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Blubber and buoyancy: monitoring the body condition of free-ranging seals using simple dive characteristics

Overview of attention for article published in Journal of Experimental Biology, October 2003
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  • Average Attention Score compared to outputs of the same age and source

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Citations

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245 Mendeley
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Title
Blubber and buoyancy: monitoring the body condition of free-ranging seals using simple dive characteristics
Published in
Journal of Experimental Biology, October 2003
DOI 10.1242/jeb.00583
Pubmed ID
Authors

M. Biuw

Abstract

Elephant seals regularly perform dives during which they spend a large proportion of time drifting passively through the water column. The rate of vertical change in depth during these "drift" dives is largely a result of the proportion of lipid tissue in the body, with fatter seals having higher (more positive or less negative) drift rates compared with leaner seals. We examined the temporal changes in drift rates of 24 newly weaned southern elephant seal (Mirounga leonina) pups during their first trip to sea to determine if this easily recorded dive characteristic can be used to continuously monitor changes in body composition of seals throughout their foraging trips. All seals demonstrated a similar trend over time: drift rates were initially positive but decreased steadily over the first 30-50 days after departure (Phase 1), corresponding to seals becoming gradually less buoyant. Over the following approximately 100 days (Phase 2), drift rates again increased gradually, while during the last approximately 20-45 days (Phase 3) drift rates either remained constant or decreased slightly. The daily rate of change in drift rate was negatively related to the daily rate of horizontal displacement (daily travel rate), and daily travel rates of more than approximately 80 km were almost exclusively associated with negative changes in drift rate. We developed a mechanistic model based on body compositions and morphometrics measured in the field, published values for the density of seawater and various body components, and values of drag coefficients for objects of different shapes. We used this model to examine the theoretical relationships between drift rate and body composition and carried out a sensitivity analysis to quantify errors and biases caused by varying model parameters. While variations in seawater density and uncertainties in estimated body surface area and volume are unlikely to result in errors in estimated lipid content of more than +/-2.5%, variations in drag coefficient can lead to errors of >or =10%. Finally, we compared the lipid contents predicted by our model with the lipid contents measured using isotopically labelled water and found a strong positive correlation. The best-fitting model suggests that the drag coefficient of seals while drifting passively is between approximately 0.49 (roughly corresponding to a sphere-shaped object) and 0.69 (a prolate spheroid), and we were able to estimate relative lipid content to within approximately +/-2% lipid. Our results suggest that this simple method can be used to estimate the changes in lipid content of free-ranging seals while at sea and may help improve our understanding of the foraging strategies of these important marine predators.

Mendeley readers

The data shown below were compiled from readership statistics for 245 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
United States 4 2%
South Africa 3 1%
Spain 2 <1%
Australia 2 <1%
Czechia 1 <1%
Brazil 1 <1%
Germany 1 <1%
Italy 1 <1%
United Kingdom 1 <1%
Other 5 2%
Unknown 224 91%

Demographic breakdown

Readers by professional status Count As %
Researcher 54 22%
Student > Ph. D. Student 44 18%
Student > Master 33 13%
Student > Bachelor 32 13%
Student > Postgraduate 14 6%
Other 45 18%
Unknown 23 9%
Readers by discipline Count As %
Agricultural and Biological Sciences 158 64%
Environmental Science 39 16%
Earth and Planetary Sciences 7 3%
Veterinary Science and Veterinary Medicine 5 2%
Medicine and Dentistry 3 1%
Other 10 4%
Unknown 23 9%

Attention Score in Context

This research output has an Altmetric Attention Score of 3. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 01 January 2016.
All research outputs
#1,793,173
of 7,447,574 outputs
Outputs from Journal of Experimental Biology
#1,695
of 4,042 outputs
Outputs of similar age
#88,284
of 285,068 outputs
Outputs of similar age from Journal of Experimental Biology
#70
of 134 outputs
Altmetric has tracked 7,447,574 research outputs across all sources so far. This one has received more attention than most of these and is in the 62nd percentile.
So far Altmetric has tracked 4,042 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 10.3. This one is in the 48th percentile – i.e., 48% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 285,068 tracked outputs that were published within six weeks on either side of this one in any source. This one has gotten more attention than average, scoring higher than 66% of its contemporaries.
We're also able to compare this research output to 134 others from the same source and published within six weeks on either side of this one. This one is in the 44th percentile – i.e., 44% of its contemporaries scored the same or lower than it.