The Marine Realm
The Marine Realm
The Marine Realm
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Chapter 4<br />
Environments<br />
and Life
What is your current classification?<br />
A. Freshman<br />
B. Sophomore<br />
C. Junior<br />
D. Senior
Guiding Questions<br />
• What factors determine the ecological<br />
niches of species, and by what means do<br />
species obtain nutrition?<br />
• What factors govern the geographic<br />
distribution of species?<br />
• What factors govern the distribution of<br />
aquatic life?
Environmental Differences<br />
• Tropical vs Polar - Terrestrial and <strong>Marine</strong><br />
• Low vs High Elevation<br />
• Shallow vs Deep<br />
• Wet vs Dry
Hypsometric Curve<br />
• Curve showing the proportions of the<br />
Earth’s surface above and below sea level
Hypsometric Curve
Climate<br />
• Climate<br />
– Controls distribution of species globally<br />
– Has changed through time<br />
• Plate tectonics and other changes affect<br />
climate
Ecology<br />
• Ecology<br />
– Study of the factors that govern the distribution and<br />
abundance of organisms in natural environments<br />
• Habitats<br />
– Environments on or close to Earth’s surface inhabited<br />
by life<br />
• Terrestrial<br />
• Aquatic<br />
– <strong>Marine</strong><br />
– Freshwater
Ecology<br />
• Ecologic niche<br />
– <strong>The</strong> way a species relates to its environment, including food,<br />
nutrients, physical and chemical conditions<br />
• Life habit<br />
– <strong>The</strong> way a species lives within its niche<br />
• Limiting factors<br />
– Naturally occurring, restricting condition (physical and chemical)<br />
– Competition<br />
• Shared drive for limited resources<br />
– Predation
Competition<br />
Arises because organisms share space<br />
Predation also comes in here by<br />
possibly limiting or preventing another<br />
species from inhabiting a particular<br />
environment.
Ecosystem<br />
• Ecosystem<br />
– Organisms of a community and the physical<br />
environment they occupy<br />
• Population<br />
– Group of individuals that belong to a single<br />
species and live together in a particular area
Ecosystem<br />
• Ecologic community<br />
– Populations of several species living in a habitat<br />
• Producers<br />
– Photosynthesizing organisms; foundation of community<br />
• Consumers<br />
– Herbivores: feed on producers<br />
– Carnivores: feed on other consumers
• Biota<br />
Ecosystem<br />
– Fauna: animals and protozoans of an ecosystem<br />
– Flora: plants and plantlike protists<br />
• Food chain<br />
– Sequence of consumption for producers to consumers
Food Web<br />
• Food web<br />
– More complex than simple food chain<br />
• More common<br />
– Several species occupy each level
Ecosystem<br />
• Parasites<br />
– Feed on living<br />
organisms<br />
• Scavengers<br />
– Feed on organisms<br />
that are already dead
Ecology<br />
<strong>The</strong> movement of materials through an ecosystem.<br />
Components within ovals are consumers.
Figure 4-35<br />
(p. 134)<br />
Interdependence<br />
of photosynthesis<br />
and respiration.
Figure 4-38 (p. 136)<br />
Simple pyramid of ocean life.
Biogeography<br />
<strong>The</strong> distribution and abundance of<br />
organisms on a broad geographic<br />
scale.
Biogeography<br />
• Temperature<br />
• Moisture<br />
• Nutrients
• Diversity<br />
Ecosystem<br />
– <strong>The</strong> variety of species that live together within a<br />
community<br />
• Lower in more difficult habitats<br />
• Predation influences diversity<br />
– Heavy can reduce diversity<br />
– Moderate can increase diversity by reducing competition<br />
• Opportunistic species<br />
– Species that specialize in invading newly vacated<br />
habitats
Biogeography<br />
• Distribution and<br />
abundance of<br />
organisms on a broad<br />
geographic scale<br />
• Limiting factors<br />
– Diversity increases<br />
toward equator<br />
– Barriers can affect<br />
dispersal
Life Habitats<br />
<strong>The</strong> mode by which an organism lives, feeds<br />
in an environment<br />
1. Tropical vs. Polar<br />
2. Low vs high altitude<br />
3. Shallow vs deep<br />
4. Benthic vs. Planktonic
Atmosphere<br />
• Regulates Earth’s<br />
temperature (-18°C w/o<br />
atmosphere)<br />
• Composition<br />
– N 2 , O 2 , CO 2<br />
• Tilt of the Earth affects<br />
solar insulation,<br />
temperature, and climate
In our present atmosphere,<br />
concentrations of O 2 and CO 2 are:<br />
A. O 2 > CO 2<br />
B. O 2 < CO 2<br />
C. O 2 = CO 2
<strong>The</strong> Atmosphere<br />
• Nitrogen -78%<br />
• Oxygen - 21%<br />
• Carbon dioxide (CO 2 ) - 0.037% or 370 ppm<br />
• Methane (CH 4 ) - 0.00018% or 1800 ppb
Solar Radiation<br />
Daylight<br />
Which receives more hours of daylight?<br />
Equator vs Poles<br />
<strong>The</strong> amount of daylight (# of hours) averaged<br />
over a year is the same at the poles as at the<br />
equator
Solar<br />
Radiation
Solar Radiation<br />
• Temperature difference is due to the angle<br />
of the sunlight and the albedo<br />
• In the high latitudes, the sun hits at a low<br />
angle and therefore the unit energy of<br />
sunlight is spread over a large crosssectional<br />
area of the earth’s surface. In the<br />
tropics, the sun hits directly and therefore is<br />
much more concentrated
Solar Radiation
Solar Radiation<br />
Albedo refers to the<br />
reflectivity of the Earth’s<br />
surface<br />
1. Snow and ice is very<br />
reflective - much of the<br />
solar radiation is reflected<br />
by to the solar system<br />
2. Water has a low albedo and<br />
absorbs a lot of the solar<br />
radiation
Solar Radiation
Solar Radiation
Solar Radiation<br />
• When do we have summers?<br />
• True or False<br />
• Summers on Earth occur when it passes<br />
closest to the Sun
Solar Radiation<br />
• Obliquity or Tilt (23.5°) of the to Earth’s<br />
rotational axis<br />
• This tilt gives us seasons. Summer is when<br />
the northern or southern hemisphere is<br />
point towards the Sun
• Regulates Earth’s<br />
temperature<br />
• Composition<br />
– N 2 , O 2 , CO 2<br />
• Tilt of the Earth<br />
affects solar<br />
insulation,<br />
temperature, and<br />
climate<br />
Atmosphere
Solar Radiation<br />
Heat Capacity
Movement of Air mass<br />
• Rises at Eq. and sinks near Poles<br />
• <strong>The</strong> high solar radiation at the equator heats<br />
the air masses, causing them to rise<br />
(buoyant).<br />
• As the air rises, the temperature of the air<br />
mass decreases
Atmospheric Circulation<br />
• Net transport<br />
– Air sinks at the poles,<br />
rises at the equator<br />
– Simplified model<br />
• No tilt<br />
• No Coriolis effect
Rising Air<br />
As the air rises, the temperature of the air mass<br />
decreases (adiabatic lapse rate 5°C/km)<br />
Cold air holds less water vapor. Voila, rain and the<br />
tropical rainforest. Low pressure systems<br />
usually have rain because the rising air drop<br />
water as the air ascends and cools
Rising Air
Atmospheric Circulation<br />
• Coriolis effect<br />
• Earth’s rotation<br />
causes air and water<br />
masses to be defected<br />
to the right<br />
(clockwise) in the<br />
northern hemisphere<br />
– Counterclockwise for<br />
southern hemisphere
Atmospheric Circulation<br />
• If we reverse the direction<br />
and launch a rocket from<br />
Panama towards<br />
Washington DC, which<br />
way will it curve?<br />
• A = Right<br />
• B = Left<br />
• C = Not at all because<br />
Panama is close to the Eq.
Coriolis force<br />
• Deflection of moving objects to the right in<br />
the No. Hemisphere and left in the So.<br />
Hemisphere
Coriolis<br />
Force
Atmospheric Circulation<br />
• Actual pattern is more<br />
complex<br />
– Three circulation cells<br />
– Trade winds, westerlies,<br />
easterlies<br />
• Intertropical convergence<br />
zone<br />
– Northern, southern trade<br />
winds converge near<br />
equator<br />
• Changes seasonally
Temperature Variations<br />
• Atmosphere retains<br />
heat<br />
• Solar radiation<br />
– Absorbed and turned<br />
into heat energy<br />
– Reflected<br />
• 6-10% ocean<br />
• 5-30% forest<br />
• 45-95% ice and snow
• As the dry air<br />
descending<br />
around 30°<br />
begins to<br />
flow back<br />
towards the<br />
Eq. it is<br />
deflected to<br />
the right.<br />
Trade winds
Trade winds<br />
As the dry air descending around 30° begins to flow back<br />
towards the Eq. it is deflected to the right.
Trade winds<br />
<strong>The</strong> NE and SE trades converge on the<br />
latitude where the maximum in<br />
convection (rising air) is occurring.<br />
This is the warmest location. Today,<br />
this is between 4 and 10°N and is<br />
termed the Inter-Tropical<br />
Convergence Zone (ITCZ)
<strong>The</strong> Terrestrial <strong>Realm</strong><br />
• Latitudinal Zones and Vegetation<br />
• Rain forests<br />
• Deserts<br />
• Savannah Grasslands<br />
• Temperate Forest<br />
• Conifer or Evergreen Forest<br />
• Tundra
Terrestrial <strong>Realm</strong><br />
• Vegetation follows<br />
climatic zone<br />
– Tropical rain forest<br />
– Desert savannahs<br />
– Temperate forests<br />
– Polar tundra
Terrestrial <strong>Realm</strong><br />
• Tropical Climates<br />
– 18–20° C (64–68° F)<br />
– 0–30° latitude<br />
• Tropical Rain Forest<br />
– Dense vegetation
Rain forests<br />
• develop under the<br />
tropical low<br />
pressure systems.<br />
Rising air dumps<br />
lots of rain. Found<br />
within a few<br />
degrees near the<br />
equator
Terrestrial <strong>Realm</strong><br />
• Deserts<br />
– Dry trade winds<br />
remove moisture<br />
– 20–30° north and<br />
south of the equator<br />
– < 25 cm rain/year<br />
– Little vegetation<br />
• Savannah, grasslands<br />
– Too dry to support<br />
forests
• (
Savannah Grasslands<br />
• found between Rain forest<br />
and Desert and receive<br />
seasonal rain falls. Not<br />
enough rain throughout the<br />
year to support woodland
Tundra<br />
- Arctic ecosystem where<br />
layer beneath soil remains<br />
frozen throughout the year.
Terrestrial <strong>Realm</strong><br />
• Poles<br />
– Defined by ice sheets<br />
and glaciers today<br />
– Absent or reduced at<br />
times in the past
Terrestrial <strong>Realm</strong><br />
• Glaciers<br />
– Ice in motion<br />
– Glide and spread<br />
– Present at high<br />
latitudes and high<br />
elevations near equator
Terrestrial <strong>Realm</strong><br />
• Tundra<br />
– Limited water<br />
– Grasses, sedges, lichens,<br />
shrubs dominate<br />
– Cannot support tall trees<br />
• Evergreen coniferous<br />
forests<br />
– South of tundra<br />
– Spruce, pine, fir
Terrestrial <strong>Realm</strong><br />
• Temperate forests<br />
– Longer summers, slightly warmer<br />
– Deciduous trees<br />
• Maples, oaks, beeches<br />
• Mediterranean climate<br />
– Dry summers, wet winters<br />
– Common 40° N and S of equator<br />
• Californian, Mediterranean region
Climate<br />
• Altitude<br />
– Similar to latitudinal<br />
gradient<br />
– At base<br />
• Deciduous forest<br />
– On slopes<br />
• Evergreen forest<br />
• Tundra above tree-line<br />
– At top<br />
• Glaciers
Climate<br />
• Mountains<br />
• Rain shadow<br />
– Prevailing winds bring<br />
moisture<br />
• Precipitation on<br />
windward side<br />
• Aridity on leeward side<br />
– Rain shadows common<br />
on east side of North<br />
American mountain<br />
chains
Climate<br />
• Seasonal Change<br />
– High heat capacity of<br />
water<br />
• Less change in ocean<br />
temperatures than on<br />
land<br />
• Monsoon Circulation<br />
– Summer winds flow<br />
onshore; bring rain<br />
– Winter winds offshore
Plants as Climate Indicators<br />
• Sensitive indicators of<br />
change<br />
– Cycads<br />
• Tropics and subtropics<br />
today<br />
• Fossil distribution<br />
allows reconstruction<br />
of climate patterns
Plants as Climate Indicators<br />
• Leaf Margins<br />
– Tropics<br />
• Smooth, waxy margins<br />
– Temperate climates<br />
• Jagged margins
• Ocean currents<br />
– Wind driven<br />
– Follow atmospheric patterns<br />
• Trade winds<br />
– Push waters west; form<br />
equatorial currents<br />
– Equatorial countercurrents<br />
• Return flow<br />
• Gyres<br />
– Clockwise in Northern<br />
Hemisphere<br />
– Gulf Stream<br />
<strong>Marine</strong> <strong>Realm</strong>
<strong>Marine</strong> <strong>Realm</strong><br />
• Circumpolar current<br />
– Circles Antarctica<br />
– Very cold
<strong>Marine</strong> <strong>Realm</strong><br />
• Polar circulation<br />
– Sea ice leads to more<br />
saline water<br />
– Cold, dense waters<br />
sink<br />
– Antarctic waters<br />
• Flow north at depth<br />
– Arctic waters<br />
• Flow south at depth
<strong>Marine</strong> <strong>Realm</strong><br />
• Ocean circulation<br />
– Waves<br />
• Surface waves<br />
– Wind driven<br />
– Break when seafloor interacts at shallow depths<br />
– Tides<br />
• Cause major movement of water in oceans<br />
• Due to rotation of solid Earth beneath bulges of<br />
water produced by gravitational attraction of the<br />
moon
<strong>Marine</strong> <strong>Realm</strong><br />
• Continental Shelf<br />
– Submarine extension of<br />
continental landmass<br />
• Shelf break<br />
– Edge of shelf<br />
• ~200 m w.d.<br />
• Continental Slope<br />
• Continental Rise<br />
• Abyssal Plain
Figure 4-31 (p. 131)<br />
Classification of marine environments.<br />
(After Hedgspeth, UJ. W., ed. 1957. Treatise of <strong>Marine</strong> Ecology and Paleoecology. Geological Society<br />
of America Memoirs 67(1): 18.)
<strong>The</strong> <strong>Marine</strong> <strong>Realm</strong><br />
• <strong>The</strong> depth of the Sea<br />
• Moving from the beach seaward, one crosses a<br />
consistent pattern of water depth changes. <strong>The</strong><br />
continental shelf extends from the shoreline to<br />
the continental shelf break. Water depths over<br />
the shelf vary from 0 to ~200 m. This<br />
environment is very important for benthic<br />
communities because the photic zone in the<br />
ocean extends only down to 200m. Consider the<br />
implications for primary production
<strong>The</strong> <strong>Marine</strong> <strong>Realm</strong><br />
• <strong>The</strong> Shelf break marks the distal edge of<br />
the shelf where seaward of this point, water<br />
depths increase at a greater rate (3 to<br />
5°slope) compared with the shelf (1 to<br />
2°slope).
<strong>The</strong> <strong>Marine</strong> <strong>Realm</strong><br />
• Continental Slope.<br />
• Typically, the slope extends down to 3000<br />
to 3500 m. Near the base of the slope is the<br />
transition from continental to oceanic crust.
<strong>The</strong> <strong>Marine</strong> <strong>Realm</strong><br />
• <strong>The</strong> Slope gives way to the Continental<br />
Rise. This is a less steep surface that<br />
segways to the Abyssal Plain (the ocean<br />
floor). <strong>The</strong> Rise is created as sediments are<br />
transported down the slope in turbidity<br />
currents.
<strong>The</strong> <strong>Marine</strong> <strong>Realm</strong><br />
• At the base of the slope and out on the<br />
abyssal plain, the slope decreases<br />
significantly and the sediments are<br />
dropped, forming the Rise
Figure 4-31 (p. 131)<br />
Classification of marine environments.<br />
(After Hedgspeth, UJ. W., ed. 1957. Treatise of <strong>Marine</strong> Ecology and Paleoecology. Geological Society<br />
of America Memoirs 67(1): 18.)
<strong>Marine</strong> <strong>Realm</strong><br />
• Near shore<br />
– Barrier islands<br />
– Marshes<br />
– Epicontinental seas
• Photic Zone<br />
– Region of ocean where<br />
enough light penetrates to<br />
permit photosynthesis<br />
• Pelagic life<br />
– Plankton<br />
• Phytoplankton<br />
• Zooplankton<br />
– Nekton<br />
• Benthic life<br />
– Suspension feeders<br />
– Deposit feeders<br />
<strong>Marine</strong> <strong>Realm</strong>
<strong>Marine</strong> <strong>Realm</strong><br />
• <strong>Marine</strong> Biogeography<br />
– Tropical<br />
– Subtropical<br />
– Transitional<br />
– Subarctic
Figure 4-36 (p. 135)<br />
Major ocean surface currents.
<strong>Marine</strong> <strong>Realm</strong><br />
• Corals<br />
– Most require warm water<br />
– Common in tropics<br />
• Reef builders<br />
– Coral polyp<br />
– Builds coral cup<br />
– Connected to other polyps<br />
• Symbiotic relationship<br />
with algae
• Salinity<br />
<strong>Marine</strong> <strong>Realm</strong><br />
– Limiting factor near shore<br />
– Oceanic<br />
• 35 ppt<br />
– Brackish<br />
• Lower than marine<br />
• Bays, lagoons<br />
– Hypersaline<br />
• Higher than marine<br />
• Hot arid climates
<strong>The</strong> portion of the temperature-depth curve in the<br />
ocean that shows maximum change is the thermocline.
Deep Water Circulation
Atmospheric Circulation<br />
• If we reverse the direction<br />
and launch a rocket from<br />
Panama towards<br />
Washington DC, which<br />
way will it curve?<br />
• A = Right<br />
• B = Left<br />
• C = Not at all because<br />
Panama is close to the Eq.