It's November. Temperatures have moderated, daylight is short, and nature is yawning.
I remember years ago, we had a group of kiddos over, enjoying themselves, catching some fish, and being mesmerized by the ponds, fall colors, trees, and our chickens. At dusk, a couple of boys were watching the chickens as they methodically made their way into the chicken house and hopped up on their roosts, done for the day.
As it got dark, we stoked the fire pit with plenty of dried oak, fired it up, enjoyed the heat, and watched embers as they cascaded upward with each piece of split wood tossed into the mix. As the fire began to wane in the quiet of the evening, one pre-teen boy was reflecting on the day. He asked a question.
"Do ponds sleep?"
I smiled and gave my answer. "Sort of; they sure do calm way down and sleep in their own way."
"How?" he asked. We were in the middle of making S'mores, and his marshmallow was about to catch on fire. The other kids scrunched up and waited for the discussion...and to blow out their own flaming marshmallows and add chocolate to melt into their graham cracker sandwich.
I explained.
"As the water cools, everything that lives in it cools, too. Plants go dormant for the most part, fish metabolism slows, and amphibians prepare for their own rest. Aquatic animals are cold-blooded, which means body temperatures are similar to water temperatures. As cold-blooded living things become chilled, they aren't as active. When they aren't as active, their heartbeat slows down. Their metabolism rates slow, and they don't need as much food. They won't grow much, and they won't move as fast. While they don't go to sleep like we do, they definitely slow down. In the fall, when temperatures are perfect, fish thrive, eat, grow, gain weight, and store body fat. That way, in winter, they can metabolize some of their fat for energy.
Plants in winter?
Different plants prefer different temperature growth windows, and as those windows close, they either slow down, go dormant and sink, or die off. That's why it's essential for us to know what kinds of plants we have...so we'll know what to expect next spring when the water begins to warm again. It's also important to know those plants to understand what to expect from them in cold water. As they decompose, aquatic plants that die will add to the biological oxygen demand. That's important to know, especially in areas of the country where ponds freeze over. Plants decomposing under ice will consume oxygen...which isn't easily replaced.
Another interesting point about cooler water is that its affinity for oxygen rises. That means it can hold more oxygen, which assists waning bacteria to do what they do to compost decaying organic matter. So, even though our ponds "rest", they don't totally stop doing what they do.
Add another little outside factor with which ponds must deal.
"Deciduous trees drop leaves as their sap falls so the trees can rest for the winter. Leaves from nearby trees fall into the pond.
The water does its best to compost those leaves, but when the water cools, most of the natural bacteria that live in water and break down organic matter die off and sink. Not all of it, but some of it dies. That means we have lots of leaves steeping in the water like tea. Tannins are added to the water, sometimes altering the water chemistry. Water with low alkalinity can see its pH drop during cold.
So, during the winter, the fish slow down, aquatic insects hide or disappear, turtles go dormant, and the water rests.... but doesn't stop.
Ice will soon form on the water in parts of the nation, insulating those ponds from the most frigid temperatures. When snow-covered or milky-looking, that ice also prevents sunlight from entering the water. Photosynthesis stops dead in its tracks, and that water under the ice is on its own - dark, cold, and mostly at rest. Plants continue to take up oxygen in the dark, and fish continue to breathe, even when they don't move around. Plants can't photosynthesize without sunlight. They respire, using oxygen.
"So, yes, ponds rest...sort of. They don't completely stop, but they slow down, way down.
"That doesn't mean you are immune to pond problems in winter. The problems change, but are less likely to happen, with some exceptions (up north where winterkill is an issue)."
By the time I finished my mini-biology lesson, the boys had roasted and eaten half a bag of marshmallows, an entire pack of graham crackers, and three Hershey's chocolate bars.
They were getting a bit sleepy...go figure.
Reprinted with permission from Pond Boss Magazine
