and Aroclor 1254) dissolved in acetone. Astrangia concentrated a 1 ppm 

 dose of the mixture at a rate of 1 ppm per hour over a three hour period. 

 Acropora concentrated a 0.5 ppm dose at the rate of 380 ppb per hour. 

 From this data, we chose the dose range of 10 to 1000 ppb, and a three 

 hour dose time for our TEKTITE experiments. 



In respiration experiments, pre-dose and control measurements indicated: 



(1) boring algae contributed insignificantly to oxygen production in the 

 coral heads (thus corroborating prior data by Kanwisher & Wainwright) ; 



(2) compensation values of subtidal corals were low, less than 100 foot- 

 candles in some species, and photosynthesis to respiration proportions were 

 much lower than those published previously for intertidal or shallow sub- 

 tidal corals; and (3) in spite of reduced light levels (maximum 1500 fc) , 

 corals monitored in situ at 50 feet appeared to release as much oxygen as 

 they consumed in a complete diurnal cycle. 



Respiration values for three of the coral heads are shown in Figure 1 a-c. 

 Values above the dashed horizontal line represent photosynthetically 

 generated oxygen in ml per liter, while the values below the dashed line 

 represent oxygen utilized by respiration. The length of the lines (abcissa) 

 represents one hour. Net photosynthesis (N) and respiration (R) are from 

 direct measurements. Gross photosynthesis (G) is calculated from net 

 photosynthesis plus respiration. The ratio of gross photosynthesis to 

 respiration (P/R) is given at the termination of the lines at "G" . Slopes 

 labelled "0" are those obtained prior to dosing, while "I" represents a 

 first, and "II" a second dose of 1 ppm organochlorine . 



In every instance, respiration increased slightly after dosing with the 

 organochlorines . At the same time, photosynthesis decreased significantly, 

 usually more than twice the rate of the respiration increase. The total 

 effect is revealed by the P/R ratio, which at 1000 fc is decreased between 

 16 and 22% (or between 12 and 20% at 500 fc) . A second dose (II) , elicited 

 an additional, approximately equal drop in the P/R ratio, so that photo- 

 synthesis/respiration was depressed about 33% over normal (pre-dose) values. 

 The results are summarized in Table 1. 



A coral must reach an average P/R value of 2.0 for the 12 hours of daylight 

 to obtain a 24 hour average of 1.0. It is obvious from the P/R values in 

 Table 1 that only above 1000 fc--a situation which prevails only for about 

 4 hours of the day, with a maximum of 1500 fc--does the P/R ratio exceed 

 2.0. The appropriate calculations have not been made, but it is likely that 

 the 12 hour daylight averages for our undosed corals do not exceed 2.0. The 

 corals we tested at 50 feet, then, were generating about as much oxygen 

 during a diurnal period as they use. 



Another measurement which reveals the alterations in coral metabolism brought 

 about by organochlorines is the compensation value, which is the light level 

 at which 0„ produced by photosynthesis equals the Oo used in metabolism. 

 (P/R = l.Oj. The organochlorine load consistently increases the compensation 

 value, as shown in Table 2. 



VI-232 



