32 results on '"Evamaria W. Koch"'
Search Results
2. Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions.
- Author
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Lina Mtwana Nordlund, Evamaria W Koch, Edward B Barbier, and Joel C Creed
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Medicine ,Science - Abstract
Threats to and loss of seagrass ecosystems globally, impact not only natural resources but also the lives of people who directly or indirectly depend on these systems. Seagrass ecosystems play a multi-functional role in human well-being, e.g. food through fisheries, control of erosion and protection against floods. Quantifying these services reveals their contributions to human well-being and helps justify seagrass conservation. There has been no comprehensive assessment as to whether seagrass ecosystem services are perceived to vary over the globe or amongst genera. Our study compiles the most complete list of ecosystem services provided by seagrasses so far, including bioregional- and genus-specific information from expert opinion and published studies. Several seagrass ecosystem services vary considerably in their (known) provision across genera and over the globe. Seagrasses genera are clearly not all equal with regard to the ecosystem services they provide. As seagrass genera are not evenly distributed over all bioregions, the presence of an ecosystem service sometimes depends on the genera present. Larger sized seagrass genera (e.g. Posidonia, Enhalus) are perceived to provide more substantial and a wider variety of ecosystem services than smaller species (e.g. Halophila, Lepilaena). Nevertheless, smaller species provide important services. Our findings point out data gaps, provide new insight for more efficient management and recommend caution in economic valuation of seagrass services worldwide. more...
- Published
- 2016
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- View/download PDF
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3. Influence of Shoreline Stabilization Structures on the Nearshore Sedimentary Environment in Mesohaline Chesapeake Bay
- Author
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Lawrence P. Sanford, Cindy M. Palinkas, and Evamaria W. Koch
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0106 biological sciences ,Shore ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Ecology ,010604 marine biology & hydrobiology ,Sediment ,Context (language use) ,Estuary ,Aquatic Science ,01 natural sciences ,Sedimentary depositional environment ,Oceanography ,Erosion ,Environmental science ,Sedimentary rock ,Ecology, Evolution, Behavior and Systematics ,Riprap ,0105 earth and related environmental sciences - Abstract
Shorelines around many estuaries and coastal embayments are rapidly eroding (approximately several meters/year), with more rapid erosion rates expected in the future due to natural and anthropogenic stressors. In response, a variety of techniques have been used to stabilize shorelines, but there are limited quantitative, long-term data available about their effects on the sedimentary environment immediately adjacent to them (i.e., the nearshore). This study evaluated changes in sediment characteristics (mud and organic content) and accumulation rates associated with installation of breakwaters, riprap, and living shorelines with (“hybrid”) and without (“soft”) a structural component. 210Pb (half-life 22.3 years) geochronologies were used to identify horizons in core profiles that corresponded to years when structures were built. Sites with naturally eroding shorelines (i.e., no structures) were used as a control group at which any sedimentary changes represent broad environmental trends, in contrast to changes at the protected sites that also include the influence of structures. Observations were placed within the context of modeled wave climate, shoreline-erosion rates, land use, dominant sediment source, and the apparent effect on submersed aquatic vegetation (SAV) inhabiting the nearshore sedimentary environment. The main conclusion of this study is that there was no “one size fits all” answer to anticipated impacts of structures on nearshore sedimentary environments. Instead, specific changes associated with structures depended on individual site characteristics, but could be predicted with multiple linear regression models that included structure type, shoreline-erosion rate, dominant sediment source, and land use. Riprap or breakwater installation had either positive or no obvious impact on SAV at six of seven sites but negatively impacted SAV at one riprapped site. No obvious impacts on SAV were observed at living shoreline sites. more...
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- 2017
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4. The Influence of Breakwaters on Nearshore Sedimentation Patterns in Chesapeake Bay, USA
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Deborah J. Shafer, Nicole Barth, Evamaria W. Koch, and Cindy M. Palinkas
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0106 biological sciences ,010504 meteorology & atmospheric sciences ,Ecology ,Chesapeake bay ,010604 marine biology & hydrobiology ,Sediment ,Sedimentation ,01 natural sciences ,Oceanography ,Breakwater ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology - Abstract
Palinkas, C.M.; Barth, N.; Koch, E.W., and Shafer, D.J., 2016. The influence of breakwaters on nearshore sedimentation patterns in Chesapeake Bay, USA. This study describes nearshore Chesapeake Bay sedimentation at sites adjacent to and landward of 24 segmented breakwaters, varying in age (1–19 years) and physical setting. Grain-size and organic-content profiles are examined at the breakwater-protected sites to assess potential changes induced by breakwater installation as well as at the adjacent-exposed sites to establish historical trends. Sedimentation rates at all sites are calculated with 210Pb (half-life 22.3 years). At the breakwater-protected sites, these rates largely reflect preconstruction sedimentation because of the long half-life of 210Pb relative to breakwater ages. Determining the postconstruction sedimentation rate can be more difficult because the signature of breakwater influence in the sedimentological record can be obscured. For example, if the source of sediment is not affec... more...
- Published
- 2016
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5. The interactive effects of water flow and reproductive strategies on seed and seedling dispersal along the substrate in two sub-tropical seagrass species
- Author
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Evamaria W. Koch, Dale M. Booth, Kenneth H. Dunton, and Kelly M. Darnell
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Seagrass ,biology ,Thalassia testudinum ,Water flow ,Seedling ,Ecology ,Seed dispersal ,Halodule wrightii ,Biological dispersal ,Aquatic Science ,biology.organism_classification ,Substrate (marine biology) ,Ecology, Evolution, Behavior and Systematics - Abstract
We quantified the effects of water flow on secondary seed and seedling dispersal for two seagrass species with different reproductive strategies: turtle grass ( Thalassia testudinum ) whose large seeds (15.1 ± 0.8 mm tall) have the potential for long distance dispersal by current-mediated transport of buoyant fruits, and shoal grass ( Halodule wrightii ), whose small seeds (2.1 ± 0.1 mm tall) are released adjacent to the parent plant and create a persistent seed bank. Results from field dispersal experiments in Texas indicate that under normal flow conditions (mean water velocity − 1 ), turtle grass seedling movement is greater over bare sand than within seagrass beds and seedlings have the potential to move up to 2.1 m d − 1 . Fine hairs on the seedling base trap sand grains, which likely leads to final seedling establishment after a few days and a potential secondary dispersal distance along the substrate of − 1 , but seed entrapment in sediment ripples likely limits the total secondary dispersal distance to more...
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- 2015
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6. Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions
- Author
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Joel C. Creed, Edward B. Barbier, Evamaria W. Koch, and Lina Mtwana Nordlund
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Conservation of Natural Resources ,Multidisciplinary ,Alismatales ,010504 meteorology & atmospheric sciences ,biology ,Ecology ,Zosteraceae ,lcsh:R ,Fisheries ,Correction ,lcsh:Medicine ,Hydrocharitaceae ,010501 environmental sciences ,biology.organism_classification ,01 natural sciences ,Ecosystem services ,Fishery ,Geography ,Seagrass ,Humans ,lcsh:Q ,lcsh:Science ,Ecosystem ,0105 earth and related environmental sciences - Abstract
Threats to and loss of seagrass ecosystems globally, impact not only natural resources but also the lives of people who directly or indirectly depend on these systems. Seagrass ecosystems play a multi-functional role in human well-being, e.g. food through fisheries, control of erosion and protection against floods. Quantifying these services reveals their contributions to human well-being and helps justify seagrass conservation. There has been no comprehensive assessment as to whether seagrass ecosystem services are perceived to vary over the globe or amongst genera. Our study compiles the most complete list of ecosystem services provided by seagrasses so far, including bioregional- and genus-specific information from expert opinion and published studies. Several seagrass ecosystem services vary considerably in their (known) provision across genera and over the globe. Seagrasses genera are clearly not all equal with regard to the ecosystem services they provide. As seagrass genera are not evenly distributed over all bioregions, the presence of an ecosystem service sometimes depends on the genera present. Larger sized seagrass genera (e.g. Posidonia, Enhalus) are perceived to provide more substantial and a wider variety of ecosystem services than smaller species (e.g. Halophila, Lepilaena). Nevertheless, smaller species provide important services. Our findings point out data gaps, provide new insight for more efficient management and recommend caution in economic valuation of seagrass services worldwide. more...
- Published
- 2017
7. Coastal Ecosystems: A Critical Element of Risk Reduction
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Colin D. Woodroffe, Michael W. Beck, Denise J. Reed, Iris Möller, Bregje K. van Wesenbeeck, Eric Wolanski, Pamela Rubinoff, Anna McIvor, Thomas J. Spencer, Evamaria W. Koch, Ty V. Wamsley, Trevor Tolhurst, Mark Spalding, Spencer, Thomas [0000-0003-2610-6201], and Apollo - University of Cambridge Repository more...
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seagrass ,media_common.quotation_subject ,Storm surge ,hybrid engineering ,storm surge ,Coastal planning ,Ecosystem ,reef ,Function (engineering) ,Environmental planning ,risk reduction ,wave attenuation ,Ecology, Evolution, Behavior and Systematics ,Coastal hazards ,Nature and Landscape Conservation ,media_common ,mangrove ,geography ,geography.geographical_feature_category ,Ecology ,Self repair ,sea-level rise ,salt marsh ,Salt marsh ,Environmental science ,Element (criminal law) - Abstract
The conservation of coastal ecosystems can provide considerable coastal protection benefits, but this role has not been sufficiently accounted for in coastal planning and engineering. Substantial evidence now exists showing how, and under what conditions, ecosystems can play a valuable function in wave and storm surge attenuation, erosion reduction, and in the longer term maintenance of the coastal profile. Both through their capacity for self repair and recovery, and through the often considerable cobenefits they provide, ecosystems can offer notable advantages over traditional engineering approaches in some settings. They can also be combined in "hybrid" engineering designs. We make 10 recommendations to encourage the utilization of existing knowledge and to improve the incorporation of ecosystems into policy, planning and funding for coastal hazard risk reduction. more...
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- 2013
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8. Sediment Accumulation Rates and Submersed Aquatic Vegetation (SAV) Distributions in the Mesohaline Chesapeake Bay, USA
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Evamaria W. Koch and Cindy M. Palinkas
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Shore ,geography ,geography.geographical_feature_category ,Ecology ,biology ,Ephemeral key ,Sediment ,Aquatic Science ,biology.organism_classification ,Current (stream) ,Oceanography ,Seagrass ,Aquatic plant ,Sedimentary rock ,Bay ,Ecology, Evolution, Behavior and Systematics ,Geology - Abstract
This study assesses spatial and temporal sedimentological trends in four mesohaline Chesapeake Bay submersed aquatic vegetation (SAV) habitats, two with persistent SAV beds and two with ephemeral SAV beds, to determine their relationship to current and historical sediment characteristics—grain size, organic content, and accumulation rates. In general, grain size is similar among all sites, and subsurface sediment differs from surficial sediment only at one site where a thin surficial sand layer (∼2–3 cm) is present. This thin sand layer is not completely preserved in the longer-term sedimentary record even though it is critical to determining whether the sediment is suitable for SAV. Evidence for nearshore fining, similar to that observed in the deeper waters of the Bay, is present at the site where the shoreline has been hardened suggesting that locations with hardened shorelines limit exchange of coarser (sandy) material between the shore and nearshore environments. Whether the fining trend will continue to a point at which the sediment will become unsuitable for SAV in the future or whether some new type of equilibrium will be reached cannot be addressed with our data. Instead, our data suggest that SAV presence/absence is related to changes in sedimentary characteristics—persistent beds have relatively steady sediment composition, while ephemeral beds have finer sediments due to reduced sand input. Additionally, sediment accumulation rates in the persistent beds are ∼9 mm/year, whereas rates in the ephemeral beds are ∼3 mm/year. Thus, the ephemeral sites highlight two potential sedimentary controls on SAV distribution: the presence of a sufficiently thick surficial sand layer as previously postulated by Wicks (2005) and accumulation rates high enough to bury seeds prior to germination and/or keep up with sea-level rise. more...
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- 2012
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9. The value of estuarine and coastal ecosystem services
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Edward B. Barbier, Sally D. Hacker, Chris Kennedy, Evamaria W. Koch, Adrian C. Stier, and Brian R. Silliman
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Hydrology ,geography ,Marsh ,geography.geographical_feature_category ,Flood myth ,Damages ,Storm surge ,Environmental science ,Storm ,Wetland ,Vegetation ,Surge ,Ecology, Evolution, Behavior and Systematics - Abstract
The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively. more...
- Published
- 2011
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10. Modeling the Effects of Oyster Reefs and Breakwaters on Seagrass Growth
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Shih-Nan Chen, Elizabeth W. North, Roger I. E. Newell, Evamaria W. Koch, Katharine A. Smith, Fengyan Shi, and Raleigh R. Hood
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Oyster ,geography ,geography.geographical_feature_category ,Ecology ,biology ,Seston ,Sediment ,Estuary ,Aquatic Science ,biology.organism_classification ,Seagrass ,Oceanography ,biology.animal ,Wave height ,Environmental science ,Eastern oyster ,Reef ,Ecology, Evolution, Behavior and Systematics - Abstract
Seagrass beds have declined in Chesapeake Bay, USA as well as worldwide over the past century. Increased seston concentrations, which decrease light penetration, are likely one of the main causes of the decline in Chesapeake Bay. It has been hypothesized that dense populations of suspension-feeding bivalves, such as eastern oysters (Crassostrea virginica), may filter sufficient seston from the water to reduce light attenuation and enhance seagrass growth. Furthermore, eastern oyster populations can form large three-dimensional reef-like structures that may act like breakwaters by attenuating waves, thus decreasing sediment resuspension. We developed a quasi-three-dimensional Seagrass-Waves-Oysters-Light-Seston (SWOLS) model to investigate whether oyster reefs and breakwaters could improve seagrass growth by reducing seston concentrations. Seagrass growth potential (SGP), a parameter controlled by resuspension-induced turbidity, was calculated in simulations in which wave height, oyster abundance, and reef/breakwater configuration were varied. Wave height was the dominant factor influencing SGP, with higher waves increasing sediment resuspension and decreasing SGP. Submerged breakwaters parallel with the shoreline improved SGP in the presence of 0.2 and 0.4 m waves when sediment resuspension was dominated by wave action, while submerged groins perpendicular to the shoreline improved SGP under lower wave heights (0.05 and 0.1 m) when resuspension was dominated by along-shore tidal currents. Oyster-feeding activity did not affect SGP, due to the oysters’ distance from the seagrass bed and reduced oyster filtration rates under either low or high sediment concentrations. Although the current implementation of the SWOLS model has simplified geometry, the model does demonstrate that the interaction between oyster filtration and along-shore circulation, and between man-made structures and wave heights, should be considered when managing seagrass habitats, planning seagrass restoration projects, and choosing the most suitable methods to protect shorelines from erosion. more...
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- 2009
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11. The Role of Currents and Waves in the Dispersal of Submersed Angiosperm Seeds and Seedlings
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Evamaria W. Koch, A. Dale Magoun, M. Stephen Ailstock, Dale M. Booth, and Deborah J. Shafer
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Ecology ,biology ,Water flow ,Stuckenia pectinata ,Seed dispersal ,biology.organism_classification ,Potamogeton perfoliatus ,Settling ,Seedling ,Botany ,Biological dispersal ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,Ruppia maritima - Abstract
We tested the hypothesis that currents, waves, and sediment grain size affect the dispersal of seeds and seedlings of the submersed angiosperms Ruppia maritima, Potamogeton perfoliatus and Stuckenia pectinata. Seed settling velocities and initiation of motion of seeds and seedlings and distance transported were quantified on four sediment types under a range of currents and waves in a flume. The rapid settling velocities of R. maritima and S. pectinata seeds and the increased settling velocity of P. perfoliatus in currents above 8 cm/second suggest that primary dispersal of these species is localized to the general area colonized by their parents. Once settled within a bed, seeds are exposed to weak currents and waves, and are likely to be subject to sediment deposition which may further limit dispersal. In contrast, in restoration projects, the absence of vegetation is likely to make seeds more vulnerable to grazing and transport, and may contribute to the lack of plant establishment. If seeds germinate without being buried, they are susceptible to secondary dispersal at relatively low current velocities and small wave heights due to the drag exerted on the cotyledon. Sand grains tend to stick to the seed coat and rootlet of P. perfoliatus seedlings, perhaps a mechanism to reduce the chances of being displaced following germination. These data reveal the close links between sediment, water flow, and submersed angiosperm seedling establishment; these parameters should be considered when using seeds for restoration of submersed angiosperms. more...
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- 2009
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12. Non-linearity in ecosystem services: temporal and spatial variability in coastal protection
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Eric Wolanski, Brian R. Silliman, Sally D. Hacker, Stephen Polasky, Edward B. Barbier, Chris J. Kennedy, Carrie V. Kappel, Evamaria W. Koch, Benjamin S. Halpern, Gerardo M. E. Perillo, Nyawira A. Muthiga, Elise F. Granek, Jurgenne H. Primavera, and Denise J. Reed more...
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0106 biological sciences ,Marsh ,010504 meteorology & atmospheric sciences ,Wetland ,ECOSYSTEM SERVICES ,01 natural sciences ,Ciencias de la Tierra y relacionadas con el Medio Ambiente ,Ecosystem services ,Ecosystem ,14. Life underwater ,COASTAL WETLANDS ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,geography ,Ecosystem health ,geography.geographical_feature_category ,Ecology ,business.industry ,010604 marine biology & hydrobiology ,Environmental resource management ,Cumulative effects ,Coral reef ,15. Life on land ,13. Climate action ,NON-LINEAR SYSTEMS ,Environmental science ,Spatial variability ,Meteorología y Ciencias Atmosféricas ,business ,CIENCIAS NATURALES Y EXACTAS - Abstract
Natural processes tend to vary over time and space, as well as between species. The ecosystem services these natural processes provide are therefore also highly variable. It is often assumed that ecosystem services are pro- vided linearly (unvaryingly, at a steady rate), but natural processes are characterized by thresholds and limit- ing functions. In this paper, we describe the variability observed in wave attenuation provided by marshes, mangroves, seagrasses, and coral reefs and therefore also in coastal protection. We calculate the economic con- sequences of assuming coastal protection to be linear. We suggest that, in order to refine ecosystem-based man- agement practices, it is essential that natural variability and cumulative effects be considered in the valuation of ecosystem services. Fil: Koch, Evamaria W.. University of Maryland Center for Environmental Scienc; Estados Unidos Fil: Barbier, Edward B.. University of Wyoming; Estados Unidos Fil: Silliman, Brian R.. University of Florida; Estados Unidos Fil: Reed, Denise J.. University of New Orleans; Estados Unidos Fil: Perillo, Gerardo Miguel E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina Fil: Hacker, Sally D.. Oregon State University; Estados Unidos Fil: Granek, Elise F.. Portland State University; Estados Unidos Fil: Primavera, Jurgenne H.. Asian Fisheries Development Center; Filipinas Fil: Muthiga, Nyawira. Western Indian Ocean Project; Kenia Fil: Polasky, Stephen. University of Minnesota; Estados Unidos Fil: Halpern, Benjamin S.. University of California Santa Barbara; Estados Unidos Fil: Kennedy, Christopher J.. University of Wyoming; Estados Unidos Fil: Kappel, Carrie V.. University of California Santa Barbar; Estados Unidos Fil: Wolanski, Eric. James Cook University; Australia more...
- Published
- 2009
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13. A nearshore model to investigate the effects of seagrass bed geometry on wave attenuation and suspended sediment transport
- Author
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Elizabeth W. North, Shih-Nan Chen, Evamaria W. Koch, Fengyan Shi, and Lawrence P. Sanford
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Ecology ,biology ,Wave propagation ,Attenuation ,Sediment ,Geometry ,Aquatic Science ,biology.organism_classification ,Flume ,Seagrass ,Parasitic drag ,Wave height ,Sediment transport ,Ecology, Evolution, Behavior and Systematics ,Geology - Abstract
The effects of seagrass bed geometry on wave attenuation and suspended sediment transport were investigated using a modified Nearshore Community Model (NearCoM). The model was enhanced to account for cohesive sediment erosion and deposition, sediment transport, combined wave and current shear stresses, and seagrass effects on drag. Expressions for seagrass drag as a function of seagrass shoot density and canopy height were derived from published flume studies of model vegetation. The predicted reduction of volume flux for steady flow through a bed agreed reasonably well with a separate flume study. Predicted wave attenuation qualitatively captured seasonal patterns observed in the field: wave attenuation peaked during the flowering season and decreased as shoot density and canopy height decreased. Model scenarios with idealized bathymetries demonstrated that, when wave orbital velocities and the seagrass canopy interact, increasing seagrass bed width in the direction of wave propagation results in higher wave attenuation, and increasing incoming wave height results in higher relative wave attenuation. The model also predicted lower skin friction, reduced erosion rates, and higher bottom sediment accumulation within and behind the bed. Reduced erosion rates within seagrass beds have been reported, but reductions in stress behind the bed require further studies for verification. Model results suggest that the mechanism of sediment trapping by seagrass beds is more complex than reduced erosion rates alone; it also requires suspended sediment sources outside of the bed and horizontal transport into the bed. more...
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- 2007
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14. SeagrassNet monitoring across the Americas: case studies of seagrass decline
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Eric Fernandez, Frederick T. Short, Jeffrey L. Gaeckle, Joel C. Creed, Evamaria W. Koch, and Karine Matos Magalhães
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Ecology ,biology ,Climate change ,Aquatic Science ,biology.organism_classification ,Monitoring program ,Seagrass ,Geography ,Habitat ,Marine protected area ,Eutrophication ,Transect ,Ecology, Evolution, Behavior and Systematics ,Trophic level - Abstract
Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world’s oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action. more...
- Published
- 2006
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15. Modeling seagrass density and distribution in response to changes in turbidity stemming from bivalve filtration and seagrass sediment stabilization
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Evamaria W. Koch and Roger I. E. Newell
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biology ,Sediment ,Aquatic Science ,Sedimentation ,Bivalvia ,biology.organism_classification ,Turbidite ,Oceanography ,Seagrass ,Environmental Chemistry ,Crassostrea ,Turbidity ,Oyster reef restoration ,Geology ,General Environmental Science - Abstract
In many areas of the North American mid-Atlantic coast, seagrass beds are either in decline or have disappeared due, in part, to high turbidity that reduces the light reaching the plant surface. Because of this reduction in the areal extent of seagrass beds there has been a concomitant diminishment in dampening of water movement (waves and currents) and sediment stabilization. Due to ongoing declines in stocks of suspension-feeding eastern oysters (Crassostrea virginica) in the same region, their feeding activity, which normally serves to improve water clarity, has been sharply reduced. We developed and parameterized a simple model to calculate how changes in the balance between sediment sources (wave-induced resuspension) and sinks (bivalve filtration, sedimentation within seagrass beds) regulate turbidity. Changes in turbidity were used to predict the light available for seagrass photosynthesis and the amount of carbon available for shoot growth. We parameterized this model using published observations and data collected specifically for this purpose. The model predicted that when sediments were resuspended, the presence of even quite modest levels of eastern oysters (25 g dry tissue weight m−2) distributed uniformly throughout the modeled domain, reduced suspended sediment concentrations by nearly an order of magnitude. This increased water clarity, the depth to which seagrasses were predicted to grow. Because hard clams (Mercenaria mercenaria) had a much lower weight-specific filtration rate than eastern oysters; their influence on reducing turbidity was much less than oysters. Seagrasses, once established with sufficiently high densities (>1,000 shoots m−2), damped waves, thereby reducing sediment resuspension and improving light conditions. This stabilizing effect was minor compared to the influence of uniformly distributed eastern oysters on water clarity. Our model predicted that restoration of eastern oysters has the potential to reduce turbidity in shallow estuaries, such as Chesapeake Bay, and facilitate ongoing efforts to restore seagrasses. This model included several simplifiying assumptions, including that oysters were uniformly distributed rather than aggregated into offshore reefs and that oyster feces were not resuspended. more...
- Published
- 2004
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16. Habitat requirements for submerged aquatic vegetation in Chesapeake Bay: Water quality, light regime, and physical-chemical factors
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Kenneth A. Moore, Peter Bergstrom, Lee Karrh, Virginia Carter, Evamaria W. Koch, Laura Murray, Michael D. Naylor, Richard Batleson, Charles L. Gallegos, David J. Wilcox, Nancy B. Rybicki, J. Court Stevenson, Jurate M. Landwehr, W. Michael Kemp, and William S. Hunley more...
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Hydrology ,geography ,geography.geographical_feature_category ,Tidal range ,Estuary ,Vegetation ,Aquatic Science ,Water column ,Aquatic plant ,Environmental Chemistry ,Environmental science ,Water quality ,Bay ,General Environmental Science ,Total suspended solids - Abstract
We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where monitoring data are available for five water quality variables that govern light availability at the leaf surface. We developed independent estimates of the minimum light required for SAV survival both as a percentage of surface light passing though the water column to the depth of SAV growth (PLW min) and as a percentage of light reaching reaching leaves through the epiphyte layer (PLL min). Value were computed by applying, as inputs to this algorithm, statistically dervived values for water quality variables that correspond to thresholds for SAV presence in Chesapeake Bay. These estimates ofPLW min andPLL min compared well with the values established from a literature review. Calcultations account for tidal range, and total light attenuation is partitioned into water column and epiphyte contributions. Water column attenuation is further partitioned into effects of chlorophylla (chla), total suspended solids (TSS) and other substances. We used this algorithm to predict potential SAV presence throughout the Bay where calculated light available at plant leaves exceededPLL min. Predictions closely matched results of aerial photographic monitoring surveys of SAV distribution. Correspondence between predictions and observations was particularly strong in the mesohaline and polythaline regions, which contain 75–80% of all potential SAV sites in this estuary. The method also allows for independent assessment of effects of physical and chemical factors other than light in limiting SAV growth and survival. Although this algorithm was developed with data from Chesapeake Bay, its general structure allows it to be calibrated and used as a quantitative tool for applying water quality data to define suitability of specific sites as habitats for SAV survival in diverse coastal environments worldwide. more...
- Published
- 2004
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17. Periphyton as a UV-B filter on seagrass leaves: a result of different transmittance in the UV-B and PAR ranges
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Evamaria W. Koch and Leslie A. Brandt
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biology ,Chemistry ,Plant Science ,Aquatic Science ,biology.organism_classification ,medicine.disease_cause ,Filter (aquarium) ,Horticulture ,Seagrass ,Botany ,Transmittance ,medicine ,Epiphyte ,Zostera ,Periphyton ,Ultraviolet - Abstract
Periphyton is considered detrimental to seagrasses as it reduces the amount of light, i.e. photosynthetically available radiation (PAR), that reaches the plant surface. This study evaluated the possibility that periphyton can also be beneficial to seagrasses by reducing ultraviolet (UV)-B radiation that reaches seagrass leaves. Periphyton on UV-B transparent artificial leaves transmitted a significantly lower amount of radiation in the UV-B than in the PAR range. Therefore, periphyton is an effective UV-B filter on seagrass leaves. more...
- Published
- 2003
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18. Sediment resuspension in a shallow Thalassia testudinum banks ex König bed
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Evamaria W. Koch
- Subjects
Suspended solids ,biology ,Ecology ,Sediment ,Plant Science ,Aquatic Science ,biology.organism_classification ,Deposition (geology) ,Sedimentary depositional environment ,Seagrass ,Oceanography ,Thalassia testudinum ,Erosion ,Environmental science ,Sedimentary rock - Abstract
Seagrass beds have been described as depositional environments due to their capacity to reduce current velocity and to attenuate wave energy. As sediment accretes in seagrass beds, they become shallower and may reach a depth where an equilibrium between deposition/erosion and plant mortality maintains the depth of the bed relatively constant. Although data on sediment deposition in seagrass beds is available, little is known about sediment resuspension in these plant communities. In the present study, suspended sediment concentrations in a Thalassia testudinum bed and an adjacent unvegetated area were compared over part of a neap tide and correlated with the prevailing hydrodynamic conditions. Sediment resuspension in the unvegetated area was induced mainly by waves while in the seagrass meadow it was caused by intensification of speed near the bottom during the flood tide. Under these conditions, suspended solid concentrations were higher within the meadow than in the adjacent unvegetated area. The sediment resuspension within the meadow during non-extreme conditions (neap tide and relatively calm winds) suggests that sediment resuspension is an integral part of sedimentary processes occurring in healthy seagrass beds which may be contrary to the commonly-held perception that seagrass beds are only sinks and not sources of suspended matter. more...
- Published
- 1999
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19. Water flow in tide- and wave-dominated beds of the seagrass Thalassia testudinum
- Author
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Evamaria W. Koch and Giselher Gust
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Ecology ,biology ,Water flow ,Turbulence ,Microclimate ,Mixing (process engineering) ,Aquatic Science ,biology.organism_classification ,Oceanography ,Water column ,Seagrass ,Thalassia testudinum ,Environmental science ,Mean flow ,Ecology, Evolution, Behavior and Systematics - Abstract
Biological processes in seagrass meadows are regulated by the exchange of momentum, heat and mass between the surrounding water and the plants and thus may strongly depend on the characteristics of water flow and turbulence. Comparisons of mean flow profiles, turbulence distribution and mixing in meadows of the seagrass Thalassia testudinum colonizing 2 hydrodynamically different sites (wave-dominated and tide-dominated) suggest that the hydrodynamic microclimate and consequently mixing within seagrass beds strongly depend on the hydrodynamic forces (waves and currents) acting on the plants. Unidirectional flows deflect the water over the meadow (skimming flows), which potentially leads to lower mixing between the water above and within the meadow. In contrast, waves cause the blades to move back and forth, increasing the exchange between the water column and that within the meadow. Therefore, the hydrodynamic conditions prevailing in the seagrass habitat (waves, tides) change the pattern of flow attenuation and mixing within the vegetation. more...
- Published
- 1999
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20. Coastal Ecosystem-Based Management with Nonlinear Ecological Functions and Values
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Denise J. Reed, David M. Stoms, Elise F. Granek, Jurgenne H. Primavera, Shankar Aswani, Gerardo M. E. Perillo, Evamaria W. Koch, Stephen Polasky, Lori A. Cramer, Chris J. Kennedy, Sally D. Hacker, Edward B. Barbier, Eric Wolanski, Brian R. Silliman, Carrie V. Kappel, and David Bael more...
- Subjects
Conservation of Natural Resources ,Cost-Benefit Analysis ,Fisheries ,Wetland ,Aquaculture ,Trees ,Sand dune stabilization ,Ecosystem services ,Penaeidae ,Water Movements ,Animals ,Ecosystem ,Lythraceae ,geography ,Alismatales ,Multidisciplinary ,geography.geographical_feature_category ,Ecology ,biology ,Land use ,Coral reef ,Anthozoa ,Thailand ,biology.organism_classification ,Wood ,Seagrass ,Wetlands ,Salt marsh ,Rhizophoraceae ,Environmental science - Abstract
A common assumption is that ecosystem services respond linearly to changes in habitat size. This assumption leads frequently to an “all or none” choice of either preserving coastal habitats or converting them to human use. However, our survey of wave attenuation data from field studies of mangroves, salt marshes, seagrass beds, nearshore coral reefs, and sand dunes reveals that these relationships are rarely linear. By incorporating nonlinear wave attenuation in estimating coastal protection values of mangroves in Thailand, we show that the optimal land use option may instead be the integration of development and conservation consistent with ecosystem-based management goals. This result suggests that reconciling competing demands on coastal habitats should not always result in stark preservation-versus-conversion choices. more...
- Published
- 2008
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21. Estuarine and Coastal Ecosystems and Their Services
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Adrian C. Stier, Evamaria W. Koch, Sally D. Hacker, Brian R. Silliman, and Edward B. Barbier
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geography ,geography.geographical_feature_category ,Marsh ,biology ,Ecology ,Coral reef ,biology.organism_classification ,Sand dune stabilization ,Ecosystem services ,Fishery ,Seagrass ,Salt marsh ,Seascapes ,Environmental science ,Ecosystem - Abstract
The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological functions and their services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. We cite estimates of the key economic values arising from these services, and discuss how the natural variability of ECE impacts their benefits, the synergistic relationships of ECE across seascapes, and the management implications. more...
- Published
- 2011
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22. Ecosystem Services as a Common Language for Coastal Ecosystem-Based Management
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Chris J. Kennedy, Carrie V. Kappel, Mary Ruckelshaus, David M. Stoms, Lori A. Cramer, Brian R. Silliman, Stephen Polasky, Eric Wolanski, Sally D. Hacker, David Bael, Shankar Aswani, Gerardo M. E. Perillo, Evamaria W. Koch, Nyawira A. Muthiga, Edward B. Barbier, Elise F. Granek, and Denise J. Reed more...
- Subjects
Conservation of Natural Resources ,Ecosystem health ,Ecology ,business.industry ,Communication ,Environmental resource management ,ECOSYSTEM SERVICES ,Ecosystem-based management ,Ecosystem services ,Ciencias de la Tierra y relacionadas con el Medio Ambiente ,ComputingMilieux_GENERAL ,ECOSYSTEM-BASED MANAGEMENT ,Ecosystem management ,Terrestrial ecosystem ,Ecosystem ,Coastal management ,business ,Meteorología y Ciencias Atmosféricas ,Management process ,ComputingMilieux_MISCELLANEOUS ,Ecology, Evolution, Behavior and Systematics ,COASTAL WETLANDS ,CIENCIAS NATURALES Y EXACTAS ,Nature and Landscape Conservation - Abstract
Ecosystem-based management is logistically and politically challenging because ecosystems are inherently complex and management decisions affect a multitude of groups. Coastal ecosystems, which lie at the interface between marine and terrestrial ecosystems and provide an array of ecosystem services to different groups, aptly illustrate these challenges. Successful ecosystem-based management of coastal ecosystems requires incorporating scientific information and the knowledge and views of interested parties into the decision-making process. Estimating the provision of ecosystem services under alternative management schemes offers a systematic way to incorporate biogeophysical and socioeconomic information and the views of individuals and groups in the policy and management process. Employing ecosystem services as a common language to improve the process of ecosystem-based management presents both benefits and difficulties. Benefits include a transparent method for assessing trade-offs associated with management alternatives, a common set of facts and common currency on which to base negotiations, and improved communication among groups with competing interests or differing worldviews. Yet challenges to this approach remain, including predicting how human interventions will affect ecosystems, how such changes will affect the provision of ecosystem services, and how changes in service provision will affect the welfare of different groups in society. In a case study from Puget Sound, Washington, we illustrate the potential of applying ecosystem services as a common language for ecosystem-based management. Fil: Granek, Elise F.. Environmental Science & Management, Portland State University, Portland, OR 97207, U.S.A.; Estados Unidos Fil: Polasky, Stephen. Department of Applied Economics, Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN 55108, U.S.A.; Estados Unidos Fil: Kappel, Carrie V.. National Center for Ecological Analysis and Synthesis, University of California Santa Barbara, Santa Barbara, CA 93101, U.S.A.; Estados Unidos Fil: Reed, Denise J.. Department of Earth and Environmental Sciences, University of New Orleans, New Orleans, LA 70148, U.S.A.; Estados Unidos Fil: Stoms, David M.. Bren School of Environmental Science and Management, University of California Santa Barbara, Santa Barbara, CA 93106, U.S.A.; Estados Unidos Fil: Koch, Evamaría W.. Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, MD 21613, U.S.A.; Estados Unidos Fil: Kennedy, Chris J.. Department of Economics and Finance, University of Wyoming, Laramie, WY 82071, U.S.A.; Estados Unidos Fil: Cramer, Lori A.. Department of Sociology, Oregon State University, Corvallis, OR 97331, U.S.A.; Estados Unidos Fil: Hacker, Sally D.. Department of Zoology, Oregon State University, Corvallis, OR 97331, U.S.A.; Estados Unidos Fil: Barbier, Edward B.. Department of Economics and Finance, University of Wyoming, Laramie, WY 82071, U.S.A.; Estados Unidos Fil: Aswani, Shankar. Department of Anthropology and IGP Marine Science, University of California Santa Barbara, Santa Barbara, CA 93106, U.S.A.; Estados Unidos Fil: Ruckelshaus, Mary. NOAA Fisheries Northwest Fisheries Science Center, Seattle, WA 98112, U.S.A.; Estados Unidos Fil: Perillo, Gerardo Miguel E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina Fil: Silliman, Brian R.. Zoology Department, University of Florida, Gainesville, FL 32611, U.S.A.; Estados Unidos Fil: Muthiga, Nyawira. Wildlife Conservation Society, Mombassa, 80107; Kenia Fil: Bael, David. Department of Applied Economics, University of Minnesota, St. Paul, MN 55108, U.S.A.; Estados Unidos Fil: Wolanski, Eric. ACTFR, James Cook University & Australian Institute of Marine Science, Townsville, Queensland 4810; Australia more...
- Published
- 2009
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23. Branch, micropropagule and tissue culture of the red algaeEucheuma denticulatum andKappaphycus alvarezii farmed in the Philippines
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Clinton J. Dawes and Evamaria W. Koch
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Eucheuma ,biology ,business.industry ,Plant Science ,Red algae ,Aquatic Science ,Kappaphycus ,biology.organism_classification ,Kappaphycus alvarezii ,Aquaculture ,Micropropagation ,Botany ,Eucheuma denticulatum ,business ,Axenic - Abstract
Three forms of the iota-producing carrageenophyte,Eucheuma denticulatum, and four forms of the kappa-producing carrageenophyte,Kappaphycus alvarezii, obtained from seaweed farms in the Philippines have been grown in the laboratory under unialgal and axenic conditions. Comparison of media indicates that seed stocks of both species can be cultured using enriched seawater media ranging from ESS and SWMD-1 to inexpensive soil extract (Erdshreiber's) or holding in sterile seawater for up to three weeks. Micropropagation has been successful with at least two forms of each species resulting in clonal propagation from axenic explants within 4 to 8 weeks. Callus development and branch regeneration has also been induced in two forms of each species. The results indicate that culture facilities in the farming areas of the Philippines could maintain high-yielding and rapidly growing seed stock for the seaweed farmers. more...
- Published
- 1991
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24. Attached Bacterial Populations Shared by Four Species of Aquatic Angiosperms▿
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Evamaria W. Koch and Byron C. Crump
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DNA, Bacterial ,Genotype ,Molecular Sequence Data ,Fresh Water ,Nucleic Acid Denaturation ,Applied Microbiology and Biotechnology ,DNA, Ribosomal ,Plant Roots ,Magnoliopsida ,Plant Microbiology ,Rivers ,RNA, Ribosomal, 16S ,Sequence Homology, Nucleic Acid ,Botany ,Gammaproteobacteria ,Cluster Analysis ,Seawater ,Vallisneria americana ,Atlantic Ocean ,Betaproteobacteria ,Phylogeny ,Ecology ,biology ,Bacteria ,Maryland ,Stuckenia pectinata ,fungi ,Alphaproteobacteria ,Bacteroidetes ,food and beverages ,Genes, rRNA ,Biodiversity ,Sequence Analysis, DNA ,biology.organism_classification ,DNA Fingerprinting ,Plant Leaves ,Zostera marina ,Electrophoresis, Polyacrylamide Gel ,Temperature gradient gel electrophoresis ,Food Science ,Biotechnology - Abstract
Symbiotic relationships between microbes and plants are common and well studied in terrestrial ecosystems, but little is known about such relationships in aquatic environments. We compared the phylogenetic diversities of leaf- and root-attached bacteria from four species of aquatic angiosperms using denaturing gradient gel electrophoresis (DGGE) and DNA sequencing of PCR-amplified 16S rRNA genes. Plants were collected from three beds in Chesapeake Bay at sites characterized as freshwater (Vallisneria americana), brackish (Potomogeton perfoliatusandStuckenia pectinata), and marine (Zostera marina). DGGE analyses showed that bacterial communities were very similar for replicate samples of leaves from canopy-forming plantsS. pectinataandP. perfoliatusand less similar for replicate samples of leaves from meadow-forming plantsZ. marinaandV. americanaand of roots of all species. In contrast, bacterial communities differed greatly among plant species and between leaves and roots. DNA sequencing identified 154 bacterial phylotypes, most of which were restricted to single plant species. However, 12 phylotypes were found on more than one plant species, and several of these phylotypes were abundant in clone libraries and represented the darkest bands in DGGE banding patterns. Root-attached phylotypes included relatives of sulfur-oxidizingGammaproteobacteriaand sulfate-reducingDeltaproteobacteria. Leaf-attached phylotypes included relatives of polymer-degradingBacteroidetesand phototrophicAlphaproteobacteria. Also, leaves and roots of three plant species hosted relatives of methylotrophicBetaproteobacteriabelonging to the familyMethylophilaceae. These results suggest that aquatic angiosperms host specialized communities of bacteria on their surfaces, including several broadly distributed and potentially mutualistic bacterial populations. more...
- Published
- 2008
25. Waves in Seagrass Systems: Review and Technical Recommendations
- Author
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Evamaria W. Koch, Shih-Nan Chen, Deborah J. Shafer, Lawrence P. Sanford, and Jane McKee Smith
- Subjects
Background information ,biology ,business.industry ,Environmental resource management ,Ocean current ,Modeling perspective ,biology.organism_classification ,Ecosystem services ,Variety (cybernetics) ,Oceanography ,Seagrass ,Wind wave ,Environmental science ,Ecosystem ,business - Abstract
Seagrasses are rooted flowering marine plants that provide a variety of ecosystem services to the coastal areas they colonize. Attenuation of currents and waves and sediment stabilization are often listed among these services. Although we have a reasonably good understanding of how currents affect seagrasses and vice-versa, less is known about interactions between waves and seagrasses, and standard methods for research on waves in seagrass systems have not yet been established. This report presents background information needed to inform and encourage further studies on waves in seagrass systems from both field and modeling perspectives. It reviews current knowledge of waves in seagrass systems, encompassing field and laboratory data as well as modeling efforts. It then describes various methods for measuring waves in seagrass colonized areas and modeling the dynamics of wave-seagrass interactions. Standardization of experimental designs, instrumentation, analyses, and modeling approaches to allow for ready comparison between studies is encouraged. more...
- Published
- 2006
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26. Fluid Dynamics in Seagrass Ecology—from Molecules to Ecosystems
- Author
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Jennifer Verduin, Evamaria W. Koch, Josef Daniel Ackerman, and Mike van Keulen
- Subjects
Seagrass ,Oceanography ,Ecology ,Ecology (disciplines) ,Fluid dynamics ,Benthic boundary layer ,Zostera marina ,Ecosystem ,Biology ,biology.organism_classification - Published
- 2006
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27. Effect of ultraviolet-B radiation on salt marsh vegetation: Trends of the genus Salicornia along the Americas
- Author
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L. S. Neves, M. Bertiller, G. M. Tourn, Yasmín Detrés, L. B. Pinedo, Roy A. Armstrong, O. A. Bianciotto, Evamaria W. Koch, A. Beeskow, N. A. San Roman, C. S. B. Costa, and A. Y. Blessio
- Subjects
Chlorophyll ,Chlorophyll a ,Salicornia ,Ultraviolet Rays ,Climate ,Population ,Wetland ,Chenopodiaceae ,Photosynthesis ,Biochemistry ,chemistry.chemical_compound ,Botany ,Physical and Theoretical Chemistry ,education ,geography ,education.field_of_study ,geography.geographical_feature_category ,biology ,Chlorophyll A ,Puerto Rico ,Temperature ,Agriculture ,General Medicine ,Pigments, Biological ,South America ,biology.organism_classification ,chemistry ,Salt marsh ,Wetlands ,Shoot ,Salts ,Plant Shoots - Abstract
The effects of natural UV-B radiation on growth, photosynthetic and photoprotective pigment composition of different Salicornia species were analyzed in salt marshes at three different sites along the Americas (Puerto Rico, southern Brazil and Patagonia, Argentina). Plants were exposed to different levels of UV-B radiation for 1-2 years in situ as well as in outdoor garden UV-B exclusion experiments. Different UV-B levels were obtained by covering plants with UV-B opaque (blocked 93-100% of ambient UV-B) and UV-B attenuating (near-ambient) filters (reduced 20-25% of UV-B). Unfiltered plants were exposed to natural irradiance. UV-B filters had significant effects on temperature and photosynthetic pigments (due to changes in PAR; 400-700 nm). The growth of Salicornia species was inhibited after 35 to 88 days of exposure to mean UV-B radiation dosages between 3.6 and 4.1 kJ m(-2) day(-1). The highest number of branches on the main shoot (S. bigelovii and S. gaudichaudiana) and longest total length of the branches (S. gaudichaudiana) were observed in the UV-B opaque treatment. Salicornia species responded to increasing levels of UV-B radiation by increasing the amount of UV-B absorbing pigments up to 330%. Chromatographic analyses of seedlings and adult S. bigelovii plants found seven different UV-B absorbing flavonoids that are likely to serve as UV-B filtering pigments. No evidence of differential sensitivity or resilience to UV-B radiation was found between Salicornia species from low-mid latitudes and a previously published study of a high-latitude population. more...
- Published
- 2006
28. Measurements of physical parameters in seagrass habitats
- Author
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Evamaria W. Koch and Jennifer Verduin
- Subjects
Current (stream) ,Salinity ,Seagrass ,Oceanography ,Water column ,biology ,Habitat ,Turbulence ,Temperature salinity diagrams ,Environmental science ,Current velocity ,biology.organism_classification - Abstract
Seagrass environments are characterized by physical conditions, like temperature, salinity, currents, waves, turbulence, and light. This chapter provides the methods for quantifying temperature, salinity, currents, waves, and turbulence in seagrass habitats, and describes simple, yet biologically relevant techniques that can be easily applied throughout the world. It begins with the description of two simple methods of obtaining accurate temperature data in seagrass habitats, including sediments and the water column, followed by a description of how to obtain salinity data from research vessels or directly in the seagrass habitat. Temperature and salinity can be influenced by tides and, therefore, caution needs to be taken when collecting and interpreting these data. A large variety of current meters are available in the market. Their appropriateness for seagrass research is discussed and the dye tracking method is described in detail for quantification of current velocity in seagrass-colonized areas. The same technique is later applied to the quantification of turbulence in seagrass beds. Dye tracking is a simple and inexpensive technique that allows scientists around the world to make currents and turbulence an integral part of the analysis of their data. more...
- Published
- 2001
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29. Sedimentation adjacent to naturally eroding and breakwater-protected shorelines in Chesapeake Bay
- Author
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Evamaria W. Koch, Nicole Barth, and Cindy M. Palinkas
- Subjects
Shore ,geography ,geography.geographical_feature_category ,Oceanography ,Benthic zone ,Breakwater ,Sediment ,Ecosystem ,Spatial variability ,Sedimentary rock ,Sedimentation ,Geology - Abstract
Sediment characteristics, especially grain size and organic content, in nearshore Chesapeake Bay environments show significant temporal and spatial variability. This can impact benthic organisms, particularly submerged aquatic vegetation (SAV), which are important components of the ecosystem. In order to better understand how these changes are reflected in the stratigraphic record, the radiochemical and textural properties of sediment at four sites are examined. Fine and organic material are observed to increase at some nearshore locations, whereas others have experienced a shift toward lower-organic, coarser sediments. These changes are likely related to local variations in sedimentary processes. Other, more recent, perturbations are due to breakwater construction, which can trap fine and organic material in the protected area. Accumulation rates inshore of the breakwater are ~2–4 times higher than in adjacent exposed locations, and this change is coincident with breakwater construction. Thus, because sedimentary processes vary according to physical setting, local trends must be discerned to determine whether a given site may be suitable for SAV restoration. more...
- Published
- 2010
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30. Mediated Modeling of the Impacts of Enhanced UV-B Radiation on Ecosystem Services
- Author
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Gustavo A. Ferreyra, Serge Demers, Robert Costanza, Evamaria W. Koch, Oscar A. Bianciotto, Fernando Momo, Marjan van den Belt, Maria Vernet, and Susana Beatriz Diaz
- Subjects
geography ,Marsh ,geography.geographical_feature_category ,Primary producers ,business.industry ,Global warming ,Environmental resource management ,Stakeholder ,Primary production ,Climate change ,General Medicine ,Biochemistry ,Ecosystem services ,Environmental science ,Economic impact analysis ,Physical and Theoretical Chemistry ,business - Abstract
This article describes the use of group model building to facilitate interaction with stakeholders, synthesize research results and assist in the development of hypotheses about climate change at the global level in relation to UV-B radiation and ecosystem service valuation. The objective was to provide a platform for integration of the various research components within a multidisciplinary research project as a basis for interaction with stakeholders with backgrounds in areas other than science. An integrated summary of the scientific findings, along with stakeholder input, was intended to produce a bridge between science and policymaking. We used a mediated modeling approach that was implemented as a pilot project in Ushuaia, Argentina. The investigation was divided into two participatory workshops: data gathering and model evaluation. Scientists and the local stakeholders supported the valuation of ecosystem services as a useful common denominator for integrating the various scientific results. The concept of economic impacts in aquatic and marsh systems was represented by values for ecosystem services altered by UV-B radiation. In addition, direct local socioeconomic impacts of enhanced UV-B radiation were modeled, using data from Ushuaia. We worked with 5 global latitudinal regions, focusing on net primary production and biomass for the marine system and on 3 plant species for the marsh system. Ecosystem service values were calculated for both sectors. The synthesis model reflects the conclusions from the literature and from experimental research at the global level. UV-B is not a significant stress for the marshes, relative to the potential impact of increases in the sea level. Enhanced UV-B favors microbial dynamics in marine systems that could cause a significant shift from primary producers to bacteria at the community level. In addition, synergetic effects of UV-B and certain pollutants potentiate the shift to heterotrophs. This may impact the oceanic carbon cycle by increasing the ratio of respiratory to photosynthetic organisms in surface waters and, thus, the role of the ocean as a carbon sink for atmospheric CO2. In summary, although changes in the marine sector due to anthropogenic influences may affect global climate change, marshes are expected to primarily be affected by climate change. more...
- Published
- 2006
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31. Beyond Light: Physical, Geological, and Geochemical Parameters as Possible Submersed Aquatic Vegetation Habitat Requirements
- Author
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Evamaria W. Koch
- Subjects
chemistry.chemical_classification ,Hydrology ,geography ,geography.geographical_feature_category ,Sediment ,Estuary ,Vegetation ,Aquatic Science ,Habitat ,chemistry ,Aquatic plant ,Environmental Chemistry ,Environmental science ,Organic matter ,Epiphyte ,General Environmental Science ,Total suspended solids - Abstract
When determining the suitability of a certain area as a habitat for submersed aquatic vegetation (SAV), light and parameters that modify light (epiphytes, total suspended solids, chlorophyll concentration, nutrients) are the first factors to be taken into consideration. As a result, in the past 10 years, light has been the major focus of SAV research. Even so, we are still unable to explain why SAV often occurs in one area but is absent just a few meters away. Recent studies have shown that SAV may not occur in areas where light levels are adequate but other parameters like wave energy and sulfide concentrations are excessive. It is time to look beyond light when determining SAV habitat requirements. This paper summarizes the impact that physical (waves, currents, tides, and turbulence), geological (sediment grain size and organic matter), and geochemical (mainly sulfide) parameters may have on SAV habitat suitality. Light remains an integral part of the discussion but the focus shifts from maximum depths of distribution (determined mainly by light) to the range SAV can colonize between the maximum and minimum depths of distribution (determined mainly by physical forces). This paper establishes minimum depths of occurrence resulting from the effects of tides and waves, preferred ranges in particle size, organic content, and sulfide, as well as lilfide, as well as limits on currents and waves as related to the capacity to stay rooted at one extreme and diffusive boundary layer constrains at the other. more...
- Published
- 2001
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32. Germination and Algal-Free Laboratory Culture of Widgeon Grass, Ruppia maritima
- Author
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Evamaria W. Koch, César Vieira Cordazzo, and Ulrich Seeliger
- Subjects
Potamogetonaceae ,Microbiological culture ,Germination ,Aquatic plant ,Botany ,Environmental Chemistry ,Cold storage ,Aquatic Science ,Biology ,Sterilization (microbiology) ,biology.organism_classification ,General Environmental Science ,Ruppia maritima - Abstract
A methodology for the isolation ofRuppia maritima L. into algal-free laboratory culture is described. Seeds were surface sterilized with 96% ethyl alcohol of pH 2, kept for several months in cold storage at 7°C, and subsequently transferred to 25°C to induce germination. Basic culture conditions are discussed and a vessel of easy maintenance and sterilization forRuppia culture in ground glass sediments is presented. Minor modifications of this methodology might permit contaminant-free laboratory cultures of other estuarine and marine spermatophytes. more...
- Published
- 1984
- Full Text
- View/download PDF
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