scholarly journals Metabolism drives demography in an experimental field test

2021 ◽  
Vol 118 (34) ◽  
pp. e2104942118
Author(s):  
Lukas Schuster ◽  
Hayley Cameron ◽  
Craig R. White ◽  
Dustin J. Marshall
Keyword(s):  
Metabolic Rate ◽  
Field Experiment ◽  
Energy Use ◽  
Marine Invertebrate ◽  
Classic Theory ◽  
Energy Equivalence ◽  
Theoretical Predictions ◽  
Equivalence Theory ◽  
Species Comparisons ◽  
Impacts Of Climate Change

Metabolism should drive demography by determining the rates of both biological work and resource demand. Long-standing “rules” for how metabolism should covary with demography permeate biology, from predicting the impacts of climate change to managing fisheries. Evidence for these rules is almost exclusively indirect and in the form of among-species comparisons, while direct evidence is exceptionally rare. In a manipulative field experiment on a sessile marine invertebrate, we created experimental populations that varied in population size (density) and metabolic rate, but not body size. We then tested key theoretical predictions regarding relationships between metabolism and demography by parameterizing population models with lifetime performance data from our field experiment. We found that populations with higher metabolisms had greater intrinsic rates of increase and lower carrying capacities, in qualitative accordance with classic theory. We also found important departures from theory—in particular, carrying capacity declined less steeply than predicted, such that energy use at equilibrium increased with metabolic rate, violating the long-standing axiom of energy equivalence. Theory holds that energy equivalence emerges because resource supply is assumed to be independent of metabolic rate. We find this assumption to be violated under real-world conditions, with potentially far-reaching consequences for the management of biological systems.

scholarly journals Coulometric measurement of oxygen consumption during development of marine invertebrate embryos and larvae

1995 ◽  
Vol 198 (1) ◽  
pp. 19-30 ◽  
Author(s):  
O Hoegh-Guldberg ◽  
D Manahan
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Energy Use ◽  
Oxygen Sensor ◽  
Marine Invertebrate ◽  
Measurement Techniques ◽  
Larval Growth ◽  
Oxygen Sensors ◽  
Single Individual ◽  
Metabolic Rates

Determining the metabolic rate of larval invertebrates from aquatic habitats is complicated by the problems of small size and the scarcity of suitable measurement techniques. In this study, coulometric respirometry (a new technique for the study of marine embryos and larvae) was used to explore several issues associated with the rate of energy use during embryonic and larval development of marine invertebrates from three phyla. Coulometric respirometry measures rates of oxygen consumption under normoxic conditions by electrochemically replacing the oxygen consumed by organisms during an experiment. This technique is based on the assumption that all electrons consumed by the anodic reactions result in the production of oxygen. We verify this assumption using direct measurements of oxygen production and show that the technique is sensitive enough (1 nmol O2 h-1) to quantify the oxygen consumption of a single individual swimming freely in a relatively large volume (2 ml). Continuous measurements can span days, and embryos in the coulometric respiration chambers develop to the larval stage at normal rates of differentiation. Measurements of metabolic rates were made with the coulometric respirometer during the complete life-span of larvae of three species (asteroid, Asterina miniata; bivalve, Crassostrea gigas; echinoid, Dendraster excentricus). For these species, metabolic power equations had mass exponents near unity (0.9­1.1), showing that metabolic rate scales isometrically with mass during larval growth. Metabolic rates were independent of the concentration of larvae used in the respirometer chambers for a range of larval concentrations from 4 to 400 larvae ml-1 (coulometric respirometer) and from 241 to 809 larvae ml-1 (polarographic oxygen sensor). Metabolic rates were measured using coulometric respirometry and two other commonly used techniques, polarographic oxygen sensors and Winkler's titration. Polarographic oxygen sensors in small, sealed chambers (100 µl) consistently gave the lowest values (by as much as 80 %) for the asteroid, echinoid and molluscan larvae. By comparison, rates of oxygen consumption measured using coulometric respirometry and Winkler's titration (to measure the change in oxygen concentration over time) were similar and consistently higher. Although the polarographic oxygen sensor is the most widely used method for measuring the metabolism of small animals in sealed 100­1000 µl chambers, it appears that the metabolism of some larvae is adversely affected by the conditions within these respirometers.

scholarly journals Validating accelerometry-derived proxies of energy expenditure using the doubly-labelled water method in the smallest penguin species

Biology Open ◽  
2021 ◽  
pp. bio.055475
Author(s):  
G. J. Sutton ◽  
J. A. Botha ◽  
J. R. Speakman ◽  
J. P. Y. Arnould
Keyword(s):  
Energy Expenditure ◽  
Metabolic Rate ◽  
Energy Use ◽  
Travel Speed ◽  
Specific Energy Expenditure ◽  
Doubly Labelled Water ◽  
Data Collection And Analysis ◽  
Behavioural Patterns ◽  
Free Ranging ◽  
The Relationship

Understanding energy use is central to understanding an animal's physiological and behavioural ecology. However, directly measuring energy expenditure in free-ranging animals is inherently difficult. The doubly-labelled water (DLW) method is widely used to investigate energy expenditure in a range of taxa. Although reliable, DLW data collection and analysis is both financially costly and time consuming. Dynamic body acceleration (e.g. VeDBA) calculated from animal-borne accelerometers has been used to determine behavioural patterns, and is increasingly being used as a proxy for energy expenditure. Still its performance as a proxy for energy expenditure in free-ranging animals is not well established and requires validation against established methods. In the present study, the relationship between VeDBA and the at-sea metabolic rate calculated from DLW was investigated in little penguins (Eudyptula minor) using three approaches. Both in a simple correlation and activity-specific approaches were shown to be good predictors of at-sea metabolic rate. The third approach using activity-specific energy expenditure values obtained from literature did not accurately calculate the energy expended by individuals. However, all three approaches were significantly strengthened by the addition of mean horizontal travel speed. These results provide validation for the use of accelerometry as a proxy for energy expenditure and show how energy expenditure may be influenced by both individual behaviour and environmental conditions.

scholarly journals Ants under crowded conditions consume more energy

2008 ◽  
Vol 4 (6) ◽  
pp. 613-615 ◽  
Author(s):  
Tuan T Cao ◽  
Anna Dornhaus
Keyword(s):  
Metabolic Rate ◽  
Social Insects ◽  
Energy Use ◽  
Social Space ◽  
The Social ◽  
Cent Increase ◽  
Worker Behaviour

Social insects live in colonies consisting of many workers, where worker interactions play an important role in regulating colony activities. Workers interact within the social space of the nest; therefore, constraints on nest space may alter worker behaviour and affect colony activities and energetics. Here we show in the ant Temnothorax rugatulus that changes in nest space have a significant effect on colony energetics. Colonies with restricted nest space showed a 14.2 per cent increase in metabolic rate when compared with the same colonies in large uncrowded nests. Our study highlights the importance of social space and shows that constraints on social space can significantly affect colony behaviour and energy use in ants. We discuss the implications of our findings regarding social insects in general.

scholarly journals Influence of food, body size, and fragmentation on metabolic rate in a sessile marine invertebrate

2019 ◽  
Vol 138 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Lukas Schuster ◽  
Craig R. White ◽  
Dustin J. Marshall
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Marine Invertebrate ◽  
Influence Of Food ◽  
Food Body

scholarly journals Energy Use and Labor Productivity in Ethiopia: The Case of the Manufacturing Industry

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2714 ◽  
Author(s):  
Selamawit G. Kebede ◽  
Almas Heshmati
Keyword(s):  
Panel Data ◽  
Labor Productivity ◽  
Alternative Model ◽  
Manufacturing Industry ◽  
Energy Use ◽  
Manufacturing Industries ◽  
Dynamic Panel ◽  
Control Variables ◽  
Theoretical Predictions ◽  
Dynamic Panel Estimator

This study investigates the effect of energy use on labor productivity in the Ethiopian manufacturing industry. It uses panel data for the manufacturing industry groups to estimate the coefficients using the dynamic panel estimator. The study’s results confirm that energy use increases manufacturing labor productivity. The coefficients for the control variables are in keeping with theoretical predictions. Capital positively augments productivity in the industries. Based on our results, technology induces manufacturing’s labor productivity. Likewise, more labor employment induces labor productivity due to the dominance of labor-intensive manufacturing industries in Ethiopia. Alternative model specifications provide evidence of a robust link between energy and labor productivity in the Ethiopian manufacturing industry. Our results imply that there needs to be more focus on the efficient use of energy, labor, capital, and technology to increase the manufacturing industry’s labor productivity and to overcome the premature deindustrialization patterns being seen in Ethiopia.

Structural Multi-Damage Identification Based on Modal Strain Energy Equivalence Index Method

2014 ◽  
Vol 14 (07) ◽  
pp. 1450028 ◽  
Author(s):  
Hui Yong Guo ◽  
Zheng Liang Li
Keyword(s):  
Energy Dissipation ◽  
Structural Damage ◽  
Strain Energy ◽  
Damage Identification ◽  
Index Method ◽  
Modal Strain Energy ◽  
Energy Equivalence ◽  
Before And After ◽  
Accurate Expression ◽  
Equivalence Theory

In order to solve structural multi-damage identification problems, a damage detection method based on modal strain energy equivalence index (MSEEI) is presented. First, an accurate expression of modal strain energy (MSE) before and after damage occurs is given. Then, according to the energy equivalence theory that the change in MSE caused by the damage should be equivalent to the energy dissipation caused by the same damage, an energy equivalence equation is deduced. Finally, four roots of the energy equivalence equation are found and a MSEEI is obtained from the four roots. Simulation results demonstrate that the proposed MSEEI method can identify structural damage locations and extent with good accuracy. Identification precision of the proposed method is clearly better than that of the modal strain energy dissipation ratio index (MSEDRI) method.

scholarly journals Energetics of stress: linking plasma cortisol levels to metabolic rate in mammals

2016 ◽  
Vol 12 (1) ◽  
pp. 20150867 ◽  
Author(s):  
Catherine G. Haase ◽  
Andrea K. Long ◽  
James F. Gillooly
Keyword(s):  
Metabolic Rate ◽  
Plasma Cortisol ◽  
Physiological Stress ◽  
Stress Hormone ◽  
Short Term ◽  
Primary Stress ◽  
Baseline Concentrations ◽  
Species Comparisons ◽  
Point Of Departure

Physiological stress may result in short-term benefits to organismal performance, but also long-term costs to health or longevity. Yet, we lack an understanding of the variation in stress hormone levels (i.e. glucocorticoids) that exist within and across species. Here, we present comparative analyses that link the primary stress hormone in most mammals (i.e. cortisol) to metabolic rate. We show that baseline concentrations of plasma cortisol vary with mass-specific metabolic rate among cortisol-dominant mammals, and both baseline and elevated concentrations scale predictably with body mass. The results quantitatively link a classical measure of physiological stress to whole-organism energetics, providing a point of departure for cross-species comparisons of stress levels among mammals.

scholarly journals How to estimate community energy flux? A comparison of approaches reveals that size-abundance trade-offs alter the scaling of community energy flux

2020 ◽  
Vol 287 (1933) ◽  
pp. 20200995
Author(s):  
Giulia Ghedini ◽  
Martino E. Malerba ◽  
Dustin J. Marshall
Keyword(s):  
Energy Flux ◽  
Energy Use ◽  
Size Distributions ◽  
Complex Species ◽  
Trade Offs ◽  
Energy Equivalence ◽  
Phytoplankton Communities ◽  
Metabolic Suppression ◽  
Highly Correlated ◽  
Species Specific

Size and metabolism are highly correlated, so that community energy flux might be predicted from size distributions alone. However, the accuracy of predictions based on interspecific energy–size relationships relative to approaches not based on size distributions is unknown. We compare six approaches to predict energy flux in phytoplankton communities across succession: assuming a constant energy use among species (per cell or unit biomass), using energy–size interspecific scaling relationships and species-specific rates (both with or without accounting for density effects). Except for the per cell approach, all others explained some variation in energy flux but their accuracy varied considerably. Surprisingly, the best approach overall was based on mean biomass-specific rates, followed by the most complex (species-specific rates with density). We show that biomass-specific rates alone predict community energy flux because the allometric scaling of energy use with size measured for species in isolation does not reflect the isometric scaling of these species in communities. We also find energy equivalence throughout succession, even when communities are not at carrying capacity. Finally, we discuss that species assembly can alter energy–size relationships, and that metabolic suppression in response to density might drive the allometry of community energy flux as biomass accumulates.

Correlates of seasonal changes in metabolism in Atlantic harbour seals (Phoca vitulina concolor)

1998 ◽  
Vol 76 (8) ◽  
pp. 1520-1528 ◽  
Author(s):  
D A Rosen ◽  
D Renouf
Keyword(s):  
Energy Expenditure ◽  
Metabolic Rate ◽  
Total Energy ◽  
Energy Intake ◽  
Body Mass ◽  
Seasonal Changes ◽  
Energy Use ◽  
Phoca Vitulina ◽  
Harbour Seals ◽  
Gross Energy

This study tested the hypothesis that seasonal variation in resting metabolic rate (RMR) was more closely related to changes in total energy use than to energy intake. It also quantified the extent to which variation in metabolism contributed to changes in total energy expenditure. RMR, gross energy intake, and body mass and composition were measured in six captive Atlantic harbour seals (Phoca vitulina concolor) over 16 months. Gross energy intake during the year (across all seals) averaged 25.4 ± 4.1 MJ/d (mean ± SD). The energy used by the seals Eused a composite measure of energy expenditure from ingested energy and tissue catabolism) averaged 19.2 ± 3.4 MJ/d. RMR averaged 11.2 ± 1.5 MJ/d during the year, while mass-corrected metabolism declined with age. The seals displayed significant changes in both absolute and mass-corrected metabolism during the year. Overall, Eused was a stronger predictor of changes in metabolism than either gross energy intake or body mass. Mass-corrected metabolic rate was more closely related to Eused than was absolute metabolism. Energy changes in metabolism during the year (range = 6.9 ± 1.9 MJ/d) were minor compared with those in Eused (27.8 ± 7.3 MJ/d). These results suggest that seasonal changes in metabolism were a response to, or facilitated by, concurrent changes in Eused but were not the cause of variation in Eused. Rather, variation in both RMR and Eused was the result of changes in other bioenergetic components of the seals' energy budget, such as activity.

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