Ammen plants increasing in length faster than the coastal group 

 (4.38 vs 0.833 cm.mo' 1 , respectively). 



Figure 2 presents typical data for photosynthesis versus 

 irradiance curves of coastal Laminaria digitata following the 

 initial sampling of this population in June 1987. Similar curves 

 were obtained for all groups of plants, although values for 

 respiration, light compensation point, initial slope of the P vs I 

 response (alpha) and light saturated rates of photosynthesis did 

 vary between sites, and between plant group. These differences 

 were compared by using the P vs I curves to calculate the 

 following characteristics: respiration (umoles 2 . g f wt" 1 .hr' 1 ) : 

 the mean oxygen consumption in the dark; alpha ([umoles 2 . g f 

 wt" 1 .hr' 1 ]/ [umoles photons. m" 2 . s" 1 ]) : the slope of the initial, 

 light limited region of the P vs I curve; P max (umoles 2 . g f 

 wt" 1 .hr' 1 ) : the average value of light saturated photosynthesis; 

 I k , the photon flux density required to just saturate 

 photosynthesis (umoles photons. m" 2 . s' 1 ) : P max /alpha; the light 

 compensation point, where photosynthesis just balances respiration 

 (umoles photons. m' 2 .s" 1 ) : calculated from alpha values and 

 respiration rates. 



Figure 3 presents data on the maximum rate of photosynthesis 

 of the two groups of plants both initially and after growth at the 

 three transplant sites. Initial P m a x values were significantly 

 greater for coastal Laminaria digitata than Ammen plants (0.8 06 vs 

 0.234 umoles. cm' 2 . s" 1 ) . The P m a x of the coastal plants did not 

 change significantly at any of the transplant sites. In contrast, 

 Ammen plants transplanted to both the 1 and 15 m coastal sites and 

 the 30 m Ammen site did exhibit considerable increases in P m a x (to 

 between 0.526 and 0.683 umoles . cm' 2 . s" 1 ) , although the rates were 

 always lower than those of the coastal group. 



Alpha values for the initial and transplanted plants are 

 shown in Figure 4 . Alpha values of coastal plants were 

 significantly higher than those of the Ammen Laminaria in all 

 cases except the 15 m coastal site. Alpha values were highest in 

 the initial samples (0.052 and 0.035 [umole. cm" 2 .hr' 1 ]/ [umole 

 photons. m' 2 . s" 1 ] for coastal and Ammen plants, respectively) and 

 lowest in the 30 m transplants (0.052 and 0.035 [umole. cm' 2 

 .hri]/[umole photons .m" 2 . s' 1 ] for coastal and Ammen plants, 

 respectively) . 



I k values for photosynthesis are shown in Figure 5. There 

 were no significant differences between the two groups of plants 

 either initially or at any of the transplant sites. I k values 

 were lowest in the initial samples (7.21 and 15.60 umole 

 photons .m" 2 . s' 1 in Ammen and coastal plants, respectively) and 

 highest at the 30 m transplant site (7.21 and 15.60 umole 

 photons. m" 2 . s" 1 in Ammen and coastal plants, respectively). 



Figure 6 shows data for the light compensation points of 

 Ammen and coastal Laminaria sampled initially in June 1987 and 

 after growth at the transplant sites. With the exception of the 



31 



