shore and density often decreases sea- 

 ward. This pattern is unfortunate be- 

 cause man's impacts generally occur im- 

 mediately adjacent to the shoreline; if 

 the seagrasses were richer in the off- 

 shore waters the severity of man's im- 

 pact on seagrasses might be lessened. 

 Seagrasses support a rich community of 

 invertebrates and fishes, indeed the 

 Thalassia community is one of the rich- 

 est known in the tropics, rivaling that 

 of the coral reef in diversity and num- 

 bers of animals (de Sylva 1976; Voss 

 1976; Thorhaug and Roessler 1977). When 

 the seagrasses are removed, the animal 

 community becomes depauperate in those 

 areas (Bader et al . 1972; Roesser et al . 

 1974; and Thorhaug et al . 1974). 



Another major point is that after 

 being removed, regrowth of seagrass oc- 

 curs very slowly, especially for Thalas- 

 sia , the dominant species in the sub- 

 tropical and tropical climates. Revege- 

 tation rates vary among species of sea- 

 grasses. Thalassia testudinum has not 

 recolonized in many areas in South Flor- 

 ida and the Caribbean even 50 years 

 after it was removed. 



NEEDS FOR RESTORATION OF SEAGRASSES 



Why do we need to restore seagrass- 

 es? First, many marine and estuarine 

 areas throughout the continental United 

 States and Caribbean are increasingly 

 being damaged by man's activities. Very 

 often this damage occurs just adjacent 

 to the shoreline where seagrass communi- 

 ties are present, and years or decades 

 are required for them to return natural- 

 ly to their former condition. The impact 

 is often a combination of effects such 

 as urban runoff, sewage, bul kneading, 

 and others. It is in the public interest 

 to restore thse biologically rich areas 

 for recreation, sport and commercial 

 fisheries, esthetic considerations, and 

 sediment retention (worth $83,000/acre). 



Second, it is important to restore 

 seagrass into areas directly damaged in 

 the past by building programs (such as 

 filled areas for bridges and causeways 

 or artificial land formations) accom- 

 plished before restoration techniques 

 were available. Thirdly, the seagrasses 

 are one of the few groups of marine 

 plants known to have diseases. In the 

 1930's, most of the eel grass in the 



North Atlantic disappeared due to the 

 "wasting disease"; changes in the popu- 

 lations of the associated animals occur- 

 red. The U.S. Fish and Wildlife Service 

 pioneered the restoration efforts in the 

 United States for seagrasses after the 

 wasting disease. However, a solution 

 was never found. It seems highly desir- 

 able to have techniques to replant sea- 

 grasses if this phenomenon occurs again. 



HISTORY OF RESTORATION OF SEAGRASSES 



The history of restoring seagrasses 

 is in its infancy, compared to restora- 

 tion of other plant systems, for the 

 same reasons that major work in sublit- 

 toral marine botany is very recent com- 

 pared to that of land botany. Seagrass 

 restoration began almost simultaneous 

 with the development of SCUBA equipment. 

 In 1947 Addy attempted seagrass trans- 

 planting for the U.S. Biological Survey 

 on the Northeast coast of the U.S. as 

 well as between Pacific and Atlantic 

 coasts to recolonize stocks denuded by 

 wasting disease; there were no notable 

 achievements and many transplants fail- 

 ed. In 1960 the Florida State Board of 

 Conservation became concerned about the 

 effect of real estate development in 

 shallow bays. From 1960 to the present 

 the latter organization has attempted 

 transplants mostly with plugs (Fuss and 

 Kelley 1969; Kelly et al . 1971; Phillips 

 1974, Phillips in this volume; and Van 

 Breedveld 1976). Van Breedvelds' at- 

 tempts with a posthole digger were the 

 most successful. 



Phillips in 1964 and 1965 conducted 

 reciprocal transplant experiments across 

 tidal zones in Puget Sound and trans- 

 plants between Alaska and Puget Sound 

 (Phillips 1974). An attempt at turfing 

 seagrasses by Ranwell et al . (1974), who 

 transplanted Zostera nol tii and Zostera 

 marina on a pilot trial scale in Norfolk 

 and Suffolk, Great Britain on intertidal 

 mud flats, was successful. The most pro- 

 mising method of large-scale restoration 

 of seagrass communities has been by 

 seed. The first large-scale restoration 

 by seed was done by Thorhaug (1974) in 

 Biscayne Bay, Florida. Thorhaug and 

 Phillips are both presently working on 

 transplantation techniques. 



The objectives of this section of 

 the paper are to review the techniques 



107 



