Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations
Abstract Background The energy requirements of free-ranging marine mammals are challenging to measure due to cryptic and far-ranging feeding habits, but are important to quantify given the potential impacts of high-level predators on ecosystems. Given their large body size and carnivorous lifestyle,...
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ftdatacite:10.6084/m9.figshare.c.3626639 2023-05-15T16:05:37+02:00 Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations JL Maresh T. Adachi A. Takahashi Y. Naito DE Crocker M. Horning TM Williams DP Costa 2015 https://dx.doi.org/10.6084/m9.figshare.c.3626639 https://figshare.com/collections/Summing_the_strokes_energy_economy_in_northern_elephant_seals_during_large-scale_foraging_migrations/3626639 unknown Figshare https://dx.doi.org/10.1186/s40462-015-0049-2 CC BY 4.0 https://creativecommons.org/licenses/by/4.0 CC-BY Evolutionary Biology FOS Biological sciences 59999 Environmental Sciences not elsewhere classified FOS Earth and related environmental sciences Ecology Collection article 2015 ftdatacite https://doi.org/10.6084/m9.figshare.c.3626639 https://doi.org/10.1186/s40462-015-0049-2 2021-11-05T12:55:41Z Abstract Background The energy requirements of free-ranging marine mammals are challenging to measure due to cryptic and far-ranging feeding habits, but are important to quantify given the potential impacts of high-level predators on ecosystems. Given their large body size and carnivorous lifestyle, we would predict that northern elephant seals (Mirounga angustirostris) have elevated field metabolic rates (FMRs) that require high prey intake rates, especially during pregnancy. Disturbance associated with climate change or human activity is predicted to further elevate energy requirements due to an increase in locomotor costs required to accommodate a reduction in prey or time available to forage. In this study, we determined the FMRs, total energy requirements, and energy budgets of adult, female northern elephant seals. We also examined the impact of increased locomotor costs on foraging success in this species. Results Body size, time spent at sea and reproductive status strongly influenced FMR. During the short foraging migration, FMR averaged 90.1 (SE = 1.7) kJ kg−1d−1 – only 36 % greater than predicted basal metabolic rate. During the long migration, when seals were pregnant, FMRs averaged 69.4 (±3.0) kJ kg−1d−1 – values approaching those predicted to be necessary to support basal metabolism in mammals of this size. Low FMRs in pregnant seals were driven by hypometabolism coupled with a positive feedback loop between improving body condition and reduced flipper stroking frequency. In contrast, three additional seals carrying large, non-streamlined instrumentation saw a four-fold increase in energy partitioned toward locomotion, resulting in elevated FMRs and only half the mass gain of normally-swimming study animals. Conclusions These results highlight the importance of keeping locomotion costs low for successful foraging in this species. In preparation for lactation and two fasting periods with high demands on energy reserves, migrating elephant seals utilize an economical foraging strategy whereby energy savings from reduced locomotion costs are shuttled towards somatic growth and fetal gestation. Remarkably, the energy requirements of this species, particularly during pregnancy, are 70–80 % lower than expected for mammalian carnivores, approaching or even falling below values predicted to be necessary to support basal metabolism in mammals of this size. Article in Journal/Newspaper Elephant Seals DataCite Metadata Store (German National Library of Science and Technology) |
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DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
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language |
unknown |
topic |
Evolutionary Biology FOS Biological sciences 59999 Environmental Sciences not elsewhere classified FOS Earth and related environmental sciences Ecology |
spellingShingle |
Evolutionary Biology FOS Biological sciences 59999 Environmental Sciences not elsewhere classified FOS Earth and related environmental sciences Ecology JL Maresh T. Adachi A. Takahashi Y. Naito DE Crocker M. Horning TM Williams DP Costa Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations |
topic_facet |
Evolutionary Biology FOS Biological sciences 59999 Environmental Sciences not elsewhere classified FOS Earth and related environmental sciences Ecology |
description |
Abstract Background The energy requirements of free-ranging marine mammals are challenging to measure due to cryptic and far-ranging feeding habits, but are important to quantify given the potential impacts of high-level predators on ecosystems. Given their large body size and carnivorous lifestyle, we would predict that northern elephant seals (Mirounga angustirostris) have elevated field metabolic rates (FMRs) that require high prey intake rates, especially during pregnancy. Disturbance associated with climate change or human activity is predicted to further elevate energy requirements due to an increase in locomotor costs required to accommodate a reduction in prey or time available to forage. In this study, we determined the FMRs, total energy requirements, and energy budgets of adult, female northern elephant seals. We also examined the impact of increased locomotor costs on foraging success in this species. Results Body size, time spent at sea and reproductive status strongly influenced FMR. During the short foraging migration, FMR averaged 90.1 (SE = 1.7) kJ kg−1d−1 – only 36 % greater than predicted basal metabolic rate. During the long migration, when seals were pregnant, FMRs averaged 69.4 (±3.0) kJ kg−1d−1 – values approaching those predicted to be necessary to support basal metabolism in mammals of this size. Low FMRs in pregnant seals were driven by hypometabolism coupled with a positive feedback loop between improving body condition and reduced flipper stroking frequency. In contrast, three additional seals carrying large, non-streamlined instrumentation saw a four-fold increase in energy partitioned toward locomotion, resulting in elevated FMRs and only half the mass gain of normally-swimming study animals. Conclusions These results highlight the importance of keeping locomotion costs low for successful foraging in this species. In preparation for lactation and two fasting periods with high demands on energy reserves, migrating elephant seals utilize an economical foraging strategy whereby energy savings from reduced locomotion costs are shuttled towards somatic growth and fetal gestation. Remarkably, the energy requirements of this species, particularly during pregnancy, are 70–80 % lower than expected for mammalian carnivores, approaching or even falling below values predicted to be necessary to support basal metabolism in mammals of this size. |
format |
Article in Journal/Newspaper |
author |
JL Maresh T. Adachi A. Takahashi Y. Naito DE Crocker M. Horning TM Williams DP Costa |
author_facet |
JL Maresh T. Adachi A. Takahashi Y. Naito DE Crocker M. Horning TM Williams DP Costa |
author_sort |
JL Maresh |
title |
Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations |
title_short |
Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations |
title_full |
Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations |
title_fullStr |
Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations |
title_full_unstemmed |
Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations |
title_sort |
summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations |
publisher |
Figshare |
publishDate |
2015 |
url |
https://dx.doi.org/10.6084/m9.figshare.c.3626639 https://figshare.com/collections/Summing_the_strokes_energy_economy_in_northern_elephant_seals_during_large-scale_foraging_migrations/3626639 |
genre |
Elephant Seals |
genre_facet |
Elephant Seals |
op_relation |
https://dx.doi.org/10.1186/s40462-015-0049-2 |
op_rights |
CC BY 4.0 https://creativecommons.org/licenses/by/4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.6084/m9.figshare.c.3626639 https://doi.org/10.1186/s40462-015-0049-2 |
_version_ |
1766401514218192896 |