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An offline version from:
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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1 About us ..
Hello,
this story has been illustrated and written for you by climate scientists who work
in the OOMPH project. They try to better understand the life of algae (such as
Agatha).
That's us.
We would like to tell you here, with the help of Agatha, about life in the oceans.
This is the logo of our
project.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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Content
Chapter
page
1
About us
2
2
Life in the oceans
4
3
How was Agatha born?
5
4
Where can you find me?
7
5
Observed by scientists
8
6
Of which size are we?
9
7
What do we look like?
10
8
How do we grow?
11
9
What is plankton?
13
10
Why we are important?
15
11
How do we reproduce
16
12
How long do we live?
18
13
The population of algae during the year
19
14
What is an algal bloom?
22
15
Salts from the sea
23
16
Currents in the ocean
25
17
Gas exchange with the air
27
18
Clouds over the ocean
28
19
We still have to learn a lot
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Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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2 Life in the ocean
If you hear “life in the ocean”, what do you think about? Have you ever thought
about which creatures are living there?
Write the names of the creatures next to the following photos. You will find the
solution at the end of the next chapter.
fishes
mussels
crabs
Certainly, these creatures would be among the first you would have named had
you not already read the title. However, all of these animals could not live if
there wasn't anything for them to eat. There are also smaller creatures in the
ocean. These smaller creatures serve as food for the larger ones. Algae belong to
this group of smaller creatures.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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3 How was Agatha born?
Here you see enlarged photos of different algae:
Algae do not have eyes and they do not have a mouth. They cannot speak and
can’t tell you anything. Nevertheless, we would like to make them talk, and this is
why we invented Agatha Algae.
1) We were looking for an algae which
is simple to draw and found the drawing
of volvox, an algae species, on the
Internet.
2) Starting with a small
volvox algae, we made it
even simpler by cutting
off the two little filaments.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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3) Afterwards we coloured
her green so that she looks a
bit more friendly. Most algae
are green because of
chlorophyll. But we will say
something about this later.
4) The final touches on Agatha were
made with the help of a painting
program where she was given two
eyes and a mouth (features
which no real alga would have).
Now Agatha is going to tell you a bit about her family and the life in the water.
Solution of Life in the Ocean:
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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4 Where can you find me?
Hello, I am Agatha.
You can find me anyplace
where there is sufficient water. I
may be in lakes, in the oceans or
in other humid locations.
If the Earth surface was a cake with 10 pieces,
then seven parts would be water and three parts
would be land. You can see from this that there
are a lot of places where I can live on Earth.
In the real world land and water are certainly spread a bit differently.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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5 Observed by scientists
Just like humans are not equally spread out on land, algae are also not equally
spread throughout the oceans. We prefer to live where we can find enough
food. In recent years, scientists have been observing where we are spread in
the oceans. Since there are not ships everywhere on the ocean, scientists
use satellites from space to see where we are.
Satellites are
machines which have
been launched by a
rocket into space.
Right now, they
are orbiting the
Earth
while measuring
different sorts of light
and making photos.
The scientists draw maps of the regions where we
are found more often and in larger numbers. Here
is a map from the Atlantic Ocean. The land is
black and the sea is coloured. In blue regions
there are few algae, in green regions more, in
yellow regions an even higher number, and in
orange and red regions really a lot.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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6 Of which size are we?
We algae are simple creatures. Most often, people think of us as plants. But
some of my relatives also have similarities with bacteria and simple animals. I
have many relatives and they look all very different from one another. Some
are tiny and consist of only one cell. Others are big and consist of a large
number of cells.
From the sea and the beaches you may
know my larger relatives, the brown algae
and red algae. Brown algae may grow up
to 30 meters long or longer. Both brown
and red algae have a leaf-shaped or
thread-like structure and consist of many
cells.
The smallest of my relatives are only a few of a
hundredth of a millimetre across and cannot be seen
with the naked eye. They live in lakes or humid soils.
This means the difference between the smallest (20
µm) and the largest algae (20 m) is as large as the
difference between a pea (4 mm) and a mid-size
town (4 km).
From the size of a pea ...
… to a mid-sided town is
the difference between very
small and very big algae.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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7 What do we look like?
We not only have very different sizes from one another, we also look very
different.
Big algae, like red algae or brown algae, look like
leaves or big underwater plants.
The smallest algae consist of only one cell and do not
look like leaves or underwater plants at all.
In many algae the cells form filamentlike structures. Except for the first
one, the photos shown here are
all greatly enlarged.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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Sometimes we also group in circle
shaped colonies, for example me and my
closest relatives from the volvox family.
8 How do we grow?
We do not need a lot for living. To start with, we need nutrients in the water:
phosphate, nitrate, iron and a few others. In addition to nutrients, we need
sunlight. We form the components of our body from water and the gas carbon
dioxide. Carbon dioxide is available everywhere in the air and also dissolved in
the water. These are the most important compounds we take up or release:
Oxygen
Carbon dioxide
Water
Biomolecules
Energy
In our cells we have a green substance which is called chlorophyll. Chlorophyll
transforms the light of the sun into energy. We call this method of biological
energy production photosynthesis. We need this energy for the factories in our
bodies in the same way as you need the energy from your food. But a big
difference is that you need oxygen in order to live, while we actually produce it.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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That’s how I produce biomolecules from water and carbon dioxide.
Water and carbon dioxide go slowly into a biofactories in my body.
With the help of energy from the sun …
a reaction is taking place in my body. And
after this …
the carbon dioxide and water have been
turned into oxygen and a biomolecule.
And now I am ready for the next turn.
The biomolecules build up my body. The
oxygen goes back to the water or the air.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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9 What is plankton?
Scientists seldom speak about algae, they speak more often about
“phytoplankton”. But what do they mean by this?
If you go for a swim or travel somewhere by boat, you decide where you would
like to go. The same is true of fish in the ocean. When they swim, they like to
go to places where there is food and prey available. These places are often
streams in the ocean where nutrients are transported along with some
creatures.
I have to admit that sharks will never use a motor boat as the one in this picture is.
However, the shark and the boat are both mobile in the water and can go,
under their own power, in any direction they choose.
Other creatures, like myself on the air matress in this picture, are just floating
and may not be able to make their own movements. Some examples of such
creatures are bacteria or algae or other little animals (for example, jelly-fish).
It could also be you, if you were to lie on an air-mattress and do nothing. All
creatures (plants and animals) without own motive power are called “plankton”.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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One group of plankton are
bacteria. My own group,
called algae, are also
plankton. We live on light and
water just like plants on land
do. That is to say that we both
carry out photosynthesis.
Plankton which are plantlike are called “phytoplankton”
(“phyto” is the Greek word for
plant). My relatives the
diatoms make up most of the
phytoplankton in the oceans.
These are diatoms. They are really tiny.
Other plankton are similar to
animals. We call them zooplankton
(you probably know that the
word "zoo" has something to do with
animals).
Here is a picture of some
little Zooplankton.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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10 Why we are important?
In nature, species live off one another. Caterpillars eat leaves, birds eat
caterpillars and cats hunt for birds. We call this a food chain. Each link in the
food chain is connected to another.
There are creatures in the food chain that can live almost independently of
other creatures. Trees and grasslands for example grow by taking up light,
water, carbon dioxide and a few nutrients from the ground. But they do not
depend on other animals and plants.
The same is true in the sea. Here it is us, the simple algae, which are the first
link in the chain. We live only from light, water, carbon dioxide and a few
nutrients. We are eaten by tiny animals (zooplankton). Larger animals like crabs
and fishes eat the smaller ones.
The predatory fish eats the smaller fish, the smaller fish eats the shrimp, the shrimp eats the algae.
Being the first link in the food chain, we are very important since all other
creatures off of us.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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11 How do we reproduce?
I would not be on this planet if algae did not reproduce. You are human. So you
know that children are born if there is a sexual relationship between a mother
and father. The sperm of a father comes into contact with the egg-cell (ovum)
of a mother. We call this sexual propagation since a contribution is required
from both a male and female.
Sexual reproduction also takes place among advanced
algae. For example an alga with the name Ulva has
both female and male forms.
The alga Ulva
If the egg-cell
(female) and the
sperm (male) from
Ulva come together
[A], a new plant is
formed (S). We
call this new plant
a Sporophyte, since
she is carrying both
female and male
spores. The spores
in turn develop into
male and female
algae after their
release [B].
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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For many simpler algae we cannot tell whether they
are male or female. In this case, new algae can
be formed by division of a single cell. For my
relatives from the species Chlamydomonas, the
method of reproduction is somewhat mixed:
Agatha is dividing and two
algae are formed.
[A] As long as conditions in the water are good (the green area) the algae float
around and propagate by cell division.
As soon as conditions in the water become more difficult (orange area), two algae
can merge and form one cell. [B]. The merged cell forms a strong wall to protect
itself from the harsh conditions [C] and is able to survive this time as a “spore”
(for example the winter).
As soon as conditions become better again, four new algae are formed from the
spore [D], which propagate again by cell division.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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12 How long do we live?
I have to hurry up in telling you this story, because my life is short. I may only
live for one day. In comparison with humans, we propagate much faster but also
die much sooner.
Individual cells in your body die
and are replaced. We also die,
and what is left of the cells are
eaten by bacteria. Although
one algae alone is not of much
importance, many algae
together can feed many
bacteria.
Bacteria in the ocean are so small that 10,000
fit in a drop of water. They cannot be seen with
our eyes. This image is greatly enlarged
and was taken using a microscope.
When eating algae cells, bacteria deconstruct our biomolecules, using up oxygen
and re-release nutrients and carbon dioxide. This often takes place in deeper
layers of the oceans because bacteria do not need light.
After our death the biomolecules from
our body sink to deeper layers of the
water.
Here they are picked up by the biofactories of bacteria.
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The bacteria decompose them and form
carbon dioxide and water again.
The carbon dioxide can dissolve in the
ocean, be used by other algae or go to
the air.
The series of illustrations above shows what happens inside a tiny bacterium in
the ocean. The sinking biomolecules (green triangles) of the dying algae are
decomposed by the bacteria with the help of oxygen. Other algae can take up
again the carbon dioxide produced by bacteria in the path moving in the opposite
direction as shown in chapter 8.
13 The population of algae during the year
You should not think of algae only as single creatures but also as a living
community. How does a community of algae develop in the ocean during the
year? The best conditions for growth and reproduction are in the spring or
autumn.
This is how the algal population develops during the year.
Although there is always enough carbon dioxide and water for our algal
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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community, sometimes there is a lack of light or nutrients. The amount of light
and nutrients causes our population to rise or fall. The amount of light depends
on the season and changes from month to month. The amount of nutrients
depends on how well mixed the water is. When there are more nutrients, this
means that water is well mixed and that fresh water is coming up from deeper
down in the ocean. This is the case when the surface water becomes cooler (in
autumn and in winter) and allows warmer water from deeper down to rise.
In the winter, surface water and deep ocean
water are exchanged. Warmer water rises
(red arrow ) while cooler water is mixed
downwards (dark blue arrow).
In spring the surface water warms up and
the exchange is slowed down.
In summer the exchange stops since the
warmest water is laying on top.
In autumn the exchange slowly starts again
since the surface layer begins to cool.
In the spring, the water is full of nutrients and well mixed. The amount of
sunlight increases, we reproduce, and our population increases.
In summer we have a lot of light but we quickly use up all the nutrients since the
ocean is no longer well mixed. At this time our population decreases.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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Algae with plentiful nutrients (black
points) in spring ...
... with a lot of light but few nutrients
(no mixing) in the summer.
In autumn nutrients begin to come back to the surface. We reproduce again as
long as there is enough light.
In the winter there are enough nutrients, but there is not enough light for
photosynthesis. The population shrinks again.
14 What is an algal bloom?
If algae appear in large amounts we call it an algal bloom. Such algal blooms can
cover giant areas of water that can be as large as whole countries.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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Normally, we algae are
useful creatures.
But sometimes you can
have too much of a good
thing. For instance, there
can be too many algae
around when humans feed
us too much. What do I
mean by this?
A satellite took this photo of an algal bloom in the
Atlantic ocean. On the right in the photo is a part of
France.
The same nutrients we get from mixing in the ocean (nitrate, phosphate, iron)
are also often found in the fertilizers you use for farming and can be found in
waste waters that enter the oceans through rivers at the coasts. If there are a
lot of nutrients and also a lot of light, like in the spring or summer,
we reproduce more than usual.
Yikes! Countless little algae colour the whole water green.
Why this is a problem?
The more algae there are, the more die. This means more food for bacteria which
then reproduce. More bacteria consume more oxygen in the water. Oxygen is
needed for breathing, not only for humans, but also for fish.
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If the bacteria use up too
much oxygen, there is not
enough left for the fish to
breathe and they die.
15 Salts from the sea
Algae can produce biomolecules from carbon dioxide and water. But for this we
also need nitrogen (N) and phosphorus (P) and also some other compounds like
iron. They are needed by every creature.
If you could see the smallest
bricks making up our bodies, they might
look like this:
This molecule saves the building
instructions for our bodies and is made up
of different atoms: carbon (green),
hydrogen (white), oxygen (red), in
addition to nitrogen (blue) and
phosphorus (yellow).
Nitrogen and phosphorus can only be taken up into our bodies as
salts (nitrate and phosphate) from the ocean water.
Phosphate
The images above show coloured models that chemists build in order
to imagine how the tiny molecules look.
Nitrate
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In reality however the salts look like
the salt for cooking in your kitchen. And
when the salts are dissolved in water …
well, then you don’t see anything at all.
This is how many salts look, if they are
not dissolved in water.
However, we do not need to put salt on our food like
you. We take up the salt immediately from the water.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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16 Currents in the ocean
Deep in the sea it is dark. Since we need sunlight, we cannot go into deeper
water. If all the nutrients next to the surface are used up, this means that we
cannot reproduce until new nutrients appear. From where do the new
nutrients come?
We saw that warm water rises from the
deeper water layers if the surface water
becomes colder.
Water exchange in winter
Here you see the ways in which the ocean water slowly migrates around the world. Warm water is
red, cold water is blue.
Large areas of sinking or rising waters help to stir up the ocean and, along with
the motion of the earth, help to create continuously moving currents. These
currents flow like a river, but much much slower.
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In the deep water there are many
nutrients since there are no algae
around which can use them up. At
locations where deep water from the
ocean comes up, the living conditions
are notably favourable for algae.
Cold water with many nutrients is
pushed up next to the coast.
This is the case next to the west coast
of Africa and South America. Some
scientists from the OOMPH team went
with a research ship to the region
west of Africa in order to learn more
about algae.
Research ship Meteor
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17 Gas exchange with the air
Why are we little algae so interesting to scientists?
We not only produce biomolecules for our own growth along with oxygen, we
also contribute to the production of other chemical compounds in the ocean
water. Some of these compounds leave the sea and go up into the air.
Large amounts of gas enter or
leave the ocean. This exchange
of gases is important for the
climate on our planet. Where
there are lots of algae, we may
help determine what goes in and
what comes out.
Algae produce gases, which rise from the
ocean.
Do you doubt that gases can dissolve in water? Just take
a bottle of sparkling water. Shake it and you can see how
much gas comes out. All of this gas is carbon dioxide
which was dissolved in the water.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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18 Clouds over the ocean
There is a lot going on in the air. Many chemical processes take place although
you can't see most of them with your eyes. Most of the gases are changed
chemically. Some of them become carbon dioxide which is taken up again by
the algae. Other gases go back to the ocean with the rain.
1
2
3
4
Algae - gases - crystals - water droplets - cloud formation ...
this is taking place over the ocean
Of particular interest are a few gases which contain sulphur. They turn into little
crystals of sulphur salts. These salts attract water and droplets form in the air.
Many water droplets form clouds.
This is how the life of Agatha alga has an influence on the clouds over the ocean.
And certainly this is rather exciting for climate scientists, because clouds cover
our sky.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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1
2
3
4
They warm the Earth in cool nights, but they also keep out the radiation from the
sun. In this way they regulate our climate.
19 We still have to learn a lot
We have to say Goodbye to Agatha now. But as
scientists, we still have to learn a lot about her
relatives. As humans we are busy changing our
planet. For example, we heat up the air and the
water of the oceans. This has consequences for
the life of algae.
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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Changes in the lives of algae
will mean changes for other
creatures on the food chain
from fish in the ocean to
humans on land and the climate
in general. Everything is
connected. But how everything
is linked up is difficult to
understand.
In the bottles we keep algae under varying
conditions.
We keep algae under certain
conditions and investigate what they
do, when it becomes cooler, warmer,
lighter or darker. That's why we take
samples from the oceans and
investigate the life and gases in them.
We take water samples from different
depths.
This is also why we go again and again out
to the ocean in research ships in order to
learn more. If you would like to read about
what is going on during such an ocean
cruise, then take a look in our cruise
diary on the OOMPH education website.
The End
Agatha Alga – Ocean science for the young – www.atmosphere.mpg.de/enid/OOMPHedu
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