II-E-9 



Burkholder, P.R., L.M. Burkholder, and J. A. Rivero. 1959. Some chemical 



constituents of turtle grass, Thalassia testudinum . Bulletin of the 



Torrey Botanical Club 86:88-93. 



This study was initiated in order to find out more about the magnitude, 

 chemical composition, and possible value of Thalassia to the marine 

 life of tropical regions. Some simple comparisons of proximate analyses 

 were made between Thalassia and other primary crops of grasses from 

 Georgia, and phytoplankton from Long Island Sound. 



Determinations were made for several parameters, such as protein, fat, 

 ash, and crude fibre, on various materials. It was found that turtle 

 grass, Thalassia testudinum , is abundant in the shallow, well-illuminated 

 waters of Puerto Rico and other tropical areas. The standing crop of 

 Thalassia , ranging up to about 33 tons per acre, provides shelter for 

 many species of animals and contains large amounts of basic foodstuffs 

 in the form of proteins (13 percent), crude fibre (16 percent), and 

 other carbohydrates (36 percent). 



Quantitative determinations of aspartic and glutamic acids and ten 

 essential amino acids were performed. Among the 12 amino acids assayed, 

 the most abundant were aspartic and glutamic acids, arginine, lysine 

 and leucine. Tryptophan was relatively scarce. 



The quantitative distribution of marine bacteria, adjacent to and in 

 beds of Thalassia , was studied in a channel lying between Magueyes 

 Island and the mainland near La Parguera. It was determined that marine 

 bacteria convert organic constituents of Thalassia to microparticulate 

 food suitable for protozoa, which are in turn available to smaller and 

 larger animals. Microscopic studies on microbial decomposition of 

 non-sterile, macerated Thalassia leaves indicated that '^ery large 

 populations of bacteria rapidly developed, and that these, in all 

 experiments with mixed cultures, were promptly followed by tremendous 

 growths of ciliated protozoa. It seems probable that many predatory 

 animals, which live in the meadows of turtle grass, may be feeding 

 upon microbial populations of bacteria, ciliates, and other transformers, 

 which are supported by chemical constituents of Thalassia . Some fishes, 

 notably the ballahoo, may feed almost exclusively on leaves of Thalassia 

 at certain times. It seems probable, however, that the greatest use 

 of the primary production of turtle grass is mediated through microbial 

 conversions of organic matter in the leaves, rhizomes and roots. (H.D.) 



Keywords: turtle grass, productivity, phytoplankton, Puerto Rico 



86 



