Download 01A-2 - Etudes

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Topic 01A:
Introduction to Oceanography
Online Lecture:
Basic Concepts of Oceanography
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Oceanography: A Science of Maps
○ In science, diagrams & pictures are important.
Look for
the fish!
In oceanography, we look at a LOT of maps & pictures.
○ When looking at a map, the FIRST thing to do is
to determine its point-of-view .
– bird’s-eye-view (view from above, plan view, map view)
– side-view (cross-section, profile)
Side-View
Bird's-Eye-View
Land
Ocean
Land
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Label your map of the world
○ Please familiarize yourself with:
– 7 continents
Direction?
– 5 oceans
– position of the Equator & Poles
– the 4 directions (north, east, south, west)
Common Misconceptions about Plankton
“Plankton” means
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“wanderers”
○ Plankton – ocean algae (“plants”) & animals that:
– try to float
– drift with waves & currents
● some can swim,
but are not “good” swimmers
○ most of the biomass in the ocean consists
of tiny pelagic organisms (pelagic = planktonic)
○ many animals grab / strain / filter the
tiny plankton from the water (this is
called “suspension” or “filter” feeding)
– not all plankton are small
e.g., jellyfish
Phytoplankton
There are 2 major kinds of plankton….
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Dinoflagellate
Diatoms
Coccolithophore
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Phytoplankton
○ tiny (single-celled)
○ algae (like plants)
○ make their own food using a process
called photosynthesis:
light + carbon dioxide + water
→ carbohydrates + oxygen
“food” =
carbohydrates =
sugars =
glucose
○ to carry out photosynthesis, they need
– sunlight
– nutrients
There is plenty of CO2
and water in the ocean.
Mr. Ray
(the science teacher)
in Finding Nemo:
“Seaweed is cool,
seaweed is fun,
seaweed makes its food
from the rays of the Sun.”
Nutrients
could call them “minerals,” but not “vitamins.”
○ chemicals / molecules in ocean water
○ washed off the land into the ocean
when it rains
They are
NOT soil
(sediments).
○ are needed to make the molecular “tools”
that carry out photosynthesis (to make “food”)
– like a hammer is used to build a house,
or a spatula is used to make a hamburger
○ are needed to make shells, typically made of:
– calcium carbonate
“Got milk?”
– silica “glass”
○ Nutrients are fertilizers, not food.
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Why Photoplankton Are Important
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Small Organisms,
Big Impact
food for the animals we eat
make over 50% of the oxygen we breathe
reduce the greenhouse effect
remains become “fossil fuels” (e.g., oil)
Zooplankton
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Copepods
“Arrow Worm”
krill
Jellyfish
Slug
Simplified Food Chain
1
phytoplankton
2
“Trophic Levels”
(Steps in the Food Chain)
3
4
zooplankton
small fish
Simplified Ocean Food Chain
animals undergo respiration,
the opposite of photosynthesis
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big fish
Earth
About how much
of the Earth
is covered
by the ocean?
about 70%
Irony of
the name
“Earth.”
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Size of the Ocean & Shape of the Ocean Floor
○ What is the average depth of the ocean?
○ Most of the ocean bottom is pretty flat :
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2.5 miles
(4 km)
– continental shelves: flat areas near the continents
– abyssal plains: deep, flat areas (2-3 miles deep)
– continental slope: steep area connecting
the continental shelves & plains
Land,
Continent
Continental
Slope
Mid-Ocean
Abyssal
Ridge
Plain
Continental
Shelf
Trench
Continental
Shelf
Continental
Slope
Abyssal
Plain
Mid-Ocean Abyssal
Ridge
Plain
The Mid-Ocean Ridge
Underwater Chain of
Volcanic Mountains
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I often abbreviated it “MOR”
Trenches
Close to Land!
Continents
or Island Chains
Mariana Trench:
Deepest Place in the World
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Most in the Pacific Ocean
Volcanoes: Located Next to Trenches
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Ring of
Fire
Volcanic Mountains & Island are common next to trenches
Earthquakes: happen next to trenches
and the Mid-Ocean Ridge
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“10. The Abyss”
Sediments & the Sea Floor
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Rocks
Washed or
Blown Off
the Land
Sediments Composed of Shells
May also include mucus;
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fecal pellets; and the
dead, decaying parts
of organisms.
2 major categories of sediments: rocks & shells
2 major kinds of biological sediments:
calcium carbonate & silica
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Winds
○ Warm air rises
( low density )
and cold air sinks
( high density)
○ Air gets pushed
away from the
cold place, and
moves in to replace
the rising warm air
“Convection Cell”
Winds cause waves
and currents.
High Altitude
Winds
Surface
Winds
Warm
Cold
Ocean
Current
Clouds and rain occur where air rises.
Skies are clear where air sinks.
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Ocean Currents
○ like a river in the ocean,
water is flowing from place to place
○ affect the climate:
a warm current makes the climate…
– warmer
– more humid (& more rain),
because more water evaporates from the ocean
○ can bring up or push down nutrients,
affecting the amount of life in the ocean
Evaporate
≠ Rise
The Water Cycle
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Most of our drinking water comes from ocean!
Bacteria
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○ single-celled organisms that do not have a “nucleus”
to store & protect their DNA
○ “recyclers”:
breakdown (“decompose”)
dead, decaying material,
releasing nutrients back
into the environment
– Why is releasing
nutrients important?
Algae (like phytoplankton) need nutrients
to build their shells and carry out photosynthesis
(make their own food)
→ fertilizing the next generation of algae
for animals to eat…
Humans and the Ocean I
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○ We will look at a variety of issues,
including overfishing, coastal development,
common ocean pollutants, etc…
Humans and the Ocean
○ Humans sometimes add nutrients to the ocean
(e.g., sewage, fertilizers)
– can cause the growth of “good” ocean life, but
also diseasing-causing bacteria and toxic algae
Most nutrients enter the ocean naturally (are washed
off the land), not owing to human activities.
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But Wait, There’s More!
○ Nature of Science: Hypotheses, Theories, & Observations
○ Water Chemistry (the Chemistry of Life):
What’s so special about water molecules?
○ Waves, Beaches, and Tides
○ Coral Reefs, Kelp Forests, & Deep-Sea Life
○ Tsunami, Hurricanes, & El Niño
○ Plate Tectonics (e.g., Earthquakes and Volcanoes)
○ Global Warming, the Greenhouse effect, & Pollution
“25. Darla!,” End of “26. Goodbye Dory”