release of phosphorus by the same animal under various conditions. The effect of the factors investigated on the rate of calcium uptake was strikingly different in the light and in the dark. In the dark, the rate increased linearly with increase in temperature (15°- 32℃) and also with increase in the ambient calcium concentration from 0 to 200 mg/1. A steady state was maintained for calcium concentrations from 200 to 600mg/1. A drastic decrease occured in solutions of 75 to 25% sea water, and a lesser decrease in 125% sea water. The rate decreased linearly with the logarithmic increase in the ambient phosphate concentration from 10^<-7> (natural sea water) to 10^<-2> M. In the light, the rate of calcium uptake was maximum at 24℃, and in natural and 75% sea water. Deviations from either of these conditions resulted in de crease in the rate of calcium uptake. Uptake rates increased linearly with increase in the ambient calcium concentration from 0 to 400 mg/1 and with a steeper slope from 400 to 600 mg/1. The effect of the ambient phosphate concentration on calcium uptake was not clear but there was a general trend of decrease in the uptake rate with increasing concentration of phosphate. The greatest difference in the rate of calcium uptake "between the dark and light conditions was observed at the lower phosphate concentrations. Dinitrophenol completely inhibited calcium uptake at concentrations of 10^<-4>M and higher both in the light and in the dark. At a concentration of 10^<-5>M a complete inhibition was observed in the dark but not in the light The removal of zooxanthellae from the animal caused a decrease in the rate of calcium uptake to 1/12 the control value in the light and to 1/8 in the dark. These ratios were unaltered in the polyps devoid of zooxanthellae kept in the same containner with the normal polyps. The rate of phosphorus uptake from sea water supplemented with phosphate (2.7μg-at. P/1) was approximately two times greater in the light than in the dark. Net uptake occurred both in the light and in the dark at this phosphate concentration, while net release occurred in the light and in the dark in natural sea water (0.27 μg-at. P/1). In the light, the pholyps devoid of zooxanthellae absorbed phosphorus at the rate 1/8 that of the normal polyps; in the dark this ratio was about 1/6. Some indication of interaction between the normal and zooxanthella - free polyps in the same container was observed. The effect of temperature on phosphorus uptake was about the same as that on calcium uptake. Approximately the same quantity of organic phosphorus (particulate and dissolved ) was released in the light as in the dark, while nine times more inorganic phosphorus was released in the dark than in the light. More organic phosphate labelled with P^<32> was released by the normal polyps than by the zooxanthella-free polyps under both light and dark conditions.
Type Local :紀要論文
Publisher :琉球大学理工学部
URI :http://hdl.handle.net/20.500.12000/23427
Citation :琉球大学理工学部紀要. 理学編 = Bulletin of Science & Engineering Division, University of Ryukyus. Mathematics & natural sciences no.13 p.59 -122
Appears in Collections:No.13 (1970/06)

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