scholarly journals Species-specific phototaxis of coral larvae causes variation in vertical positioning during dispersal

2020 ◽  
Author(s):  
Aziz J Mulla ◽  
Che-Hung Lin ◽  
Shunichi Takahashi ◽  
Yoko Nozawa
Keyword(s):  
Field Experiments ◽  
Coral Species ◽  
Vertical Position ◽  
Coral Larvae ◽  
Phototactic Behavior ◽  
Key Factor ◽  
Different Depths ◽  
Species Specific ◽  
Oceanic Currents ◽  
Vertical Positioning

AbstractControlling vertical positioning is a key factor limiting the distance coral larvae can travel, as oceanic currents are faster closer to surface. Currently, the vertical position of coral larvae is assumed to be determined by buoyant, lipid-rich gametes. However, here we show that some, but not all, coral species can control vertical positioning by phototaxis. We first examined the effect of light on the vertical positioning of larvae from five different coral species in the laboratory. We found that larvae from P. verrucosa, but not from other coral species, show phototaxis towards light and accumulate near the surface. This behavior was consistent at any age and at any time during the day. In field experiments, using P. verrucosa larvae at three different depths (1, 7 and 15 m), the accumulation of larvae in the top half of transparent chambers was observed at all depths. However, such behavior failed to occur in dark chambers. We conclude that larvae from P. verrucosa, but not all coral species, accumulate close to the seawater surface as a result of actively swimming towards sunlight. This finding provides a new hypothesis that phototactic behavior is a key factor in regulating vertical positioning for the dispersal of coral larvae.

Photo-movement of coral larvae influences vertical positioning in the ocean

Coral Reefs ◽  
2021 ◽  
Author(s):  
Aziz J. Mulla ◽  
Che-Hung Lin ◽  
Shunichi Takahashi ◽  
Yoko Nozawa
Keyword(s):  
Coral Larvae ◽  
Vertical Positioning

Alerting and Message Components in Songs of Rufous-Sided Towhees

Behaviour ◽  
1981 ◽  
Vol 76 (3-4) ◽  
pp. 223-249 ◽  
Author(s):  
Douglas G. Richards
Keyword(s):  
Signal Detection Theory ◽  
Field Experiments ◽  
Species Recognition ◽  
Defense Responses ◽  
Time Of Arrival ◽  
Sufficient Information ◽  
Passerine Birds ◽  
Frequency Range ◽  
Narrow Frequency Range ◽  
Species Specific

AbstractIn numerous species of passerine birds the initial few notes of the song have a narrow frequency range and wide temporal spacing when compared with the rest of the song. This structure is well adapted for high detectability when the song is acoustically degraded during passage through the environment. The song of the rufous-sided towhee (Pipilo eythrophtalmus) consists of relatively tonal introductory syllables followed by a complex rapid trill. The trill is capable of carrying more information than the introduction, but is inherently less detectable at a distance owing to degradation by reverberation, amplitude fluctuation, and frequency-dependent attenuation. Signal detection theory predicts that the detectability of the trill will be increased when it is preceded by the introductory syllables, owing to the removal of uncertainty concerning the time of arrival of the signal. This is alerted detection. I performed field experiments using playback of recorded song to towhees to test the hypothesis that these introductory syllables facilitate detection of conspecific song at a distance. Tape recordings of normal and artificially degraded full songs, introduction, and trills were played to territorial male towhees. Normal songs, degraded songs, and normal trills elicited strong territorial defense responses, indicating recognition as adequate species-specific song, and confirming that sufficient information is contained in the trill for species recognition. Degraded trills alone elicited little response. Both normal and degraded introductions also elicited little response, demonstrating that the increased response to a degraded full song over that to a degraded trill is not due to any species-specific characteristics of the introduction, but rather to its function as an alerting stimulus.

scholarly journals Wind drives drought responses of green roof vegetation in two substrates

2018 ◽  
Author(s):  
Arkadiusz Przybysz ◽  
Konstantin Sonkin ◽  
Arne Sæbø ◽  
Hans Martin Hanslin ◽  
Keyword(s):  
Biological Diversity ◽  
Green Roof ◽  
Green Roofs ◽  
Plant Performance ◽  
Succulent Plant ◽  
Hieracium Pilosella ◽  
Key Factor ◽  
Substrate Moisture ◽  
Species Specific ◽  
Functional And Phylogenetic Diversity

The multifunctionality and delivery of ecosystem services from green roofs is improved by biological diversity of the roof vegetation. However, the frequency and intensity of drought episodes on extensive green roofs may limit the use of non-succulent species and the potential functional and phylogenetic diversity of the vegetation. Wind accelerates water use by plants and desiccation of the green roof substrate, and may be a key factor in selection of non-succulent plant species for green roofs. In this study, we tested wind interactions with green roof substrate composition and the effects on plant and substrate water balance, overall plant performance, and wilting and survival of three non-succulent species (Plantago maritima L., Hieracium pilosella L., and Festuca rubra L.) under realistic prolonged water deficit conditions. We found that, regardless of species or substrate tested, wind accelerated drought response. Drought-stressed plants exposed to wind wilted and died earlier, mostly due to more rapid desiccation of the growth substrate (critical substrate moisture content was 6-8%). The moderate wind levels applied did not affect plant performance when not combined with drought. Species with contrasting growth forms showed similar responses to treatments, but there were some species-specific responses. This highlights the importance of including wind to increase realism when evaluating drought exposure in non-succulent green roof vegetation.

scholarly journals Optimizing Sowing Depth of Tef for Irrigated Mediterranean Conditions: From Laboratory to Field Studies

Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1983
Author(s):  
Shiran Ben-Zeev ◽  
Shane Kerzner ◽  
Onn Rabinovitz ◽  
Yehoshua Saranga
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Field Trials ◽  
Eragrostis Tef ◽  
Sowing Depth ◽  
New Crops ◽  
Different Depths ◽  
Plant Emergence ◽  
Increasing Demand ◽  
Mediterranean Conditions

Developing new crops adapted to arid conditions is a promising approach to meet the increasing demand for food production under expanding aridity. Tef [Eragrostis tef (Zucc.) Trotter] is a C4 cereal crop cultivated mainly in Ethiopia and the Horn of Africa, and known for its high resilience to stressful environments. Due to their tiny size, tef seeds are traditionally sown by broadcasting and lightly covering with soil. Under semiarid Mediterranean conditions, a deeper sowing may guarantee seedling establishment while saving on irrigation water. The objective of this study was, therefore, to determine the effects of sowing depth on tef emergence, development, lodging, and productivity. Tef seeds were sown at different depths in test tubes and pots, and in two field experiments. In tubes and pots, time from sowing to emergence increased about twofold and emergence rate decreased in the deepest sowing (3 cm) treatment compared to controls (0 cm). In the pot and field trials, deep sowing (3 cm) significantly reduced plant height, shoot and root biomass, and lodging. Sowing depths of 1–2 cm allowed successful plant establishment while not exacting penalties on plant emergence or development; hence this range appears to be optimal for sowing irrigated tef.

scholarly journals Novel Multiplex and Loop-Mediated Isothermal Amplification (LAMP) Assays for Rapid Species and Mating-Type Identification of Oculimacula acuformis and O. yallundae (Causal Agents of Cereal Eyespot), and Application for Detection of Ascospore Dispersal and in planta Use

2020 ◽  
Author(s):  
Kevin M. King ◽  
Gavin J. Eyres ◽  
Jon West ◽  
Clara Siraf ◽  
Pavel Matusinsky ◽  
...  
Keyword(s):  
Multiplex Pcr ◽  
Mating Type ◽  
Field Experiments ◽  
Lamp Assay ◽  
Isothermal Amplification ◽  
In Planta ◽  
Loop Mediated Isothermal Amplification ◽  
Multiplex Pcr Assay ◽  
Species Specific ◽  
Oculimacula Acuformis

Eyespot, caused by the related fungal pathogens Oculimacula acuformis (OA) and O. yallundae (OY), is an important cereal stem-base disease in temperate parts of the world. Both species are dispersed mainly by splash-dispersed conidia but are also known to undergo sexual reproduction yielding apothecia containing ascospores. Field diagnosis of eyespot can be challenging with other pathogens causing similar symptoms, which complicates eyespot management strategies. Differences between OA and OY (e.g. host pathogenicity and fungicide sensitivity) require that both be targeted for effective disease management. Here, we develop and apply two molecular methods for species-specific and mating-type (MAT1-1 or MAT1-2) discrimination of OA and OY isolates. First, a multiplex PCR-based diagnostic assay targeting the MAT idiomorph region was developed allowing simultaneous determination of both species and mating type. This multiplex-PCR assay was successfully applied to type a global collection of isolates. Second, the development of loop-mediated isothermal amplification (LAMP) assays targeting beta-tubulin sequences is described, which allow fast (<9 min) species-specific discrimination of global OA and OY isolates. The LAMP assay can detect very small amounts of target DNA (1 pg) and was successfully applied in planta. In addition, mating-type specific LAMP assays were also developed for rapid (<12 min) genotyping of OA and OY isolates. Finally, the multiplex PCR-based diagnostic was applied, in conjunction with spore trapping in field experiments, to provide evidence of the wind dispersal of ascospores from a diseased crop. The results indicate an important role of the sexual cycle in the dispersal of eyespot.

scholarly journals Evaporite Dissolution Rate through an on-site Experiment into Piezometric Tubes Applied to the Real Case-Study of Quinis (NE Italy)

Geosciences ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 298 ◽  
Author(s):  
Chiara Calligaris ◽  
Lisa Ghezzi ◽  
Riccardo Petrini ◽  
Davide Lenaz ◽  
Luca Zini
Keyword(s):  
Field Experiments ◽  
Hydrological Regime ◽  
Climatic Conditions ◽  
Water Level Fluctuations ◽  
Geochemical Data ◽  
Data Logger ◽  
Water Geochemistry ◽  
Rock Samples ◽  
Ne Italy ◽  
Different Depths

The present paper deals with a field experiments on evaporite rock samples and groundwater investigations in the Quinis test site, a hamlet of the Enemonzo municipality in NE Italy, were sinkholes occurred in the past and are still occurring causing severe damage to the existing infrastructures. The area is characterised by a Carnian evaporitic bedrock made of gypsum and anhydrite mantled by alluvial and colluvial deposits. In order to evaluate the loss of weight and volume of the subcropping evaporites as responsible for sinkholes, a field-experiment was carried out. Inside seven piezometers, at different depths, evaporitic rock samples were exposed to the naturally occurring variable climatic conditions such as degree of humidity, different air flow and hydrodynamic. The rock samples were installed at the beginning of April 2017 in the dry sections of piezometric tubes, in the vadose zone and in the phreatic zone. Data related to water level fluctuations were recorded by using data-logger devices and highlight significant changes in the water table. After 13 months of data recording (May 2018), rock samples were removed, reweighted and the volume loss measured. In addition, water from piezometer-experiment, representative of the groundwater circulation, were collected at different depths. The obtained results indicate that rock sample reduction is dependent on the hydrological regime and water chemistry and not on the number of days during which the samples remained submersed. In particular, the water geochemistry highlights the possible role in gypsum/anhydrite dissolution due to NaCl water admixing in a complex scenario. In additional, the geochemical data highlight the occurrence of some potentially toxic elements (As, Fe, Mn) at concentrations of concern in some water. This approach represents a novel contribution in the study of karst hazard in evaporites adding a tile to the knowledge of the fast evolutionary processes which cause sinkhole formation.

scholarly journals High p CO 2 promotes coral primary production

2019 ◽  
Vol 15 (7) ◽  
pp. 20180777 ◽  
Author(s):  
T. Biscéré ◽  
M. Zampighi ◽  
A. Lorrain ◽  
S. Jurriaans ◽  
A. Foggo ◽  
...  
Keyword(s):  
Papua New Guinea ◽  
Coral Species ◽  
Dark Respiration ◽  
Metabolic Flexibility ◽  
Field Observations ◽  
Coral Mortality ◽  
Strong Decrease ◽  
Adverse Conditions ◽  
Species Specific ◽  
Photosynthesis And Respiration

While research on ocean acidification (OA) impacts on coral reefs has focused on calcification, relatively little is known about effects on coral photosynthesis and respiration, despite these being among the most plastic metabolic processes corals may use to acclimatize to adverse conditions. Here, we present data collected between 2016 and 2018 at three natural CO 2 seeps in Papua New Guinea where we measured the metabolic flexibility (i.e. in hospite photosynthesis and dark respiration) of 12 coral species. Despite some species-specific variability, metabolic rates as measured by net oxygen flux tended to be higher at high p CO 2 ( ca 1200 µatm), with increases in photosynthesis exceeding those of respiration, suggesting greater productivity of Symbiodiniaceae photosynthesis in hospite , and indicating the potential for metabolic flexibility that may enable these species to thrive in environments with high p CO 2 . However, laboratory and field observations of coral mortality under high CO 2 conditions associated with coral bleaching suggests that this metabolic subsidy does not result in coral higher resistance to extreme thermal stress. Therefore, the combined effects of OA and global warming may lead to a strong decrease in coral diversity despite the stimulating effect on coral productivity of OA alone.

scholarly journals Low-frequency acoustic signal created by rising air-gun bubble

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. P119-P128
Author(s):  
Daniel Wehner ◽  
Martin Landrø
Keyword(s):  
Acoustic Signal ◽  
Field Experiments ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Frequency Signal ◽  
Low Frequencies ◽  
Air Bubble ◽  
Rising Bubble ◽  
Air Gun ◽  
Different Depths

In the seismic industry, there is increasing interest in generating and recording low frequencies, which leads to better data quality and can be important for full-waveform inversion. The air gun is a seismic source with a signal that consists of the (1) main impulse, (2) oscillating bubble, and (3) rising of this air bubble. However, there has been little investigation of the third characteristic. We have studied a low-frequency signal that could be created by the rising air bubble and find the contribution to the low-frequency content in seismic acquisition. We use a simple theory and modeling of rising spheres in water and compute the acoustic signal created by this effect. We conduct tank and field experiments with a submerged buoy that is released from different depths and record the acoustic signal with hydrophones along the rising path. The experiments simulate the signal from the rising bubble separated from the other two effects (1 and 2). Furthermore, we use data recorded below a single air gun fired at different depths to investigate if we can observe the proposed signal. We find that the rising bubble creates a low-frequency signal. Compared with the main impulse and the oscillating bubble effect of an air-gun signal, the contribution of the rising bubble is weak, on the order of 1/900 depending on the bubble size. By using large air-gun arrays tuned to create one big bubble, the contribution of the signal can be increased. The enhanced signal can be important for deep targets or basin exploration because the low-frequency signal is less attenuated.

scholarly journals A calculation method of gas emission zone in a coal mine considering main controlling factors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yong Chen ◽  
Ronghua Liu ◽  
Pushi Xuan
Keyword(s):  
Numerical Simulation ◽  
Permeability Coefficient ◽  
Field Experiments ◽  
Logistic Function ◽  
Measured Data ◽  
Gas Content ◽  
Coal Seam Gas ◽  
Gas Emission ◽  
Drainage Design ◽  
Different Depths

AbstractThe gas emission zone is an important parameter for the space–time effect of coal excavation and gas emission. In this paper, according to the effect of roadway excavation, a numerical model of gas emission zone based on the evolution of stress and permeability was established to obtain the width of gas emission zone with different pressure and permeability coefficient. Then the numerical simulation results were verified by measuring the gas content at different depths. Through numerical simulation and field measured data, the theoretical calculation formula is established on the basis of comprehensive consideration of the influencing factors of gas emission zone. The results showed that the gas emission zone increases with the increase of coal seam gas pressure and permeability coefficient when the roadway section and exposure time are the same. The measured gas emission zone, when taking gas content as the index with the same logistic function growth curve, matches the measured results with a relative error of 1.3 to 6%. The validity of the model is also verified by field experiments. The results can provide guidance for mine gas emission and gas drainage design.

scholarly journals Serum Complement Sensitivity as a Key Factor in Lyme Disease Ecology

1998 ◽  
Vol 66 (3) ◽  
pp. 1248-1251 ◽  
Author(s):  
Klaus Kurtenbach ◽  
Henna-Sisko Sewell ◽  
Nick H. Ogden ◽  
Sarah E. Randolph ◽  
Patricia A. Nuttall
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Lyme Borreliosis ◽  
Disease Ecology ◽  
Specific Pattern ◽  
Serum Complement ◽  
Key Factor ◽  
Species Specific

ABSTRACT The sensitivity of Borrelia burgdorferi sensu lato to animal sera was analyzed. Complement-mediated borreliacidal effects were observed with particular combinations of host serum andBorrelia genospecies. The species-specific pattern of viability and/or lysis is highly consistent with the pattern of reservoir competence of hosts for B. burgdorferi sensu lato, suggesting a key role of complement in the global ecology of Lyme borreliosis.

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