scholarly journals Diel oxygen fluctuation drives the thermal response and metabolic performance of coastal marine ectotherms

2021 ◽  
Vol 288 (1953) ◽  
pp. 20211141
Author(s):  
J. M. Booth ◽  
M. Fusi ◽  
F. Giomi ◽  
E. C. N. Chapman ◽  
K. Diele ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Marine Invertebrates ◽  
Metabolic Response ◽  
Thermal Sensitivity ◽  
Thermal Response ◽  
Oxygen Availability ◽  
Coastal Vegetation ◽  
Climate Anomalies ◽  
Coastal Marine ◽  
Metabolic Performance

Coastal marine systems are characterized by high levels of primary production that result in diel oxygen fluctuations from undersaturation to supersaturation. Constant normoxia, or 100% oxygen saturation, is therefore rare. Since the thermal sensitivity of invertebrates is directly linked to oxygen availability, we hypothesized that (i) the metabolic response of coastal marine invertebrates would be more sensitive to thermal stress when exposed to oxygen supersaturation rather than 100% oxygen saturation and (ii) natural diel fluctuation in oxygen availability rather than constant 100% oxygen saturation is a main driver of the thermal response. We tested the effects of oxygen regime on the metabolic rate, and haemocyanin and lactate levels, of velvet crabs ( Necora puber ) and blue mussels ( Mytilus edulis ), under rising temperatures (up to 24°C) in the laboratory. Oxygen supersaturation and photosynthetically induced diel oxygen fluctuation amplified animal metabolic thermal response significantly in both species, demonstrating that the natural variability of oxygen in coastal environments can provide considerable physiological benefits under ocean warming. Our study highlights the significance of integrating ecologically relevant oxygen variability into experimental assessments of animal physiology and thermal response, and predictions of metabolic performance under climate warming. Given the escalating intensity and frequency of climate anomalies, oxygen variation caused by coastal vegetation will likely become increasingly important in mitigating the effects of higher temperatures on coastal fauna.

scholarly journals Dissolved Oxygen in Heterogeneous Environments Dictates the Metabolic Rate and Thermal Sensitivity of a Tropical Aquatic Crab

2021 ◽  
Vol 8 ◽  
Author(s):  
Marco Fusi ◽  
Daniele Daffonchio ◽  
Jenny Booth ◽  
Folco Giomi
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Saturation ◽  
Thermal Sensitivity ◽  
Thermal Response ◽  
Respiratory Physiology ◽  
Heterogeneous Environments ◽  
Mud Crab ◽  
Low Oxygen ◽  
Coastal Habitats ◽  
Seagrass Meadows

Oxygen availability, together with water temperature, greatly varies in coastal habitats, especially in those characterized by elevated primary production. In this study, we investigate the combined role of dissolved oxygen and temperature on the thermal physiological response of the mud crab Thalamita crenata living in an equatorial system of coastal habitats. We sampled temperature, oxygen and salinity in T. crenata habitats, mangrove creeks and fringes and seagrass meadows, at Gazi Bay (Kenya). We found that seagrass meadows exhibited higher temperature and oxygen saturation than the mangrove habitats during the day, creating conditions of oxygen supersaturation. By investigating the effect of different levels of oxygen saturation on the thermal response of T. crenata, we demonstrated that the respiratory physiology of this ectotherm has a pronounced resistance to heat, directly influenced by the amount of dissolved oxygen in the water. Under low oxygen saturation levels, the mud crab significantly reduced its metabolism, becoming temperature-independent. This result shows that aquatic species can modulate their thermal response in a stringent dependency with water oxygen saturation, corroborating previous findings on the thermal response of T. crenata under supersaturation. This contribution provides further support for the need to adopt an ecologically-relevant approach to forecast the effect of climate change on marine ectothermal species.

scholarly journals Increased Thermal Sensitivity of a Tropical Marine Gastropod Under Combined CO2 and Temperature Stress

2021 ◽  
Vol 8 ◽  
Author(s):  
Jay J. Minuti ◽  
Charlee A. Corra ◽  
Brian S. Helmuth ◽  
Bayden D. Russell
Keyword(s):  
Defense Mechanism ◽  
Thermal Sensitivity ◽  
Interactive Effects ◽  
Lethal Temperature ◽  
Weather Extremes ◽  
Short Term ◽  
Metabolic Plasticity ◽  
The Face ◽  
Metabolic Performance ◽  
Maximum Metabolic Rate

The ability of an organism to alter its physiology in response to environmental conditions offers a short-term defense mechanism in the face of weather extremes resulting from climate change. These often manifest as multiple, interacting drivers, especially pH and temperature. In particular, decreased pH can impose constraints on the biological mechanisms which define thermal limits by throwing off energetic equilibrium and diminishing physiological functions (e.g., in many marine ectotherms). For many species, however, we do not have a detailed understanding of these interactive effects, especially on short-term acclimation responses. Here, we investigated the metabolic plasticity of a tropical subtidal gastropod (Trochus maculatus) to increased levels of CO2 (700 ppm) and heating (+3°C), measuring metabolic performance (Q10 coefficient) and thermal sensitivity [temperature of maximum metabolic rate (TMMR), and upper lethal temperature (ULT)]. Individuals demonstrated metabolic acclimation in response to the stressors, with TMMR increasing by +4.1°C under higher temperatures, +2.7°C under elevated CO2, and +4.4°C under the combined stressors. In contrast, the ULT only increased marginally in response to heating (+0.3°C), but decreased by −2.3°C under CO2, and −8.7°C under combined stressors. Therefore, although phenotypic plasticity is evident with metabolic acclimation, acute lethal temperature limits seem to be less flexible during short-term acclimation.

scholarly journals Warming effect on nitrogen fixation in Mediterranean macrophyte sediments

2019 ◽  
Vol 16 (1) ◽  
pp. 167-175 ◽  
Author(s):  
Neus Garcias-Bonet ◽  
Raquel Vaquer-Sunyer ◽  
Carlos M. Duarte ◽  
Núria Marbà
Keyword(s):  
N2 Fixation ◽  
Thermal Sensitivity ◽  
Thermal Response ◽  
Sharp Decrease ◽  
Posidonia Oceanica ◽  
Global Ocean ◽  
Thermal Dependence ◽  
High Productivity ◽  
Marine Macrophytes ◽  
The Impact

Abstract. The Mediterranean Sea is warming faster than the global ocean, with important consequences for organisms and biogeochemical cycles. Warming is a major stressor for key marine benthic macrophytes. However, the effect of warming on marine N2 fixation remains unknown, despite the fact that the high productivity of macrophytes in oligotrophic waters is partially sustained by the input of new nitrogen (N) into the system by N2 fixation. Here, we assess the impact of warming on the N2 fixation rates of three key marine macrophytes: Posidonia oceanica, Cymodocea nodosa, and Caulerpa prolifera. We experimentally measured N2 fixation rates in vegetated and bare sediments at temperatures encompassing current summer mean (25 and 27 ∘C), projected summer mean (29 and 31 ∘C), and projected summer maximum (33 ∘C) seawater surface temperatures (SSTs) by the end of the century under a scenario of moderate greenhouse gas emissions. We found that N2 fixation rates in vegetated sediments were 2.8-fold higher than in bare sediments at current summer mean SST, with no differences among macrophytes. Currently, the contribution of N2 fixation to macrophyte productivity could account for up to 7 %, 13.8 %, and 1.8 % of N requirements for P. oceanica, C. nodosa, and C. prolifera, respectively. We show the temperature dependence of sediment N2 fixation rates. However, the thermal response differed for vegetated sediments, in which rates showed an optimum at 31 ∘C followed by a sharp decrease at 33 ∘C, and bare sediments, in which rates increased along the range of the experimental temperatures. The activation energy and Q10 were lower in vegetated than bare sediments, indicating the lower thermal sensitivity of vegetated sediments. The projected warming is expected to increase the contribution of N2 fixation to Mediterranean macrophyte productivity. Therefore, the thermal dependence of N2 fixation might have important consequences for primary production in coastal ecosystems in the context of warming.

scholarly journals Linking thermal adaptation and life-history theory explains latitudinal patterns of voltinism

2019 ◽  
Vol 374 (1778) ◽  
pp. 20180547 ◽  
Author(s):  
Jacinta D. Kong ◽  
Ary A. Hoffmann ◽  
Michael R. Kearney
Keyword(s):  
Life History ◽  
Thermal Sensitivity ◽  
Thermal Adaptation ◽  
Thermal Response ◽  
Life Cycles ◽  
Development Rate ◽  
Latitudinal Gradients ◽  
Seasonal Temperature ◽  
Egg Development ◽  
Latitudinal Patterns

Insect life cycles are adapted to a seasonal climate by expressing alternative voltinism phenotypes—the number of generations in a year. Variation in voltinism phenotypes along latitudinal gradients may be generated by developmental traits at critical life stages, such as eggs. Both voltinism and egg development are thermally determined traits, yet independently derived models of voltinism and thermal adaptation refer to the evolution of dormancy and thermal sensitivity of development rate, respectively, as independent influences on life history. To reconcile these models and test their respective predictions, we characterized patterns of voltinism and thermal response of egg development rate along a latitudinal temperature gradient using the matchstick grasshopper genus Warramaba . We found remarkably strong variation in voltinism patterns, as well as corresponding egg dormancy patterns and thermal responses of egg development. Our results show that the switch in voltinism along the latitudinal gradient was explained by the combined predictions of the evolution of voltinism and of thermal adaptation. We suggest that latitudinal patterns in thermal responses and corresponding life histories need to consider the evolution of thermal response curves within the context of seasonal temperature cycles rather than based solely on optimality and trade-offs in performance. This article is part of the theme issue ‘Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen’.

scholarly journals Local-Scale Thermal History Influences Metabolic Response of Marine Invertebrates To Warming

2021 ◽  
Author(s):  
Racine E. Rangel ◽  
Cascade J.B. Sorte
Keyword(s):  
Climate Change ◽  
Metabolic Rate ◽  
Thermal History ◽  
Metabolic Response ◽  
Thermal Sensitivity ◽  
Hermit Crabs ◽  
Future Climate Change ◽  
Tide Pool ◽  
Time Periods ◽  
The Relationship

Abstract As climate change continues, anticipating species’ responses to rising temperatures, requires an understanding of the relationship between metabolic rate and thermal sensitivity, which itself may vary over space and time. We measured metabolic rates of three representative marine invertebrate species (hermit crabs Pagurus hirsutiusculus, periwinkle snails Littorina sitkana, and mussels Mytilus trossulus) and evaluated the relationship between thermal sensitivity (Q10) and thermal history. We tested the hypothesis that thermal history drives thermal sensitivity and quantified how this relationship differs over time (short-term to seasonal time scales) and between species. Organisms were collected from tide pools in Sitka, Alaska where we also recorded temperatures to characterize thermal history prior to metabolic rate assays. Using respirometry, we estimated mass-specific oxygen consumption (MO2) at ambient and increased temperatures for one individual per species per tide pool across three seasons. We evaluated relationships between thermal sensitivity and pool temperatures for time periods ranging from 1 day to 3 months prior to collection. For all species, thermal sensitivity was related to thermal history for the shorter time periods (1 day to 1 week). However, the direction of the relationships and most important thermal parameters (i.e., maximum, mean, or range) differed between species and seasons. We found that on average, P. hirsutiusculus and L. sitkana were more thermally sensitive than M. trossulus. These findings show that variability in thermal history over small spatial scales influences individuals’ metabolic response to warming and may be indicative of these species’ ability to acclimate to future climate change.

Numerical simulations of concealed residential sprinkler head activation time in a standard thermal response room test

2020 ◽  
Vol 42 (1) ◽  
pp. 98-111
Author(s):  
Charlie Hopkin ◽  
Michael Spearpoint
Keyword(s):  
Response Time ◽  
Residential Buildings ◽  
Thermal Sensitivity ◽  
Computational Modelling ◽  
Thermal Response ◽  
Fire Dynamics ◽  
Effective Response ◽  
Fire Dynamics Simulator ◽  
Time Index ◽  
Factor C

It is common for sprinkler heads in residential buildings to be of the concealed type. Key parameters for the thermal sensitivity of sprinkler heads are the response time index (m½s½) and conductivity factor (C factor, m½s−½). BS 9252:2011 and BS EN 12259-14:2020 outline test methods to determine whether sprinkler heads achieve adequate thermal sensitivity, stipulating that a room test be undertaken for concealed heads. In carrying out this test, neither the response time index nor C factor is defined. This paper uses computational modelling tools Fire Dynamics Simulator and B-RISK to simulate the room test. In running these simulations, maximum values for the ‘effective’ response time index and C factor needed to pass the room test can be estimated, assuming concealed heads can be represented as equivalent pendent heads. Initial deterministic simulations are used to calibrate results between Fire Dynamics Simulator and B-RISK. Monte Carlo modelling is then utilised within B-RISK, with variable parameters for the response time index and C factor (C), to estimate the relationship between the two parameters necessary to pass the room test. As a result, it is proposed that this relationship can be represented using a simple, empirical power law equation of response time index = 100 (5.4–C)2/3, where C < 5.4. Practical application: The results indicate that the minimum RTI and C factor values needed to pass the room test are greater than those needed to pass wind tunnel testing methods. In observing that equivalency is not demonstrated by the room test, and by defining the RTI/C factor relationship needed to pass the test, this paper provides fire safety engineers with amended values for concealed heads to be adopted in future assessments. In the absence of any detailed specification for sprinkler heads, it is recommended that an RTI of 290 m½s½ and a C factor of 0.5 m½s−½ may be applied.

scholarly journals Neurovascular Uncoupling under Mild Hypoxic Hypoxia: An EEG–fMRI Study in Rats

2012 ◽  
Vol 32 (10) ◽  
pp. 1853-1858 ◽  
Author(s):  
Akira Sumiyoshi ◽  
Hideaki Suzuki ◽  
Hiroaki Shimokawa ◽  
Ryuta Kawashima
Keyword(s):  
Magnetic Resonance Imaging ◽  
Oxygen Saturation ◽  
Enzymatic Synthesis ◽  
Neurovascular Coupling ◽  
Oxygen Availability ◽  
Hypoxic Hypoxia ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Fmri Study ◽  
Messenger Molecules

The effects of oxygen availability on neurovascular coupling were investigated using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), in addition to the monitoring of physiological parameters, in 16 α-chloralose-anesthetized rats. Mild hypoxic hypoxia (oxygen saturation=83.6±12.1%) induced significant reductions in fMRI responses ( P<0.05) to electrical stimulation in the forepaw, but EEG responses remained unchanged. In addition, the changes in oxygen saturation were linearly correlated with the changes in the fMRI responses. These data further emphasize the importance of oxygen availability, which may regulate neurovascular coupling via the oxygen-dependent enzymatic synthesis of messenger molecules.

scholarly journals Adenosine receptors mediate the hypoxic ventilatory response but not the hypoxic metabolic response in the naked mole rat during acute hypoxia

2015 ◽  
Vol 282 (1800) ◽  
pp. 20141722 ◽  
Author(s):  
Matthew E. Pamenter ◽  
Yvonne A. Dzal ◽  
William K. Milsom
Keyword(s):  
Adenosine Receptors ◽  
Metabolic Response ◽  
Ventilatory Response ◽  
Acute Hypoxia ◽  
Thermal Response ◽  
Hypoxia Tolerance ◽  
Hypoxic Ventilatory Response ◽  
Adenosine Receptor Antagonist ◽  
Ventilatory Responses ◽  
Mole Rat

Naked mole rats are the most hypoxia-tolerant mammals identified; however, the mechanisms underlying this tolerance are poorly understood. Using whole-animal plethysmography and open-flow respirometry, we examined the hypoxic metabolic response (HMR), hypoxic ventilatory response (HVR) and hypoxic thermal response in awake, freely behaving naked mole rats exposed to 7% O 2 for 1 h. Metabolic rate and ventilation each reversibly decreased 70% in hypoxia (from 39.6 ± 2.9 to 12.1 ± 0.3 ml O 2 min −1 kg −1 , and 1412 ± 244 to 417 ± 62 ml min −1 kg −1 , respectively; p < 0.05), whereas body temperature was unchanged and animals remained awake and active. Subcutaneous injection of the general adenosine receptor antagonist aminophylline (AMP; 100 mg kg −1 , in saline), but not control saline injections, prevented the HVR but had no effect on the HMR. As a result, AMP-treated naked mole rats exhibited extreme hyperventilation in hypoxia. These animals were also less tolerant to hypoxia, and in some cases hypoxia was lethal following AMP injection. We conclude that in naked mole rats (i) hypoxia tolerance is partially dependent on profound hypoxic metabolic and ventilatory responses, which are equal in magnitude but occur independently of thermal changes in hypoxia, and (ii) adenosine receptors mediate the HVR but not the HMR.

Sign in / Sign up

Export Citation Format

Share Document