individually using 35 mm Kodachrome 64 film, then preserved in 

 buffered formalin in seawater and transferred to 70% ethanol 

 after several days for long-term storage. We noted that the 

 erect fan-shaped, bryozoan Idmidronea atlantica did not survive 

 transport and handling very well; the initial Hasselblad photos 

 were thus the only accurate record of its abundance. After 

 storage, Idmidronea was removed by clipping each colony just 

 above its small encrusting base. Plates were photographed again, 

 this time using black and white Panatomic X film in the 

 laboratory. 



Abundances of individual species on the collected plates 

 were quantified by tracing outlines of the colonies or 

 individuals on clear plastic overlays of the final black and 

 white photos, digitizing the outline on an Apple II 

 microcomputer with graphics tablet digitizer, then using the 

 Apple II program to calculate surface area of the colony (method 

 in Sebens 1986). Once the tracing map was complete, the 

 shipboard 35 mm photographs were projected onto the tracings to 

 determine if any colonies had been lost during transport and 

 storage. Any that appeared were then traced onto the final map. 

 Imidronea atlantica was traced on paper from the original 

 Hasselblad photographs; the area circumscribed by the branch 

 tips was digitized and calculated in the same manner. The tube- 

 worms Spirorbis spp. were counted directly on each plate, then a 

 subsample of 20 individuals was digitized for surface area and 

 counts were converted to area where needed. Total bare space on 

 panels was calculated by overlaying a grid of 200 randomly placed 

 2 mm circles on the final outline map of the plate and counting 

 the number of dots that fell on unoccupied space (method in 

 Sebens 1986). Another category of 'unoccluded space' was 

 defined as the amount of bare space that was not also covered by 

 the canopy of Idmidronea , which usually reached down to within a 

 millimeter or two of the substratum. This was also determined 

 using 200 random circles. All percent cover values were arcsine- 

 transformed for calculation of mean and standard deviation. 

 Differences between inner and outer groups and between depths 

 were tested with Analysis of Variance followed by Student-Newman- 

 Keuls Multiple Comparison Test ( Sokal and Rohlf, 1969). Bryozoan 

 species were identified using several sources, primarily Osburn 

 (1910) and Rogick and Croasdale (1949). In addition to the 

 plates collected after one year, the other twelve plates per rack 

 were returned to the appropriate DRS and twelve new plates were 

 attached to record the second year's initial community 

 development. Panels that were not removed were used to record 

 the second and third year of community development. 



Granite Blocks and Slabs 



Granite blocks (15 x 30 x 10 cm approx. dimensions) were 

 embedded two per concrete base with rope handles, then were 

 placed at all depths (30, 50, 65, 80 m) in summer 1985. Upper 

 surfaces of these blocks were photographed by SCUBA divers at 30 

 m and by the 35 mm camera on the Johnson Sea Link at all other 



49 



