Concepts and Controversies in Tidal Marsh Ecology

In 1968 when I forsook horticulture and plant physiology to try, with the help of Sea Grant funds, wetland ecology, it didn’t take long to discover a slim volume published in 1959 by the University of Georgia and edited by R. 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. 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 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 18 years later, the view of marsh function is still undergoing additional modification, and we are slowly unravelling the complexities of biogeochemical cycles, nutrient exchange, and the links between primary producers and the marsh/estuary fauna. Yet, since Teal's…