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Metabolic costs of capital energy storage in a small ‐ bodied ectotherm

View Article: PubMed Central - PubMed

ABSTRACT

Reproduction is energetically financed using strategies that fall along a continuum from animals that rely on stored energy acquired prior to reproduction (i.e., capital breeders) to those that rely on energy acquired during reproduction (i.e., income breeders). Energy storage incurs a metabolic cost. However, previous studies suggest that this cost may be minimal for small‐bodied ectotherms. Here I test this assumption. I use a laboratory feeding experiment with the European green crab Carcinus maenas to establish individuals with different amounts of energy storage. I then demonstrate that differences in energy storage account for 26% of the variation in basal metabolic costs. The magnitudes of these costs for any individual crab vary through time depending on the amount of energy it has stored, as well as on temperature‐dependent metabolism. I use previously established relationships between temperature‐ and mass‐dependent metabolic rates, combined with a feasible annual pattern of energy storage in the Gulf of Maine and annual sea surface temperature patterns in this region, to estimate potential annual metabolic costs expected for mature female green crabs. Results indicate that energy storage should incur an ~8% increase in metabolic costs for female crabs, relative to a hypothetical crab that did not store any energy. Translated into feeding, for a medium‐sized mature female (45 mm carapace width), this requires the consumption of an additional ~156 mussels annually to support the metabolic cost of energy storage. These results indicate, contrary to previous assumptions, that the cost of energy storage for small‐bodied ectotherms may represent a considerable portion of their basic operating energy budget. An inability to meet these additional costs of energy storage may help explain the recent decline of green crabs in the Gulf of Maine where reduced prey availability and increased consumer competition have combined to hamper green crab foraging success in recent years.

No MeSH data available.


Mass of individual Carcinus maenas at the conclusion of an 8‐week feeding experiment as a function of the carapace width (x‐axis) and the weight of the hepatopancreas (relative weight shown by circle size)
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ece32861-fig-0002: Mass of individual Carcinus maenas at the conclusion of an 8‐week feeding experiment as a function of the carapace width (x‐axis) and the weight of the hepatopancreas (relative weight shown by circle size)

Mentions: Experimental diet had a strong impact on energy storage as approximated using the HSI. Specifically, energy storage increased strongly with the mass‐specific consumption of animal tissue (linear model parameter estimate 1.32 ± 0.15, t = 8.91, p ≪ .0001, adj. R2 = .67, Figure 1). Crab body mass increased with both the carapace width of the crab (linear model parameter estimate 0.23 ± 0.02, t = 13.01, p ≪ .0001, Figure 2) and with the mass of the hepatopancreas (linear model parameter estimate 5.22 ± 0.69, t = 7.61, p ≪ .0001, multiple adjusted R2 = .87, Figure 2). Partial linear regression indicated that residual body mass increased with residual hepatopancreas mass after controlling for differences in body size based on carapace width (linear model parameter estimate = 5.22 ± 0.68, t = 7.71, p ≪ .0001, adj. R2 = .61, Figure 3).


Metabolic costs of capital energy storage in a small ‐ bodied ectotherm
Mass of individual Carcinus maenas at the conclusion of an 8‐week feeding experiment as a function of the carapace width (x‐axis) and the weight of the hepatopancreas (relative weight shown by circle size)
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC5383487&req=5

ece32861-fig-0002: Mass of individual Carcinus maenas at the conclusion of an 8‐week feeding experiment as a function of the carapace width (x‐axis) and the weight of the hepatopancreas (relative weight shown by circle size)
Mentions: Experimental diet had a strong impact on energy storage as approximated using the HSI. Specifically, energy storage increased strongly with the mass‐specific consumption of animal tissue (linear model parameter estimate 1.32 ± 0.15, t = 8.91, p ≪ .0001, adj. R2 = .67, Figure 1). Crab body mass increased with both the carapace width of the crab (linear model parameter estimate 0.23 ± 0.02, t = 13.01, p ≪ .0001, Figure 2) and with the mass of the hepatopancreas (linear model parameter estimate 5.22 ± 0.69, t = 7.61, p ≪ .0001, multiple adjusted R2 = .87, Figure 2). Partial linear regression indicated that residual body mass increased with residual hepatopancreas mass after controlling for differences in body size based on carapace width (linear model parameter estimate = 5.22 ± 0.68, t = 7.71, p ≪ .0001, adj. R2 = .61, Figure 3).

View Article: PubMed Central - PubMed

ABSTRACT

Reproduction is energetically financed using strategies that fall along a continuum from animals that rely on stored energy acquired prior to reproduction (i.e., capital breeders) to those that rely on energy acquired during reproduction (i.e., income breeders). Energy storage incurs a metabolic cost. However, previous studies suggest that this cost may be minimal for small‐bodied ectotherms. Here I test this assumption. I use a laboratory feeding experiment with the European green crab Carcinus maenas to establish individuals with different amounts of energy storage. I then demonstrate that differences in energy storage account for 26% of the variation in basal metabolic costs. The magnitudes of these costs for any individual crab vary through time depending on the amount of energy it has stored, as well as on temperature‐dependent metabolism. I use previously established relationships between temperature‐ and mass‐dependent metabolic rates, combined with a feasible annual pattern of energy storage in the Gulf of Maine and annual sea surface temperature patterns in this region, to estimate potential annual metabolic costs expected for mature female green crabs. Results indicate that energy storage should incur an ~8% increase in metabolic costs for female crabs, relative to a hypothetical crab that did not store any energy. Translated into feeding, for a medium‐sized mature female (45 mm carapace width), this requires the consumption of an additional ~156 mussels annually to support the metabolic cost of energy storage. These results indicate, contrary to previous assumptions, that the cost of energy storage for small‐bodied ectotherms may represent a considerable portion of their basic operating energy budget. An inability to meet these additional costs of energy storage may help explain the recent decline of green crabs in the Gulf of Maine where reduced prey availability and increased consumer competition have combined to hamper green crab foraging success in recent years.

No MeSH data available.