used them to plant several eroding shore sites. They found these cordgrass- 

 mussel plugs (termed "bioconstructs") to be more tolerant to wave activity 

 than other plugs (Fig. 27). Locating a harvestable source for this type of 

 plug will be considerably more difficult; however, where available, bio- 

 constructs are advantageous . 



Figure 27. Cordgrass-mussel plugs of Pacific cordgrass. 



b. Soils and Salinity . Pacific cordgrass can be established in either 

 sand or fine-grained sediments. However, it is more likely to be nutrient- 

 limited in sandy substrates (Barko, et al., 1977). Purer (1942) observed 

 cordgrass in saline environments from 22 to 30 parts per thousand. Floyd and 

 Newcombe ( 1976) found germination rates higher in freshwater than in salini- 

 ties of 10, 20, and 30 parts per thousand. Phleger (1971) subjected adult 

 Pacific cordgrass plants to salt solutions of to 40 parts per thousand and 

 found that growth was best in freshwater. However, the Phleger experiment 

 lasted only 8 weeks and should not be considered conclusive. The transplanted 

 adult plants certainly began the experiment with an accumulation of salt in 

 plant tissues. In general, plantings are not likely to be effective when used 

 in saline environments much above 35 parts per thousand. 



c. Planting Zone . Submergence by the tides is probably the most impor- 

 tant environmental factor affecting the distribution of intertidal plants. 

 Pacific cordgrass is remarkably well adapted to withstand long periods of 

 inundation. Most plants exchange gasses (breath) through small openings in 

 their leaves known as stomata (from Greek meaning "mouth"). In Pacific cord- 

 grass the stomata are sunken, and the "liplike" guard cells which surround the 

 stomata are accompanied by subsidiary cells equipped with branched papilla 

 (tiny fingerlike projections). It is speculated that these papilla trap air 

 bubbles and prevent the wetting of the stomatal apparatus during submergence 

 (Kasapligil, 1976). Like several other members of the genus Spartina, smooth 



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