Ascophyllum in our area has proven to be a particularly sensitive 

 indicator of thermal incursion. Analyses of data from three growing 

 seasons show year-to-year variability in total growth, but extremely 

 consistent seasonal and station-to-station trends. At all stations, 

 growth starts in March - April; maximum growth rates occur July - August, 

 and growth is very low in late autumn and winter. Ascophyllum is not 

 present within 25 m of the discharge, but plants at the experimental 

 stations (FL, 70 m from discharge and FH, 100 m) grew significantly 

 faster than at the control stations (WP, 2 km from discharge and GN, 6 

 km). Average growth is illustrated in Figure 7. The ability of Ascophyllum 

 to respond to a slight thermal enhancement emphasizes its applicability 

 as a monitoring tool. Ascophyllum mortality, measured as plant loss and 

 tip loss, is also variable between years; however, no station-to-station 

 trends are evident, and mortality is not correlated with proximity to 

 discharge. 



The Ascophyllum growth studies, together with the proposed Ascophyllum 

 recolonization experiments, will provide base-line data that will be 

 particularly useful in assessing the impact of the quarry cut widening 

 and Unit 3 operation. If the increased volume of heated effluent has 

 any biological impact on the rocky shore, it will be evidenced first in 

 the Ascophyllum populations near Fox Island. 



SUMMARY AND CONCLUSIONS 



The present rocky shore sampling program was designed to assess the 

 effects of operation of Millstone 1 and 2 and the construction of Millstone 

 3 upon the intertidal community in the vicinity of Millstone Point. The 

 sampling sites (Fig. 2 and 3) were selected to represent a range of 

 exposure to prevailing wind and waves, from relatively high exposure 



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