Plants at lower depths decreased and 

 then died. 



SEEDS 



Addy in 1947 planted Zostera seeds 

 but the plants did not grow. Phillips 

 planted 45 Zostera seeds in Puget Sound 

 anchored to iron pipes with rubber bands 

 and had no success, probably because the 

 seeds were transplanted from shallow 

 water to depths deeper than Zostera gen- 

 eral ly grows in the area, indicating 

 that seedlings may have high light re- 

 quirements. 



One of the most successful seeding 

 methods to date was that of Thorhaug 

 (1974). Roots were gathered by hand from 

 densely fruiting beds in the Caribbean. 

 They were immediately dehisced and the 

 seeds separated from the fruit pods. 

 Seeds were transported back to Miami un- 

 der running seawater conditions. Some of 

 the seeds were kept in a nursery while 

 others were immediately planted. Various 

 growth-promoting chemicals were used. 

 NAA soaks at 10% for 1 hr appeared to 

 have significantly increased root propa- 

 gation of the seedlings. Long soak times 

 and higher concentration of this auxin 

 did not appear to affect the root growth 

 significantly. 



Planting techniques include plastic 

 12-cm (5-inch) anchors (with monofila- 

 ment attached to locate the seedlings) 

 secured about each seedling. Two paral- 

 lel corridors (150 by 6 m or 492 by 

 20 ft) were planted at the Turkey Point 

 Power Plant discharge canal, Biscayne 

 Bay, Florida, in a 9.3-ha (23-acre) area 

 previously denuded of Thalassia and 

 other microphytes by heated effluents. 

 (Offstream cooling was employed at the 

 time of planting, so that thermal efflu- 

 ents were no longer being released.) 

 Previous to thermal discharges, this 

 area had supported a lush meadow of sea- 

 grasses. Seedlings began growing imme- 

 diately upon dehiscing. Up to 10 roots 

 per plant appeared in the first 3 weeks, 

 which enabled the plants to begin to 

 anchor themselves. After 4 mo, one api- 

 cal men stem per plant appeared on 50% 

 of the seedlings. After 5 mo, 89% of 

 the seedlings had apical meristems. 

 Thousands of seeds were planted in 

 mid-September 1973 at various intervals: 

 0.25, 0.1, and 0.5 m (0.82, 0.33, and 



1.64 ft). Leaf growth was vigorous in 

 the months immediately following the 

 planting. New short shoots were sent up 

 from the rhizomal apical meristem after 

 9 mo, and apical meristems were between 

 0.3 to 0.5 m (1 to 1.6 ft) (Table 2). 

 Leaf and rhizome growth was vigorous 

 after 8 mo; roots per blade group were 

 8.6 cm (3.4 in) with a maximum length of 

 roots 14.0 cm (5.5 inches). After 2.5 

 yr dense areas of Thalassia with 500- 

 1,000 blades/m 2 (46-93 blades/ft 2 ) had 

 developed in the transplanted areas 

 whereas control areas had to 10 

 blades/m 2 (0 to 1 blade/ft 2 ). The per- 

 centage of success was approximately 

 80%, which was higher than most of the 

 other methods. Twenty-one percent of 

 the plants were missing, and it is 

 estimated that 10% of these missing 

 plants remained in an area of several 

 hundred feet surrounding the planted 

 matrix. 



Observations showed that the animal 

 community began reestablishing itself 

 almost immediately after the transplants 

 were set. Foraminifera covered the young 

 seedling blades. Fish, certain crusta- 

 ceans, and mollusks moved back into the 

 area. (There has been no quantitative 

 study of animal community reassemblage 

 on any seagrass transplant effort.) The 

 Thalassia planted in a Halodule zone ap- 

 peared to grow more vigorously in the 

 first few months than that planted in a 

 zone of green algae (chiefly Penicillus 

 capitatus ), or that planted in a bare 

 peat zone. 



The major result from this large- 

 scale planting was that plants expanded 

 laterally in a vigorous manner within 

 the first year (rhizome length growing 

 to 0.5 m [1.6 ft] while sending up many 

 short shoots with further blade groups). 

 After 2.5 yr the transplant area was 

 covered with moderately dense Thalassia . 

 We are continuing to study this succes- 

 sion and hope to begin studying the ani- 

 mal community in the restored versus 

 natural and nonrestored areas. 



A second seedling feasibility study 

 was made in North Biscayne Bay, Florida. 

 Areas included dredge spoil islands; 

 bottoms damaged by sewage pollution, by 

 dredging or general urban runoff; areas 

 of high tidal currents; and areas of 

 shiftinq sand. Feasibility plots of 

 0.25 w? (2.6 ft 2 ) were planted in fall 



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