Transcript Oceans--make up nearly three quarters of the surface of the earth

Physical environment comprises
temperature, wind, moisture,
salinity, pH, fire.
Physical environment is strong
influence on biological
distributions and processes
Earth’s shape, axis of rotation,
and revolution around the sun
each year, as well as physical
properties of earth, air, and
water determine general
patterns of climate and the
physical environment
organisms inhabit.
• The shape of the earth influences the amount of
insolation different areas of the earth receive
• Shape of earth also influences the direction of
winds and currents
• Earth’s axis of rotation and revolution around
sun affect seasonality of weather patterns.
• Physical properties of air, land, and water
influence movement of air masses and rainfall in
particular regions
• The shape of the earth influences the amount of
insolation different areas of the earth receive
• Shape of earth also influences the direction of
winds and currents
• Earth’s axis of rotation and revolution around
sun affect seasonality of weather patterns
• Physical properties of air, land, and water
influence movement of air masses and rainfall in
particular regions
Coriolis effect
• The deflection of wind or water due to the
earth’s rotation
Problem
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If a mass of air is moving from 30
degrees south up toward the equator,
which way will the wind be deflected?
Problem
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If a mass of air is moving from 30
degrees north up toward 60 degrees
north, which way will the wind be
deflected?
Winds create currents
• The shape of the earth influences the amount of
insolation different areas of the earth receive
• Shape of earth also influences the direction of
winds and currents
• Earth’s axis of rotation and revolution around
sun affect seasonality of weather patterns
• Physical properties of air, land, and water
influence movement of air masses and rainfall in
particular regions
Equinox
• Either of two times of year (March 21 and
September 22) when the sun and Earth’s
positions are such that day and night are
exactly 12 hours everywhere on Earth
• The shape of the earth influences the amount of
insolation different areas of the earth receive
• Shape of earth also influences the direction of
winds and currents
• Earth’s axis of rotation and revolution around
sun affect seasonality of weather patterns
• Physical properties of air, land, and water
influence movement of air masses and rainfall in
particular regions
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Warm air holds more water and is less
dense than cold air, therefore rain results
from the cooling of moist air
High specific heat of water—more heat
energy is needed to change the
temperature of a given amount of water
compared to a given amount of land
• Patterns of air movement and temperature
influence where wet and dry areas are
found
Biomes—major ecological zones
corresponding to a climatic zone with a
typical vegetation structure, for example,
temperate deciduous forest, desert, tropical
savanna
Biomes are distinct from biogeographic
regions
Smaller-scale (regional) patterns of
physical factors within the larger
patterns
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Urban areas are much warmer than
surrounding areas within a biome
Mountains influence climate by
influencing moisture patterns
Physical factors on a very fine
scale
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Wind and nest orientation
Temperature will vary above and below
ground
Temperature, salinity, and moisture
levels all change drastically from low tide
to high tide in the intertidal zone
Aquatic environments
Important property of water—water
is densest at 4ºC
• Ice floats
• Warm water stays above cool water
• Salty water is denser than less salty water
Thermocline—the boundary
layer in the water between surface
warmer waters and deeper, cooler
waters, where the temperature
gradient is greater than that of
the warmer layer above and the
colder layer below.
Thermal stratification
• Stable in tropics yearround
• Upper waters are
warm, well-lit and
oxygen-rich
• Lower waters are
cold, dark, and
oxygen-poor
• Overturn occurs at
higher latitudes
• Oxygen is brought to
lower levels and
nutrients are brought
to upper levels
Overturn
• Vertical mixing of the water column in a
lake caused by temperature changes over
the seasons
Overturn in temperate lakes means they
tend to be quite productive (produce
biomass), compared to tropical lakes
Oceans--make up nearly three
quarters of the surface of the
earth but their boundaries are
less clear-cut than those of the
landmasses
Differences between terrestrial and
oceanic environments
• Major oceans are connected, unlike the continents
• Water is constantly moving and moves organisms with it
• Temperature, light, and other environmental gradients
along the horizontal axis tend to change more smoothly
and gradually than on land
• Depth--environmental gradients may be quite steep
along the vertical axis
• Plants do not provide physical structure in the oceans
Thermal and solar
stratification
Anchored plants only near surface
Deep water is very cold
Oceanic biomes
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Arctic
Subarctic
Northern Temperate
Northern Subtropical
Tropical
Southern Subtropical
Southern Temperate
Subantarctic
Antarctic
Vertical classification of oceanic
areas
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Continental shelf
Continental slope
Abyssal plain
Trenches
Water circulates horizontally in the
oceans
• Coriolis effect causes wind patterns which cause
currents or gyres.
• Current primarily flows clockwise in northern
hemisphere and counter-clockwise in southern
hemisphere
• Continent of Antarctica is enclosed by cold,
eastward flowing waters.
• Indian Ocean has complex current patterns
because of seasonal wind direction shift
Water also circulates vertically in
the oceans
• In polar regions there is bottom water
• In North Atlantic and Pacific, evaporation
leads to convergences
• Winds and upwelling
• Water also rises in areas of divergences
Complete vertical circulation
takes 275 years in Atlantic, 250
years in Indian Ocean, and 510
years in Pacific
We know little about marine
organisms
• Census of marine life
• Our knowledge of distributions of marine
organisms tends to be more primitive than
for terrestrial organisms
Areas of upwellings are areas
with rich fisheries
Fishery
• A place for catching fish
• Also, the occupation, industry, or season
of catching fish (or other sea creatures)
Most of the largest fisheries are based on
small fish like sardines and anchovies
• Nutrient-rich areas (often associated with
upwellings) like the coasts of California,
Japan, South Africa, Chile, and Argentina
have very productive fisheries in some
years
The productivity of these fisheries
fluctuates dramatically over time
• Catches may be huge for a decade or two
and then collapse and reappear 1-3
decades later
Global warming and cooling affect
productivity, perhaps through affects on food
sources
• Anchovies eat large zooplankton
• Sardines eat small zooplankton and
phytoplankton
Differences in mobility affect species’ ability
to respond to climate change
• Some species of sardines are migratory
and can move toward the poles during
warmer periods
• Some species of anchovies are not as
mobile
Hunting pressure also contributes
to declines
• Anchovies used for human consumption
• Anchovies also used to provide fish meal
for aquaculture systems
How do we determine distributions
of marine organisms?
• Example—Mesoplodon spp. or beaked
whales
Stranded specimens
• Sick animals may not behave normally
• Carcasses may be pushed great distances
• Identification of carcasses may be difficult