Aquatic food web response to patchy shading along forested headwater streams

In forested streams, changes in age and structure of riparian vegetation have been shown to directly influence the amount of light reaching the stream benthos. The potential for light to directly impact primary productivity in forested streams is generally understood, but most field experiments exploring reach-scale in-stream light dynamics have evaluated large changes in riparian vegetation. Fewer studies have quantified influences of smaller changes in irradiance, particularly how patchy in-stream light developed with complex riparian forests affects stream biota. We applied patches of shade, covering ∼50% of three manipulation reaches, which were each paired with an unmanipulated reference reach. We quantified changes in stream light availability, benthic periphyton, and aquatic macroinvertebrate, fish, and salamander biomass using a before–after control–impact study design. Patchy shading decreased localized and reach-scale light and reduced periphyton, macroinvertebrate, fish, and salamander biomass in manipulation sites relative to the reference reaches. Results suggest that moderate changes in stream light, such as those that occur through stand development and small-scale disturbance processes, can impact stream biota through bottom-up processes.

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Applications of Chemically Modified Clay Minerals and Clays to Water Purification and Slow Release Formulations of Herbicides

Minerals ◽

10.3390/min11010009 ◽

2020 ◽

Vol 11 (1) ◽

pp. 9

Author(s):

Tomas Undabeytia ◽

Uri Shuali ◽

Shlomo Nir ◽

Baruch Rubin

Keyword(s):

Clay Minerals ◽

Field Experiments ◽

Slow Release ◽

Freeze Fracture ◽

Nano Particles ◽

Organic Cations ◽

Small Scale ◽

High Exposure ◽

Model Calculations ◽

Slow Release Formulations

This review deals with modification of montmorillonite and other clay-minerals and clays by interacting them with organic cations, for producing slow release formulations of herbicides, and efficient removal of pollutants from water by filtration. Elaboration is on incorporating initially the organic cations in micelles and liposomes, then producing complexes denoted micelle- or liposome-clay nano-particles. The material characteristics (XRD, Freeze-fracture electron microscopy, adsorption) of the micelle– or liposome–clay complexes are different from those of a complex of the same composition (organo-clay), which is formed by interaction of monomers of the surfactant with the clay-mineral, or clay. The resulting complexes have a large surface area per weight; they include large hydrophobic parts and (in many cases) have excess of a positive charge. The organo-clays formed by preadsorbing organic cations with long alkyl chains were also addressed for adsorption and slow release of herbicides. Another examined approach includes “adsorptive” clays modified by small quaternary cations, in which the adsorbed organic cation may open the clay layers, and consequently yield a high exposure of the siloxane surface for adsorption of organic compounds. Small scale and field experiments demonstrated that slow release formulations of herbicides prepared by the new complexes enabled reduced contamination of ground water due to leaching, and exhibited enhanced herbicidal activity. Pollutants removed efficiently from water by the new complexes include (i) hydrophobic and anionic organic molecules, such as herbicides, dissolved organic matter; pharmaceuticals, such as antibiotics and non-steroidal drugs; (ii) inorganic anions, e.g., perchlorate and (iii) microorganisms, such as bacteria, including cyanobacteria (and their toxins). Model calculations of adsorption and kinetics of filtration, and estimation of capacities accompany the survey of results and their discussion.

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Assessing impacts of COVID-19 on aquatic food system and small-scale fisheries in Bangladesh

Marine Policy ◽

10.1016/j.marpol.2021.104422 ◽

2021 ◽

Vol 126 ◽

pp. 104422

Author(s):

Atiqur Rahman Sunny ◽

Sharif Ahmed Sazzad ◽

Shamsul Haque Prodhan ◽

Md. Ashrafuzzaman ◽

Gopal Chandra Datta ◽

...

Keyword(s):

Food System ◽

Small Scale ◽

Small Scale Fisheries ◽

Aquatic Food

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Effects of increased flooding on riparian vegetation: Field experiments simulating climate change along five European lowland streams

Global Change Biology ◽

10.1111/gcb.13687 ◽

2017 ◽

Vol 23 (8) ◽

pp. 3052-3063 ◽

Cited By ~ 18

Author(s):

Annemarie G. Garssen ◽

Annette Baattrup-Pedersen ◽

Tenna Riis ◽

Bart M. Raven ◽

Carl Christian Hoffman ◽

...

Keyword(s):

Climate Change ◽

Riparian Vegetation ◽

Field Experiments ◽

Lowland Streams

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Progress towards small-scale field trials of coastal enhanced weathering of olivine

10.5194/egusphere-egu21-14112 ◽

2021 ◽

Author(s):

Stephen Romaniello ◽

Shanee Stopnitzky ◽

Tom Green ◽

Francesc Montserrat ◽

Eric Matzner ◽

...

Keyword(s):

Real World ◽

Field Experiments ◽

Ecological Impact ◽

Field Trials ◽

Research Strategy ◽

Unintended Consequences ◽

Ecological Impacts ◽

Small Scale ◽

Climate Mitigation ◽

Stage Of Development

Slow progress towards achieving global greenhouse gas emissions targets significantly increases the likelihood that future climate efforts may require not only emissions cuts but also direct climate mitigation via negative emissions technologies (IPCC AR5). Currently, such technologies exist at only a nascent stage of development, with significant uncertainties regarding their feasibility, cost, and potential unintended consequences and/or co-benefits.Coastal enhanced weathering of olivine (CEWO) has been suggested as one potential pathway for achieving net negative CO2 emissions at scale. CEWO involves the mining of olivine-rich ultramafic rocks (such as dunite) for incorporation during beach augmentation and restoration work. While grinding this rock into increasingly fine particle sizes is essential for increasing its surface area and reactivity, this step is also costly and energetically expensive. CEWO attempts to minimize this cost and energy penalty by relying on wave and tidal action to provide ongoing physical weathering of olivine grains once distributed on beaches. Laboratory experiments and carbon emissions assessments of CEWO suggest that these approaches may be technically feasible and carbon negative, but significant uncertainties remain regarding the real-world kinetics of coastal olivine dissolution. Furthermore, concerns about the fate and ecological impact of nickel (Ni) and chromium (Cr)&#8212;potentially toxic trace metals found in olivine&#8212;require careful evaluation.In 2019, Project Vesta was established as a nonprofit, philanthropically funded effort to evaluate the technical feasibility and ecological impacts of CEWO through a dedicated research program ultimately culminating in small-scale, real-world field trials of CEWO. This presentation will provide an overview and discussion of our overall research strategy, share insights from interim modeling and mesocosm experiments designed to ensure the practicality and safety of future field experiments, and explain our approach for ensuring transparent, responsible, and ethical research oversight and governance.

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Non-Linear Space-Time Evolution of Wave Groups With a High Crest

Volume 2: Safety and Reliability; Pipeline Technology ◽

10.1115/omae2003-37161 ◽

2003 ◽

Author(s):

Felice Arena ◽

Francesco Fedele

Keyword(s):

Time Evolution ◽

Field Experiments ◽

Surface Displacement ◽

Fixed Time ◽

Space Time ◽

Second Order ◽

Small Scale ◽

Free Surface Displacement ◽

Non Linear ◽

Space Time Evolution

The theory of quasi-determinism, for the mechanics of linear three-dimensional waves, was obtained by Boccotti in the eighties. The first formulation of the theory deals with the largest crest amplitude; the second formulation deals with the largest wave height. The theory was verified in the nineties with some small-scale field experiments. In this paper the first formulation of Boccotti’s theory, valid for the space-time domain, is extended to the second order. The analytical expressions of the non-linear free surface displacement and velocity potential are obtained. Therefore the space-time evolution of a wave group, to the second-order in a Stokes expansion, when a very large crest occurs at a fixed time and location, is investigated. Finally the second-order probability of exceedance of the crest amplitude is obtained, as a function of two deterministic parameters.

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Mission-driven research for stratospheric aerosol geoengineering

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1811022116 ◽

2019 ◽

Vol 116 (4) ◽

pp. 1089-1094 ◽

Cited By ~ 15

Author(s):

Douglas G. MacMartin ◽

Ben Kravitz

Keyword(s):

Radiative Forcing ◽

Field Experiments ◽

Research Effort ◽

Science Research ◽

Global Scale ◽

Stratospheric Aerosol ◽

Small Scale ◽

Exploratory Research ◽

Climate Risks ◽

Research Activities

The last decade has seen broad exploratory research into stratospheric aerosol (SA) geoengineering, motivated by concern that reducing greenhouse gas emissions may be insufficient to avoid significant impacts from climate change. Based on this research, it is plausible that a limited deployment of SA geoengineering, provided it is used in addition to cutting emissions, could reduce many climate risks for most people. However, “plausible” is an insufficient basis on which to support future decisions. Developing the necessary knowledge requires a transition toward mission-driven research that has the explicit goal of supporting informed decisions. We highlight two important observations that follow from considering such a comprehensive, prioritized natural-science research effort. First, while field experiments may eventually be needed to reduce some of the uncertainties, we expect that the next phase of research will continue to be primarily model-based, with one outcome being to assess and prioritize which uncertainties need to be reduced (and, as a corollary, which field experiments can reduce those uncertainties). Second, we anticipate a clear separation in scale and character between small-scale experimental research to resolve specific process uncertainties and global-scale activities. We argue that the latter, even if the radiative forcing is negligible, should more appropriately be considered after a decision regarding whether and how to deploy SA geoengineering, rather than within the scope of “research” activities.

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Attractiveness of thermally different, uniformly black targets to horseflies: Tabanus tergestinus prefers sunlit warm shiny dark targets

Royal Society Open Science ◽

10.1098/rsos.191119 ◽

2019 ◽

Vol 6 (10) ◽

pp. 191119 ◽

Cited By ~ 2

Author(s):

Gábor Horváth ◽

Ádám Pereszlényi ◽

Tímea Tóth ◽

Szabolcs Polgár ◽

Imre M. Jánosi

Keyword(s):

Field Experiments ◽

Elevated Temperatures ◽

Thermal Characteristics ◽

Optical Characteristics ◽

Degree Of Polarization ◽

Small Scale ◽

Host Animal ◽

Reflected Light ◽

Scale Models ◽

Imaging Polarimetry

From a large distance tabanid flies may find their host animal by means of its shape, size, motion, odour, radiance and degree of polarization of host-reflected light. After alighting on the host, tabanids may use their mechano-, thermo-, hygro- and chemoreceptors to sense the substrate characteristics. Female tabanids prefer to attack sunlit against shady dark host animals, or dark against bright hosts for a blood meal, the exact reasons for which are unknown. Since sunlit darker surfaces are warmer than shady ones or sunlit/shady brighter surfaces, the differences in surface temperatures of dark and bright as well as sunlit and shady hosts may partly explain their different attractiveness to tabanids. We tested this observed warmth preference in field experiments, where we compared the attractiveness to tabanids ( Tabanus tergestinus ) of a warm and a cold shiny black barrel imitating dark hosts with the same optical characteristics. Using imaging polarimetry, thermography and Schlieren imaging, we measured the optical and thermal characteristics of both barrels and their small-scale models. We recorded the number of landings on these targets and measured the time periods spent on them. Our study revealed that T. tergestinus tabanid flies prefer sunlit warm shiny black targets against sunlit or shady cold ones with the same optical characteristics. These results support our new hypothesis that a blood-seeking female tabanid prefers elevated temperatures, partly because her wing muscles are more rapid and her nervous system functions better (due to faster conduction velocities and synaptic transmission of signals) in a warmer microclimate, and thus, she can avoid the parasite-repelling reactions of host animals by a prompt take-off.

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Herbicide Inputs for a New Agronomic Crop, Annual Wormwood (Artemisia annua)

Weed Technology ◽

10.1017/s0890037x00033376 ◽

1991 ◽

Vol 5 (1) ◽

pp. 117-124 ◽

Cited By ~ 12

Author(s):

Charles T. Bryson ◽

Edward M. Croom

Keyword(s):

Clinical Trials ◽

Weed Control ◽

Crop Production ◽

Large Scale ◽

Field Experiments ◽

Production Systems ◽

Artemisia Annua ◽

Small Scale ◽

Herbicide Treatments ◽

Large Scale Cultivation

Annual wormwood has been cultivated on a small scale for production of the artemisinin class of antimalarial drugs in sufficient quantities for preclinical and clinical trials. Large scale cultivation will require a reliable, efficient crop production system. Production systems using 32 herbicides alone or in combinations were evaluated in growth chamber, greenhouse, and field experiments at Stoneville, MS from 1985 through 1988. The herbicide treatments that provided the best weed control were (A) metolachlor at 2.2 kg ai ha-1preemergence (PRE), (B) chloramben at 2.2 kg ai ha-1(PRE), or (C) trifluralin at 0.6 kg ai ha-1preplant soil incorporated (PPI) followed by fluazifop at 0.2 + 0.2 kg ai ha-1postemergence broadcast (POST) and acifluorfen at 0.6 kg ai ha-1(POST). These herbicide production systems provided excellent weed control (≥85%) and minimal crop injury (≤10%) with no effect on crop height or weight at harvest. Production of artemisinin was not reduced by herbicide treatments A, B, and C in 1987 and treatments B and C in 1988 when compared with the hand-weeded plots.

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The Effects of Small-Scale Turbulence on Air–Sea Heat Flux

Journal of Physical Oceanography ◽

10.1175/2010jpo4491.1 ◽

2011 ◽

Vol 41 (1) ◽

pp. 205-220 ◽

Cited By ~ 17

Author(s):

Fabrice Veron ◽

W. Kendall Melville ◽

Luc Lenain

Keyword(s):

Field Experiments ◽

Renewal Theory ◽

Small Scale ◽

Surface Renewal ◽

Near Surface ◽

Turbulence Measurements ◽

Renewal Time ◽

Surface Turbulence ◽

The Mean ◽

Renewal Events

Abstract The air–sea exchange of heat is mainly controlled by the molecular diffusive layer adjacent to the surface. With an order of magnitude difference between the kinematic viscosity and thermal diffusivity of water, the thermal sublayer is embedded within its momentum analog: the viscous sublayer. Therefore, the surface heat exchange rates are greatly influenced by the surface kinematics and dynamics; in particular, small-scale phenomena, such as near-surface turbulence, have the greatest potential to affect the surface fluxes. Surface renewal theory was developed to parameterize the details of the turbulent transfer through the molecular sublayers. The theory assumes that turbulent eddies continuously replace surface water parcels with bulk fluid, which is not in equilibrium with the atmosphere and therefore is able to transfer heat. The so-called controlled-flux technique gives direct measurements of the mean surface lifetime of such surface renewal events. In this paper, the authors present results from field experiments, along with a review of surface renewal theory, and show that previous estimates of air–sea scalar fluxes using the controlled-flux technique may be erroneous if the probability density function (PDF) of surface renewal time scales is different from the routinely assumed exponential distribution. The authors show good agreement between measured and estimated heat fluxes using a surface renewal PDF that follows a χ distribution. Finally, over the range of forcing conditions in these field experiments, a clear relationship between direct surface turbulence measurements and the mean surface renewal time scale is established. The relationship is not dependent on the turbulence generation mechanism. The authors suggest that direct surface turbulence measurements may lead to improved estimates of scalar air–sea fluxes.

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Understory biomass measurement based on SfM data by a manual low-flying drone under the canopy

10.5194/egusphere-egu2020-14009 ◽

2020 ◽

Author(s):

Yupan Zhang ◽

Yuichi Onda ◽

Hiroaki Kato ◽

Xinchao Sun ◽

Takashi Gomi

Keyword(s):

Point Cloud ◽

Light Availability ◽

Understory Vegetation ◽

Airborne Lidar ◽

Vegetation Coverage ◽

Coefficient Of Determination ◽

Small Scale ◽

Cloud Data ◽

Dense Point ◽

Understory Biomass

Understory vegetation has the important effect that cannot be ignored on Evapotranspiration. In previous studies, laser scanner was used to measure small-scale biomass and airborne LiDAR was used to assess light availability to understory vegetation, which in turn was converted to understory biomass production. However, it is difficult to measure watershed-scale understory biomass with high resolution. In this study, Structure from Motion (SfM) was used to reconstruct understory vegetation structure by a manual low-flying drone under the canopy with radial paths in a line thinning plantation and a spot thinning plantation made by Japanese cedar and cypress. By generating Orthomosaic image and dense point cloud data, we then extracted Excess Green Index (ExG) and Canopy Height Model (CHM), combining with understory biomass data from field harvesting to establish a quantitative relationship between the CHM and biomass, which was then used to map biomass and vegetation coverage in the study area. The results indicated that (1) a flight height of 7-10 meters is more conducive to understory vegetation reconstruction, with a photo quality greater than 0.8 and a point cloud density of more than 20 points/cm2. (2) a regression cubic model based on the CHM has acceptable accuracy and biomass estimate capability (P<0.01), with a coefficient of determination of 0.75. (3) compared with the spot thinning, the understory biomass under the line thinning scenario was higher(average biomass 3.03kg/m2). (4) vegetation coverage based on the ExG index of visible light analysis was affected by ambient light(strong sunlight on a sunny day), and it cannot reflect the seasonal changes of understory vegetation biomass. These results disclosed the potential of the dense point cloud from drone SfM for estimating understory biomass. With this method, we will measure more than 5000m2 of headwater catchment and output a understory biomass map.&#160;

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