Script for
Oceans Life - Past and Present
This slideshow is designed for upper primary, but can be used with multiple age groups including adults. It is an attempt to provide background information on climate change and how important oceans are to the overall driver of climate on the surface of the Earth.
On the animation the blue are cold surface currents and the red is
warm surface currents. Point out
that the currents are different as you go down with depth.
This presentation looks at present day marine life and see what clues we
can find from marine fossils. We can
tell changes of climate through time because of the fossils.
Background
Oceanography is the scientific study of the ocean.
Traditionally, the Earth has been viewed from land. However, if you look at the
Earth from outer space, the oceans comprise 71% of the Earth’s surfaces. The
continents are really only the tops of high mountains from the ocean bottom.
Oceanography is concerned with studying the biology, geology, chemistry, and
physics of the oceans.
The oceans have
evolved distinct features that are unique among the other planets in the Solar
System. The oceans harbor entire populations of organisms that use the marine
environment to their benefit. The oceans also provide humans with valuable
nutrition, transportation, and weather. Many organisms originated in the sea.
The marine environments are more stable by continuously supplying the needs of
organisms than the unforgiving land environments.
Marine water
has many elements and compounds dissolved, creating the term “salt” water
(including Na, Cl, Mg, C, P). There are
also other components like silicic acid that are important to creating shells.
Humans and most organisms require fresh
water to survive. Most organisms on
land require oxygen. Marine animals
also require oxygen, which is dissolved in water.
The interaction
of the oceans and atmosphere creates our weather.
Slide 2.
Why are oceans important?
We need to look at present oceans.
The surface of the water has dissolved gases so available to
organisms including oxygen and carbon dioxide.
Fish have developed gills that allow them to capture oxygen from the
water. Although water is H2O,
organisms cannot take the oxygen out of water.
In this picture carbon dioxide is
seeping from the ocean floor near Ischia, Italy from volcanic activity.
It becomes dissolved within the marine water.
Marine plants, both large and small can take this carbon dioxide and use
it in their photosynthetic process.
Oceans are important because they
create currents, on the surface and with depth.
The difference of warm water and cold water; density (caused by dilution
of a normal 35 parts per million).
Oceans also maintain cold and heat slower than land.
The interaction causes weather patterns.
Also just the fact that the earth rotates causes what is called the
Coriolis effect (a deflection to the right in the Northern Hemisphere and left
in Southern Hemisphere)
Over time this would affect the
biological life. The clues they
leave through time are fossils. The
information tells a story of climate change through time.
Slide 3.
Land and Water
Compare land
with water on the surface of the Earth.
There is about 71% of the surface that is water (both marine and fresh).
Look at the position of land vs water.
If you compare northern and southern hemisphere there is a pattern.
North and South America (land and land); Europe and Africa (land and
land); Atlantic (ocean and ocean); Pacific
(ocean and ocean); but India Ocean and Asia (ocean and land).
The difference in cooling and warming of water and land, makes this area
the origin of most weather patterns and then goes east.
Rotation of the Earth (Coriolis Effect) creates this dynamic system.
Slide 4.
Water Masses with Depth
Atmosphere and
Oceans as they interact together are basis of our weather.
Temperature and
density can define a water or atmospheric mass. Different
organisms live in different water masses.
Cold water organisms will not be abundant in warm water.
Slide 5.
World Wide Circulation
In the oceans
warmer water can hold more salt, and colder water holds less salt. Salt water is
more dense than fresh water of the same temperature. The salt water will layer
itself below the fresh water. Warm water is less dense than cold water. So cold
water will layer under warm water. Add the combination of different amounts of
salt and different temperature and you have a layering effect in the water
column. The world’s oceans are a three-dimensional nightmare of layers of
different water masses that can move in different directions.
Bottom
topography can act as a barrier to water masses already in motion. If a cold
saline water mass is moving along the bottom and "hits" a mountain it would be
forced upwards. This is one form of upwelling. This would displace the water
masses above it, causing lots of movement.
The entire cycle can take 1000 years to complete.
Slide 6.
Present Day Carbon Cycle
The Earth is a dynamic system.
Interaction of land, sea, and air causes changes of certain molecules.
Carbon is one of those.
Carbon is also present in the Earth's atmosphere,
soils, oceans, and crust. When
viewing the Earth as a system, these components can be referred to as carbon
pools (sometimes also called stocks or reservoirs) because they act as
storage houses for large amounts of carbon.
Any movement of carbon between these reservoirs is called a flux.
In any integrated system, fluxes connect reservoirs together to create
cycles and feedbacks
Carbon cycle takes into account biological
activity on earth including humans.
Through time it has changed. Fossils
give an insight of the earth’s former concentration and distribution of
organisms.
At the sir-sea boundary, atmospheric CO2 is
dissolved in water. Near surface,
many photosynthetic plankton convert the dissolved CO2
into organic carbon. In
addition, waster and Co2 molecules react to form carbonate ions
(HCO3’). Carbonate ions are
used by many marine organisms to form calcium carbonate shells.
As these marine organisms die, the resulting debris falls from the near
the surface into deeper water. This
sedimentation increases adsorption of carbon from the atmosphere by removing
carbon from surface waters. The rate
of carbon movement to the deep ocean also depends on a circulation pattern
called the ocean conveyor belt.
Slide 7. Important
gases through Time
Different organisms produce different
gases. When plants became abundant
they released more oxygen then they consumed.
The oxygen we have in the air today is because of plants over time. Not
only land plants, but water plants. Gases in the Earth’s atmosphere has changed
through time. Biological life has
influence the atmosphere, but the atmosphere has influenced the evolution of
organisms on Earth.
Gases in the atmosphere influence what ions are
available in the water. Some of the gases
can interact with organisms to evolve shell making.
The atmosphere
is similar to the oceans in that air masses can move from one part of the earth
to another bases on temperature and pressure.
Air takes up space and has weight. It is made of a mixture of different gases
which changes with altitude. At the surface of the Earth, air is a mixture of
the gases including nitrogen, oxygen, argon, carbon dioxide, hydrogen, and
various other rare gases. The percentage of carbon dioxide varies slightly
depending on the presence of vegetation. There are also traces of ammonia,
hydrogen sulfide, oxides, sulfur dioxide, and other gases. The percentage of dry
air varies little at different locations on the Earth's surface.However, as you
travel upward in the atmosphere the percentage of the gases changes. At 800 km
there is only hydrogen and helium in about equal proportions
Slide 8.
Six Kingdoms
Of the 6 Kingdoms most have
representatives that live in the ocean.
Some like fungi are rare, but others like lower Animalia are very common.
Present day organisms help understand past organisms and the number of
calcareous organisms help scientists interpret the elements in past oceans.
Porifera
many cells working together
mainly marine
calcareous, siliceous, spongin
lives in clean, medium to deep water
Cnidaria
Includes jellyfish, corals, sea anenomes
lives near shore to deep marine
have tentacles with stinging cells (nematocysts)
calcareous outer skeletons (corals)
Arthropods
Includes insects, crabs, shrimp
segmented with appendages
has an exoskeleton (protection on outside)
made of chitin or calcareous
Mollusk
includes abalone, bivalves, gastropods
soft bodied animals
make a shell of calcium carbonate
lives in mud, sandy, forests, soil, rivers, lake, and marine
Echinoderms
includes sand dollar, sea star, sea urchin
marine
5 part “star” symmetry
spicules and plates made of calcium carbonate
Brachiopods
abundant in ancient oceans
calcareous shells
lophotrochozoan organisms
Bryozoans
Abundant in ancient oceans
calcareous shells
lophotrochozoan organisms
Organisms in the ocean take up ions and
incorporate them into their existence.
Shells usually are for protection, while bones are usually part of the
living organism’s metabolic stability.
The two pictures show the difference between the make up of shell and
bone. Bone tends to be “holey” to
allow blood vessels to go through the living bone.
Shell on the other hand, is not porous and meant to be more “solid.”
Background
It is every drop of water’s dream to live at sea level. Water precipitates on
land and travels to sea through rivers. The rivers erode the land and chemically
dissolves the components of rocks into ions. Over eons of time, most elements
become dissolved in seawater. These ions help give the "flavor" to salt water.
Salt in the ocean comes from rocks on land. The rain that
falls on the land contains some dissolved carbon dioxide from the surrounding
air. This causes the rainwater to be slightly acidic due to carbonic acid (which
forms from carbon dioxide and water).
Many of these
ions can be combined into molecules that are used by living organisms. For
example, little critters (protist) like foraminifers require CaCO3
(calcium carbonate) to make skeletons. Radiolaria, another protozoa require SiO2
(silica dioxide) to make their skeleton. Small plants, mainly diatoms which live
on the ocean’s surface use SiO2 to make their skeleton.
Diatom contribute the majority of oxygen in the water and the atmosphere.
Calcium carbonate usually crystallizes as calcite or
aragonite seawater. The outcome affects many different processes — including the
global carbon cycle, neutralizing carbon dioxide in the atmosphere into a stable
mineral and limiting its buildup in the air. It also affects the formation of
shells and corals, whose aragonite shells are vulnerable to the ocean
acidification associated with climate change.
Bone is made of
calcium phosphate
Remember life
evolved from marine to land. Fossils
support this evolution.
Slide 10.
Why are
shells in the ocean
The
ocean’s chemical system is complicated and always changing. The minerals are
dissolved in water and are in solution until either chemical or biological
reactions in the oceans precipitate the different compounds.
Organisms
that live in the marine environment tend to use two types of compounds, calcium
carbonate (CaCO3) and silica dioxide (SiO2). Biological
processes can actually transform the ions into microscopic minerals that grow
with the organism. Calcium carbonate is a mineral called calcite. When
incorporated into a biological system it is usually in a "disordered" form
called aragonite. Most mollusks use calcium carbonate in their shells.
Slide 11.
Radiolarians and Diatoms SiO2
Silica
dioxide is also a common mineral, in the form of quartz. Siliceous sponges use
opaline silica for its skeleton.
Silicate, or silicic acid, is a
very important nutrient in the ocean. Unlike the other major nutrients such as
phosphate, nitrate, or ammonium, which are needed by almost all marine plankton,
silicate is an essential chemical requirement only for certain biota such as
diatoms, radiolaria, silicoflagellates, and siliceous sponges. The dissolved
silicate in the ocean is converted by these various plants and animals into
particulate silica (SiO2), which serves primarily as structural
material (i.e., the biota’s hard parts).
Slide 12.
The life of the
San Francisco Bay is dominated by little critters. None of the organisms
of the San Francisco Bay mud life are exceptionally beautiful nor unique,
but all are part of a food web.
In an
ecosystem, organisms play different roles in the food web. There are
primary producers,
primary consumers, and then
different levels of secondary consumers.
However before
you determine the position of an organisms in a food web you need to identify
the organisms first. In this lab, the students will first take a
look at the different organisms of the mud (from the San Francisco
Bay) and then they will analyze their positions in the food chain.
Slide 13.
San Francisco Bay Mollusk Fauna
Gastropods are a diverse group of mollusk. Some are herbivores and some are carnivores. The carnivore gastropods have an enhanced "radula" that can drill through a shell from either a clam or gastropod. So in recent shells you can determine how the shells died.
Read Murder in the Mud (storybook), which tells a
story of the food chain in the San Francisco Bay mud.
https://msnucleus.org/member/life_snail/snail.html
Slide 14. Interpreting Data
This is a good eample of how we can see how a clam died by looking for evidence
of predation. Using the information
on the bay mud fauna by looking for these “holes” or borings.
It gives you some idea of how organisms die in the past.
Present is Key to the Past.
Slide 15.
Capitola, California
Capitola is a small community on the north part of the Monterey Bay.
It is noted for its nice sunny days and surfer waves, especially for
beginners. Its cliffs are impressive, revealing a look through time.
Notice how steep the cliffs are near the beach.
These rocks tell a story of life during the Miocene to Pliocene.
Slide 16.
Purisima Formation in Capitola
The Purisima Formation is an environment of
shallow marine (marine terraces) that were deposited from the Miocene to
Pliocene (3-7 million years ago).
Many of these layers of fossils were caused by storms in shallow seas that
ripped up clam beds and redeposited them on what we call marine terraces.
Uplift in the area caused by emerging coastline due to faulting.
You can trace this type of fossil and sediment formation along the
coastline. You also find other
marine mammal and invertebrate fossils.
Slide 17. Changes due to
Plate Tectonics.
Oceans is home to many organisms, and their
skeletons tell a story of change through time. So
when you find shells in the mountains, you need to consider that the mountains
were under ocean. Tectonic forces
change ocean to land (and land to oceans).
Need to consider that as land masses move, the
wind and currents change also.
Erosion of land will input dissolved elements in the water.
Organisms will adapt…. Present is key to the past.
Together the information provides a story of a changing world.
Climate change occurs naturally, fueled by the
changing land and water masses.
Chemical reactions on land and water also play a major role.
Humans because of their ability to change their surrounding do contribute
to the overall chemical cycling, and can cause major changes over a shorter
period of time.
Slide 18.
The key part for children to understand is that change is part of the evolution
of the Earth and life. Science helps
us understand how it changes.