649 research outputs found
Microclimate and resource quality determine resource use in a range-expanding herbivore
The consequences of climate change for biogeographic range dynamics
depend on the spatial scales at which climate influences focal species directly
and indirectly via biotic interactions. An overlooked question concerns the
extent to which microclimates modify specialist biotic interactions, with
emergent properties for communities and range dynamics. Here, we use
an in-field experiment to assess egg-laying behaviour of a range-expanding
herbivore across a range of natural microclimatic conditions. We show that
variation in microclimate, resource condition and individual fecundity can
generate differences in egg-laying rates of almost two orders of magnitude
in an exemplar species, the brown argus butterfly (Aricia agestis). This
within-site variation in fecundity dwarfs variation resulting from differences
in average ambient temperatures among populations. Although higher temperatures did not reduce female selection for host plants in good condition, the
thermal sensitivities of egg-laying behaviours have the potential to accelerate
climate-driven range expansion by increasing egg-laying encounters with
novel hosts in increasingly suitable microclimates. Understanding the sensitivity of specialist biotic interactions to microclimatic variation is, therefore,
critical to predict the outcomes of climate change across species’ geographical
ranges, and the resilience of ecological communities
Applications of digital imaging and analysis in seabird monitoring and research
Rapid advances in digital imaging technology offer efficient and cost‐effective methods for measuring seabird abundance, breeding success, phenology, survival and diet. These methods can facilitate understanding of long‐term population trends, and the design and implementation of successful conservation strategies. This paper reviews the suitability of satellites, manned aircraft, unmanned aerial vehicles (UAVs), and fixed‐position, handheld and animal‐borne cameras for recording digital photographs and videos used to measure seabird demographic and behavioural parameters. It considers the disturbance impacts, accuracy of results obtained, cost‐effectiveness and scale of monitoring possible compared with ‘traditional’ fieldworker methods. Given the ease of collecting large amounts of imagery, image processing is an important step in realizing the potential of this technology. The effectiveness of manual, semi‐automated and automated image processing is also reviewed. Satellites, manned aircraft and UAVs have most commonly been used for population counts. Spatial resolution is lowest in satellites, limiting monitoring to large species and those with obvious signs of presence, such as penguins. Conversely, UAVs have the highest spatial resolution, which has allowed fine‐scale measurements of foraging behaviour. Time‐lapse cameras are more cost‐effective for collecting time‐series data such as breeding success and phenology, as human visits are only required infrequently for maintenance. However, the colony of interest must be observable from a single vantage point. Handheld, animal‐borne and motion‐triggered cameras have fewer cost‐effective uses but have provided information on seabird diet, foraging behaviour and nest predation. The last of these has been important for understanding the impact of invasive mammals on seabird breeding success. Advances in automated image analysis are increasing the suitability of digital photography and videography to facilitate and/or replace traditional seabird monitoring methods. Machine‐learning algorithms, such as Pengbot, have allowed rapid identification of birds, although training requires thousands of pre‐annotated photographs. Digital imaging has considerable potential in seabird monitoring, provided that appropriate choices are available for both image capture technology and image processing. These technologies offer opportunities to collect data in remote locations and increase the number of sites monitored. The potential to include such solutions in seabird monitoring and research will develop as the technology evolves, which will be of benefit given funding challenges in monitoring and conservation
The formation of secondary organic aerosol from the isoprene + OH reaction in the absence of NO<sub>x</sub>
The reaction of isoprene (C<sub>5</sub>H<sub>8</sub>) with hydroxyl radicals has been
studied in the absence of nitrogen oxides (NO<sub>x</sub>) to determine physical
and chemical characteristics of the secondary organic aerosol formed.
Experiments were conducted using a smog chamber operated in a steady-state
mode permitting measurements of moderately low aerosol levels. GC-MS analysis
was conducted to measure methyl butenediols in the gas phase and
polyols in the aerosol phase. Analyses were made to obtain several bulk
aerosol parameters from the reaction including values for the organic mass
to organic carbon ratio, the effective enthalpy of vaporization
(ΔH<sub>vap</sub><sup>eff</sup>), organic peroxide fraction, and the aerosol yield.
<br><br>
The gas phase analysis showed the presence of methacrolein, methyl vinyl
ketone, and four isomers of the methyl butenediols. These gas-phase
compounds may serve as precursors for one or more of several compounds
detected in the aerosol phase including 2-methylglyceric acid, three
2-methyl alkenetriols, and two 2-methyl tetrols. In contrast to most
previous studies, the 2-methyl tetrols (and the 2-methyl alkenetriols) were
found to form in the absence of acidic sulfate aerosol. However, reaction
conditions did not favor the production of HO<sub>2</sub> radicals, thus allowing
RO<sub>2</sub>+RO<sub>2</sub> reactions to proceed more readily than if higher
HO<sub>2</sub> levels had been generated.
<br><br>
SOA/SOC (i.e. OM/OC) was found to average 1.9 in the absence of NO<sub>x</sub>.
The effective enthalpy of vaporization was measured as 38.6 kJ mol<sup>−1</sup>,
consistent with values used previously in modeling studies. The yields in
this work (using an independent technique than used previously) are lower than
those of Kroll et al. (2006) for similar aerosol masses. SOC yields reported
in this work range from 0.5–1.4% for carbon masses between 17 and
49 μgC m<sup>−3</sup>
Determinación de la actividad endo-proteolítica en cebada malteada = Endoproteolytic activity assay in malting barley
La hidrólisis de las proteínas de cebada en péptidos y aminoácidos es uno de los procesos más importantes en la germinación de la cebada. La degradación de las proteínas de reserva del endosperma promueven tanto el aumento de la concentración de nitrógeno amínico como la modificación del endosperma, facilitando la movilidad del agua y, por ende, de las enzimas. La actividad proteolítica es el resultado de actividades conjuntas de exo- y endo-peptidasas. Las proteínas de cebada son solubilizadas inicialmente por las endo-peptidasas y luego por las exo-peptidasas. Se han descrito cuatro tipos de endo-peptidasas: serin, cisteín, aspartic y metalo. El objetivo del trabajo consistió en la puesta a punto de un método enzimático para determinar la actividad endo-proteolítica de estas cuatro enzimas, utilizando un método rápido, colorimétrico, con dos sustratos diferentes: azo-gelatina y azo-caseína. Se optimizaron las condiciones de ensayo: pH, tiempo y temperatura de reacción. El sustrato azo-gelatina presentóvarias dificultades para estandarizar un método colorimétrico que sea reproducible. En cambio, el sustrato azo-caseína fue muy consistente y permitió realizar las curvas de estandarización para las cuatro enzimas. Luego el método se aplicó exitosamente para la determinación de la actividad endo-proteolítica en cebada, malta y mosto cervecero
Influence of aerosol acidity on the chemical composition of secondary organic aerosol from β-caryophyllene
The secondary organic aerosol (SOA) yield of β-caryophyllene photooxidation is enhanced by aerosol acidity. In the present study, the influence of aerosol acidity on the chemical composition of β-caryophyllene SOA is investigated using ultra performance liquid chromatography/electrospray ionization-time-of-flight mass spectrometry (UPLC/ESI-TOFMS). A number of first-, second- and higher-generation gas-phase products having carbonyl and carboxylic acid functional groups are detected in the particle phase. Particle-phase reaction products formed via hydration and organosulfate formation processes are also detected. Increased acidity leads to different effects on the abundance of individual products; significantly, abundances of organosulfates are correlated with aerosol acidity. To our knowledge, this is the first detection of organosulfates and nitrated organosulfates derived from a sesquiterpene. The increase of certain particle-phase reaction products with increased acidity provides chemical evidence to support the acid-enhanced SOA yields. Based on the agreement between the chromatographic retention times and accurate mass measurements of chamber and field samples, three β-caryophyllene products (i.e., β-nocaryophyllon aldehyde, β-hydroxynocaryophyllon aldehyde, and β-dihydroxynocaryophyllon aldehyde) are suggested as chemical tracers for β-caryophyllene SOA. These compounds are detected in both day and night ambient samples collected in downtown Atlanta, GA and rural Yorkville, GA during the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS)
Using citizen science image analysis to measure seabird phenology
Developing standardized methodology to allow efficient and cost-effective ecological data collection, particularly at scale, is of critical importance for understanding species' declines. Remote camera networks can enable monitoring across large spatiotemporal scales and at relatively low researcher cost, but manually analysing images and extracting biologically meaningful data is time-consuming. Citizen science image analysis could reduce researcher workload and increase output from large datasets, while actively raising awareness of ecological and conservation issues. Nevertheless, testing the validity of citizen science data collection and the retention of volunteers is essential before integrating these approaches into long-term monitoring programmes. In this study, we used data from a Zooniverse citizen science project, Seabird Watch, to investigate changes in breeding timing of a globally declining seabird species, the Black-legged Kittiwake Rissa tridactyla. Time-lapse cameras collected >200 000 images between 2014 and 2023 across 11 locations covering the species' North Atlantic range (51.7°N–78.9°N), with over 35 000 citizen science volunteers ‘tagging’ adult and juvenile Kittiwakes in images. Most volunteers (81%) classified images for only a single day, and each volunteer classified a median of five images, suggesting that high volunteer recruitment rates are important for the project's continued success. We developed a standardized method to extract colony arrival and departure dates from citizen science annotations, which did not significantly differ from manual analysis by a researcher. We found that Kittiwake colony arrival was 2.6 days later and departure was 1.2 days later per 1° increase in latitude, which was consistent with expectations. Year-round monitoring also showed that Kittiwakes visited one of the lowest latitude colonies, Skellig Michael (51.8°N), during winter, whereas birds from a colony at similar latitude, Skomer Island (51.7°N), did not. Our integrated time-lapse camera and citizen science system offers a cost-effective means of measuring changes in colony attendance and subsequent breeding timing in response to environmental change in cliff-nesting seabirds. This study is of wide relevance to a broad range of species that could be monitored using time-lapse photography, increasing the geographical reach and international scope of ecological monitoring against a background of rapidly changing ecosystems and challenging funding landscapes
Microclimate and resource quality determine resource use in a range-expanding herbivore
This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this recordData accessibility:
The supporting data are available via the Dryad repository at https://doi.org/10.5061/dryad.3ffbg79j1 [46]. The supporting R code is available via Zenodo at https://doi.org/10.5281/zenodo.4898844 [47].
The data are provided in the electronic supplementary material [67].The consequences of climate change for biogeographic range dynamics depend on the spatial scales at which climate influences focal species directly and indirectly via biotic interactions. An overlooked question concerns the extent to which microclimates modify specialist biotic interactions, with emergent properties for communities and range dynamics. Here, we use an in-field experiment to assess egg-laying behaviour of a range-expanding herbivore across a range of natural microclimatic conditions. We show that variation in microclimate, resource condition and individual fecundity can generate differences in egg-laying rates of almost two orders of magnitude in an exemplar species, the brown argus butterfly (Aricia agestis). This within-site variation in fecundity dwarfs variation resulting from differences in average ambient temperatures among populations. Although higher temperatures did not reduce female selection for host plants in good condition, the thermal sensitivities of egg-laying behaviours have the potential to accelerate climate-driven range expansion by increasing egg-laying encounters with novel hosts in increasingly suitable microclimates. Understanding the sensitivity of specialist biotic interactions to microclimatic variation is, therefore, critical to predict the outcomes of climate change across species' geographical ranges, and the resilience of ecological communities.Natural Environment Research Council (NERC
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