60 



CO 



(O 50 

 Ul 



z 



X 



o 



o 



UJ 



o. 



CO 





40 



SO- 



OT 



UJ 20 



10 





SPONGES | 



CORALS I 



60 90 



DEPTH (FT) 



m 



120 



Figure 1 . Species richness (SR) values obtained from digitized 

 photo-quadrats of Mission I. Dashed lines = SR values pooled over 

 all depths. Open histogram bars = SRvalues pooled for each depth. 

 Shaded bars = mean SR values for 0.5m^ quadrats + S.D. line. 



deeper reefs (t-test: p < .001 at 90' (df=27) and 120' (df=26)). 

 Interestingly, although the percent cover of sponges (8.0 + 4.9 at 

 60', 19.1 + 12.5 at 90' and 12.3 + 9.5 at 120 ' ) and corals (18.3 + 

 10.6 at 60^, 23.8 + 13.2 at 90 1 and 39.1 + 23.1 at 120') was not 

 significantly different at 90', corals occupy considerably more area 

 than sponges at both 60' and 120' (t-test: p< .001). 



The greatest number of both total interactions and overgrowths 

 (per m^) occurred at the 120' depth (Fig. 2). While the frequency of 

 standoffs was relatively consistent over all depths, overgrowths 

 increased to a mean of 9.0 + 5.4 at 120'. The frequencies of over- 

 growths at 10', 60' and 90' were not significantly different from 

 each other, but at 120' were much greater than at all other depths 

 (t-test: p< .01 for 30'; p< .001 for 10', 60' and 90'). 



CO 



10 



° A 



— CM ° 



I- 2 



<-> 6 



1 



i t^---|... 



*s 



I 



20 



40 60 80 



DEPTH (FT) 



100 120 



Figure 2 . 

 depth. T 

 standoffs 



lumber of interactions per m2 (+ or - S.D. lines) versus 

 total number of interactions, = overgrowths, S = 



57 



