The populations of Ascophyllum at our study sites have remained 

 stable over the past four years (in terms of abundance measured as 

 percent cover), implying that plant growth is balanced by loss of plant 

 materia] over the year. Other researchers (e.g., Chock and Mathieson 

 (1983), working in New Hampshire) have reported that 50% of the autumn 

 standing crop is lost to storms and ice-rafting. In our area as well, 

 plant loss was related primarily to storms in autumn (Fig. 7a) . The 

 gradual loss of plants at Giants Neck through the summer may have been 

 attributable to bathers and fishermen. In this study, the term "plant 

 loss" is not meant to imply removal of holdfast and all attached axes, 

 but onl}' breakage oi the axis lielow tlie base tag. Recovery of 

 Ascophyllum populations onto denuded substrata is very slow (Knight and 

 Parke 1950); but if the holdfast survives, other axes can continue to 

 grow (Printz 1956; Baardseth 1970; Keser et al . 1981). Vegetative 

 propagation and lateral proliferation can quickly replace lost material, 

 maintaining the extensive Ascophyllum populations in our study area. 



Breakage could also occur above the base tag, either between the 

 base tag and the colored tape used as a tip tag, or between the tip tag 

 and the growing apex. Therefore, tip mortality was examined in two 

 ways; as surviving tapes, and as surviving tapes with at least one 

 viable apex. This distinction was made to determine if the causes of 

 mortality differed between stations. Loss of tip tags implies 

 mechanical removal and immediate loss of plant material. Loss of viable 

 apices may reflect a more subtle effect; damage to the apical cell would 

 imply a potential loss of biomass, due to lack of growth. However, 

 viable tip loss and tape loss decreased by about the same order of 

 magnitude within stations from month to month (indicating mortality due 

 to breakage of the branch below the tape) , and only the loss of tagged 

 tips is presented (Fig. 7b). 



A different pattern was noted last year (NUSCo 1983); at the Fox 

 Island statioi: during the summer months, there was high tip mortality 

 while most tapes remained intact. This loss of tips was attributed to 

 heavy epiphytism, causing snagging and increased resistance to wave 

 action. Fpiphytism was not seen to be a contributing factor to apical 

 damage in the 1982-83 growing season. Grazing by Littorina , however. 



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