scholarly journals Dynamic symbioses reveal pathways to coral survival through prolonged heatwaves

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Danielle C. Claar ◽  
Samuel Starko ◽  
Kristina L. Tietjen ◽  
Hannah E. Epstein ◽  
Ross Cunning ◽  
...  
Keyword(s):  
Anthropogenic Disturbance ◽  
Natural Experiment ◽  
Elevated Temperatures ◽  
Equatorial Pacific ◽  
The Other ◽  
Stress Resilience ◽  
Algal Symbiont ◽  
Disturbed Areas ◽  
Coral Recovery ◽  
Heat Tolerant

AbstractProspects for coral persistence through increasingly frequent and extended heatwaves seem bleak. Coral recovery from bleaching is only known to occur after temperatures return to normal, and mitigation of local stressors does not appear to augment coral survival. Capitalizing on a natural experiment in the equatorial Pacific, we track individual coral colonies at sites spanning a gradient of local anthropogenic disturbance through a tropical heatwave of unprecedented duration. Unexpectedly, some corals survived the event by recovering from bleaching while still at elevated temperatures. These corals initially had heat-sensitive algal symbiont communities, endured bleaching, and then recovered through proliferation of heat-tolerant symbionts. This pathway to survival only occurred in the absence of strong local stressors. In contrast, corals in highly disturbed areas were already dominated by heat-tolerant symbionts, and despite initially resisting bleaching, these corals had no survival advantage in one species and 3.3 times lower survival in the other. These unanticipated connections between disturbance, coral symbioses and heat stress resilience reveal multiple pathways to coral survival through future prolonged heatwaves.

scholarly journals Are orchid bees at risk? First comparative survey suggests declining populations of forest-dependent species

2013 ◽  
Vol 73 (2) ◽  
pp. 367-374 ◽  
Author(s):  
A Nemésio
Keyword(s):  
Atlantic Forest ◽  
Anthropogenic Disturbances ◽  
The Other ◽  
Orchid Bees ◽  
Orchid Bee ◽  
Disturbed Areas ◽  
Eastern Brazil ◽  
Forest Remnants ◽  
Declining Populations ◽  
Comparative Survey

The two largest Atlantic Forest remnants in the state of Espírito Santo, eastern Brazil, namely ‘Reserva Biológica de Sooretama’ (REBIO Sooretama) and ‘Reserva Natural Vale’ (RNV), were surveyed for their orchid-bee faunas. Seventeen scent baits were used to attract orchid-bee males. Three-thousand, two hundred and twenty-five males belonging to 24 species were actively collected with insect nets during 100 hours in March, April and December, 2009. In comparison with a previous study in the same area twelve years before, it is evident that the abundance of all forest-dependent orchid bees analysed declined around 50%, and it was statistically significant (P = 0.022) for Euglossa marianae Nemésio, 2011, the most sensitive to anthropogenic disturbances of all Atlantic Forest orchid bees. On the other hand, the abundance of populations of species tolerant to open or disturbed areas rose. Possible explanations are discussed.

Newly Developed Heat Resistant Magnesium Alloy by Thixomolding®

2005 ◽  
Vol 488-489 ◽  
pp. 287-290 ◽  
Author(s):  
Tadayoshi Tsukeda ◽  
Ken Saito ◽  
Mayumi Suzuki ◽  
Junichi Koike ◽  
Kouichi Maruyama
Keyword(s):  
Aluminum Alloy ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Die Casting ◽  
The Other ◽  
Heat Resistant ◽  
Higher Temperature ◽  
Better Than

We compared the newly developed heat resistant magnesium alloy with conventional ones by Thixomolding® and aluminum alloy by die casting. Tensile properties at elevated temperatures of AXEJ6310 were equal to those of ADC12. In particular, elongation tendency of AXEJ6310 at higher temperature was better than those of the other alloys. Creep resistance of AXEJ6310 was larger than that of AE42 by almost 3 orders and smaller than that of ADC12 by almost 2 orders of magnitude. Fatigue limits at room temperature and 423K of AXEJ6310 was superior among conventional magnesium alloys.

Changes in escape behaviour of black iguanas (Ctenosaura similis) over an anthropogenic disturbance gradient

Behaviour ◽  
2021 ◽  
pp. 1-21
Author(s):  
Pooja Panwar ◽  
Pilar Angélica Gómez-Ruiz ◽  
Matthew N. Zipple ◽  
Luis Sandoval
Keyword(s):  
Human Disturbance ◽  
Protected Area ◽  
Anthropogenic Disturbance ◽  
Escape Behaviour ◽  
Human Presence ◽  
Disturbed Areas ◽  
Disturbance Gradient ◽  
The Impact ◽  
Ctenosaura Similis ◽  
Flight Initiation

Abstract Studies on the impact of human activity on animal behaviour are critical for understanding the extent to which humans affect ecological dynamics. Previous studies have found that human presence alters antipredator behaviours, which can be measured by flight initiation distance (FID). We investigated escape behaviour of 96 black iguanas (Ctenosaura similis) across a gradient of human disturbance in six sites inside a protected area in Costa Rica. We used a field experiment to test for effect of human disturbance on FID. We found that individuals from higher disturbance sites had shorter FIDs, meaning that black iguanas from disturbed areas allow closer approaches. This finding is consistent with the prediction that some animals become more habituated to human presence as the degree of human disturbance increases. We propose that black iguanas’ ability to alter their behaviour in response to humans’ presence could make them especially adept at invading new environments.

scholarly journals X-ray examination of certain copper-zinc alloys at elevated temperatures

1934 ◽  
Vol 145 (854) ◽  
pp. 258-267 ◽  
Keyword(s):  
Elevated Temperatures ◽  
Close Contact ◽  
Thin Sheet ◽  
Thin Foil ◽  
The Other ◽  
Copper Sheet ◽  
Zinc Alloys ◽  
Β Phase ◽  
Copper Zinc ◽  
Thermo Couple

This investigation is a continuation of the word on copper-zinc alloys reported in previous papers. Our previous measurements were made on quenched alloys, and it was assumed that the conditions prevailing at any temperature at the moment of quenching were retained in the quenched samples. In the present word an attempt is made to investigate the validity of this assumption by examining the alloys at the actual temperatures of annealing. Attention is directed mainly to the β-phase in tire pure region and in the mixed regions on either side of the pure phase. It was hoped that such measurements might also throw more light on the nature of the β-transformation. Apparatus and Method of Experiment . The precision camera was the same in principle as that previously used and described, with modifications in deign for high temperature word. It was made entirely of invar except that three silica rods connected the portion of the drum carrying the film to that carrying the sample. By this device the one part was well insulated thermally from the other. In order to take photographs in vacuo , the camera was fitted into a brass box with a removable lid and water-cooled sides; inside the box, the heater, consisting of "Kanthal" resistance wire embedded in alundum cement, was mounted. To hold the sample, which was in the form of fine filings on thin foil, against the camera frame, a thin sheet of copper foil was used. This was anchored with insulating porcelain beads and wire springs to the camera frame carrying the film. To minimize the heat passing from the sample to the camera frame, a thin sheet of mica of definite thickness was used around the slot over which the sample was placed. The sample was heated by bringing the heater, shaped to the contour of the camera frame, into close contact with a similarly shaped copper sheet about 1⋅5 mm. thick, into which the "hot" junction of one thermo-couple was silver-soldered; this in turn pressed against the foil on which the sample was mounted. Leads for the thermo-couple pyrometers—one to measure the approximate temperature of the sample photographed and the other to measure the camera temperature near tire film—passed through insulated plugs in one side of the box. On the opposite side, leads to the heater were similarly inserted. An outlet for exhausting the box completed the construction.

Structure of [(CH3)2NH2]2CoCl4 at elevated temperatures

1999 ◽  
Vol 55 (5) ◽  
pp. 752-757 ◽  
Author(s):  
Amir H. Mahmoudkhani ◽  
Vratislav Langer
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Phase Transitions ◽  
Physical Properties ◽  
Electric Conductivity ◽  
Title Compound ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
The Other ◽  
Cell Parameters

The crystal structure of the title compound, dimethylammonium tetrachlorocobaltate(II), has been determined at four temperatures between 297 and 366 K, in order to investigate possible phase transitions at 313 and 353 K [Kapustianik, Polovinko & Kaluza et al. (1996). Phys. Status Solidi A, 153, 117–122]. We found that there is no significant change either in the hydrogen-bonding network or in the cell parameters, apart from a linear dilatation with temperature. This study reveals that the anomalous variation in electric conductivity and some of the other physical properties of the compound cannot be explained by structural changes.

scholarly journals The Algal Symbiont Modifies the Transcriptome of the Scleractinian Coral Euphyllia paradivisa During Heat Stress

2019 ◽  
Vol 7 (8) ◽  
pp. 256 ◽  
Author(s):  
Dalit ◽  
Keren ◽  
Eviatar ◽  
Hiba ◽  
Gal ◽  
...  
Keyword(s):  
Heat Stress ◽  
Differentially Expressed Genes ◽  
Elevated Temperatures ◽  
Negative Impact ◽  
Global Climate ◽  
Differentially Expressed ◽  
Heat Stress Response ◽  
Stress Genes ◽  
Mutualistic Symbiosis ◽  
Algal Symbiont

The profound mutualistic symbiosis between corals and their endosymbiotic counterparts, Symbiodiniaceae algae, has been threatened by the increase in seawater temperatures, leading to breakdown of the symbiotic relationship—coral bleaching. To characterize the heat-stress response of the holobiont, we generated vital apo-symbiotic Euphyllia paradivisa corals that lacked the endosymbiotic algae. Using RNA sequencing, we analyzed the gene expression of these apo-symbionts vs. symbiotic ones, to test the effect of the algal presence on the tolerance of the coral. We utilized literature-derived lists of “symbiosis differentially expressed genes” and “coral heat-stress genes” in order to compare between the treatments. The symbiotic and apo-symbiotic samples were segregated into two separate groups with several different enriched gene ontologies. Our findings suggest that the presence of endosymbionts has a greater negative impact on the host than the environmental temperature conditions experienced by the holobiont. The peak of the stress reaction was identified as 28 °C, with the highest number of differentially expressed genes. We suggest that the algal symbionts increase coral holobiont susceptibility to elevated temperatures. Currently, we can only speculate whether coral species, such as E. paradivisa, with the plasticity to also flourish as apo-symbionts, may have a greater chance to withstand the upcoming global climate change challenge.

Effect of Nd on Microstructures and Properties of AZ31 Wrought Mg Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 301-304
Author(s):  
Wei Qiu ◽  
En Hou Han ◽  
Lu Liu
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Mg Alloys ◽  
The Other ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructures And Mechanical Properties ◽  
Re Elements

Addition of RE elements to Al-containing Mg alloys can improve properties of Mg alloys at elevated temperatures. In the present investigation, hot-extruded AZ31+x%Nd. (x=0.1,0.3,0.6and1.0 wt%) wrought Mg alloy were prepared .The effects of Nd on microstructures and mechanical properties at room temperature of new alloy were investigated. The investigation found that Nd can bring about two kind of precipitation phases . One is AlNd phase, the other is AlNdMn phase, which were identified as Al11Nd3 and Al8NdMn4 by X-ray diffraction and TEM.

DECOMPOSITION OF C60 MOLECULES ON Si(100)(2 × 1) SURFACE

2000 ◽  
Vol 11 (05) ◽  
pp. 1067-1076
Author(s):  
ŞAKIR ERKOÇ ◽  
ŞENAY KATIRCIOĞLU
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Phase Change ◽  
Elevated Temperatures ◽  
Model Potential ◽  
The Other ◽  
Dynamics Simulation ◽  
High Coverage ◽  
Other Hand ◽  
Low Coverage

We have investigated the decomposition of C 60 molecules with low and high coverages on Si(100)(2×1) surface at elevated temperatures. We also investigated the decomposition of an isolated C 60 molecule. We employed molecular-dynamics simulation using a model potential. It has been found that C 60 decomposes on Si(100) surface after 1000 K in the case of low coverage (0.11), however in high coverage case (0.67), C 60 molecules decompose after 900 K. On the other hand, isolated C 60 molecule decomposes after 7500 K, interestingly it shows a phase change from 3D to 2D at higher temperatures.

The Relation of the Southern Trade Winds to Upwelling Processes During the Last 75,000 years

1977 ◽  
Vol 8 (3) ◽  
pp. 324-338 ◽  
Author(s):  
Adolfo Molina-Cruz
Keyword(s):  
Regression Analysis ◽  
South America ◽  
Deep Sea ◽  
Coastal Upwelling ◽  
Equatorial Pacific ◽  
The Other ◽  
Trade Winds ◽  
Equatorial Undercurrent ◽  
The Earth ◽  
Radiolarian Assemblages

In the equatorial Pacific, between the Galapagos Islands and the coast of South America, two kinds of upwelling of oceanic waters occur. One is related to coastal upwelling and the other to surfacing of the Equatorial Undercurrent. Both of those processes are associated with the development of the southeast trade winds blowing in this area. Coastal upwelling is increased when the trade winds are intensified, and the surfacing of the Equatorial Undercurrent occurs when the trades weaken. The development of coastal upwelling and the surfacing of the Equatorial Undercurrent are inferred from the radiolarian assemblages in the sediments. The abundance of quartz, opal, and radiolarian assemblages in the deep-sea sediments of this area, as well as the distance from the sample locations to land and to the quartz source, is correlated with the intensity of the trade winds (in February and August) through multiple regression analysis. The chronostratigraphy of core V19-29 (3°35′S, 83°56′W), used in this study, is inferred on basis of its δ180 record. During the last 75,000 years, the fluctuations in intensity of the trade winds have been concurrent with or preceded the fluctuations in the amount of ice stored on the continents. In general, the wind velocity of the winter trades has been intensified during cool climatic stages of the earth (δ180 stages 4 and 2) and they have been relaxed during warm stages (δ180 stages 3 and 1). Seasonal contrast of the trade winds has also fluctuated within time, having been relatively high during the upper part of δ180 stage 3.

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