166 



L. HILLIS-COLINVAUX 



Table XII. Light Intensities at Glory Be Reef, North Shore of Jamaica"'"' 



Date 



Time 



Light intensity 

 Depth ift-c) 



(m) {meter in case) 



Ratio water 

 to air (%) 



Location 



16.6.69 



16.9.68 



August 



0728 

 0735 

 0812 

 0735 

 0820 

 9745 



0825 



0747 

 0810 

 0830 



0836 



1115 

 1230 

 1250 



+ 2 



-1-5 



—1-5 



—1-5 



-1-5 



-3-7 



-3-7 







+ 2-5 

 -2 

 + 2-5 

 



-0-5 



440\ 

 320/ 



200-300 



1000 



700 



600-1000 



1500 



73 



-3-1 1000-1200 

 -1-5 <200 

 -1-8 20001 



3000J 



6400-7200" 

 3000-5000 



6400 



1500" 



800 



67 



47-69 



(-78) 



53 



Shaded beach steps 

 Shaded quadrat site (Q^) 

 Shaded quadrat site (Q^) 

 Patch of light north of Q^ 

 Patch of light north of Q^ 

 Range on sand patches 



outside zooanthid reef 

 Dune sand pass in 



zooanthid reef 

 Urchin barren 

 Red algal patch under rock 

 Halimeda sand without 



plants 

 Halimeda sand without 



plants 

 Sun in and out of clouds 

 Qi, sun in and out of clouds 



Odum and Odum (1954), 

 with Weston light 

 meter, Enewetak Atoll 



Odum and Odum (1954), 

 with Weston light 

 meter, Enewetak Atoll 



" For description of sites see Section X. 



'' Intensities were measured with a Gossen Tri-Lux foot-candle meter in an underwater 

 case. 



The most successful method for controlling the other epiphytes, once 

 established, has been by hand cleaning, an operation which is tedious 

 and time-consuming. The soft red and green algae can usually be 

 plucked off their hosts fairly easily, but many of the blue-greens, with 

 their slimy coatings and mats, must be scraped off, using tools such as a 

 fingernail for the thalli, or a long-handled aquarium cleaner with razor 

 blade for the sides of the aquarium. Tissues also are helpful for cleaning 

 aquarium sides and retaining some of the material. Mats and slime 

 coatings on the sand can be lifted off. 



External or internal water filters, which may be initially useful for 

 avoiding phytoplankton blooms or eliminating or minimizing successful 



