CONCLUSIONS /RECOMMENDATIONS 



If, as it appears, subtidal corals at the depth studied are maintaining a 

 diurnal Go balance at very close to 1.0, then any alteration which drops 

 this value to significantly less than 1.0 may result in profound alterations 

 in the reef community. Reef-associated animals are well known to be 

 physiologically and genetically ill-adapted to fluctuations in their environ- 

 ment, and probably would respond adversely to a decrease in productivity of 

 reef corals and associated algae. 



Convincing evidence exists that the photosynthetically-active zooxanthellae 

 not only contribute to the over-all coral metabolism, but also mediate 

 coral growth. If this ability is inhibited, as our data suggests, the 

 deposition rate of calcium carbonate in the form of coral skeleton versus the 

 rate of dissolution by mechanical , biological (such as the activities of 

 boring organisms) , and chemical means could be reduced to the extent that a 

 gradual decrease in reef mass results . 



Our data on the effectiveness of organochlorines in inhibiting photo- 

 synthesis indicates that diurnal P/R O2 balance can be decreased below 

 1.0. We believe this information justifies a critical examination of the 

 effects of organochlorines on the reef ecosystem. We wish to state clearly, 

 however, that our present information does not suggest that reefs are 

 threatened by organochlorines . 



Aside from the lack of completed GLC analysis on our experimental material, 

 a valid question regarding the ecological significance of the data is 

 whether organochlorines do, or could, ever occur in the water impinging upon 

 coral reefs in the concentrations we used. The answer is, probably not. We 

 believe, however, that the dosage of 1 ppm is not more than one order of 

 magnitude greater than can be found in marine waters adjacent to some in- 

 dustrial or agricultural centers. Certainly a dosage of 10 ppb is within the 

 expected range, even if the compounds must be dissolved in the water. before 

 being absorbed by the animals. (There is good evidence that solution is 

 not necessary, and that undissolved, suspended particles of chlorinated hydro- 

 carbons can be taken up directly by animals) . We subjected the corals to 

 higher doses, but for comparatively brief time spans, on the theory that we 

 might rapidly obtain as high residue loads as might occur in corals subjected 

 to lesser concentrations over longer time spans (corals are known for their 

 longevity, which may approach perpetuity). An additional objection might be 

 that corals could acclimate to slowly accumulated residue loads, or lose 

 them by metabolism or exchange with the environment, but react in the manner 

 we describe when subjected to a rapid build-up of residue load. The validity 

 of our method cannot be further tested until we can compare the analysis of 

 residue loads in our experimental corals with residues presently found in 

 corals from "naturally" polluted areas. The quantitative analysis should tell 

 us the rate of organochlorine uptake, the rate at which these compounds are 

 exchanged or metabolized, and provide data on presently normal residue levels 

 in corals from Lameshur Bay. 



To date, none of the GLC analysis has been done on the corals from Mission 10- 

 50 due to lack of funds. As of March 1, however, support has been obtained. 

 The results will be available by late April. 



VI-236 



