115. SAND- JENSEN, K. , "Biomass Net Production and Growth Dynamics in an Eel- 

 grass iZosteva mavina L.) Population in Vellerup Vig, Denmark," Ophelia, 

 Vol. 14, Helsingaer, Denmark, Nov. 1975, pp. 185-201. 



The biomass of an eelgrass population in Vellerup Vig, Denmark, showed a 

 seasonal pattern, March to October 1974, with the peak in August. Biomass of 

 leaves and flowering turions was quadrupled; biomass of rhizomes doubled from 

 March to August. The maximum total biomass was 433 grams dry weight per 

 square meter. The leaf population was determined by a leaf -marking technique, 

 which also made it possible to estimate the rhizome population. From 9 April 

 to 16 October 1974, the leaf production was 856 grams dry weight per square 

 meter and the rhizome production 241 grams dry weight per square meter, which 

 made a total of 1,097 grams dry weight per square meter. The dominance of 

 leaf production, though leaf and rhizome biomass were of the same magnitude, 

 resulted from a higher turnover rate of leaves ,(1.8 percent per day) than of 

 rhizomes (0.7 percent per day). On the average a new leaf was produced on 

 each turion every 14 days. The lifespan of the leaves was about 56 days. 

 Total radiation and not temperature seemed to control leaf production. The 

 maximum leaf production rate of 7.9 grams dry weight per square meter per day 

 in mid-June coincided with maximum radiation. The total production was 3.8 

 times the net increase of total biomass and 2.5 times the maximum total 

 biomass. 



116. SCHUBEL, J.R., "Some Coimnents on Seagrasses and Sedimentary Processes," 

 Special Report No. 33, John Hopkins University, Chesapeake Bay Institute, 

 Baltimore, Md., Nov. 1973. 



This report provides a brief review of some of the important relation- 

 ships between seagrasses and sediments, and indicates a few of the problem 

 areas where further research is needed. 



117. SCOFFIN, T.P., "The Trapping and Binding of Subtidal Carbonate Sediments 

 by Marine Vegetation in Bimini Lagoon, Bahamas," Jourmal of Sediment 

 Petvology, Vol. 40, No. 1, Mar. 1970, pp. 249-273. 



In the shallow-water lagoon of Bimini, Bahamas, the following plants are 

 sufficiently abundant to influence sedimentation locally: red mangroves 

 (Rhisophova mangle), turtlegrass {Thalaesia testudinum) , macroscopic green 

 algae {Peniaillus, Batophora, Halimeda, Hhipoaephalue, and Udotea) and micro- 

 scopic red, green and blue-green algae-forming surface mats of intertwining 

 filaments iLauvenoia, Enteromorpha, Lynghya, and Sahisothrix) . Plants were 

 observed under conditions of tidal currents and artificial unidirectional 

 currents produced in an underwater flume, and measurements were made of the 

 abilities of the plants to trap and bind the carbonate sediment. The density 

 of plant growth is crucial in the reduction of current strength at the 

 sediment-water interface. The most effective baffles are Rhizophora roots 

 exposed above the sediment, dense Thalassia blades and Thalassia blades with 

 dense epiphytic algae, Lauvenaia intvioata and Polysiphonia havanensis* All 

 three types can reduce the water velocity from a speed sufficiently high to 

 transport loose sand grains along the bottom in clear areas (30 centimeters 

 per second) to zero at the sediment-water interface in the vegetated areas. 

 The strongest binders of sediment are the roots of Rhizophora and Thalassia. 

 These two hardy plants trap and bind sediment for a sufficient time to produce 

 an accumulation higher than in nearby areas without dense mangroves or grass. 

 Macroscopic green algae growth is not sufficiently dense, and the holdfasts 



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