are too weak to appreciably affect the accumulation of sediment although they 

 provide a degree of stabilization to the substrate. Algal mats trap sediment 

 chiefly by adhesion of grains to the sticky filaments. Their ability to 

 resist erosion by unidirectional currents varies considerably depending on mat 

 type, smoothness of surface and continuity of the cover. The intact areas of 

 dense Enteromorpha mats can withstand currents five times stronger than those 

 that erode loose unbound sand grains. Premature erosion of mats by currents 

 occurs at breaks in the mat surface caused by the burrowing action of ani- 

 mals. Algal mats were found to be ephemeral features and consequently do not 

 build up thick accumulations of sediment as do dense grass and mangroves. The 

 thickest accumulation of sediment in the lagoon correlate with deepest bedrock 

 surfaces. The distribution of many plants in the lagoon is directly and 

 indirectly controlled by the depth to bedrock; e.g., red mangroves on high 

 bedrock, turtlegrass in sediment-filled depressions. 



118. SOMERS, G.F., ed. , "Seed-Bearing Halophytes as Food Plants," Report No. 

 DEL-SG-3-75, College of Marine Studies, University of Delaware, Newark, 

 Del., June 1974. 



The report discusses seed-bearing halophytes as food sources for man and 

 domesticated animals. Contributions covered such subjects as domestication of 

 wild rice, use of seagrasses and terrestrial halophytes as food plants, adap- 

 tation of present crops to saline habitats, and problems in managing saline 

 soils. 



119. STEVENSON, J.C., and CONFER, N.M. , "Summary of Available Information of 

 Chesapeake Bay Submerged Vegetation," Report No. FWS/OBS-78/66, Office of 

 Biological Services, U.S. Fish and Wildlife Service, Washington, D.C., 

 Aug. 1978. 



Submerged aquatic species tend to inhabit the shallow, shoreline areas of 

 the bay and its subestuaries, primarily limited to depths of 3 meters or less. 

 Species vary as to salinity and temperature tolerance, morphology, preferred 

 bottom substrate, susceptibility to chemical pollutants, and general distri- 

 bution. There are approximately 11 species of submerged aquatic vegetation 

 dominant in the waters of the Chesapeake Bay. Submerged aquatic flora con- 

 stitutes the principal source of food for waterfowl and some fish; the flora 

 provides direct and indirect food and shelter for many of the small host 

 organisms that are eaten by fish and other predators. The spawning activities 

 of certain organisms require submerged aquatic vegetation. The vegetation 

 purifies the water by removing various noxious substances and returning 

 oxygen, shades the underlying waters and sediments from solar heating, and 

 provides an important source of detritus. Submerged aquatics help stabilize 

 sediments and reduce shoreline erosion. 



120. TAYLOR, J.L., SALOMAN, C.H. , and PREST, K.W. , Jr., "Harvest and Regrowth 

 of Turtle Grass (Thalassta testudinum) in Tampa Bay, Florida," Fiehevies 

 Bulletin, Vol. 71, No. 1, Jan. 1973, pp. 145-148. 



A comparison of leaf growth and new leaf production in plots of cut and 

 uncut turtlegrass (Thalassia teetudinum) indicated that plants suffered no 

 damage when harvested twice during a 6-month season in Boca Clega Bay (Tampa 

 Bay), Florida. In deeper or warmer waters where the growing season is pro- 

 tracted, three or more cuttings per year may prove practical. 



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