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There are also biomes underwater. Walk with us as we explore some AQUATIC
biomes found on Earth. You may wonder what happens between one biome and
another. There is a grey area where the two biomes mix traits. An ECOTONE
is the that border between one biome and another.
RUNNING
FRESHWATER
Standing on the shore of the river you look down and see the water moving
by. Generally these rivers move from the mountains all the way to the
ocean of a lake. It may rain on a mountain and the water collects in the
river. The area which feeds the river is called a WATERSHED. You'll see
lots of life in the water, that's probably because of all the Oxygen in
there. You'll see fish and a lot of algae, but generally it's filled with
producers.
STANDING
FRESHWATER
From a river to a lake or pond. The water doesn't move very quickly here
at all. It gives animals a chance to grow up, you'll find larger fish,
insects and plants in this lake. Scientists divide lakes into two major
levels...LIMNETIC (the top) and PROFUNDAL (the deeper part). They even
have names for the shore (LITTORAL) and the very bottom on the floor of
the lake (BENTHIC). You'll find most of the activity in the limnetic zone.
MARSHES
AND ESTUARIES
These are the regions where the freshwater meets the saltwater. It will
always be found near the coast. In estuaries fresh and saltwater mix constantly
and this allows for huge amounts of marine life to exist. It turns out
that this is a great area for fish to lay their eggs. The water is quiet
and still and when the fish are really tiny they can hide in the cloudy
(BRACKISH) water. When you look around you'll see all sorts of birds like
cranes and storks and insects who lay their eggs in the still water too.
INTERTIDAL
ZONE
Where the waves hit the coast you'll find the intertidal zones. Tides
are controlled by the gravity of the moon and go up and down every day.
As they rise and fall, they leave a patch of coast under the water when
the tide is high. The same area is dry and exposed when the tide lowers.
It's usually very rocky here with lots of algae and small creatures. You
can walk around when the tide is low and find sea urchins, sea stars and
all sorts of birds and insects looking around with you.
SUBTIDAL
There is an area near the coasts of continents which is always under water.
You can find coral reefs and most of the fish in this region. You'll also
find larger fish because they have more room to swim and more little fish
to eat. There are also huge sandy plains in this subtidal region. Because
of all of the waves and activity there is a lot of Oxygen in the water
to support the wildlife.
OCEANIC
There comes a point where the floor of the ocean just drops away. Now
you are in the deep ocean biome. Scientist break it into three layers.
At the surface is the EUPHOTIC zone. There is a large amount of sunlight
and Oxygen, but very few nutrients (they all fall to the bottom of the
ocean). You'll find many small organisms who are photosynthetic. As we
move down we get to the BATHYAL zone. The water is very dim, no little
organisms here, just some fish who feed on the organisms at the surface.
At the bottom of the ocean is the ABYSSAL zone. The bottom of the ocean,
pitch black, no producers, little Oxygen, extremely cold, high pressure.
But there are things alive. They usually feed on the dead that fall from
the surface layers. Then of course there are the predators who swim through
the murky depths.
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