SUMMARY 



1 . Water temperature is an important environmental parameter afTecting local rocky intertidal communities. 

 At sampling stations exposed to ambient water temperatures, communities closely resemble those 

 studied throughout New Bngland. The Millstone area flora has exhibited consistent patterns of spatial 

 and temporal distribution during 2-unit operation. Since 1979, 158 species have been reported: 73 

 reds, 40 browns, and 45 greens. Quantitative studies show intertidal /.onation patterns typical of rocky 

 shores throughout New England: the high intertidal was dominated by barnacles, the mid intertidal 

 by barnacles and fucoids, and the low intertidal was dominated by Chondrus. Degree of exposure to 

 waves and storms played a determining role in the structure of rocky intertidal communities, either 

 directly by minimizing desiccation and providing nutrients, or indirectly by influencing the distribution 

 of grazers and predators. Changes to local rocky shore communities have been minor (except for the 

 alteration at FE after the second cut opening) and predictable, based on naturally occurring cycles, 

 indicating that environmental conditions during 2-unit operation have been stable. 



2. The intertidal community at Fox Island-Exposed was unimpacted by 2-unit operation, prior to the 

 opening of the second quarry cut in August 1983. Subsequent qualitative and quantitative collections 

 show exceptions to the typical spatial and temporal trends noted elsewhere (and evident at FE 

 previously). Physiological limits of many species were exceeded at 28 "C in late summer 1984, resulting 

 in a decrease in species number at FE. Perennials were replaced by opportunistic species (ephemerals); 

 a decrease in browns with a concomitant increase in greens with extended temporal patterns was 

 reported. The resulting community resembled that found in the discharge quarry. 



3. Recolonization experiments were undertaken to isolate factors that influence the stnicture of local 

 rocky intertidal communities. In the Millstone area, recolonization was influenced by time of year in 

 which denuding occurred, and it was related to degrcx of exposure and intertidal height. For example, 

 -ecolonizafion was rapid in the high intertidal of an exposed station and slow in the low intertidal of 

 a sheltered station. 



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