Frozen Pond: Newsletter Challenge (November 2011)

That's it.

As "This comment is very useful/insightful with respect to the original Blog Entry", I vote accordingly.

Bugger - I was all excited and now I just get to add a GA

What will be the temperature of water below ice?.

Generally 0°C to slightly above that, depending on the size of the pond and the temperature of the earth underlying it.

A side effect is that the fish will have a higher relative density in the lighter, colder water and will stay below the freezing area. Assuming it doesn't want to expend extra effort to become a part of the ice.

I was just going to say that, I think you should give me half your points!

Bazzer

That's that one sorted then! I'm sorry I missed it.

It allows the ice to float above, the fish frogs, vegetation to live below. If I would have been the first, I would have given myself the GA for being that smart.

If you were that smart, you'd know that you can't give yourself a GA.

When water expands before it freezes it's density becomes less therefore the ice formed floats on the surface of the unfrozen water. It it didn't expand and become less dense unlike other materials the pond would freeze from the bottom up and kill all of the fish.

This is what I don't understand, If water expands before it freezes why are the experts saying that "when the ice caps melt the water level will rise by whatever hundreds of feet" & as most ice has air in it & icebergs float mostly below the surface, then surely the levels would drop rather than rise. Just a thought.

Bazzer

For floating icebergs that melt, the water level stays the same. Melting ice packs on land would increase the water level of whatever body of water they drained to.

The Arctic ice cap is mostly or all free floating ice. Much of the Antarctic ice cap the ice is on land. If the Arctic ice cap melts sea level may actually lower. If the Antarctic ice cap melted it may raise the sea level, but enough to effect more than the lower coastal areas, I do not Know.

what about greenland and the scandinavian and north american glaciers?

I agree with you. It doesnt expand until it freezes. Rankinstein.

In addition as the water freezes, it heats up the water just below it. The density of this water increases so it sinks. This causes the circulation of the water that keeps the ice from rapidly filling the pond from the top.

The question was about liquid water expansion between 4° C and 0° C, not about ice having a lower density than liquid water.

Could it be that an expansion still in the liquid phase will trigger some defense mechanism in the fish (antifreeze, glucose, protein…)?

brgds

Snel

Looking at it from the perspective of the fish: Being cold blooded creatures, a fish's metabolism will slow down in cold water, however, a fish will use this expanded cold water to his advantage.

As water gets colder and expands, it also becomes more oxygenated. The fish know this, and will swim into the cold water periodically to boost oxygen levels in the blood stream. This gives them a boost of stamina before moving back into warmer water below to feed.

Water expands to its maximum at 4°C. Then as it turns to ice, it expands again. That is why ice floats on water that is between 4 and 0°C.

The water under that top level of ice is between 0 and 4°C.

As the water freezes down from the top, the ice (a reasonable insulator now) steadily gets thicker, the 0-4° water gets lower and lower, but slower and slower as the ice gets thicker.

Generally here where I live, it is unheard of that water freezes to more than about 20" deep, so yard deep ponds are safe for the fishes.....in more northern areas that will not be true.....

I posted slightly wrongly, apologies. Water is at its densest at 4°C.......I was on another planet when I wrote that!! Sorry....

When it cools further, it gets less dense......

Apologies to all concerned!!!

ENGINEER.........is correct

Hi Andy...........could not resist that one.

why also do fish quit eating when the water get cold? My pond fish won't even come up for food when it gets cold but not yet frozen.

Don't tell that to the ice fishermen on the Great Lakes!

In reply as to why fish appear to stop eating in winter:
as the water gets colder their metabolism goes down and they use and need less food. They don't stop eating they just eat much less. if your fish are grazers (i.e. gold fish and koi) they get enough from the bottom of the pond.

There is typo it is oC and not 4oC

My applogy for this typo

Now when a pond begins to freeze and the water density changes the fish sense the change and avoid the ice, because if they touch the ice flow it could freeze the skin and they will be trapped like sticking your tongue to a metal pole. That's why it's important for the fish.

buddy5, I will tell you, that is one of more intriguing things I have read at CR4 today.

Can you elaborate on this explanation:
Is this equally applicable north and south of the equator?
Can't the fish sense they are being trapped and swim away?
You said "...trapped like sticking your tongue to a metal pole." What does that mean?

I am looking forward to your discussion.

Oh, and welcome my friend, welcome to CR4.

You've not seen Dumb and Dumber?

Ah. That clears it up nicely.

I misread it as this sort of thing:

...trapped like sticking your tongue with a metal pole.

Ya know, all this discussion about oxygenated water is interesting... does this not become completely moot if the pond freezes solid? That is, after all, the question.

Pond minnows survive, mine did. Rankinstein.

The ice contacting water will be about freezing temperature. The fish won't stick. The ice on a pole is air temperature. When I stuck my tounge to the side of a piece of highway equipment about 60 years ago, the temperature was about 30 below zero (F). It took some of the skin off before I got my tounge loose. This was in Montana.

Wow, finally the correct answer! I learned this in High School biology. Without this effect the pond(s) would become anaerobic (stagnant) and toxic to most organisms on the bottom. BTW the HS class was awesome as we studied and compared a creek, a river and a pond close by the school.

Quite a system, eh?

Indeed. Life on earth, as we know it, would not be possible if this small detail (water reaching it's max density at 4^o) were not so.

SomeOne must have really known what He was doing when He came up with this!

not so frequent

What did you intend to say, I simply did not understand it, sorry!!

Are you a non English as a first language person? Maybe I can help if you write it in your normal language, I will do my best to get it translated for us here....

I've been engineer much longer than the six month - you spelled!

Andy's signature is a joke even older than he is. Okay, it's not particularly funny, but he's trying....

_{I'll set 'em up, you nod 'em in!}

LOL and fully correct!!!

Sadly many simply don't get it, they just feel that I can't be an Engineer if I can't spell....

(Many others here prove daily that to be not true!!)

Ha Ha!

One more of these cool joke's and it will be winter

^Brother!

Great that the joke is now understood!
Aufwiedersehen!

It's a joke, showing how even people with spelling difficulties can become Engineers, but its really only a joke if English is your first language.......I guess yours is not if that is also your real name Wilhelm H.Koen......Guten Tag wirkt besser vieleicht?

I may change it to something more multi lingual, if I find something I like as many here are simply not fluent enough in English for such things......sorry.

Don't change. You are wonderfully affluent. Let the water flow off the frozen duck's back. Rankinstein.

... showing how even people with spelling difficulties can become Engineers ...

engineering is not for showing and not for spelling!

If you meant me not being able to spell in English (my German spelling needs a dictionary!), you are completely wrong again. I spell quite well and I can also use the spellchecker if needed (as all of us here can!). My spelling is far better than many here (not too difficult to achieve!!)

My sig was wrongly spelt so as to make a joke, but it only works for those who understand English well!

Obviously you do not (Teutonic humour only maybe?)

"My sig was wrongly spelt ..."

Dinkelacker and grünkern, the German breakfast of champions!

Your answer is very good. My red slider turtle died because he didn't have the rotting plant materials in his tank when it cooled and he hibernated, I thought this was to the lack of oxygen, or so the petmasters say. Rankinstein.

Assuming the ice will completely cover the surface of the water, if the expansion occurred after freezing, the water pressure would increase and the amount of free oxygen O² (gas pressure law) would be diminished as oxygen would combine with nitrogen, hydrogen and other elements making compounds and this would be detrimental for the fish. Now if we apply a simple biological equation we get the result: No oxygen=dead fish.

Fish do "winterkill" in late winter, but not as a result of a pressure rise. The ice does in fact expand, but it either expands up or buckles against the shore or in the middle of the pond. The ice does not seal against the shore to form a pressure vessel and the water of course does not change mass when it changes to ice, so the year-round water pressure within the pond stays the same with depth below the surface (the pressure at a given depth is actually a little less than in Summer, since the ice is less dense than liquid water).

Winterkill is either the result of the ice reaching the bottom of the pond or the result of low levels of dissolved oxygen gas in the water. These low levels are usually the result of water weeds or algea dying and rotting due to low light levels. Lakes with excessive plant growth (due to fertilizers or livestock runoff) are called "eutrophic" and suffer this fate quite often up North.

Some fish can tolerate low oxygen levels better than others. Game fish tend to be the first to go, and the carp and bullheads can survive this situation better, so they tend to take over shallow lakes in the upper Midwest. If you want championship carp fishing, now you know where to go!

Phil - Interesting answer - real ice fishing technology!! But I challenge the concept that the hydrostatic pressure is affected bythe physical state of the liquid,, Pressure is the result of the weight of the liquid, not the density. Therefor the hydrostatic pressure is the same whether the top is frozen or not..

Fully correct...

In winter it may even be higher as the water level may actually be higher than in summer!!!

I'm sorry - I'm not being clear. When I say "the pressure at a given depth is actually a little less than in Summer, since the ice is less dense than liquid water" I mean the depth at which the fish sits relative to the surface of the water vs. the surface of the ice and water. For example, if the fish is suspended 2 meters under the surface of the water in summer the density of the material over it will be about 1 g/cm cubed. But, if the fish is suspended 2 m under the surface of the ice in winter (perhaps the ice is 1 meter thick or so) the density of the material over it will be slightly less than 1, since the ice is less dense than the water. Hence, the water pressure at a given depth under the surface of the ice will be less than under the surface of the water.

One can check this empirically by going ice fishing. When you drill your hole, you will find the surface of the water is a bit lower than the level of the ice through which you drilled, because the ice is floating on the water. Of course the water pressure below is equalized at given depth below you. So, if the fish is 2m below the surface of the ice, it is a bit less than 2m below the surface of the water in the hole you drilled. Same fish, same time, so that is your proof!

Now if you have your a*** ice hole, do any fish swimming under the a*** ice hole experience a lower hydrostatic pressure too?

Why don't fish die then everywhere where ice forms on water in winter?

Maybe they haven't read the same book as you have? (the fish I mean!!)

I always understood that oxygen was more prevalent/easily accepted in cold water than warm, which is why fish have more problems in breathing when the weather is warm, than when its cold.

There was also a great explanation or two from several people in how the oxygenated water actually reaches the fish in winter.....I do not propose to try and explain it better than it already was from those other people!

On most of the lakes around here (Minnesota, northern US) the fish survive the ice covering on the lakes for the following reasons:

some light does penetrate the ice and snow, allowing a low level of photosynthesis

The fish become less active

In deep and poorly fertilized lakes, there is not enough plant matter left over from the Summer to deplete the oxygen when it rots.

Many lakes in this area are deep, and have the capacity to store a large amount of dissolved O2 simply by virtue of their volume. Deep lakes rarely winterkill.

Oxygen does indeed dissolve more readily in cold water than in warm, but if that oxygen gets used up by the decay process over the winter time it just doesn't matter; it's still not there!

Will read up on posts explaining how oxygen reaches fish when I have the time - am now at work!

I work too, your answers are very good+++, I'm learning, yes , it's possible. Rankinstein

Pressure will not change, what gives you that idea, ice is not a perfect impervious coating. Rankinstein.

The lighter and solid ice will form on the top of the pond, leaving warmer liquid water on the bottom of the pond for the fish to swim in.

if the water is freezing - the colling water of 4°C expands and lets the iceshelf crack!

the liquid water under the iceshelf can fetch oxygen!

but the frozen water has a density 1/9th lighter than the liquid water - and this expanding ice breaks the iceshelf if the expanding cooling water (below 4°C) doesn't!

IO

Above all it lets higher TDO (total dissolved Oxygen) number to increase, hence let fish and all other water creatures survive.

Wangito

Fish will normally go towards the colder water since it is denser in oxygen.However from 4c till 0c this density reverses so there will be less oxygen near the surface as it approaches freezing point. The fish will thereby go a bit lower where it is slightly warmer and has more oxygen and at the same time avoid being frozen to death as the ice cold water in fact turns to ice. God's protective mechanism to prevent fish from freezing to death!

It makes no difference.

The water was on the earth before fish (Genesis).

The fish adapted to the conditions.

The ice on top is important for humans.

Ice is needed to hold up the fishing hut's so man can cut a hole and fish without a boat.

I believe, this will not influence scientists. Rankinstein.

if the ice on the surface of the water isn't there - the fish could fly away?

As water expands, its density decreases. Therefore the ice floats to the top and forms an insulating layer, impeding further freezing. Also fish are protected which allows them to remain in liqiud water and insulated fron the cold air above.

if there's no heat flow into the water - all the water cools down and begins freezing some time!

Completely wrong and not true.

Also add the reflective properties of the ice, the earth radiates heat continually. Rankinstein.

It means these guys are coming....

http://lh3.ggpht.com/-1e97B96nwIU/SUuRYm4VQfI/AAAAAAAAAUQ/grtFuRBvJqU/s499/p3170098.jpg

Please learn how to "activate" a link.....

ice fishermen

My answer to This month's Challenge Question is:

As the cool water expands, it moves upwards to the surface. As it cools further, the water freezes on the surface.

This is important to the fish as the surface only freezes. If the water did not expand, the ice would form throughout the body of water. The fish would not appreciate this.

I remember my physics prof at university talking about this in 1963.... Yipes, I'm old!

Jamie Berry -Belleville ON Canada

water is its heaviest at 39C therefore it is liquid at the bottom of the pond.

Though the ice forms at the top and the bottom remains liquified in the fish pond, it is most important to have a bubbler going 24/7 to keep a flow of oxygen in the water.

I think it is a precaution notice to the fish to move down deeper or further away before the ice covers the surface of water....and their metabolic rate corresponds to the change.

The electron orbitals rearrange to accomodate more oxygen, and the metabolism of the fish slows to adjust. Rankinstein

If the water did not expanded at 4° C; ice would not float, there would be no water under the ice for the fish to live in. So the fish and the water would freeze. When a compound expanse the relative density decreases making the buoyancy of the compound increase compared to the compounds original state. Thus the ice floats and the fish have a place to live under the frozen lake. This month's Challenge Question: Frozen Pond We know that at a temperature of approximately 4° C, water begins to expand before freezing (0° C). Why is this fact important for the fish in a pond?

If you read through this whole blog you will learn everything you want to know, but a quick explanation is that water at 4°C is at it's most dense, so generally in a cold winter when ice forms on the surface, the water at the bottom will remain at about 4°C.

Warmer or colder water will simply rise upwards.

Where I live in Germany, the water must be at least 1 meter deep to allow the fish to survive. In colder areas, it may need to be slightly deeper, eg. deeper than the maximum thickness of ice forming. Here it maxes out at about 30cm or so.

Its quite a simple concept.

This would only be true at a given depth. The heat resivoir of the earth would take over at some depth because of the insulating properties of the ice. This would not be true of flowing water. Rankinstein.

I love fishing, and wish I could with you. I always buy the liscense, never have the time. Rankinstein.

Ice, h2o, undergoes electron orbital transformation, also becoming a thermal insulator. This is not typical of most atomic elements. The fish bask in the thermals emitted by the earth, with the ice as a nice blanket from the elements, atmosphere. Rankinstein.