scholarly journals Effects of temperature and pCO2 on the respiration, biomineralization and photophysiology of the giant clam Tridacna maxima

2019 ◽  
Author(s):  
Chloé Brahmi ◽  
Leila Chapron ◽  
Gilles Le Moullac ◽  
Claude Soyez ◽  
Benoît Beliaeff ◽  
...  
Keyword(s):  
Global Change ◽  
Shell Growth ◽  
Synergetic Effect ◽  
Thermal Conditions ◽  
Giant Clam ◽  
Photosynthetic Yield ◽  
Negative Effect ◽  
Tridacna Maxima ◽  
Two Temperatures ◽  
Kinetics Of

AbstractSuch as many other reef organisms, giant clams are today confronted to global change effects and can suffer mass bleaching or mortality events mainly related to abnormally high seawater temperatures. Despite its strong ecological and socio-economical importance, its responses to the two most alarming threats linked to global change (i.e., ocean warming and acidification) still need to be explored. We investigated physiological responses of 4-years-old Tridacna maxima specimens to realistic levels of temperature and partial pressure of carbon dioxide (pCO2) (+1.5°C and +800 μatm of CO2) predicted for 2100 in French Polynesian lagoons during the warmer season. During a 65-days crossed-factor experiment, individuals were exposed to two temperatures (29.2°C; 30.7°C) and two pCO2 (430 µatm; 1212 µatm) conditions. Impact of each parameter and their potential synergetic effect were evaluated on respiration, biomineralization and photophysiology. Kinetics of thermal and acidification stress were evaluated by performing measurements at different times of exposure (29, 41, 53, 65 days). At 30.7°C, the holobiont O2 production, symbiont photosynthetic yield, and density were negatively impacted. High pCO2 had a significant negative effect on shell growth rate, symbiont photosynthetic yield and density. Shell microstructural modifications were observed from 41 days in all temperature and pCO2 conditions. No significant synergetic effect was found. Today thermal conditions (29.2°C) appeared to be sufficiently stressful to induce a host acclimatization process. All these observations indicate that temperature and pCO2 are both forcing variables affecting T. maxima physiology and jeopardize its survival under environmental conditions predicted for the end of this century.

scholarly journals Tissue-Specific Microbiomes of the Red Sea Giant Clam Tridacna maxima Highlight Differential Abundance of Endozoicomonadaceae

2019 ◽  
Vol 10 ◽  
Author(s):  
Susann Rossbach ◽  
Anny Cardenas ◽  
Gabriela Perna ◽  
Carlos M. Duarte ◽  
Christian R. Voolstra
Keyword(s):  
Red Sea ◽  
Giant Clam ◽  
Differential Abundance ◽  
Tissue Specific ◽  
Tridacna Maxima

scholarly journals Tree-Ring Growth of Larch (Larix decidua Mill.) in the Polish Sudetes—The Influence of Altitude and Site-Related Factors on the Climate–Growth Relationship

Forests ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 663 ◽  
Author(s):  
Małgorzata Danek ◽  
Monika Chuchro ◽  
Adam Walanus
Keyword(s):  
Tree Ring ◽  
Climatic Factors ◽  
Negative Relationship ◽  
Thermal Conditions ◽  
Cambial Activity ◽  
Negative Influence ◽  
Larix Decidua ◽  
Related Factors ◽  
Local Conditions ◽  
Negative Effect

In this paper, the first study of a regional character on the influence of climatic factors on the tree-ring growth of European larch (Larix decidua Mill.) growing in the Polish Sudetes is presented. The obtained results indicate the relatively high diversity of the climatic signal observed in the tree rings of larches growing in the Sudetes. The most significant differentiating factor is altitude. The results suggest that the possible influence of local conditions (e.g., summit proximity, soil and bedrock characteristics, and exposure to strong winds) could also be of importance. A positive relationship between tree-ring growth and May temperatures was noted throughout the area; this indicates the principal importance of thermal conditions during the initial stage of cambial activity and tree-ring formation in larches from the Sudetes. The negative effect of the temperatures in the previous summer upon the tree-ring growth of larch in the subsequent year was also observed. The studies also indicate the negative influence of the water stress in summer (particularly in July of the previous year) upon the growth of trees. The negative relationship between tree-ring growth and the previous November temperature could be explained by the need for a late-autumn cooling, which affects the development of assimilation apparatus in spring of the subsequent year, which indirectly affects the tree-ring growth in the same year.

scholarly journals Advanced Oxidation Process for Degradation of Carbamazepine from Aqueous Solution: Influence of Metal Modified Microporous, Mesoporous Catalysts on the Ozonation Process

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 90 ◽  
Author(s):  
Soudabeh Saeid ◽  
Matilda Kråkström ◽  
Pasi Tolvanen ◽  
Narendra Kumar ◽  
Kari Eränen ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Advanced Oxidation Process ◽  
Degradation Products ◽  
Degradation Kinetics ◽  
Removal Rate ◽  
Influence Of Temperature On ◽  
Two Temperatures ◽  
Kinetics Of ◽  
Ozonation Process ◽  
Mcm 41

Carbamazepine (CBZ), a widely used pharmaceutical compound, is one of the most detected drugs in surface waters. The purpose of this work was to identify an active and durable catalyst, which, in combination with an ozonation process, could be used to remove CBZ and its degradation products. It was found that the CBZ was completely transformed after ozonation within the first minutes of the treatment. However, the resulting degradation products, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM) and 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD), were more resistant during the ozonation process. The formation and degradation of these products were studied in more detail and a thorough catalytic screening was conducted to reveal the reaction kinetics of both the CBZ and its degradation products. The work was performed by non-catalytic ozonation and with six different heterogeneous catalysts (Pt-MCM-41-IS, Ru-MCM-41-IS, Pd-H-Y-12-EIM, Pt-H-Y-12-EIM, Pd-H-Beta-300-EIM and Cu-MCM-41-A-EIM) operating at two temperatures 20 °C and 50 °C. The influence of temperature on degradation kinetics of CBZ, BQM and BQD was studied. The results exhibited a notable difference in the catalytic behavior by varying temperature. The higher reactor temperature (50 °C) showed a higher activity of the catalysts but a lower concentration of dissolved ozone. Most of the catalysts exhibited higher removal rate for BQM and BQD compared to non-catalytic experiments in both temperatures. The Pd-H-Y-12-EIM catalyst illustrated a higher degradation rate of by-products at 50 °C compared to other catalysts.

scholarly journals Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Microbiome ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Isis Guibert ◽  
Gael Lecellier ◽  
Gergely Torda ◽  
Xavier Pochon ◽  
Véronique Berteaux-Lecellier
Keyword(s):  
Giant Clam ◽  
Tridacna Maxima

scholarly journals Effect of Exogenous Application of Amino Acids L-Arginine and Glycine on Maize under Temperature Stress

Agronomy ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 769 ◽  
Author(s):  
Kinga Matysiak ◽  
Roman Kierzek ◽  
Idzi Siatkowski ◽  
Jolanta Kowalska ◽  
Roman Krawczyk ◽  
...  
Keyword(s):  
Amino Acids ◽  
Temperature Stress ◽  
Foliar Application ◽  
Lateral Roots ◽  
Thermal Conditions ◽  
Growth Stages ◽  
Exogenous Application ◽  
C 23 ◽  
Negative Effect ◽  
Positive Effect

Temperature strongly influences the growth of maize, particularly in the early growth stages. The exogenous application of some amino acids has been proven to have a positive effect on plant growth and development under stressful conditions. The objective of the study was to evaluate the response of maize that was grown under an optimal and stress (fluctuating) temperature to L-Arginine (L-Arg) and Glycine (Gly) application. In the study, it was assumed that the exogenously applied amino acids would alleviate the adverse effects of temperature stress on the maize height, as well as on the biomass of shoots and roots. Ten concentrations of each amino acid from 0.006 mM to 9.0 mM were tested under constant temperature conditions 20–22 °C/23–25 °C (night/day) an fluctuating stress of rising and dropping temperatures between 12–15 °C (night) and 30–38 °C (day). The amino acids were applied to the crop at growth stages V3–V4. In plants that were obtained from seeds pre-treated with L-Arg and Gly, the amino acids increased both the length of radicles and the number of lateral roots. A large discrepancy between the effects of the two amino acids was observed after foliar application. Under optimal thermal conditions, L-Arg increased the mass of shoots and roots by 55–59%. Under stress conditions, root mass was increased even by 100% when compared to the control plants. The best results were recorded at concentrations of 6 mM and 3 mM. Plants that were treated with Gly concentrations generally reached the height of untreated plants or less. It was shown that Gly applied at concentrations of 0.2 mM to 3 mM has a negative effect on the fresh mass of the crop.

scholarly journals PERSISTENCIA DEL ENDOSULFÁN EN MEDIO ACUOSO ESTÁTICO

2001 ◽  
Vol 11 ◽  
Author(s):  
ARGELIA M. L. LENARDÓN ◽  
PATRICIA M. DE LA SIERRA ◽  
FERNANDA MARINO
Keyword(s):  
River Water ◽  
Degradation Kinetics ◽  
Water Type ◽  
Ultrapure Water ◽  
First Order ◽  
First Order Kinetics ◽  
Predominant Factor ◽  
Two Temperatures ◽  
In The Beginning ◽  
Kinetics Of

Estudou-se a cinética de degradação da mistura dos isômeros alfa e beta Endosulfan em diferentes condições de trabalho. Os compostos foram adicionados em água ultrapura, água do rio, água de rio filtrada e água ultrapura com sais (salinidade similar à agua do rio utilizada). As condições de degradação escolhidas foram: escuridão e duas temperaturas (14+1 ºC e 26+1 ºC). As amostragens foram programadas de modo a se obter dados periódicos mais freqüentes no início da experiência e posteriormente mais espaçados até o seu final (230 dias). As amostras foram submetidas à microextração e analisadas por cromatografia em fase gasosa com detector de Ni63 e coluna Megabore DB-5. A degradação foi descrita de acordo com a cinética de primeira ordem, determinando-se os tempos de meia vida (t1/2) e as energias de ativação (Ea). Os dados obtidos evidenciaram que a temperatura é o fator preponderante, sendo possível deduzir que o alfaendosulfan, exceto para água ultrapura (AU), é mais influenciado pela temperatura do que o beta-endosulfan. O segundo efeito mais importante refere-se ao tipo de água utilizada como matriz, devido à influência da salinidade. PERSISTANCE OF ENDOSULFAN IN STATIC AQUEOUS MEDIUM Abstract Degradation kinetics of a mixture of alpha- and beta-Endosulfan isomers was studied under different conditions. The compounds were spiked in ultrapure water, river water, filtered water and ultrapure water with salts (similar salinity condition to that of the river water used). The degradation conditions chosen were: darkness, two temperatures (14+1 ºC e 26+1 ºC). Samplings were programmed in order to obtain more frequent periodical data in the beginning of the experience and after more spaced until its end (230 days). The samples were submitted to microextraction and then analyzed by gas chromatography through a Ni63 detector equipped with a Megabore DB-5 column. Degradation was described using first-order kinetics to determine half-life times (t1/2) and activation energies (Ea). The data obtained evidenced that temperature is the predominant factor, it can possibly be inferred that alfa-endosulfan is much more influenced than beta-endosulfan except for ultrapure water (UW). The second important effect is the water type used as matrix, due to the influence of salinity.

scholarly journals Condensation By-Products in Wet Peroxide Oxidation: Fouling or Catalytic Promotion? Part I. Evidences of an Autocatalytic Process

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 516 ◽  
Author(s):  
Asunción Quintanilla ◽  
Jose L. Diaz de Tuesta ◽  
Cristina Figueruelo ◽  
Macarena Munoz ◽  
Jose A. Casas
Keyword(s):  
Flow Reactor ◽  
Operating Conditions ◽  
Phenol Concentration ◽  
Peroxide Oxidation ◽  
Wet Peroxide Oxidation ◽  
Oxidation Performance ◽  
Negative Effect ◽  
Initial Phenol Concentration ◽  
Kinetics Of ◽  
By Products

The present work is aimed at the understanding of the condensation by-products role in wet peroxide oxidation processes. This study has been carried out in absence of catalyst to isolate the (positive or negative) effect of the condensation by-products on the kinetics of the process, and in presence of oxygen, to enhance the oxidation performance. This process was denoted as oxygen-assisted wet peroxide oxidation (WPO-O2) and was applied to the treatment of phenol. First, the influence of the reaction operating conditions (i.e., temperature, pH0, initial phenol concentration, H2O2 dose and O2 pressure) was evaluated. The initial phenol concentration and, overall, the H2O2 dose, were identified as the most critical variables for the formation of condensation by-products and thus, for the oxidation performance. Afterwards, a flow reactor packed with inert quartz beads was used to facilitate the deposition of such species and thus, to evaluate their impact on the kinetics of the process. It was found that as the quartz beads were covered by condensation by-products along reaction, the disappearance rates of phenol, total organic carbon (TOC) and H2O2 were increased. Consequently, an autocatalytic kinetic model, accounting for the catalytic role of the condensation by products, provides a well description of wet peroxide oxidation performance.

Influence of field-based nutrient enrichment on the photobiology of the giant clam Tridacna maxima

1999 ◽  
Vol 133 (4) ◽  
pp. 659-664 ◽  
Author(s):  
Not Available Not Available ◽  
O. Hoegh-Guldberg
Keyword(s):  
Nutrient Enrichment ◽  
Giant Clam ◽  
Tridacna Maxima
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