PREFACE 



Salt marshes, especially the muddy, 

 wet, intertidal portions of them that are 

 described in this report, have often been 

 considered wastelands--areas to be filled 

 to make useful land or to be dredged to 

 make useful water. From the scientific 

 point of view, the past few decades of 

 research on salt marshes have provided a 

 much better basis for evaluating marshes 

 than before. From the esthetic point of 

 view, we probably value little that has 

 not been appreciated for the last several 

 hundred years. But esthetics usually do 

 not play a large part in decisions 

 regarding the preservation of salt 

 marshes. 



Energy flow in a salt marsh was 

 outlined twenty years ago (Teal 1962) in 

 an effort to put together everything then 

 known about the way the Georgia marsh 

 system functioned. Energy transfer was 

 the descriptive tool. Since everything 

 produced within the marsh was not consumed 

 there, the author concluded that some of 

 it must be exported and, as a result, 

 contribute to the support of consumer 

 organisms in the estuaries. This export, 

 which was called "outwel 1 ing," was also 

 proposed by others (see Odum 1980, Nixon 

 1980, Dow 1982). Teal's data were based 

 on studies of the intertidal parts of the 

 salt marsh and the conclusion did not 

 really extend beyond the tidal creeks 

 within the marsh itself. The notion of 

 salt marsh support of estuarine life was 

 widely accepted and became one of the 

 arguments for salt marsh preservation. 



In the past twenty years, a good deal 

 has been learned about the way salt 

 marshes function, but there is still a 

 vigorous controversy about the role of 

 marshes as supporters of production in the 

 waters associated with them. Nixon 

 (1980), in a detailed review of the 

 guestions surrounding marsh export in its 



various possible forms, pointed out the 

 uncertainty of much of the data and the 

 limit of our understanding of the 

 interactions between marshes and coastal 

 waters. Note his comment on the 

 inadvisabil ity of trading "our credibility 

 for political advantage." It is all too 

 easy for a scientist, believing he has 

 achieved a new way of understanding some 

 natural phenomenon, to promote his idea 

 for some management purpose. This has 

 certainly happened in relation to salt 

 marshes. Both the need for, and the lack 

 of need for, the preservation of marshes 

 have been supported on the basis of 

 incomplete understanding. 



There are occasions when it is 

 necessary to act on the basis of less- 

 than-complete information. Scientists 

 should do their best to make the results 

 of their efforts available to those who 

 make decisions. If scientists do not, 

 managers will, as they must, make 

 decisions based on whatever information 

 they have. Unfortunately, those decisions 

 may be based only on politics or outdated 

 knowledge. Scientists should make the 

 best information available. They should 

 remain skeptical about their own 

 conclusions. They should be willing to 

 test their ideas repeatedly when the 

 opportunity arises. They should not go 

 to the most conservative extreme and 

 never be willing to give an opinion 

 about the wisdom of some proposed action. 

 The difficulty lies in distinguishing 

 between the best scientific judgment 

 of what the consequences of an action 

 will be, and one's personal opinion 

 about the consequences of the action 

 based on extrapolation from scientific 

 knowledge. 



This report was written to provide a 

 summary of the current state of scientific 

 knowledge about intertidal salt marshes. 



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