Seals Don’t Like Salt Water!

As Naomi mentioned in an earlier post, I recently presented some work from my Master’s at the UKRSC conference. I’m pleased to say that this part of my Master’s thesis has also recently been published in Marine Mammal Science! The title of the article is “Finescale ecological niche modeling provides evidence that lactating gray seals (Halichoerus grypus) prefer access to fresh water in order to drink”.

MMS12126header2In addition to confirming previous findings that the distribution of breeding grey seals is affected by proximity to pools of water and proximity to access points from the sea, this research also showed that the breeding females demonstrate a clear preference for access to freshwater pools, likely as a source of drinking water to avoid the water stress brought on by lactation. This can be seen very clearly on a habitat suitability map of the study site, which shows high suitability around low salinity pools of water at intermediate distances to access points:

The “warm” colours show areas of high suitability around low salinity pools. Pools too near or far from access points are of lower suitability (“cold” colours), as are high salinity pools. Some high salinity pools have been circled in green as examples. A full description of the study site and the methods are given in the article.

The “warm” colours show areas of high suitability around low salinity pools. Low salinity pools, and pools too near or far from access points are of lower suitability (“cold” colours). Some high salinity pools have been circled in green as examples. A full description of the study site and the methods are given in the article.

The abstract and a link to the full article at Marine Mammal Science are below, and those without a subscription can contact me for a PDF. I have dotted the abstract with some (hopefully) useful and interesting hyperlinks for further reference (though obviously the paper itself is the best place to go for the info!):

Many phocids are capital breeders, relying on stored reserves to sustain energetic requirements while on land. Their large body size, high energy expenditure during lactation, and the insulative effects of the blubber layer can lead to thermal stress from overheating, especially in warm and temperate climates. Thermal stress can influence fine-scale site choice on breeding colonies, and behavioral thermoregulation has been proposed as an explanation for the clear preferences shown by breeding female gray seals for proximity to pools of water. However, anecdotal observations suggest that pools of water may also be preferred for drinking, though water intake is difficult to verify without real-time physiological monitoring. Here, an alternative approach demonstrates that gray seals also require access to water for drinking. Using Ecological Niche Factor Analysis to examine fine-scale physical determinants of pupping site choice at North Rona, Scotland, we found that lactating mothers showed preference for lower salinity pools. This is most pronounced early in the season, when ambient temperatures and presumably thermal stress are greatest. Given that the cooling effect of fresh and salt water should be equivalent, the most parsimonious explanation for this preference for fresh water pools is that lactating females use these pools for drinking.

URL: http://onlinelibrary.wiley.com/doi/10.1111/mms.12126/full

I hope you enjoy reading the paper, and feel free to get in touch with any questions. Hopefully more of my Master’s research will get to publication in the coming months, so watch this space!

Best,

James

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2 responses to “Seals Don’t Like Salt Water!

  1. Pingback: A list of our research publications | Studying Seals·

  2. Pingback: Where are they now? | Studying Seals·

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