Marsh Zones Research Articles

Effects of soil abiotic factors on the plant morphology in an intertidal salt marsh, Yellow River Delta, China

Plant morphology plays important role in studying biogeography in many ecosystems. Suadea salsa, as a native plant community of northern China and an important habitat for diversity of waterbirds and macrobenthos, has often been overlooked. Nowadays, S. salsa community is facing great loss due to coastal reclamation activities and natural disturbances. To maintain and restore S. salsa community, it's important to address the plant morphology across marsh zones, as well as its relationships with local soil abiotic conditions. In our studied intertidal salt marsh, we found that less flood disturbance frequency, softer soil conditions, rich soil organic matter, total carbon and total nitrogen, lower water depth and water content, less species competition will benefit S. salsa plant in the morphology of high coverage, above-ground biomass, shoot height and leaf length. Lower soil porewater salinity will benefit the below-ground biomass of S. salsa. Thus, we recommend managers help alleviate soil abiotic stresses in the intertidal salt marshes, making the soil conditions more suitable for S. salsa growth and succession.

Distributions of salt-marsh foraminifera along the coast of SW California, USA: Implications for sea-level reconstructions

Abstract Salt-marsh foraminifera are frequently used around the world as proxies in paleoenvironmental studies of sea-level change. Quantitative reconstructions of sea-level change use transfer functions which are based on the vertical zonation of salt-marsh foraminifera with respect to the tidal frame. This paper explores for the first time the environmental factors that control the foraminiferal assemblages in Southern California marshes using modern surface samples (1 cm thick) from two marshes Seal Beach and Tijuana Estuary. The dead foraminiferal assemblages demonstrate distinct zonation across the salt-marsh surfaces which is primarily related to elevation. Other variables less important than elevation such as O2, temperature, salinity and pH additionally control the distribution pattern of these assemblages. The tidal flat and low marshes are characterized by high abundances of Miliammina fusca and calcareous species. The middle marsh is dominated by Jadammina macrescens and Trochammina inflata, while the high marsh zone is dominated by Trochamminita irregularis, Miliammina petila, J. macrescens and T. inflata. Regression modelling was used for the development of a sea-level transfer function based on a combined training set of surface samples from the two study sites. The performance of the Weighted Average – Partial Least Squares (WA-PLS) transfer function suggests a robust relationship between the observed and estimated elevations (r2Jack = 0.72), and is capable of predicting former sea levels to a precision of ± 0.09 m. Our results can be used for future paleoenvironmental reconstructions along the Southern California coast, an area that has experienced changes in sea level in the past and will be affected by future sea-level rise coupled with climate and anthropogenic changes, resulting in wide impacts on the natural coastal habitats in this region.

Ecosystem engineers drive creek formation in salt marshes.

Ecosystem engineers affect different organisms and processes in multiple ways at different spatial scales. Moreover, similar species may differ in their engineering effects for reasons that are not always clear. We examined the role of four species of burrowing crabs (Sesarma reticulatum, Eurytium limosum, Panopeus herbstii, Uca pugnax) in engineering tidal creek networks in salt marshes experiencing sea level rise. In the field, crab burrows were associated with heads of eroding creeks and the loss of plant (Spartina alterniflora) stems. S.reticulatum was closely associated with creek heads, but densities of the other crab species did not vary across marsh zones. In mesocosm experiments, S.reticulatum excavated the most soil and strongly reduced S.alterniflora biomass. The other three species excavated less and did not affect S.alterniflora. Creek heads with vegetation removed to simulate crab herbivory grew significantly faster than controls. Percolation rates of water into marsh sediments were 10 times faster at creek heads than on the marsh platform. Biomass decomposed two times faster at creek heads than on the marsh platform. Our results indicate that S.reticulatum increases creek growth by excavating sediments and by consuming plants, thereby increasing water flow and erosion at creek heads. Moreover, it is possible that S.reticulatum burrows also increase creek growth by increasing surface and subsurface erosion, and by increasing decomposition of organic matter at creek heads. Our results show that the interaction between crab and plant ecosystem engineers can have both positive and negative effects. At a small scale, in contrast to other marsh crabs, S.reticulatum harms rather than benefits plants, and increases erosion rather than marsh growth. At a large scale, however, S.reticulatum facilitates the drainage efficiency of the marsh through the expansion of tidal creek networks, and promotes marsh health.

The Distribution Of Contemporary Saltmarsh Foraminifera In A Macrotidal Estuary: An Assessment Of Their Viability For Sea-Level Studies

An analysis of dead benthic foraminiferal assemblages and associated environmental variables is presented to establish the controls on species distribution and zonation on two macrotidal saltmarshes in the Mersey estuary with the aim of evaluating the use of foraminifera in reconstructing past sea levels. The combined results from five contemporary transects from two sites illustrate that where there is a sufficient elevational range, foraminifera distribution and zonation shows a good relationship with altitude, with a high-to-middle marsh zone characterised by Haplophragmoides wilberti , Jadammina macrescens, and Miliammina fusca, and a low marsh zone composed of similar agglutinated species with calcareous species including Brizalina spp., Elphidium spp., and Haynesina spp. Cluster analysis and partial Redundancy Analysis (pRDA) reveals that the elevational control decreases with respect to other environmental variable inter-correlations when the sampling elevation range is reduced. It is proposed that this is a key issue for macrotidal environments when the contemporary sampling range represents a small proportion of the spring tidal range (i.e. <10%). Limiting the contemporary dataset to agglutinated species only, a tidal level transfer function can be obtained which offers acceptable predictability and precision (r2jack = 0.79, RMSEPjack = 0.13 m) for the reconstruction of past sea level.

Seasonal and Spatial Variations of Saltmarsh Benthic Foraminiferal Communities from North Norfolk, England

Time series foraminiferal data were obtained from samples collected from three sites at Brancaster Overy Staithe, Burnham Overy Staithe and Thornham on the North Norfolk coast over a 1-year period. At each collection point, six environmental variables—temperature, chlorophyll, sand, mud, pH and salinity—were also measured. The principle aim of this study was to examine the benthic foraminiferal fauna in regard to the temporal variability of foraminiferal abundance, seasonal trend, dominant species, species diversity and the impact of environmental variables on the foraminiferal communities in the top 1 cm of sediment over a 1-year time series. The foraminiferal assemblages at the three sites were dominated by three species: Haynesina germanica, Ammonia sp. and Elphidium williamsoni. Foraminiferal species showed considerable seasonal and temporal fluctuation throughout the year at the three investigated sites. The foraminiferal assemblage at the three low marsh zones showed a maximum abundance in autumn between September and November and a minimum abundance observed between July and August. There were two separate peaks in the abundance of Ammonia sp. and E. williamsoni, one in spring and another in autumn. In contrast, H. germanica showed a single peak in its abundance in autumn. A generalized additive modelling approach was used to explain the variation in the observed foraminiferal abundance and to estimate the significant impact of each of the environmental variables on living foraminiferal assemblages, with taxa abundance as the dependent variable. When included in the model as predictors, most of the environmental variables contributed little in explaining the observed variation in foraminiferal species abundance. However, the hypotheses for differences amongst sites, salinity and pH were significant and explained most of the variability in species relative abundance.

Carbon dioxide fluxes reflect plant zonation and belowground biomass in a coastal marsh

AbstractCoastal wetlands are major global carbon sinks; however, they are heterogeneous and dynamic ecosystems. To characterize spatial and temporal variability in a New England salt marsh, greenhouse gas (GHG) fluxes were compared among major plant‐defined zones during growing seasons. Carbon dioxide (CO2) and methane (CH4) fluxes were compared in two mensurative experiments during summer months (2012–2014) that included low marsh (Spartina alterniflora), high marsh (Distichlis spicata and Juncus gerardii‐dominated), invasive Phragmites australis zones, and unvegetated ponds. Day‐ and nighttime fluxes were also contrasted in the native marsh zones. N2O fluxes were measured in parallel with CO2 and CH4 fluxes, but were not found to be significant. To test the relationships of CO2 and CH4 fluxes with several native plant metrics, a multivariate nonlinear model was used. Invasive P. australis zones (−7 to −15 μmol CO2·m−2·s−1) and S. alterniflora low marsh zones (up to −14 μmol CO2·m−2·s−1) displayed highest average CO2 uptake rates, while those in the native high marsh zone (less than −2 μmol CO2·m−2·s−1) were much lower. Unvegetated ponds were typically small sources of CO2 to the atmosphere (&lt;0.5 μmol CO2·m−2·s−1). Nighttime emissions of CO2 averaged only 35% of daytime uptake in the low marsh zone, but they exceeded daytime CO2 uptake by up to threefold in the native high marsh zone. Based on modeling, belowground biomass was the plant metric most strongly correlated with CO2 fluxes in native marsh zones, while none of the plant variables correlated significantly with CH4 fluxes. Methane fluxes did not vary between day and night and did not significantly offset CO2 uptake in any vegetated marsh zones based on sustained global warming potential calculations. These findings suggest that attention to spatial zonation as well as expanded measurements and modeling of GHG emissions across greater temporal scales will help to improve accuracy of carbon accounting in coastal marshes.

Five years of Deepwater Horizon oil spill effects on marsh periwinkles Littoraria irrorata

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 576:135-144 (2017) - DOI: https://doi.org/10.3354/meps11827 Theme Section: Response of nearshore ecosystems to the Deepwater Horizon oil spill Five years of Deepwater Horizon oil spill effects on marsh periwinkles Littoraria irrorata Scott Zengel1,*, Jennifer Weaver2, Steven C. Pennings3, Brian Silliman4, Donald R. Deis5, Clay L. Montague6, Nicolle Rutherford7, Zachary Nixon2, Andrew R. Zimmerman8 1Research Planning, Inc. (RPI), Tallahassee, Florida 32303, USA 2Research Planning, Inc. (RPI), Columbia, South Carolina 29201, USA 3Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA 4Duke University Marine Laboratory, Beaufort, North Carolina 28516, USA 5Atkins, Jacksonville, Florida 32256, USA 6Department of Environmental Engineering Sciences, University of Florida, Gainesville, Florida 32611, USA 7Emergency Response Division, Office of Response and Restoration, National Ocean Service, National Oceanographic and Atmospheric Administration (NOAA), Seattle, Washington 98115, USA 8Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA *Corresponding author: szengel@researchplanning.comAdvance View was available online October 13, 2016 ABSTRACT: The Deepwater Horizon spill (2010) was the largest marine oil spill in US waters to date and one of the largest worldwide. To examine effects of the oil spill on an important salt marsh species over time, we conducted a meta-analysis on marsh periwinkles Littoraria irrorata using published and unpublished sources spanning more than 5 yr (2010-2015), including newly available Natural Resources Damage Assessment (NRDA) and Gulf of Mexico Research Initiative (GoMRI) data sets. We tested the hypotheses that the spill decreased mean periwinkle density, reduced mean snail shell length, and changed periwinkle size distribution. Averaged across multiple studies, sites, marsh zones (edge versus interior), and years, our synthesis revealed a negative effect of heavy oiling on periwinkles. Snail densities were reduced by 73% in heavily oiled sites across all study-zone-by-year combinations, including adverse effects for both the oiled marsh edge and oiled marsh interior, with impacts observed over more than 5 yr. Mean periwinkle shell length was somewhat reduced at the oiled marsh edge in a few cases; however, periwinkle size distributions displayed greater relative proportions of smaller adults and sub-adults, and fewer large adults, across all years. Given the spatial and temporal extent of data analyzed, this synthesis provides evidence that the Deepwater Horizon spill suppressed populations of marsh periwinkles in heavily oiled marshes for over 5 yr, and that impacts were ongoing and recovery was incomplete, likely affecting other ecosystem components, including marsh productivity, organic matter and nutrient cycling, marsh-estuarine food webs, and associated predators. KEY WORDS: Deepwater Horizon · Oil spill · Salt marsh · Marsh periwinkle · Littoraria irrorata · Ecological impacts · Ecological recovery · Gulf of Mexico Full text in pdf format PreviousNextCite this article as: Zengel S, Weaver J, Pennings SC, Silliman B and others (2017) Five years of Deepwater Horizon oil spill effects on marsh periwinkles Littoraria irrorata. Mar Ecol Prog Ser 576:135-144. https://doi.org/10.3354/meps11827 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 576. Online publication date: August 03, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Disturbance in Georgia salt marshes: variation across space and time

AbstractWe documented the frequency and effect on live biomass of five different types of disturbance over 14 years in creekbank and mid‐marsh zones of eight salt marshes dominated by Spartina alterniflora in Georgia, USA. Wrack (floating debris) and creekbank slumping were the most common disturbances at the creekbank, and snails were the most common disturbance agent in the mid‐marsh. Disturbance frequency varied among sites due to differences in plot elevation and landscape position. Wrack disturbance at the creekbank was positively correlated with plot elevation, and both initial slumping and terminal slumping of creekbank plots were negatively correlated with plot elevation. Wrack disturbance at the creekbank and snail disturbance in the mid‐marsh were also most common at barrier island vs. interior marshes. Disturbance varied up to 14‐fold among years. Wrack disturbance at the creekbank was negatively correlated with river discharge and sea level, and initial slumping of creekbank plots was also negatively correlated with sea level. The different disturbance types varied in their effects on end‐of‐year standing plant biomass. At the creekbank, wrack disturbance reduced biomass in affected plots by ~46%, but slumping did not affect biomass until the plot was totally lost. In the mid‐marsh, slumping and wrack were not important disturbances, but snail disturbance reduced biomass in affected plots by ~70%. In addition, abiotic conditions (river discharge, maximum monthly temperature, sea level, and precipitation) strongly affected year‐to‐year variation in biomass. Across the entire landscape, fewer than a quarter of the plots on average were disturbed, and disturbance reduced overall standing biomass by ~18% in the creekbank zone and ~3% in the mid‐marsh zone. Our results indicate that wrack has fairly strong effects on end‐of‐year biomass at the creekbank. Overall, however, variation in abiotic conditions among years had stronger effects on end‐of‐year standing biomass in both marsh zones than did disturbance.

Factors regulating community composition of methanogens and sulfate-reducing bacteria in brackish marsh sediments in the Min River estuary, southeastern China

Assessing the diverse communities of methanogenic Archaea and sulfate-reducing bacteria (SRB) is important to understand methane (CH4) production in wetland ecosystems. However, the vertical distribution of composition and diversity, and the effects of environmental factors on the methanogen and SRB communities in the sediments of subtropical estuarine brackish marshes have been poorly characterized. To assess the effects of variable environmental conditions on methanogenic and SRB communities in marshes, we studied three brackish marsh zones dominated by Phragmites australis, Cyperus malaccensis and Spartina alterniflora, respectively, in the Min River estuary, southeastern China. Methanogens of the Methanomicrobiales order was the dominant group at sediment depths of 0–30 cm, which indicated that the main pathway of methane production was H2/CO2 in this zone. In general, methanogens of the genus Methanoregula were dominant in the three marsh zones. For SRB, Desulfobacterales was the dominant group, and Desulfobacterium and Desulfosarcina were the predominant genera at the depth of 0–30 cm. The community composition of methanogens and SRB changed with vegetation type and soil depth. Compared with SRB, vegetation type demonstrated a stronger influence on the community composition of methanogens. Canonical correspondence analysis (CCA) analysis further revealed that the main factors affecting the methanogens community composition were EC (electric conductivity) and pH, and the main factors affecting SRB community composition were pH, SOC and TN, suggesting that pH is a common factor influencing the community compositions of both methanogen and SRB in the sediments of brackish marshes.

Responses to salinity of Spartina hybrids formed in San Francisco Bay, California (S. alterniflora × foliosa and S. densiflora × foliosa )

San Francisco Bay (SFB), which supports large populations of the California native cordgrass Spartina foliosa, has been the recipient of introductions of S. alterniflora and S. densiflora. Hybrids have arisen between the native and these exotic species. Sterile F1 S. densiflora × foliosa hybrids have formed numerous times in a number of marshes, while introgressing S. alterniflora × foliosa hybrids are fully fertile and invaded widely in SFB, especially onto naturally-open low tidal flats by inundation-tolerant hybrids. Sarcocornia pacifica, pickleweed, dominates the mid-to-upper marsh zones where the hypersaline conditions that occur during the summer drought, characteristic of this climate, exclude S. foliosa. Here we report on two glasshouse experiments investigating the salinity tolerance of hybrid Spartina. Some hybrids of both origins grew well and flowered at high salinity levels while the parental species grew little and did not flower. Our results imply that mid-zone marshes are also vulnerable to invasion by salinity-tolerant Spartina hybrids. Herbicide control implemented over the last 10 years targeting both the exotic species and their hybrids have reduced their extent. However, efforts in monitoring and management of exotic Spartina and its hybrids must continue as vast areas of tidal marsh restoration are underway and planned in SFB; colonization by Spartina hybrids tolerant to inundation and/or salinity will greatly alter restoration trajectories. These concerns are all the more vital given projections of climate change and its effects on salinity and sea level rise in SFB salt marshes.

Contrasting biogeomorphic processes affecting salt‐marsh development of the Mokbaai, Texel, The Netherlands

AbstractThe growth and decline of salt marshes may be the result of various interacting biogeomorphic processes and external factors. We present a case study of the Mokbaai on the Wadden island of Texel, where we assess the relative importance and the interaction between the biogeomorphic processes and various disturbances. We analysed changes in vegetation composition in the salt marsh and sedimentation–erosion patterns of the adjoining intertidal flat over a 30‐year period. Vegetation underwent regression in the lower parts of the marsh, i.e. the low marsh zone changed into pioneer zone. Comparing elevation measurements from 2013 and 1983 showed that the adjoining intertidal flats eroded 15–25 cm. Maintenance dredging of a nearby harbour might negatively impact the sediment balance indicating that the regression of the lower parts of the salt marsh is caused by a lack of sediment. Simultaneously, a change in the local hydrology led to vegetation succession into high and brackish salt marsh, increased organic sediment production and consequently cliff formation. The results from this case study show that, even in a relatively small salt marsh, changes in external factors may set in motion a series of biogeomorphic processes and feedbacks, leading to locally contrasting trends in spatiotemporal development. © 2016 The Authors. Earth Surface Processes and Landforms Published by John Wiley &amp; Sons Ltd.

Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species.

Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in “La Albufera” Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves—where they are presumably compartmentalized in vacuoles—and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na+ and Cl− contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K+ transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level—estimated from malondialdehyde accumulation—was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results, we concluded that although D. viscosa cannot directly compete with true halophytes in highly saline environments, it is nevertheless quite stress tolerant and therefore represents a threat for the vegetation located on the salt marshes borders, where several endemic and threatened species are found in the area of study.

Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used insitu measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P<0.001 for both). In addition, soil oxygen concentrations were lower in the low and mid-marshes relative to the high marsh (P<0.001). Net N2 O fluxes differed significantly among marsh zones (P=0.009), averaging 9.8±5.4μgNm(-2) h(-1) , -2.2±0.9μgNm(-2) h(-1) , and 0.67±0.57μgNm(-2) h(-1) in the low, mid, and high marshes, respectively. Both net N2 O release and uptake were observed in the low and high marshes, but the mid-marsh was consistently a net N2 O sink. Gross N2 O production was highest in the low marsh and lowest in the mid-marsh (P=0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise.

Bottom-up and top-down human impacts interact to affect a protected coastal Chilean marsh.

Many ecosystems, even in protected areas, experience multiple anthropogenic impacts. While anthropogenic modification of bottom-up (e.g., eutrophication) and top-down (e.g., livestock grazing) forcing often co-occurs, whether these factors counteract or have additive or synergistic effects on ecosystems is poorly understood. In a Chilean bio-reserve, we examined the interactive impacts of eutrophication and illegal livestock grazing on plant growth with a 4-yr fertilization by cattle exclusion experiment. Cattle grazing generally decreased plant biomass, but had synergistic, additive, and antagonistic interactions with fertilization in the low, middle, and high marsh zones, respectively. In the low marsh, fertilization increased plant biomass by 112%, cattle grazing decreased it by 96%, and together they decreased plant biomass by 77%. In the middle marsh, fertilization increased plant biomass by 47%, cattle grazing decreased it by 37%, and together they did not affect plant biomass. In the high marsh, fertilization and cattle grazing decreased plant biomass by 81% and 92%, respectively, but together they increased plant biomass by 42%. These interactions were also found to be species specific. Different responses of plants to fertilization and cattle grazing were likely responsible for these variable interactions. Thus, common bottom-up and top-down human impacts can interact in different ways to affect communities even within a single ecosystem. Incorporating this knowledge into conservation actions will improve ecosystem management in a time when ecosystems are increasingly challenged by multiple interacting human impacts.

Risk reduction by combining nature values with flood protection?

In the Netherlands, the concept of a multifunctional dike has already often been implemented, and has been identified as a promising climate adaptation measure. In a multifunctional dike, functions like urban development, transport infrastructure, recreation, agriculture or nature are deliberately combined with its primary flood protection function. This means that the design must be based on the requirements and life span of all different functions, while in a monofunctional dike only the flood protection function is considered. By accommodating other functions, a multifunctional dike may easier fit into, or even contribute to the quality of the landscape. Moreover, these other functions may help in financing the flood protection works, but governance is more complicated. To avoid costly adjustments forthcoming from changed safety standards, incorporation of multiple functions can require a more “robust” flood defence than a monofunctional flood defence. A robust flood defence can withstand more extreme situations than required by the present safety standards, and has a substantially lower flooding probability. Therefore, a multifunctional dike may be attractive in view of the uncertainties regarding the effects of climate change and a changing world. Moreover, it will result in reduced flood risk. As part of the Dutch Delta programme, several explorative studies on multifunctional dikes were initiated. Most studies focused on urban areas, but also in the rural area interest emerged for multifunctional dikes, e.g. for the integration of salt marshes into the flood defences. Marshes provide valuable habitat for vegetation and invertebrate species, and are important for wading birds. Furthermore, under condition of abundant sediment availability they can keep pace with sea level rise. Explorative modelling results indicate that vegetated forelands affect wave heights, even under extreme conditions. However, the inclusion of a vegetated foreland into the dike design does not automatically mean that nature values and flood protection are well integrated. Flood protection imposes rather different requirements on the extent and features of marshes than nature conservation and development. Wave damping is most effective with a high and stable marsh, while nature thrives with dynamic processes and differences in elevation. Therefore, only a design that allows natural marsh dynamics and includes different marsh zones could combine nature values with flood protection. In practice, this means a dike design with an uncertain foreland, that offers space for natural processes. The uncertainty in foreland development reduces the possible flood risk reduction. In our paper we describe the critical points of interest concerning risk reduction in this system.

Effects of Sediment Removal on Prairie Pothole Wetland Plant Communities in North Dakota

ABSTRACT This study assessed the effects of sediment removal on Prairie Pothole Region wetland plant communities in North Dakota in order to determine if this management tool improves vegetation structure that benefits wildlife. Three categories of seasonal wetlands were evaluated: reference condition, converted cropland, and excavated. Vegetation surveys were conducted in the wet meadow and shallow marsh zones of 39 seasonal wetlands located in Benson, Eddy, Towner, and Wells Counties, North Dakota. Visual obstruction readings were taken at various heights in order to assess habitat quality. There were no geographic differences in the reference wetland plant communities. However, there were significant treatment differences between the plant communities of the wet meadow and shallow marsh zones. In general, excavated wetlands showed vegetation trends similar to reference wetlands, whereas the converted cropland wetlands tended to be more cattail-choked. Visual obstruction scores and mean percent cover of...

Evolution of Çan-Etili (Çanakkale-NW Turkey) lignite basin: Sedimentology, petrology, palynology and lignite characterization

This study examines the development and sedimentology of Çan-Etili lignite basin in Biga Peninsula (NW Turkey) along with the palynologic and petrographic properties of the coals in this region. The Çan-Etili lignite basin discordantly overlies Oligocene-aged Çan volcanics. The basin consists of caldera type sedimentation developed by the combined effects of volcanism and tectonics. The volcanic rocks forming the basement of the basin consist of andesitic, dacitic and basaltic lava flows as well as agglomerates, tuff and silicified tuffs, and kaolin which is their alteration product. The basement volcanic rocks cooled from high potassium and calc-alkaline magma. The trace element geochemistry of different rocks within the volcanics reveals that they are from a volcanic arc. The Çan Formation contains lignites and consists of 6 lithofacies representing alluvial, fluvial, marsh and lacustrine environments. These lithofacies are the lower volcanogenic conglomerate, the claystone, the lignite, the laminated organic claystone, the tuff intercalated sandstone–siltstone and the upper volcanogenic conglomerate. The lignite in the basin is limnic and is formed in a non-fluvial marsh and marsh-lake environment. An abundant percentage of vegetation (Engelhardia, Sapotaceae, Cyrillaceae) is compatible with temperate and subtropical climatic conditions in the basin during sedimentation of lignite.The coals of Çan-Etili basin are humic with high sulfur content (6–6.5% average) mostly containing huminite compounds belonging to the class of lignite-low bituminous (C-A) coal. Their coalification rank is between 0.38% and 0.56% Ro. The coals are formed in limnic-limnotelmatic marsh zones based on their microlithotype components. The inorganic components of the coal mostly consist of pyrite and clay. The trace elements, As, Th, U and V, are higher than international coal standards. The coal quality is adversely affected by high sulfur content and sulfur driven trace element enrichments. The lignite reserve (possible-proved) of Çan-Etili basin is greater than a hundred million tons, and the average coal seam thickness is 17m. The lignite production in the basin is 3mt/year and 1.8 million tons of this are used in the local thermal power plant.

Testate amoebae and tintinnids as spatial and seasonal indicators in the intertidal margins of Guadiana Estuary (southeastern Portugal)

The present study gathers pioneering taxonomical and community data on testate amoebae and agglutinated tintinnids, analyzing their seasonal and spatial distribution patterns in the mesotidal system of the Guadiana Estuary, southeastern Portugal. To evaluate both groups’ potential as bioindicators in climate monitoring and paleoenvironmental reconstructions, their abundance, diversity and living proportions were compared to elevation in relation to mean sea-level, marine influence and to periods of elevated water levels. The distributions of testate amoebae and tintinnid total assemblages were also related to major physicochemical variables by means of multivariate analysis.From 49 surface sediment samples collected in winter and summer 2010, 17 species (25 strains) of testate amoebae were identified (in the 63μm fraction). The Centropyxidae, mainly represented by Centropyxis aculeata, Centropyxis arcula and Centropyxis constricta, had the greatest density (71% of total individuals), while the Difflugidae represented the most species (82% of total species). Higher diversities and densities were observed in winter in the upper estuary, where salinity is negligible, and in the middle estuary where they are concentrated at the lower levels of the intertidal zone. Few or no individuals were observed in the highest marsh zones. In winter, dead testate amoebae were dominant, with empty tests accumulating in the sediments from post-mortem transport by high river discharge. In summer, an increase in the living fraction is observed, with living testate amoebae along the entire estuary, which could indicate that some species are able to live in the lower reaches of the estuary.Along with the testate amoebae, two species of agglutinated tintinnids (>63μm), Stenosemella ventricosa and Tintinnopsis cf. lata, were abundant in the sediments. Their highest abundances were observed in summer. Living individuals were only recorded in summer, mainly in the vicinities of freshwater and sewage outflows, where elevated nutrient concentrations may be expected.The present study demonstrates that both testate amoebae and tintinnids have well defined patterns in their temporal and spatial distribution, offering high bioindicator potential in environmental/climate monitoring studies as well as in paleoenvironmental reconstructions.

Water Budget of a Shallow Aquifer in the Lower Coastal Plain: ACE Basin, SC

The expansive tidal salt marshes of South Carolina support a unique and sensitive ecosystem providing environmental and economic value to the coastal community. These tidal ecosystems are often altered by sea level rise through various processes, including the lesser-known stress of saltwater intrusion in groundwater systems. The goal of this research was to measure the baseline groundwater dynamics of an undeveloped tidal saltmarsh. Groundwater wells were installed along transects from the upland into the marsh and a culminating water budget of the watershed was developed. Analysis of water table dynamics showed that in the upland zone, evapotranspiration and precipitation were the dominant processes, whereas in the marsh zone and the uplands directly adjacent to the marsh, water table fluctuations were dominated by tides. An influencing feature for the site was the large tidal creek (Big Bay Creek), which is a tributary of the South Edisto River. The cut bank of Big Bay Creek was adjacent to the south end of the study site where tidal influence on the shallow groundwater was observed. The location of an ephemeral stream through the site was considered as a potential pathway for saltwater intrusion into the uplands, yet this was not confirmed. Groundwater response rates were likely influenced by the presence of fine-grained, well-drained sandy soils. Application of this research will assist coastal resource managers identifying pathways of marsh migration as driven by future seal level rise.

Community Structure and Abundance of Benthic Infaunal Invertebrates in Maine Fringing Marsh Ecosystems

Fringing marshes are abundant ecosystems that dominate the New England coastline. Despite their abundance, very little baseline data is available from them and few studies have documented the ecosystems services that they provide. This information is important for conservation efforts as well as for an increased understanding of how fringing marshes function compared to larger marsh meadow systems. Benthic infaunal invertebrates were sampled from cores collected from Spartina alterniflora-dominated low marsh, Spartina patens-dominated high marsh, and Phragmites australis-invaded high marsh zones of nine fringing marsh ecosystems in Casco Bay, Maine, USA. Infaunal densities and biomass were generally higher in low marsh than high marsh or P. australis cores. Invertebrate community structure was significantly different between low marsh and high marsh and P. australis cores, which was attributed to significantly higher pore water salinity, lower organic matter, total plant percent cover, and S. patens cover in low marsh zones. There were no differences in invertebrate densities, biomass, or community structure when high marsh and P. australis cores were compared. Invertebrate densities and community structure were dominated by oligochaetes in all zones. Oligochaetes were also an important component of infaunal biomass, but the less abundant and larger invertebrates such as green crabs, tanaids, and bivalves were also large contributors to biomass in the low marsh zone. Low marsh invertebrate communities were characterized by significantly higher densities of nematodes, Nereis virens, an unidentified oligochaete, the bivalves Gemma gemma and Mya arenaria, and Leptochelia rapax. High marsh invertebrate communities were characterized by higher densities of insects, specifically Culicoides sp. ceratopogonid larvae and Anurida maritima, as well as an unidentified species of mite. Our results revealed a diverse and abundant infaunal invertebrate community that likely supports similar ecosystem services in fringing marshes as invertebrates in larger marsh meadows.