This video, we're going to begin our introduction to aquatic biomes. Now aquatic biomes are those that are covered by a significant amount of water. And unlike terrestrial biomes, which are primarily characterized by their climate and vegetation, aquatic biomes are primarily characterized by their physical and chemical environments, such as their salt concentrations, for example. And we'll be able to talk more about this idea in our next video. Now aquatic biomes can be divided into 2 major categories, which are freshwater and marine biomes.

Now freshwater biomes have relatively low salt concentrations, usually less than 0.1% salt, and include things such as lakes, rivers, and streams. Now marine biomes, on the other hand, have relatively high salt concentrations, usually about 3% salt and include the world's oceans. On the left-hand side in our image, we have an example of a freshwater biome, this lake in Slovenia called Lake Bled, and on the right, we have an example of a marine biome, an ocean. It's important to note that, collectively, all of the freshwater biomes on Earth only account for just 3% of all of Earth's water, which is very little. And the rest of the water on Earth is accounted for by the marine biomes, which means that the marine biomes account for 97% of all of Earth's water.

So moving forward in our course, we're first going to cover the freshwater biomes, such as lakes, rivers, and streams, and then we'll shift our attention over to the marine biomes. So this here concludes our introduction, and I'll see you all in our next video.