TECHNIQUES FOR CREATING SEAGRASS MEADOWS IN DAMAGED AREAS 

 ALONG THE EAST COAST OF THE U.S.A. 



Anitra Thorhaug 



Department of Microbiology 



University of Miami 



Miami, Florida 33124 



DECISIONS BY GOVERNMENT AGENCIES CON- 

 CERNED WITH RESTORATION OF SEAGRASSES 



The process of restoration is one 

 of the most hopeful avenues of biology 

 for dealing with man. However, until re- 

 cently, restoration of submerged vegeta- 

 tion was not even considered a possibil- 

 ity and waterfront construction was ex- 

 pected to do a certain amount of irre- 

 versible damage to the adjacent sublit- 

 toral communities. We can no longer 

 afford to have our remaining nearshore 

 submerged resources damaged by develop- 

 ment interests. Therefore, there are 

 two alternatives: (1) save the area 

 immediately adjacent to the coast as a 

 natural strip with no development and 

 build behind this or (2) carefully write 

 permits limiting what developers can do 

 to the submerged land and then enforce 

 these measures. 



In establishing guidelines for ra- 

 tional restoration of seagrasses (or 

 other plant species) the agency with au- 

 thority immediately encounters questions 

 which it is often not prepared to answer 

 in the early stages, but which are essen- 

 tial for a successful final product. 

 What size area should be restored? What 

 species should be planted? What stand 

 density should be achieved? What time 

 period can be permitted to achieve this 

 density? 



Site specific information is neces- 

 sary to answer the above questions. The 

 developers' report may not contain this 

 information or may not be credible. The 

 questions of the size area to restore 

 will be a site specific one. Filling 

 valuable waterfront acreage may be 

 judged to warrant from 3:1 to 10:1 (re- 

 stored acres: filled acre ratios). 

 Marina building or navigational channels 

 may possibly be assessed at 1:1 to 3:1. 

 The next question is where the restora- 

 tion will occur. At many sites the 



exact area to be impacted will be re- 

 stored after the impact has occurred. 

 Other sites will require adjacent areas 

 restored because the original site will 

 not be on land or will be too deep for 

 growth of seagrasses (as in the case of 

 channels). Often a previously damaged 

 site, at some distance from the impacted 

 site, is chosen. In choosing a second 

 site, one should keep in mind suitabil- 

 ity of this site for successful restora- 

 tion (physical, chemical, and geological 

 characteristics), as well as the biolog- 

 ical suitability of this site as a sub- 

 stitute for the original (in terms of 

 nursery area and other considerations). 



The species to be planted is usual- 

 ly the dominant species found in the 

 preimpact survey. However, there are 

 several exceptions. If the area had 

 previously been impacted by man's activ- 

 ities (such as by drainage canals or 

 other effluents), the original vegeta- 

 tion may have been supplanted by other 

 species. To reestablish the original 

 vegetation, rather than that presently 

 dominant, would usually be preferable 

 unless the water quality had changed so 

 much that the original vegetation could 

 not survive. If there are two or more 

 abundant seagrass species present, one 

 of the following plans can be chosen. 

 (1) Restore several species simultane- 

 ously; (2) restore the. fastest growing 

 species first to stabilize sediment and 

 prepare the area for revegetation; then 

 restore the slower growing species into 

 this matrix; (3) restore only the spe- 

 cies which will return very slowly by 

 natural means and allow the naturally 

 faster growing species to invade; (4) 

 restore only the species needed for a 

 purpose such as a food source or as 

 nursery-stock. 



Information is often incomplete for 

 such a decision. The decision of which 

 species to plant may have a large effect 



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