at least three types of angiosperm vegetation can be associated with 

 lagoons. In temperature regions, there can be salt marsh and eel-grass 

 meadows while in the tropics there will be marine grass meadows and 

 mangrove vegetations. In addition, marine algae will be associated 

 with all three types. There are three major types of substrate 

 upon which the angiosperms can grow: mud, sand, and coral. The latter 

 is occupied only by mangrove trees. The environmental factors vary 

 depending upon the kind of lagoon. Tidal movement may be pronounced 

 or greatly dampened if the lagoon is wholly cut off from the sea. 

 Salinity may be that of ocean water; it may be much less if a major 

 river enters the lagoon, or in the tropics the water may become hyper- 

 saline through evaporation. Atoll lagoons will tend to have clear 

 water except during storm periods, whereas in sounds and calderas the 

 water is turbid from suspended silt, and the geological work of salt 

 marsh and mangrove plants can be very significant. Currents, especially 

 in sounds, must affect mangrove distribution, while wave action will 

 have an effect upon the aquatic phanerogams. Accretion of sand and 

 mud brings about slow elevation of the land and the gradual narrowing 

 of the lagoon through the slow and steady invasion of mangrove and 

 salt marsh plants. In enclosed lagoons water temperature may rise 

 considerably above that of the external seawater, but this does not 

 materially affect mangroves. A few measurements have been made of the 

 biomass of mangrove, sea-grass meadows, and salt marsh. In view of 

 the proximity of many lagoons to human settlement, there is a tendency 

 for many lagoons to be polluted to a lesser or greater degree. Man is 

 increasingly being faced with the problem of how far he is prepared to 

 let pollution affect his waterways and other natural water areas. 

 The preservation of some typical lagoons and their vegetation is also 

 a matter of urgency. This applies particularly to coastal lagoons, 

 but cannot be ignored even in the case of atoll lagoons (A, A. --modified) 



Keywords: mangroves, estuaries, salt marshes, eelgrass, coastal lagoons 



C. Marsh and Estuarine Conferences 



I-C-1 



Marine Institute of the University of Georgia. 1959. Proceedings of the 



salt marsh conference, Sapelo Island, Georgia. University of Georgia, 



Athens. 133 pp. 



The idea for the conference was conceived when it was learned that the 

 National Science Foundation was interested in encouraging meetings of 

 limited numbers of people to discuss specialized subjects, especially those 

 topics that cut across the boundaries that traditionally separate scientific 

 disciplines. The study of salt marshes is clearly an interdisciplinary 



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