Tidal salt marshes are viewed as critical habitats for the  production of fish and shellfish. As a result, considerable  legislation has been promulgated to conserve and protect these  habitats, and much of it is in effect today. The relatively young  science of ecological engineering has also emerged, and there are now  attempts to reverse centuries-old losses by encouraging sound wetland  restoration practices. Today, tens of thousands of hectares of  degraded or isolated coastal wetlands are being restored worldwide.  Whether restored wetlands reach functional equivalency to `natural'  systems is a subject of heated debate.   Equally debatable is the paradigm that depicts tidal salt marshes as  the `great engine' that drives much of the secondary production in  coastal waters. This view was questioned in the early 1980s by  investigators who noted that total carbon export, on the order of 100  to 200 g m-2 y-1 was of much lower  magnitude than originally thought. These authors also recognized that  some marshes were either net importers of carbon, or showed no net  exchange. Thus, the notion of `outwelling' has become but a single  element in an evolving view of marsh function and the link between  primary and secondary production. The `revisionist' movement was  launched in 1979 when stable isotopic ratios of macrophytes and animal  tissues were found to be `mismatched'. Some eighteen years later, the  view of marsh function is still undergoing additional modification,  and we are slowly unraveling the complexities of biogeochemical  cycles, nutrient exchange, and the links between primary producers and  the marsh/estuary fauna. Yet, since Teal's seminal paper nearly forty  years ago, we are not much closer to understanding how marshes work.  If anything, we have learned that the story is far more complicated  than originally thought. Despite more than four decades of intense  research, we do not yet know how salt marshes function as  essential habitat, nor do we know the relative contributions to  secondary production, both in situ or in the open waters of the  estuary.   The theme of this Symposium was to review the status of salt marsh  research and revisit the existing paradigm(s) for salt marsh function.  Challenge questions were designed to meet the controversy head on: Do  marshes support the production of marine transient species? If so,  how? Are any of these species marsh obligates? How much of the  production takes place in situ versus in open waters of the  estuary/coastal zone? Sessions were devoted to reviews of landmark  studies, or current findings that advance our knowledge of salt marsh  function. A day was also devoted to ecological engineering and wetland  restoration papers addressing state-of-the-art methodology and  specific case histories. Several challenge papers arguing for and  against our ability to restore functional salt marshes led off each  session. This volume is intended to serve as a synthesis of our  current understanding of the ecological role of salt marshes, and  will, it is hoped, pave the way for a new generation of research.

Concepts and Controversies in Tidal Marsh Ecology PDF

The list of books you might like