Temperature in Aquatic Biomes

by Jason Amores Sumpter
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the movement of water can have a dramatic effect on the organisms that live in it. In fact, take, for example, the river dolphins that have evolved to sleep in one hemisphere of their brain at a time, totally bizarre phenomenon that allows them to live in these waters with currents. So, you know, if they were to sleep in both hemispheres simultaneously, they probably get smashed around by the water currents. You know, could end up dying for example. So this is an adaptation based on the movement of water. Now the movement of water is also going to affect nutrient availability and we're going to take a look at that in just a second. I do want to quickly mention plankton, which are these small floating organisms in water mainly made up of diatoms, which you can see here and proto zones as well as crustaceans and these guys are gonna be a very important food source in aquatic bio MEMS. Now, speaking of that nutrient availability, the deeper waters tend to be richer in nutrients because all of that dead organic matter is gonna sink to the benthic zone and so that water is going to have more nutrients. So, ocean upwelling is this interesting phenomenon where nutrient rich, that nutrient rich water from the depths will rise up and replace surface water that's moving away from coasts in this way, adding more nutrients into the system. Now, thermo clines are pretty, I guess you could say bizarre phenomenon, they kind of go against our common experience. You know, if if we're looking at a body of water, we kind of would expect that the temperature would just go down with depth. However, you can sometimes have these distinct layers called Thermo clines, that will actually separate deeper, colder waters from warmer surface waters. And in the thermal Kline, you're gonna have this really abrupt temperature change. So, notice here that our Y axis on this chart is depth and our X axis is going to be temperature. Notice that in these deeper depths, for example, as we go down, there's very little variation in temperature, right? It's just like from there to there, you know, very small variation in temperature. However, up here, you have this rapid drop in temperature, right, barely go down in depth at all. And yet we're experiencing a massive temperature change, that is a thermal klein. So, this horizontal line that I've drawn across here is representing our thermal Kline. It's that that band were in abrupt temperature change happens and it's gonna separate these warmer surface waters up here from these colder waters of the depths. Now, water temperature can actually also lead to nutrient rich water from the bottom coming up and enriching the water closer to the surface. This is actually something that's going to happen in lakes. It's an event known as lake turnover and it's going to be due to uh seasonal temperature changes. So, in the winter. Well, you know, assuming, let's just say, this is like a, you know, smaller body of water, like a smaller lake will have ice covering the top. And surprisingly, that's actually gonna be colder than the water below the water below, will actually be a little warmer than that surface water. Now during the spring we'll have our first turnover event because as the ice melts and as uh the ice melts into the water, it's going to cool it and that cold water is going to sink, that warmer water that was at the bottom, that nutrient rich water is gonna rise up and move towards the surface. So we're gonna have some mixing of nutrients now in the summer, you're going to have a much more dramatic temperature gradient through your lake. You know, it's going to be fairly warm at the top and you know, roughly unchanged at the bottom. But what's going to happen during the fall is as that surface water cools, it's going to sink, move down and cause some of that nutrient rich water from the bottom to come up. So this seasonal turnover will actually happen both in fall and spring. And it's going to cause um you know, some mixing of the more nutrient rich water from the bottom with the surface waters of the top. And we're getting this um cycling of water due to these temperature changes. So with that, let's go ahead and flip the page