Fig. 2. Detail map of MNPS vicinity. FL = original experimental Ascophyllum site (1979-1984), FN = new experimental 

 Ascophyllum site (1985-present). 



Data Analysis 



Relative abundance of intertidcil organisms was 

 estimated on the basis of percentage of substratum 

 covered by each taxon. Unoccupied substrata 

 were classed as free space. Similarity between 

 communities was determined by a standardized 

 percentage form of the Bray-Curtis coefficient 

 (Sanders 1960), calculated as: 



Sjk= Y.™^^PijPik) 



where P(i]') is the percentage of species (i) at sta- 

 tion (j), P(ik) is the percentage at station (k), and 



(n) is the number of species in common. A 

 flexible-sorting, clustering algorithm was applied 

 to the resulting similarity matrix. The calculations 

 were performed on untransformed percentages. 



Comparisons of pre-op and 3-unit operational 

 abundances were based on the 5-mean as an index 

 of abundance. This method utilizes the assump- 

 tion that the non-zero values of percentage cover 

 are log-normally distributed; a complete descrip- 

 tion of the 5-distribution and rationale for its 

 application is included in the Delta Distribution 

 section of this report. 



14 



