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Author: Bethany Lynn Williams Publisher: ISBN: Category : Salt marsh ecology Languages : en Pages :
Book Description
Accelerated sea-level rise poses a significant threat to coastal habitats. Salt marshes are critical coastal ecosystems, providing a host of services such as storm protection, food production, and carbon storage. Persistence of salt marshes in the face of rising sea levels relies, in part, on vertical accretion. Current ecogeomorphic models and empirical studies emphasize the importance of the positive relationship between plant production and vertical accretion via sediment trapping by stems aboveground and belowground organic matter production. Thus, changes in plant production influence salt marsh persistence with sea-level rise. However, studies and models of marsh accretion do not consider the effects of animal-mediated changes in plant production. Here, I tested how two co-occurring marsh crustaceans, Uca pugnax (marsh fiddler crab) and Sesarma reticulatum (purple marsh crab), which have contrasting effects on smooth cordgrass (Spartina alterniflora) production, indirectly influence sediment deposition and belowground organic matter contribution, through observational surveys and field manipulation. S. reticulatum feeds directly on S. alterniflora, while U. pugnax facilitates S. alterniflora production through burrowing and biodeposits. I found that U. pugnax facilitated S. alterniflora biomass in some marshes, but not others. However, this facilitation of S. alterniflora biomass did not enhance sediment deposition. U. pugnax had no effect on belowground components of vertical accretion (i.e. root production and decomposition). These results suggest that in isolation, U. pugnax has little impact on saltmarsh geomorphic processes. S. reticulatum reduced S. alterniflora above- and belowground biomass; however, sediment deposition increased as S. alterniflora biomass decreased, contrary to models of ecogeomorphology. This trend was likely due to sediment being resuspended by crab bioturbation, as U. pugnax abundances were higher in S. reticulatum-grazed areas than in non-grazed areas. When U. pugnax occurred in areas of low S. reticulatum grazing, S. alterniflora biomass and sedimentation was similar to areas with only U. pugnax. I suggest that the negative impacts of S. reticulatum are exaggerated when intense grazing results in completely unvegetated areas and subsequent increases in U. pugnax density, where bioturbation erodes sediments. Thus, while S. reticulatum can increase the susceptibility of marsh sediments to physical erosion by removing vegetation, it may also do so by facilitating U. pugnax bioturbation. However, when S. reticulatum grazing intensity is low, facilitation of S. alterniflora growth by U. pugnax can mitigate the negative effect of grazing, which suggests that the net effect of these species may depend on their relative abundance. This study demonstrates that ecological interactions, in addition to physical processes, have significant effects on marsh persistence as sea level rises, and merit incorporation into ecogeomorphic models and empirical studies of marsh accretion.
Author: Bethany Lynn Williams Publisher: ISBN: Category : Salt marsh ecology Languages : en Pages :
Book Description
Accelerated sea-level rise poses a significant threat to coastal habitats. Salt marshes are critical coastal ecosystems, providing a host of services such as storm protection, food production, and carbon storage. Persistence of salt marshes in the face of rising sea levels relies, in part, on vertical accretion. Current ecogeomorphic models and empirical studies emphasize the importance of the positive relationship between plant production and vertical accretion via sediment trapping by stems aboveground and belowground organic matter production. Thus, changes in plant production influence salt marsh persistence with sea-level rise. However, studies and models of marsh accretion do not consider the effects of animal-mediated changes in plant production. Here, I tested how two co-occurring marsh crustaceans, Uca pugnax (marsh fiddler crab) and Sesarma reticulatum (purple marsh crab), which have contrasting effects on smooth cordgrass (Spartina alterniflora) production, indirectly influence sediment deposition and belowground organic matter contribution, through observational surveys and field manipulation. S. reticulatum feeds directly on S. alterniflora, while U. pugnax facilitates S. alterniflora production through burrowing and biodeposits. I found that U. pugnax facilitated S. alterniflora biomass in some marshes, but not others. However, this facilitation of S. alterniflora biomass did not enhance sediment deposition. U. pugnax had no effect on belowground components of vertical accretion (i.e. root production and decomposition). These results suggest that in isolation, U. pugnax has little impact on saltmarsh geomorphic processes. S. reticulatum reduced S. alterniflora above- and belowground biomass; however, sediment deposition increased as S. alterniflora biomass decreased, contrary to models of ecogeomorphology. This trend was likely due to sediment being resuspended by crab bioturbation, as U. pugnax abundances were higher in S. reticulatum-grazed areas than in non-grazed areas. When U. pugnax occurred in areas of low S. reticulatum grazing, S. alterniflora biomass and sedimentation was similar to areas with only U. pugnax. I suggest that the negative impacts of S. reticulatum are exaggerated when intense grazing results in completely unvegetated areas and subsequent increases in U. pugnax density, where bioturbation erodes sediments. Thus, while S. reticulatum can increase the susceptibility of marsh sediments to physical erosion by removing vegetation, it may also do so by facilitating U. pugnax bioturbation. However, when S. reticulatum grazing intensity is low, facilitation of S. alterniflora growth by U. pugnax can mitigate the negative effect of grazing, which suggests that the net effect of these species may depend on their relative abundance. This study demonstrates that ecological interactions, in addition to physical processes, have significant effects on marsh persistence as sea level rises, and merit incorporation into ecogeomorphic models and empirical studies of marsh accretion.
Author: L. R. Pomeroy Publisher: Springer Science & Business Media ISBN: 1461258936 Category : Science Languages : en Pages : 277
Book Description
Ecologists have two long-standing ways to study large ecosystems such as lakes, forests, and salt-marsh estuaries. In the first, which G. E. Hutchinson has called the holological approach, the whole ecosystem is first studied as a "black box," and its components are investigated as needed. In the second, which Hutchinson has called the merological approach, the parts of the system are studied first, and an attempt is then made to build up the whole from them. For long-term studies, the holological approach has special advantages, since the general patterns and tentative hypotheses that are first worked out help direct attention to the components of the system which need to be studied in greater detail. In this approach, teams of investigators focus on major func tions and hypotheses and thereby coordinate their independent study efforts. Thus, although there have been waves, as it were, of investigators and graduate students working on different aspects of the Georgia salt-marsh estuaries (personnel at the Marine Institute on Sapelo Island changes every few years), the emphasis on the holo logical approach has resulted in a highly differentiated and well-coordinated long-term study. Very briefly, the history of the salt-marsh studies can be outlined as follows. First, the general patterns of food chains and other energy flows in the marshes and creeks were worked out, and the nature of imports and exports to and from the system and its subsystems were delimited.
Author: Sergio Fagherazzi Publisher: American Geophysical Union ISBN: Category : Nature Languages : en Pages : 284
Book Description
Located between sea and land, salt marshes are complex environments that provide critical ecosystem functions, such as production of organic material and nutrient cycling. This book examines the geomorphology of salt marshes with emphasis on the interaction between landscape and biota.
Author: Brian R. Silliman Publisher: Univ of California Press ISBN: 9780520258921 Category : Nature Languages : en Pages : 440
Book Description
"Human Impacts on Salt Marshes provides an excellent global synthesis of an important, underappreciated environmental problem and suggests solutions to the diverse threats affecting salt marshes."—Peter B. Moyle, University of California, Davis
Author: Akana Noto Publisher: ISBN: Category : Languages : en Pages : 151
Book Description
Interactions among members of ecological communities often vary spatially in response to environmental differences. Yet interactions can also vary spatially as a result of biotic factors such as differences in species traits or variation in other species interactions. It is necessary to understand the conditions under which each of these drivers of variation has an effect in order to predict how species interactions will be affected both by changes in the environment and in biotic communities. In this thesis, I explore mechanisms that may cause species interactions to vary across space at local, regional and continental scales in salt marsh plant communities. Chapter 1 investigates the relationship between the environment (means and variability) and community diversity and stability in time-series data from the east and west coasts of North America. Chapter 2 experimentally investigates the effect of sea-level rise on species interactions within a marsh. Chapter 3 seeks to understand geographic variation in plant interactions among six sites spanning the California coast. Chapter 4 uses a common garden experiment to test whether spatial variation in species interactions are driven by differences among plant populations or the environment. Finally, Chapter 5 describes geographic patterns of variation in herbivore pressure to determine whether herbivory drives regional differences in interactions among plants. I found that changes in mean conditions, including sea level, can affect community diversity, stability and strength of species interactions. Environmental variability only affects community stability and diversity when it is relatively large, so increases in variability with climate change may cause plant community dynamics to become affected by both variability and means. Species interactions vary geographically along the west coast, but unlike on the east coast, do not show consistent trends with latitude. Rather, interaction strengths may differ due to trait variation among plant populations and differences in herbivore pressure. My thesis demonstrates that environmental conditions and local factors, including intraspecific phenotypic variation and herbivory, both determine the nature of species interactions in salt marshes, and that the west coast of North America shows geographic patterns in interactions that are distinct from those found on the east coast.
Author: Neil Saintilan Publisher: CSIRO PUBLISHING ISBN: 0643098593 Category : Science Languages : en Pages : 248
Book Description
Australian Saltmarsh Ecology presents the first comprehensive review of the ecology and management of Australian saltmarshes. The past 10 years in particular have seen a sustained research effort into this previously poorly understood and neglected resource. Leading experts in the field outline what is known of the biogeography and geomorphology of Australian saltmarshes, their fish and invertebrate ecology, the use of Australian saltmarshes by birds and insectivorous bats, and the particular challenges of management, including the control of mosquito pests, and the issue of sea-level rise. They provide a powerful argument that coastal saltmarsh is a unique and critical habitat vulnerable to the combined impacts of coastal development and sea-level rise. The book will be an important reference for saltmarsh researchers, marine and aquatic biologists, natural resource managers, environmentalists and ecologists, as well as undergraduate students and the interested layperson.
Author: Bethany Lynn Williams
Author: Bethany Lynn Williams
Author: L. R. Pomeroy
Author: Duncan M. FitzGerald
Author: Sergio Fagherazzi
Author: Stephen Patrick Long
Author: Brian R. Silliman
Author: Akana Noto
Author: Raymond Torres
Author: Neil Saintilan
Author: Louis C. Joyce