Concepts and Controversies in Tidal Marsh Ecology

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 paper nearly 40 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 the symposium papers collected here 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 around whether 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 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 understanding of the ecological role of salt marshes.

Table of Contents:
Retrospective on the Salt Marsh Paradigm.- Tidal Marshes as Outwelling/Pulsing Systems.- Salt Marsh Values: Retrospection from the end of the Century.- Sources and Patterns of Production.- Role of Salt Marshes as Part of Coastal Landscapes.- Spatial Variation in Process and Pattern in Salt Marsh Plant Communities in Eastern North America.- Eco-Physiological Controls on the Productivity of Spartina Alterniflora Loisel.- Community Structure and Functional Dynamics of Benthic Microalgae in Salt Marshes.- Structure and Productivity of Microtidal Mediterranean Coastal Marshes.- Development and Structure of Salt Marshes: Community Patterns in Time and Space.- Fate of Production within Marsh Food Webs.- Microbial Secondary Production from Salt Marsh-Grass Shoots, and Its Known and Potential Fates.- Trophic Complexity Between Producers and Invertebrate Consumers in Salt Marshes.- Trophic Linkages in Marshes: Ontogenetic Changes in Diet for Young-of-the-Year Mummichog, Fundulus Heteroclitus.- Habitat Value: Food and/or Refuge.- Factors Influencing Habitat Selection in Fishes with a Review of Marsh Ecosystems.- Salt Marsh Ecoscapes and Production Transfers by Estuarine Nekton in the Southeastern United States.- Salt Marsh Linkages to Productivity of Penaeid Shrimps and Blue Crabs in the Northern Gulf of Mexico.- Ecophysiological Determinants of Secondary Production in Salt Marshes: A Simulation Study.- Salt Marsh Ecosystem Support of Marine Transient Species.- Biogeochemical Processes.- Benthic-Pelagic Coupling in Marsh-Estuarine Ecosystems.- Twenty More Years of Marsh and Estuarine Flux Studies: Revisiting Nixon (1980).- The Role of Oligohaline Marshes in Estuarine Nutrient Cycling.- Molecular Tools for Studying Biogeochemical Cycling in Salt Marshes.- Nitrogen and Vegetation Dynamics in European Salt Marshes.- Modelling Nutrient and Energy Flux.- A Stable Isotope Model Approach to Estimating the Contribution of Organic Matter from Marshes to Estuaries.- Types of Salt Marsh Edge and Export of Trophic Energy from Marshes to Deeper Habitats.- Silicon is the Link between Tidal Marshes and Estuarine Fisheries: A New Paradigm.- Tidal Marsh Restoration: Fact or Fiction?.- Self-Design Applied to Coastal Restoration.- Functional Equivalency of Restored and Natural Salt Marshes.- Organic and Inorganic Contributions to Vertical Accretion in Salt Marsh Sediments.- Landscape Structure and Scale Constraints on Restoring Estuarine Wetlands for Pacific Coast Juvenile Fishes.- Ecological Engineering of Restored Marshes.- The Role of Pulsing Events in the Functioning of Coastal Barriers and Wetlands: Implications for Human Impact, Management and the Response to Sea Level Rise.- Influences of Vegetation and Abiotic Environmental Factors on Salt Marsh Invertebrates.- Measuring Function of Restored Tidal Marshes.- The Health and Long Term Stability of Natural and Restored Marshes in Chesapeake Bay.- Soil Organic Matter (SOM) Effects on Infaunal Community Structure in Restored and Created Tidal Marshes.- Initial Response of Fishes to Marsh Restoration at a Former Salt Hay Farm Bordering Delaware Bay.- Success Criteria for Tidal Marsh Restoration.- Catastrophes, Near-Catastrophes and the Bounds of Expectation: Success Criteria for Macroscale Marsh Restoration.- References is a Moving Target in Sea-Level Controlled Wetlands.- Linking the Success of Phragmites to the Alteration of Ecosystem Nutrient Cycles.- Restoration of Salt and Brackish Tidelands in Southern New England.

Review :
`On balance this book will be a landmark for its intended audience, North American salt marsh ecosystem ecologist and a valuable resource for students and ecologists from other disciplines interested in learning about salt marsh ecology. ...I highly recommend this book to tidal marsh scientist and graduate students because it presently provides the best and the most up to date single source of information on tidal marsh ecology.' Journal of Experimental Marine Biology and Ecology. `The book contains a tremendous amount of up to date information on salt marsh ecology and its an excellent reference for those interested in ecosystem-level processes in these systems ' Ecological Engineering 18:399-400 (2002)