{"id":88819,"date":"2023-08-28T17:06:31","date_gmt":"2023-08-28T21:06:31","guid":{"rendered":"https:\/\/newsroom.carleton.ca\/?post_type=cu_story&p=88819"},"modified":"2025-08-19T09:37:05","modified_gmt":"2025-08-19T13:37:05","slug":"northern-map-turtles-survive-staying-active","status":"publish","type":"cu_story","link":"https:\/\/carleton.ca\/news\/story\/northern-map-turtles-survive-staying-active\/","title":{"rendered":"Northern map turtles survive cold winter conditions by staying active under ice"},"content":{"rendered":"\n
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\n Northern map turtles survive cold winter conditions by staying active under ice\n <\/h1>\n \n <\/header>\n <\/div>\n\n \n <\/path>\n <\/path>\n <\/svg>\n <\/div>\n\n \n\n <\/div>\n<\/section>\n\n

This article is republished<\/a> from The Conversation under a Creative Commons licence. All photos provided by The Conversation<\/a> from various sources.<\/p>\n\n\n\n

Jessica Robichaud<\/a> is a PhD Student in aquatic ecology at Carleton University.<\/p>\n\n\n\n

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Imagine it’s winter, and you’re standing on a frozen lake or pond, when suddenly below your feet you notice hundreds of turtles. What are they doing down there below the ice?<\/p>\n\n\n\n

Freshwater turtles in temperate regions like Canada spend several months of the year braced against frigid winter conditions of temperatures around or below 0 C and the formation of ice on water bodies<\/a>.<\/p>\n\n\n\n

For all eight species of freshwater turtles in Canada<\/a>, this ice barrier \u2014 and more importantly the liquid water below it \u2014 is a refuge from the freezing temperatures above. While ice coverage protects these turtles from the harsh cold, it also presents them with a challenge: restricted access to atmospheric oxygen.<\/p>\n\n\n\n

Life under ice<\/h2>\n\n\n\n

Some species, like snapping turtles (Chelydra serpentina<\/em>) and painted turtles (Chrysemys picta<\/em>), are perfectly comfortable spending several months submerged in water depleted in oxygen<\/a>. However, some species do not fare as well without oxygen and can only survive a few weeks at a time if submerged without adequate oxygen. These species need to extract the oxygen dissolved in the water to survive.<\/p>\n\n\n\n

\"a<\/a>
A snapping turtle under ice in southern Ontario.<\/span>
\n(Lucas Foerster\/iNaturalist)<\/span>, CC BY<\/a><\/span><\/figcaption><\/figure>\n\n\n\n

The northern map turtle (Graptemys geographica<\/em>) is an example of such a species. They have also been observed engaging in locomotor activity \u2014 they keep moving around under the ice during the winter.<\/p>\n\n\n\n

Northern map turtles were observed over a century ago by marine biologists Barton Warren Evermann and Howard Walton Clark<\/a>.<\/p>\n\n\n\n

During a dive at a communal hibernation site in November 1991 in Vermont, marine biologists observed map turtles walking across the bottom of a river before ice coverage when temperatures were dropping to near 0 C<\/a>.<\/p>\n\n\n\n

These observations lead us to believe that this behaviour may be important to a map turtle’s ability to survive the winter. Why else would they tap into their limited winter energy stores to move?<\/p>\n\n\n\n

But how much do turtles really move in the winter?<\/p>\n\n\n\n

Advances in technology<\/h2>\n\n\n\n

To track the movement of northern map turtles under the ice, our team glued tri-axial accelerometers \u2014 a type of biologging device that collects data \u2014 on 40 turtles at a known overwintering site in eastern Ontario. These devices recorded the movement, depth and temperature of the turtles for the seven months they remained under the ice.<\/p>\n\n\n\n

Tri-axial accelerometers function similarly to a FitBit or Apple Watch \u2014 the devices produce a value called overall dynamic body acceleration<\/a>. This number is a measure of how much each turtle moves on a daily basis.<\/p>\n\n\n\n

Combining this information with measurements of depth and temperature, we were able to paint a detailed picture of each turtle’s behaviour without ever seeing them.<\/p>\n\n\n\n

\"a<\/a>
A northern map turtle swims underwater with a tri-axial accelerometer attached to its back.<\/span>
\n(Gr\u00e9gory Bult\u00e9)<\/span>, CC BY<\/a><\/span><\/figcaption><\/figure>\n\n\n\n

Daily movement<\/h2>\n\n\n\n

Our findings surprised us. The data showed that northern map turtles move, albeit locally, every day of the winter. While that may look different across individuals, the interesting thing here is that movement is indeed continuous throughout the winter and not that different than in the weeks before the ice locks them in for the winter.<\/p>\n\n\n\n

Although we expected some level of activity based on previous observations, we did not expect the turtles to be so fidgety all winter long.<\/p>\n\n\n\n

Oxygen appears to be in short supply under the ice<\/a>, and map turtles cannot live without it for very long, so one would expect them to take it easy to limit their oxygen consumption. Our devices also told us the turtles were milling about in water hovering around 1 C, a temperature at which most reptiles become uncontrollably lethargic<\/a>.<\/p>\n\n\n\n

Staying cool may in fact be what allows turtles to remain active. It’s likely that by staying at near-freezing temperatures, map turtles can slow their metabolic demands, thereby decreasing their need for oxygen and extending their use of this limited resource.<\/p>\n\n\n\n