1 m transplant site compensation points were always higher in 

 coastal than Ammen plants, although the difference was only 

 significant at the 30 m site. Significant differences did occur 

 between the two plant groups when data for all of the sites were 

 considered together. The only significant difference within 

 either of the groups of plants with respect to depth was in the 

 Ammen plant at the 30 m site, which had much lower compensation 

 points than those for this group at any other site (2.61 vs 8.26- 

 11.37 umole photons. m' 2 .s" 1 , respectively). 



Figure 7 presents data on the rates of respiration of the 

 Ammen and coastal plants. In all cases the respiration rates of 

 coastal plants were higher than those for the Ammen group. 

 However, these differences were only significant for the initial 

 samples and when the data for all sites were pooled. 



Figure 8 shows RUBISCO activities of the two groups of plants 

 following initial sampling and after growth at the transplant 

 sites. Significant differences occurred between the two groups of 

 plants both initially and at the 30 m site, with coastal plants 

 having higher values than the Ammen group. RUBISCO activities of 

 the coastal Laminaria were 20.96 and 44.04 nmoles.g f wt ' 1 .min' 1 

 initially and at 30 m, respectively, while those of the Ammen 

 plants were 10.35 and 13.36 nmoles.g f wt" 1 .min" 1 initially and at 

 30 m, respectively. RUBISCO activities declined in both groups of 

 plants transplanted to the 1 and 15 m coastal sites and did not 

 differ significantly between the two groups being approximately 

 3.00 nmoles.g f wt' 1 .min" 1 in all cases. 



Figures 9, 10, and 11 present data on cellular concentrations 

 of photosynthetic pigments (chlorophyll a, chlorophyll c and 

 fucoxanthin, respectively) in Ammen and coastal Laminaria . With 

 the exception of the 15 m site, coastal plants had significantly 

 more chlorophyll a than the Ammen group (Figure 9) . Highest 

 chlorophyll a levels were found in the initial, June 1987, samples 

 (0.353 and 0.661 ug.cm" 2 in Ammen and coastal plants, 

 respectively) and lowest values in the 30 m site (0.137 and 0.321 

 ug.cm' 2 in Ammen and coastal plants, respectively), with 

 intermediate levels occurring at the 1 and 15 m coastal sites. 

 Chlorophyll c (Figure 10) and fucoxanthin (Figure 11) levels did 

 not differ significantly either between sites or between the two 

 plant groups with the exception of fucoxanthin in coastal 

 Laminaria which were initially higher than those of Ammen plants 

 (0.369 and and 0.201 ug.cm" 2 , respectively). 



Figure 12 shows calculated rates of net carbon fixation in 

 the Ammen and coastal Laminaria populations over a range of daily 

 photon flux densities supplied in a 20:4 L:D photoperiod. Rates 

 were calculated from measured rates of respiration and 

 instantaneous P vs I responses assuming that total daily 

 irradiance was averaged egually over the entire photoperiod. 

 Calculated rates of net carbon fixation were greater in Ammen 

 plants than the coastal population below a photon flux density 



34 



