Hey everybody, it's Mr. Smedes, and today I'll be covering topic 1.3, which is aquatic biomes. So today we'll focus on factors that determine where aquatic biomes are found, how the species that live in them are adapted to live there, and the overall characteristics of each aquatic biome. Our objective for the day is to be able to describe the global distribution and environmental aspects of aquatic biomes.
We'll also look at different freshwater biomes and how they're an important part of the ecosystem. important source of drinking water. We'll also look at different marine biomes, which means ocean-based biomes, and we'll look at how they are an important supply of oxygen globally and an important sink for carbon dioxide globally. And then finally, we'll practice explaining an environmental concept and process at the end of today's video.
So first, we'll cover four characteristics of aquatic biomes. Salinity refers to how much salt is found in a body of water, and it determines which species can survive in this body of water. and whether or not it's suitable for drinking water.
Then we have depth. Depth is going to influence how much sunlight can penetrate the surface of the water, so how much sunlight can reach the plants below the surface for photosynthesis. So flow is the movement of water, and that's going to determine which plants can survive in that body of water.
It's also going to determine how much dissolved oxygen will be found in the water because rivers and streams and rapidly moving bodies of water. allow for better mixing of air and water, which leaves some more dissolved oxygen in the water. And then finally, we have temperature. This is very important because the warmer a body of water gets, the less dissolved oxygen it can hold, and therefore the less aquatic life it can generally support.
And that's because organisms in the water, especially animals, are going to require a lot of oxygen from that water, so it needs to have dissolved oxygen in order to support those animals. So rivers are generally going to have high dissolved oxygen and that's because the movement of the water facilitates the mixing of air and water which leads to oxygen dissolving into the water. We're also going to see high levels of nutrients found in the sediments that are carried along the bottom of rivers.
Lakes on the other hand are standing bodies of fresh water and this is really important that they're fresh because that means they are a source of drinking water around the world. Next we have the different zones of a body of water. And so the littoral zone is this shallow water around the edge of the lake or the pond. And it's going to have what we call emergent plants. So these are things like reeds and cattails where the roots of the plant are embedded in the bottom of the body of water.
But then most of the plant extends up out of the water. The limnetic zone is this zone in the middle. And this is the zone where light can reach. And so where photosynthesis is able to take place.
Then we have the profundal zone. which is too deep for light to reach and so there's not going to be any photosynthesis happening in that zone and then finally we have the benthic zone which is kind of like the murky bottom of the body of water and it's going to feature things like invertebrates that are going to live in that murky bottom in the soil that's down there it's going to be very nutrient rich because of all the sediments there containing organic materials freshwater wetlands are areas where the soil is submerged or saturated with water for at least part of the year but it's still shallow enough for what we call emergent vegetation. Remember, that's plants that have their roots in the soil, but then extend up and out of the surface of the water.
Another key distinguishing factor is that the plants that live in wetlands have to be adapted to live with their roots submerged in water. Most plants will die if their roots are totally submerged in water, and that's because they won't get enough oxygen. They'll essentially suffocate. But plants like cattails or lily pads or reeds all have adaptations that allow them to survive in submerged soils.
That is the key distinguishing factor of a wetland. They're very important because they have a whole host of benefits. One of them is that they store excess water during storms, which is going to reduce the damage from flooding.
Wetlands also recharge groundwater by absorbing rainfall into the soil, and so that's going to refill aquifers and other underground sources of water that humans rely on. They're also going to provide a natural filtration, basically. So the roots of the plants are going to trap pollutants that may be in stormwater runoff and prevent those pollutants from getting down into the groundwater beneath. And then finally, they're just a great habitat for a whole host of plant life because there's so much water and because the sediments here contain so much organic material, which provides nutrients for those plants.
So really, really diverse and productive biome. Here we have three examples of different types of freshwater wetlands, and we'll talk about how plants in each. habitat are uniquely suited to those conditions.
So we have a swamp here that's going to feature cypress trees, which are a type of coniferous or pine tree that are uniquely adapted to survive living in submerged soils. Then we have marshes. They're also going to have reeds and cattails, which like the cypress tree are uniquely adapted to survive with their roots totally submerged in water.
And then finally we have a bog and a bog is characterized by extremely acidic soil. And so we have trees like the spruce tree. and a species of moss called sphagnum moss that are uniquely adapted to survive in these very acidic soils. So we can see in each type of wetland here The plant species that are found there are uniquely adapted to survive in those conditions.
So far, we've just talked about freshwater biomes and upcoming we'll talk about marine or ocean biomes. But we have to first cover estuaries, which are sort of an in-between between fresh and saltwater biomes. So they are a mix of fresh and saltwater because they're where rivers empty out into the sea.
And so. they're going to be very productive biomes. And that's because there's going to be really high levels of nutrients contained in the sediments that are deposited in estuaries by the river.
So the river carries all of these organic sediments, and then it deposits them in the estuary when it opens out into the ocean. So that's going to make the flood plains of rivers, the areas where rivers flood up onto the land surrounding them, or deltas where rivers open out in the ocean, it's going to make them have really fertile, really productive soil. So one type of estuary is a salt marsh.
These are estuary habitats found along the coast of temperate climates and they're going to be really important breeding grounds for a ton of different fish and shellfish species. So they'll swim into the salt marsh, lay their eggs which will hatch, and then they'll swim back out to the ocean and live the rest of their life. Really, really important to supporting a bunch of different marine organisms.
Here's a picture of it here so you can see it's kind of the meandering opening of this river gradually out into the ocean. Then we have mangroves. Mangroves are a really unique habitat. They're estuaries that are found only in tropical climates, so it's got to be a lot warmer, rainier.
And the mangrove swamps are characterized by mangrove trees. These are really neat trees that have these super long stilted roots. And so the mangroves you can see here basically sit up perched kind of on these roots. And the roots are really key to the habitat.
They're going to stabilize the shoreline, so they're going to anchor the soil in place. protect it from storm surges or really high winds. They can absorb a lot of water when there's excess water from rainfall, which will prevent flooding.
And then finally, they're going to also provide a super important habitat for a bunch of different fish species that are going to basically swim among these roots, find protection from predators, find food to eat. And so they're really vital estuary habitat. Next, we have the coral reef. So the coral reef is an ecosystem found in warm shallow waters beyond the shoreline.
Really important to understand that it is one of the most biodiverse ecosystems on earth and it is the most biodiverse ecosystem found in marine biomes. It's going to feature a mutualistic relationship between coral, which is an animal, and algae, which is a plant. So coral take in carbon dioxide out of the ocean and they're going to create a calcium carbonate shell, which we refer to as the reef. It's their exoskeleton. This is going to provide a home to the algae.
So the algae will actually live in the coral reef. But then what they'll do is they'll take in some of the carbon dioxide that the coral give off through respiration. And they'll use it for photosynthesis to make sugars.
These sugars then fuel the coral and provide them with an energy source. Really important to remember that this is a mutualistic relationship, meaning that neither organism could survive without the other. But when they live together in this mutualistic way. they're able to live in an area that neither of them would be able to survive in without the help of the other.
Next we have the intertidal zone. Intertidal zones are basically a narrow band of coastline between low and high tide. So when the tide moves out each afternoon it's going to leave a lot of this area exposed to sunlight. There's also going to be a lot of crashing waves which requires the species that live in the intertidal zone to be able to basically hang on to the rocks there and anchor themselves. So we'll see that species like barnacles, sea stars, and crabs are all going to have adaptations that allow them to attach themselves to the rock and resist being pulled out when the tide goes out.
Another adaptation that they need to have is a tough outer shell or tough skin that prevents them from being dried out by that harsh sunlight that they're going to be exposed to at low tide. This prevents desiccation, which is basically... the drying out of the organism.
What we'll see here when we look at this diagram is that different organisms are uniquely adapted to live at different levels of the intertidal zone. So for example, we have the spiral wrack, which is a type of seaweed. It's adapted to live at the high tide zone because it can actually kind of curl up on itself and secrete a mucus, which acts as kind of a moisturizing substance that prevents it from drying out during low tide. So big important takeaway from the intertidal zone is that the organisms have to be uniquely adapted to live at the different areas found in the intertidal zone.
And finally we'll end with the open ocean. So the open ocean we should know is a very low productivity biome. per unit of area.
So per kilometer of the ocean, it's much less productive than a kilometer of the tropical rainforest. This is because only algae and phytoplankton can survive in much of the ocean. It's just too deep for most plants to survive. So although it has very low productivity per unit of area, it's such a large biome and it covers so much of the earth that all of the algae and phytoplankton that live in the ocean produce a huge portion of the oxygen that we need on earth in order to survive.
It's also going to be an important sink for carbon dioxide, meaning that these organisms are going to absorb a lot of carbon dioxide out of the atmosphere. And that's going to mitigate and reduce the impacts of global warming because it takes carbon dioxide out of the atmosphere. We have a couple zones we should know in the ocean.
We have the photic zone, which is the area that sunlight can reach. So that's the area where we will see photosynthesis occurring. Then we have the aphotic or the abyssal zone. This is the zone that is too deep for sunlight to reach and so there's no photosynthesis that's going to be occurring here. Really important we should know that the organisms that live in the abyssal or the aphotic zone are going to need adaptations to survive there.
So many of them have an adaptation called bioluminescence which allows them to glow giving themselves a source of light so they can see and navigate in this dark ecosystem. and also they're going to need to be adapted to sustain extremely high pressures due to all of the water that's above them so big theme from all of the aquatic biomes we should know is that the organisms that live in them need to be uniquely adapted to survive the conditions found in those biomes our practice frq for topic 1.3 today will involve concept explanation so i want you to identify an organism that's found in an aquatic biome and explain how that organism is uniquely adapted to live in that specific biome. Alright everybody, thanks for tuning in today.
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