seeding and plugging, are feasible, and the advantages of each are dis- 

 cussed. The seeding method appears to be most advantageous for dredged 

 material stabilization. The plugging method is advantageous because plugs can 

 be taken from mature beds throughout the U.S. coastal waters, whereas seeds 

 are sparse or absent in many places. Plugging also may be done year round, 

 while seeding is best in fall or spring. 



130. THORHAUG, A., and AUSTIN, C.B., "Restoration of Seagrasses with Economic 

 Analysis," Ervoivonmental Conservation, Vol. 3, No. 4, 1976, pp. 259-267. 



Planting of seagrasses by use of plugs, turfs (sods), turions (shoots), 

 and seeds is briefly described from a review of some pertinent world litera- 

 ture. The economic analysis evidently applies only to the cost of seeding 

 Thalassia. Seeding densities to yield good cover in 2.5 years cost approxi- 

 mately $25,000 per 10,000 meters. If the same amount of cover is to be 

 obtained in 0.8 year the cost will be three to five times greater. 



131. THORHAUG, A., and HIXON, R. , "Revegetation of Thalassia testudinum in a 

 Multiple-Stressed Estuary, North Biscayne Bay, Florida," Proceedings of 

 the Second Annual Conference on Restoration of Coastal Vegetation in 

 Florida, Hillsborough Community College Environmental Study Center, 

 Tampa, Fla. , May 1975, pp. 12-27. 



Plantings of Thalassia testudinum were made in the multiple-stressed 

 estuary of North Biscayne Bay, Florida. Seeds were gathered by divers and 

 tested in the varying condition of light, temperature, and flowing seawater. 

 Seeds and seedlings were planted at eight field sites. The survival rate, 

 growth, rhizome frequency, and planting techniques are discussed. 



132. THORHAUG, A., BEARDSLEY, G., and HIXON, R. , "Large Scale Transplantation 

 of Thalassia in South Florida," Proceedings of the First Annual Confer- 

 ence on Restoration of Coastal Vegetation in Florida, Hillsborough 

 Community College Environmental Study Center, Tampa, Fla., May 1974, 

 pp. 18-21. 



The marine grass Thalassia testudinum has been transplanted by sprigs on 

 a small scale by several investigators in Florida. Sprig planting is time- 

 consuming and has limited value. Only rarely does a plant without the apical 

 meristem produce a new short shoot and thus grow laterally. The alternative 

 of seed planting had not been tested until this experiment. 



Fruit was collected manually by scuba divers. Seeds were dehisced by 

 mechanical shock of freshweater and immediately cleaned and separated from 

 fruit pod. Seedlings were rapidly transported to the planting area in aerated 

 running seawater. Various concentrations and the soak time of napthalene 

 acetic acid were tested. Seedlings were kept agitated in seawater until 

 planted. Two 150-meter transects were established at Turkey Point, Biscayne 

 Bay, Florida. These transects included three major zones of regrowth: Ealo- 

 dule wrightii, green siphonaceous algae, and bare peat. Part of the plants 

 were anchored with plastic anchors, and part were without anchors. Planting 

 was at 0.5, 0.25, and 0.1 meter in a pattern repeated every 50 meters. Approx- 

 imately 15,000 seedlings was planted. Growth was vigorous. Mean growth of 

 blades after 8 months was 16.5 centimeters. Approximately 80 percent of the 

 plants remained in position; 10 percent washed out and were found in the 

 immediate area of transplanting. 



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