0%o 



10%° 20%, 



* 05 



6 01 

 6 



~i 1 - 



RESPIRATION 

 I I 



10 20 30 



ii g No CI/ mg wet Sport/no 



Figure 7. Respiration of Spartina leaves 

 grown at different salinities. The data 

 are for leaves of different ages, with the 

 youngest leaves represented by the top 

 line (J.M. Teal, unpubl. data). 



Figure 6. Salt crystals on a leaf of 

 Spartina alterniflora resulting from the 

 drying of solution secreted by the salt 

 glands on the leaves. Photo by J.M. Teal, 

 Woods Hole Oceanographic Institution. 





<\i 



20 25 30 35 40 45 



Although Spartina can effectively 

 deal with salts at normal seawater 

 concentrations, there is a limit to that 

 tolerance. As salinity increases, the 

 plants exhibit higher respiration rates 

 (Figure 7) and reduced productivity 

 (Figure 8). Above salinities of 40-45 ppt 

 thousand), the increased 

 and reduced growth become 

 obvious (Woodhouse et al. 

 and Dunn 1976). Survival at 

 these elevated salinities decreases as 

 length of exposure increases. 



(parts per 

 respiration 

 particularly 

 1972; Haines 



Spartina depends on the integrity of 

 its salt barrier to maintain its salt 

 balance. Damage to the salt barrier 

 allows full-strength seawater to enter the 

 plant, disrupting the salt balance and 



ki 



S 



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Figure 8. 



at various 

 weight and 



20 25 30 35 40 45 

 INTERSTITIAL SALINITY (%o) 



Growth of Spartina alterniflora 

 salinities as measured by wet 

 by leaf area (Nestler 1977). 



13 



