scholarly journals Plant-Mediated Rhizosphere Oxygenation in the Native Invasive Salt Marsh Grass Elymus athericus

2021 ◽  
Vol 12 ◽  
Author(s):  
Ketil Koop-Jakobsen ◽  
Robert J. Meier ◽  
Peter Mueller
Keyword(s):  
Light Exposure ◽  
Root Surface ◽  
Sediment Surface ◽  
Soil Conditions ◽  
Phenotypic Traits ◽  
High Marsh ◽  
Root Zones ◽  
Flooding Frequency ◽  
Elymus Athericus ◽  
Native Invasive

In the last decades, the spread of Elymus athericus has caused significant changes to the plant community composition and ecosystem services of European marshes. The distribution of E. athericus was typically limited by soil conditions characteristic for high marshes, such as low flooding frequency and high soil aeration. However, recently the spread of E. athericus has begun to also include low-marsh environments. A high-marsh ecotype and a low-marsh ecotype of E. athericus have been described, where the latter possess habitat-specific phenotypic traits facilitating a better adaption for inhabiting low-marsh areas. In this study, planar optodes were applied to investigate plant-mediated sediment oxygenation in E. athericus, which is a characteristic trait for marsh plants inhabiting frequently flooded environments. Under waterlogged conditions, oxygen (O2) was translocated from aboveground sources to the roots, where it leaked out into the surrounding sediment generating oxic root zones below the sediment surface. Oxic root zones were clearly visible in the optode images, and no differences were found in the O2-leaking capacity between ecotypes. Concentration profiles measured perpendicular to the roots revealed that the radius of the oxic root zones ranged from 0.5 to 2.6 mm measured from the root surface to the bulk anoxic sediment. The variation of oxic root zones was monitored over three consecutive light–dark cycles (12 h/12 h). The O2 concentration of the oxic root zones was markedly reduced in darkness, yet the sediment still remained oxic in the immediate vicinity of the roots. Increased stomatal conductance improving the access to atmospheric O2 as well as photosynthetic O2 production are likely factors facilitating the improved rhizosphere oxygenation during light exposure of the aboveground biomass. E. athericus’ capacity to oxygenate its rhizosphere is an inheritable trait that may facilitate its spread into low-marsh areas. Furthermore, this trait makes E. athericus a highly competitive species in marshes facing the effects of accelerated sea-level rise, where waterlogged sediment conditions could become increasingly pronounced.

scholarly journals Standardized mounting method of (zebrafish) embryos using a 3D-printed stamp for high-content, semi-automated confocal imaging

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
David Simon Kleinhans ◽  
Virginie Lecaudey
Keyword(s):  
Coordinate System ◽  
Light Exposure ◽  
Confocal Imaging ◽  
Model Organisms ◽  
Limiting Factor ◽  
Phenotypic Traits ◽  
Embryo Morphology ◽  
Zebrafish Embryos ◽  
High Content Imaging ◽  
3D Printed

Abstract Background Developmental biology relies to a large extent on the observation and comparison of phenotypic traits through time using high resolution microscopes. In this context, transparent model organisms such as the zebrafish Danio rerio in which developing tissues and organs can be easily observed and imaged using fluorescent proteins have become very popular. One limiting factor however is the acquisition of a sufficient amount of data, in standardized and reproducible conditions, to allow robust quantitative analysis. One way to improve this is by developing mounting methods to increase the number of embryos that can be imaged simultaneously in near-to-identical orientation. Results Here we present an improved mounting method allowing semi-automated and high-content imaging of zebrafish embryos. It is based on a 3D-printed stamp which is used to create a 2D coordinate system of multiple μ-wells in an agarose cast. Each μ-well models a negative of the average zebrafish embryo morphology between 22 and 96 h-post-fertilization. Due to this standardized and reproducible arrangement, it is possible to define a custom well plate in the respective imaging software that allows for a semi-automated imaging process. Furthermore, the improvement in Z-orientation significantly reduces post-processing and improves comparability of volumetric data while reducing light exposure and thus photo-bleaching and photo-toxicity, and improving signal-to-noise ratio (SNR). Conclusions We present here a new method that allows to standardize and improve mounting and imaging of embryos. The 3D-printed stamp creates a 2D coordinate system of μ-wells in an agarose cast thus standardizing specimen mounting and allowing high-content imaging of up to 44 live or mounted zebrafish embryos simultaneously in a semi-automated, well-plate like manner on inverted confocal microscopes. In summary, image data quality and acquisition efficiency (amount of data per time) are significantly improved. The latter might also be crucial when using the services of a microscopy facility.

Distribution of Modern Salt-marsh Foraminifera from the Eastern Mississippi Sound, U.s.a.

2019 ◽  
Vol 49 (1) ◽  
pp. 29-47 ◽  
Author(s):  
Christian Haller ◽  
Christopher G. Smith ◽  
Pamela Hallock ◽  
Albert C. Hine ◽  
Lisa E. Osterman ◽  
...  
Keyword(s):  
A Priori ◽  
Abundant Species ◽  
Environmental Data ◽  
Tidal Marshes ◽  
High Marsh ◽  
Mississippi Sound ◽  
Pascagoula River ◽  
Flooding Frequency ◽  
The Dead ◽  
The Relationship

Abstract This study documented surface distributions of live and dead foraminiferal assemblages in the low-gradient tidal marshes of the barrier island and estuarine complex of the eastern Mississippi Sound (Grand Bay, Pascagoula River, Fowl River, Dauphin Island). A total of 71,833 specimens representing 38 species were identified from a gradient of different elevation zones across the study area. We identified five live assemblages and nine biofacies for the dead assemblages from estuarine, low marsh, middle marsh, high marsh, and upland transition environments. Although dissolution of calcareous tests was observed in the dead assemblages, characteristic species and abundance patterns dependent on elevation in the intertidal zone were similar between living assemblages and dead biofacies. The assemblages from the eastern Mississippi Sound estuaries were dominated by Ammonia tepida, Cribroelphidium poeyanum, C. excavatum, and Paratrochammina simplissima. The low marshes were dominated by Ammotium salsum, Ammobaculites exiguus, and Miliammina fusca. The dominant species in the middle marshes was Arenoparrella mexicana. The most abundant species in the high marshes was Entzia macrescens. The upland–marsh transition zones were dominated by Trochamminita irregularis and Pseudothurammina limnetis. Canonical correspondence analysis was applied to assess the relationship between a priori defined biofacies and measured environmental data (elevation, grain size, organic matter, and salinity) to test the hypothesis that distribution of foraminiferal assemblages is driven by elevation and hence flooding frequency. Salinity was the second most important explanatory variable of dead assemblages. Riverine freshwater from the Pascagoula River markedly influenced the live and dead assemblages in the Pascagoula River marsh, which was represented by low diversity and densities and dominance by Ammoastuta inepta. The relationship between the measured environmental variables and assemblage distributions can be used in future Mississippi Sound paleo-environmental studies.

scholarly journals Cultural Practices Can Influence Root Development for Better Transplanting Success

1986 ◽  
Vol 4 (1) ◽  
pp. 32-34
Author(s):  
Gary W. Watson
Keyword(s):  
Fine Root ◽  
Cultural Practices ◽  
Root Surface ◽  
Soil Conditions ◽  
Root Surface Area ◽  
Root Pruning ◽  
Drastic Reduction ◽  
Root Regeneration ◽  
Careful Preparation ◽  
Nursery Stock

Stress in transplanted nursery stock is caused primarily by the drastic reduction of the root system. Unsatisfactory soil conditions at the planting site reduces root regeneration and prolongs the stress. Root pruning can be used effectively to increase the amount of fine root surface area in the root ball. Careful preparation of the planting site will provide a favorable environment for root growth following transplanting.

scholarly journals Porewater salinity in a southeastern United States salt marsh: controls and interannual variation

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5911 ◽  
Author(s):  
David Miklesh ◽  
Christof Meile
Keyword(s):  
Surface Waters ◽  
Coastal Marsh ◽  
Soil Conditions ◽  
Spatially Explicit ◽  
High Marsh ◽  
Tidal Inundation ◽  
Marsh Soil ◽  
Spatially Explicit Model ◽  
External Forcings ◽  
Porewater Salinity

In coastal marsh ecosystems, porewater salinity strongly affects vegetation distribution and productivity. To simulate marsh porewater salinity, an integrated, spatially explicit model was developed, accounting for tidal inundation, evaporation, and precipitation, as well as lateral and vertical exchanges in both surface waters and the subsurface. It was applied to the Duplin River marsh, Sapelo Island, USA, over a 3-year period, which covered both drought and wet conditions. Simulated porewater salinity in the low and high marsh correlated with Duplin River salinity, with evapotranspiration and precipitation leading to substantial variations in porewater salinities across seasons, in particular in the high marsh. The model revealed substantial interannual variability in marsh soil conditions, and—due to its process-based approach linked to external forcings—can be used to explore effects of sea level rise and changes in hydrological forcings on marsh soil conditions.

scholarly journals Plant genotype determines biomass response to flooding frequency in tidal wetlands

2021 ◽  
Vol 18 (2) ◽  
pp. 403-411
Author(s):  
Svenja Reents ◽  
Peter Mueller ◽  
Hao Tang ◽  
Kai Jensen ◽  
Stefanie Nolte
Keyword(s):  
Salt Marsh ◽  
Biomass Production ◽  
Salt Marshes ◽  
Aboveground Biomass ◽  
Plant Biomass ◽  
Growth Parameters ◽  
High Marsh ◽  
Flooding Frequency ◽  
Strong Control ◽  
Marsh Accretion

Abstract. The persistence of tidal wetland ecosystems like salt marshes is threatened by human interventions and climate change. In particular, the threat of accelerated sea level rise (SLR) has increasingly gained the attention of the scientific community recently. However, studies investigating the effect of SLR on plants and vertical marsh accretion are usually restricted to the species or community level and do not consider phenotypic plasticity or genetic diversity. To investigate the response of genotypes within the same salt-marsh species to SLR, we used two known genotypes of Elymus athericus (Link) Kerguélen (low-marsh and high-marsh genotypes). In a factorial marsh organ experiment we exposed both genotypes to different flooding frequencies and quantified plant growth parameters. With increasing flooding frequency, the low-marsh genotype showed higher aboveground biomass production compared to the high-marsh genotype. Additionally, the low-marsh genotype generally formed longer rhizomes, shoots and leaves, regardless of flooding frequency. Belowground biomass of both genotypes decreased with increasing flooding frequency. We conclude that the low-marsh genotype is better adapted to higher flooding frequencies through its ability to allocate resources from below- to aboveground biomass. Given the strong control of plant biomass production on salt-marsh accretion, we argue that these findings yield important implications for our understanding of ecosystem resilience to SLR as well as plant species distribution in salt marshes.

Influence of Environmental Factors on Seed Germination and Emergence of Asia Minor Bluegrass (Polypogon fugax)

2016 ◽  
Vol 30 (2) ◽  
pp. 533-538 ◽  
Author(s):  
Lifeng Wang ◽  
Su Jin ◽  
Lamei Wu ◽  
Xiaomao Zhou ◽  
Xiangying Liu ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Light Exposure ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Dongting Lake ◽  
Asia Minor ◽  
Soil Conditions ◽  
Lake District ◽  
Dongting Lake District

Asia minor bluegrass (AmB) is a major weed impacting rapeseed production in Dongting Lake District, China. Growth chamber experiments were conducted to determine the influence of environmental factors on germination and emergence of AmB. The optimum constant temperature for germination was around 20 C. Seeds showed germination percentages above 60% under 22/15 and 24/19 C day/night temperature regimes. Seeds could germinate in the dark, but light exposure significantly enhanced the germination percentage. More than 50% of seeds germinated over a pH range between 4 and 10. Seeds were highly sensitive to osmotic stress, and germination was completely inhibited at an osmotic potential of −0.4 MPa, indicating that it was favored by a moist environment. Increasing salinity reduced germination of AmB seeds from 58% at 0 mM to 13% at 80 mM NaCl. The highest seedling emergence (62%) was observed when seeds were placed on the soil surface, and no seedlings emerged from seeds placed at a depth of 5 cm. This work shows that the climate and soil conditions in Dongting Lake District are suitable for AmB seed germination and that no-till fields, where seeds remain on the soil surface, promote the successful establishment of the weed.

scholarly journals Evolutionary responses of a dominant plant along a successional gradient in a salt-marsh system

Plant Ecology ◽  
2021 ◽  
Author(s):  
Qingqing Chen
Keyword(s):  
Grazing Intensity ◽  
Clonal Plant ◽  
Phenotypic Traits ◽  
High Marsh ◽  
Plant Populations ◽  
Genetic Changes ◽  
Successional Gradient ◽  
Number Of Leaves ◽  
Successional Stages ◽  
Favorable Conditions

AbstractThe ecological responses of plant populations along a successional gradient have been intensively examined; however, the evolutionary responses received much less attention. Here, I explored genetic changes of key phenotypic traits of a dominant clonal plant (Elytrigia atherica) along a saltmarsh successional gradient by collecting samples along the successional gradient in the high and low marsh and growing them in a common environment (greenhouse). Additionally, to explore whether changes in traits are driven by abiotic (e.g. clay thickness) and biotic (e.g. grazing intensity) variables along the successional gradient, I measured these two variables in the field. I found that clay thickness (a proxy of total nitrogen) increased along the successional gradient both in the high and low marsh; grazing intensity from hares (the most important herbivores) decreased along the successional gradient in the high marsh but did not change in the low marsh. Meanwhile, I found that growth in number of leaves and ramets decreased, while rhizome length increased, along the successional gradient for E. atherica collected from the high marsh. Opposite trends were found for E. atherica collected from the low marsh. Results suggest that, in the high marsh, herbivores may overrule nutrients to drive trait changes. That is, at the early successional stages, E. atherica had higher growth in number of leaves and ramets to compensate for high-intensity grazing. In the low marsh, nutrients may be the dominant driver for trait changes. That is, at the late successional stages, E. atherica had higher growth in number of leaves and ramets but shorter rhizomes to maximize its expansion under the favorable conditions (higher nutrient availability). Results suggest that ecologically important abiotic and biotic variables such as nutrients and herbivores may also have a substantial evolutionary impact on plant populations.

scholarly journals Evolutionary Responses of A Dominant Plant Along a Successional Gradient in A Salt-Marsh System

2021 ◽  
Author(s):  
Qingqing Chen
Keyword(s):  
Salt Marsh ◽  
Wadden Sea ◽  
Phenotypic Traits ◽  
High Marsh ◽  
Plant Populations ◽  
Genetic Changes ◽  
Herbivore Density ◽  
Successional Gradient ◽  
Number Of Leaves ◽  
Successional Stages

Abstract The ecological responses of plant populations along the successional gradient have been intensively examined; however, the evolutionary responses remain to be elucidated. Here, I explored genetic changes of key phenotypic traits of a dominant plant along a successional gradient, and whether these changes were induced by abiotic and biotic variables. I measured key abiotic (e.g. clay thickness) and biotic variables (e.g. herbivore density) along the successional gradient in the high and low marsh in a Wadden Sea saltmarsh. Also, I collected samples of Elytrigia atherica, grew them in the greenhouse, and measured key functional traits. I found that clay thickness (a proxy of total nitrogen) increased along the successional gradient both in the high and low marsh; herbivore density from hares (the most important herbivores) decreased along the successional gradient in the high marsh. Also, I found that growth in number of leaves and ramets decreased, while rhizome length increased, along the successional gradient for E. atherica collected from the high marsh. Opposite trends were found for E. atherica collected from the low marsh. Results suggest that, in the high marsh, herbivores may overrule nutrients to drive trait changes. That is, at early successional stages, E. atherica had higher growth in number of leaves and ramets to compensate for high-density grazing. In the low marsh, nutrients were the dominant driver for trait changes. These results suggest that ecologically important abiotic and biotic variables such as nutrients and herbivores may also have a substantial evolutionary impact on plant populations.

Sign in / Sign up

Export Citation Format

Share Document