Exclusion cages 



Four series of exclusion cage studies at each of the four recolonization stations were undertaken to 

 determine the effects of grazing and predation on recolonization rates and patterns. The first series began 

 in April 1979; nine areas were selected at each station, three areas in each of three tide zones (high, mid, 

 and low tidal levels). In each area, two 20 x 20 cm patches were burned and cleared; one was covered 

 with a stainless steel mesh cage (20 x 20 x 5 cm, 3 mm mesh), the second left as a control. Each month 

 the percent cover of colonizing organisms was determined. The effect that season of denuding had on 

 rates and patterns of recolonization was determined, as with the recolonization transect experiments. 

 Subsequent series of exclusion cage experiments began in June 1980, September 1981, and December 1982; 

 each area was rebumed 15 months after the previous denuding. 



The complete series of recolonization experiments (strip transects and exclusion cages) was completed 

 under two-unit operating conditions by March 1984, but the recolonization strips were monitored bimonthly 

 until March 1986 to assess long-term recovery. The observed degree of recolonization provides a base-line 

 against which to compare the impact of Unit 3 on rates and patterns of community recovery. The entire 

 series of experiments will be repeated under three-unit conditions. 



Ascophyllum nodosum Studies 



Growth and mortality of populations of the brown perennial alga, Ascophyllum nodosum, were studied 

 at two control stations (GN, 5.5 km west of the discharge and WP, 1.5 km east of the discharge, Fig. 2) 

 and an experimental station (FF, ca. 75 m east of the original Millstone quarry cut. Fig. 3) from 1979-1984 

 Ascophyllum was eliminated from FL in summer 1984, its loss attributed to elevated water temperatures 

 resulting from the thermal plume of two operating units discharging through two quarry cuts (NUSC'o 

 1985; also Appendix RS IV, Ecological Significance of Community Changes at Fox Island). In spring 

 1985 a second experimental Ascophyllum station (FN) was established between FE and I'S (Fig. 3; ca. 

 250 in from the quarry discharges, northeast of the Fox Island-Exposed sampling site). 



Ascophyllum plants were measured at monthly intervals from April, after the onset of new vesicle 

 formation, until the following April. Fifty plants at each station were marked with a numbered plastic 

 tag at the base of each plant, and five apices were marked on each plant with colored cable ties (prior to 



