Evamaria W Koch

• PhD
• Professor (Associate) at University of Maryland Center for Environmental Science

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 ab...

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-...

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...

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 gener...

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 va...

The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. Where possible, we indicate estimates of the key economic va...

Volume 12 Ecological Economics of Estuaries and Coasts 12.01 Ecological Economics of Estuaries and Coasts 1 M van den Belt 12.02 What Are Ecosystem Services? 15 R de Groot 12.03 Valuation of Coastal Ecosystem Services 35 M van den Belt, V Forgie, and J Farley 12.04 Environmental Benefit Transfers of Ecosystem Service Valuation 55 S Liu, R Porte...

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 und...

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 refl...

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 challe...

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 vir...

The hypothesis that sediment organic content is limiting growth and distribution of the seagrass Zostera marina was tested in Chincoteague Bay, Maryland, and in a controlled mesocosm experiment. In the field, Z. marina was usually absent from areas with sediment organic content > 4%, especially compared with areas with sediment organic content < 4%...

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 provided linearly (unvaryingly, at a steady rate), but natural processes are characterized by thresholds and limiting functions. In...

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) an...

We are concerned about the assertion in the Report by E. B. Barbier et al. that vegetation reduces coastal damage during extreme events (“Coastal ecosystem-based management with nonlinear ecological functions and values,” 18 January, p. [321][1]). Although the intended point was that ecosystem

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 reef...

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...

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,...

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 inte...

Fluid dynamics is an essential component of sea-grass ecology as it affects every aspect of the plants and their habitats, from the smallest to the largest scales. Over the last decades, we have begun to understand how seagrass beds attenuate waves and currents. Now we begin a new phase of fine tuning previous findings and revising classical concep...

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...

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 res...

Seagrass colonise new areas via the dispersion of seeds or vegetative fragments. Independent of the manner of colonization, habitat requirements need to be met for the successful establishment of seagrasses. Here we report on the colonization process of Posidonia oceanica in a highly disturbed area: a gas pipeline trench at Capo Feto (SW Sicily, It...

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...

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 a...

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 t...

The effects of mass transfer resistance due to the presence of a diffusive boundary layer on the photosynthesis of the epilithic algal community (EAC) of a coral reef were studied. Photosynthesis and respiration of the EAC of dead coral surfaces were investigated for samples from two locations: the Gulf of Aqaba, Eilat (Israel), and One Tree Reef o...

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 resear...

Water movement in freshwater and marine environments affects submersed macrophytes, which also mediate water movement. The result of this complex interaction also affects sediment dynamics in and around submersed macrophyte beds. This review defines known relationships and identifies areas that need additional research on the complex interactions a...

The loss of submerged aquatic vegetation, or SAV, from shallow waters of Chesapeake Bay, which was first noted in the early 1960s, is a widespread, well-documented problem. Although other factors, such as climatic events and herbicide toxicity, may have contributed to the decline of SAV in the Bay, the primary causes are eutrophication and associat...

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. Altho...

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 coloniz...

Obstructions that protruded from a laboratory test bed into the benthic boundary layer were exposed to gradients in longitudinal velocity (δu/δz) that produced vertical pressure gradients along the surface of the obstruction. These pressure gradients generated vertical secondary flows that may have ecological significance for benthic fauna and aqua...

The disappearance of Zostera marina L. (eelgrass) in western Long Island Sound has been attributed to the eutrophication-induced increase in light attenuation in the waters of that area. In this work we explore whether the much higher tidal range in the western (3 m) than in the eastern (1 m) Sound could further reduce light availability and, there...

Photosynthetic rates of aquatic plants frequently increase with increasing current velocities. This is presumably due to a reduction in the thickness of the diffusion boundary-layer which allows for a higher carbon availability on the plant surface. Blades of the seagrasses Thalassia testudinum and Cymodocea nodosa exposed to different current velo...

Photosynthetic rates of aquatic macrophytes are affected by the diffusion of carbon through the boundary layer which decreases with increasing flow velocities. This is shown by a significant increase in photosynthetic rates of Ulva lactuca fronds exposed to friction velocities (u *) between 0.0 and 0.3 cm s–1. No further increase in photosynthetic...

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 us...

Axenic tissue cultures ofRuppia maritima L. were established and propagated clonally in vitro from terminal rhizome segments collected from Tampa Bay, Florida, USA. Cultures were maintained in a base medium consisting of synthetic seawater supplemented with half-strength Murashige and Skoog salts and 1% sucrose at pH 5.6. The effects of five cytoki...

Pigment levels, chemical constituents, and photosynthetic responses of two estuarine populations of Gracilaria verrucosa and one neretic population of G. tikvahiae were monitored before, during and after culturing in nutrient-enriched seawater. Chlorophyll a and phycoerythrin, protein, soluble carbohydrate, lipid, and energy content did not change...

Gracilaria verrucosa collected at 32%o salinity and cultured in the same salinity for 20 days showed lower photosynthetic responses when measured in 10%o than in 32%o. Plants cultured in 10%o and measured at 32 and 10%o did not show this difference suggesting distinct mechanisms of osmoregulation after a hypo- or hyperosmotic shock. Respiratory rat...

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 st...

Thesis (M.S.)--University of South Florida, 1988. Bibliography: leaves 95-99. Electronic reproduction. [Florida] : State University System of Florida, PALMM Project, 2001. (Florida heritage collection) Mode of access: World Wide Web. System requirements: Internet connectivity; Web browser software; Adobe Acrobat Reader to view and print PDF files....

Thesis (Ph. D.)--University of South Florida, 1993. Includes bibliographical references (leaves 104-113).