Maine (see Witman and Sebens 1988). These experiments included 

 artificial plates, granite slabs and blocks, artificially created 

 patches on rock wall surfaces, and natural patches in monitored 

 quadrats on rock walls. The purpose of this set of experiments 

 was to determine which species make up the early successional 

 assemblage and to find out how they occupy space and interact 

 with each other as a function of depth. In addition, we explored 

 the effects of substratum angle, large predator exclusion, and 

 water flow on the early stages of community development. Some of 

 the experiments have run for over two years to date, and we 

 expect to monitor them for several more years to determine how 

 long the entire process of community development must proceed 

 before all or most of the characteristic species have become 

 established. In this report, we present data from our first year 

 of settling plate experiments and we discuss the design of our 

 overall experimental study of community development. 



METHODS 



Artificial Settlement Panels 



In July 1985 we deployed concrete bases with upright PVC 

 corner pipes slit vertically so that settling plate racks could 

 be slid into place and removed easily using the mechanical arm of 

 the Johnson Sea Link submersible. Each removable rack held 

 twelve panels on its outer and inner surfaces, the inner surface 

 receiving somewhat less water movement and the outer surface 

 being exposed to ambient currents without obstruction (Fig.l). 

 Plates (7.5 x 7.5 cm) were constructed of 6 mm thick plexiglas 

 roughened on both sides using sandpaper. They were attached to 

 the rack with a central stainless steel nut and bolt through 

 holes in both inner and outer panels at any one position on the 

 rack. Panels thus formed a square surface approximately 34 cm on 

 a side, with 0.5 cm between plate edges. Completed racks were 

 delivered to the bottom stations on concrete bases (Depth- 

 Specific-Research-Station, or DRS ) using the Johnson Sea Link 

 submersible and were placed in position with the mechanical arm. 

 At the 30 and 50 m stations, small cable ties were used to secure 

 the racks to the DRS to prevent movement by wave surge. Racks at 

 30 m depth were placed and removed by SCUBA divers. 



Racks of panels were collected the following year using the 

 submarine's mechanical arm to lift each rack by a T-handle on 

 top and then to turn the rack so that it faced the front rack of 

 the submersible on which a Hasselblad camera with a framer rack 

 was mounted. The framer allowed positioning of the plate rack so 

 that it was completely in view and in focus. Film was 6 x 6 cm 

 format Ektachrome color transparency film, which gave excellent 

 resolution for each plate in the rack. Racks were then placed 

 individually in the front collecting basket of the submersible, 

 positioned so that plate surfaces were free of any contact. Once 

 brought back to the surface, plate racks were immediately 

 immersed in flowing seawater containers for 6-48 hrs. Six panels 

 were removed from each side of each plate rack, photographed 



47 



