of a larger, more cumbersome net. The catching power of this net was 

 tested and found to be comparable to 40 cm nets available commercially. 

 The netting was NYTAL - bolting cloth of 300 microns mesh size. At 

 the cod end there was a ring of 5 cm inside diameter, into which 

 exchangeable collectors could be fitted. The latter were perforated 

 PVC-cylinders, sides and bottom being covered with 260/u bolting cloth 

 to allow free passage of water. A lid held in place by guides capable 

 of sliding into the cylinder allowed instantaneous closing of the 

 collector and subsequent exchange without leaving the water. 



For the light experiments two iodine quartz lamps, HYDRO-PRODUCTS 

 Model LQ-10, were used. Specifications: output 10,000 lumens, color 

 temperature 3000°K. The three types of filters used transmitted blue 

 at 475 my, yellow from 550 m/u» upward and red from 650 my/upward. All 

 three filters had a transmittance factor of 857o. 



PROCEDURE 



Measured courses (Fig. 1) allowing for a 1 m^ sample were marked off 

 at each of five collecting stations which are described as follows: 



Station I - on the sand flat, 10 m from the foot of the reef and 50 m 

 from the habitat, at a depth of 23 m. 



Station II - on top of the reef between coral growths, 30 m from the 

 habitat, depth 14 m. 



Station III - along the unilluminated rear side of the habitat, 2 m 

 above the bottom, 13 m deep. 



Station IV - over the sandy bottom of a trench between two reef 

 formations, 40 m from the habitat and at a depth of 15 m. 



Station V - at the end of the sewer line, about 100 m from the habitat, 

 in the middle of a garden eel colony; sandy bottom, depth 25 m. 



These stations were visited at 0900, 1300, and 2200 hours, the first 

 collection being carried out on the 16th of October, two days after 

 full moon, the last on the 27th of October, three days before new 

 moon. The samples were made with the lower rim of the net approxi- 

 mately six inches above the substrate. Station II was chosen to give 

 clearance to the net between higher growths of coral and with only a 

 few small crevices at the bottom. The samples were rinsed in fresh 

 water and preserved in 47o formalin. In the case of the light 

 experiments, 2-liter samples were taken by means of a plexiglas 

 syringe. Sixteen combinations of light (two lamps, three color 

 filters and white light) were tested for half hour periods. 



VI-280 



