Beaver created a new pond on the property over the last year. I believe it is 2 feet deep, built in a flat, slow moving water area. I am in Western Maine & all ponds are frozen. Except this one. I went to cross it yeasterday & realized some tracks were water soaked. I retreated quickly. Would this be due to the pond being new & more decay occurring? Im looking to understand the science behind the lack of solid, safe ice. Thanks for any insight. J
Welcome to the forum!
First off, Iām a mom and HAVE to tell you there is no such thing as āSafe iceā!
Since the beavers built the pond I would suspect they have tapped the spring that feeds it, shifted the flow to suit them. But I have no real knowledge on beavers.
Yes, I think you got it
I donāt understand your reasoning here. What is decaying and how is that affecting the water temperature? Are you thinking the water is being warmed like a compost heap gives off warmth? I donāt think there will be much decay occurring in the water if it is close to freezing.
Two suggestions:
Are other ponds really frozen solid or are they a layer of ice over water? Water is most dense at 4C so the bottom of a pond will retain water well after the top has frozen. Maybe the beavers are keeping the water moving so that it doesnāt stratify, which will mean the top never gets colder than the rest. Narwhals can keep patches of open water in Arctic sea ice by constantly swimming there.
But I think the most likely answer is when you say the beavers have tapped a spring. Groundwater will be entering the pool at the annual average temperature for your area, which I expect is well above freezing point and in a small pond the turnover means it wonāt cool down to freezing point before it has left the pond.
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I know that on a larger scale (i.e., the Penobscot River), climate change takes its toll. But considering the smaller size of this pond, and the very low temperatures in recent weeks, I doubt thatās the case.
ābeavers store trees underwater for food in winterā which sounds unlikely to me. But rotting trees might affect the water temperature?
anoxic wood decomposition is very slow and would likely not be the factor for why the pond is liquid
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From Dittbrenner et al., 2022 āPast research has found evidence of warmingĀ¹āŗĀ², coolingĀ³, warming or cooling depending upon seasonā“, or no relationship between dam presence and temperatureāµ. In higher elevation headwater systems, where streams are relatively cold, temperature increases of 6ā9Ā°C were observed downstream of beaver pondsā¶. More recent studies have evaluated stream temperatures at larger scales and found that beaver ponds can also have a net cooling effectā·āŗāø due to groundwater recharge and upwellingā¹.ā
Unfortunately, I do not have access to most of the āpast researchā linked to in this paper, but beaver ponds affecting temperature has been observed. Seeing as it was observed to be a variable effect (warming, cooling, no effect), Iād agree with @jhbratton:
and
Though due to upwelling mentioned in the paper-excerpt, fully tapping a spring may not even be necessary for this effect (especially if the groundwater is ā 4Ā°C).
These are the papers linked to. I put them here to make the text more legible. (I do not much like the Harvard citation-system. Haha)
Ā¹ Avery, 2002
Ā² Patterson, 1951
Ā³ White, 1990
ā“ Avery, 1983
āµ McRae & Edwards, 1994
ā¶ Margolis et al., 2001
ā· Weber et al., 2017
āø White & Rahel, 2008
ā¹ Pollock et al., 2007
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Why isnāt there such a thing as safe ice? You should always be careful, but there absolutely is ice safe enough to walk on or even drive vehicles across.
You can trust it if you choose. Because in the course of melting or in her case, moving water, the ice will honeycomb from the bottom. One āwrongā crack or soft spotā¦
This āNo Safe Iceā is annually repeated by Department of Resources and Coast Guide officials for good reason.