Download InAConchShell - some tryout study material

Oceanography in a Conch Shell
Arcadia HS OSB
History
Just research the crucial accomplishment of the notable figures.
There are three major stages in the history of ocean research:
• Ocean exploration was the period when people explored the
ocean boundaries. Notable explorers include: The Phoenicians,
Pytheas, The Polynesians, Herodotus, the Vikings, Bartholomew
Diaz, Vasco de Gama, Ferdinand Magellan and Sebastian del
Cano.
• Early scientific investigations began when people began to
describe the ocean. Notable scientists include: James Cook,
Matthew Fontaine Maury, Charles Darwin, C. Wyville
Thomson, and Fridtjof Nansen. Also Alfred Wegener.
• Modern oceanography (oceanology) began in the twentieth
century with interdisciplinary oceanic research and use of
complex scientific instruments.
Continental margin
Planet and Basins
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Ocean basin: large portion of oceanic floor that lies deeper than
2000 meters.
The Earth’s internal spheres: inner core, outer core, mantle
(mesosphere + asthenosphere), crust (lithosphere)
3 bathymetric provinces: continental margins, deep-ocean
basins, midocean ridges. (See figures right)
Types of rock: granite (land), basalt (ocean), andesite (mix)
Isostasy: principle of mass balance; why landmasses and basins
exist.
Important concepts: continental drift (Pangaea), sea-floor
spreading (magnetic anomalies, subduction zones), plate
tectonics
Deep-ocean basin
Midocean ridge
Sediments
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Classification by grain size: colloid, mud (clay & silt), sand,
gravel
Classification by formation: terrigenous, biogenic (calcareous &
siliceous), authigenic (ferromanganese nodules, phosphorite),
volcanogenic, cosmogenous
Factors that control sedimentation include particle size and the
turbulence of the depositional environment.
Processes include bulk emplacement (slumps, slurries, turbidity
currents)
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As wind moves across the water, collision of air molecules with
water molecules inefficiently transfers energy from the air to the
water (water moves 3-4% of wind speed).
Coriolis deflection: Earth’s rotation causes moving objects
relative to the ground to be deflected to the right in the Northern
hemisphere and to the left in the Southern hemisphere.
Seawater
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Properties: high heat capacity, solvent power, covalent bond,
salinity (average 35 ppt, saltier termed brine). Seawater most
dense at 4 degrees C, freezes at -2. Also pH (acidic, basic,
buffers).
Concentration of solute in seawater measured in ppt (parts per
thousand, also ppm, ppb). There are major constituents,
nutrients, gases, and trace elements. Residence time: average
time ion remains in solution in oceans.
Principle of Constant Proportion
Gradients: thermoclines (temperature), haloclines (salinity),
pycnoclines (density)
Anoxic: no dissolved oxygen (no photosynthesis/respiration,
rather anaerobic bacteria).
Desalination: distillation, freezing, reverse osmosis,
electrodialysis, salt absorption
Hydrologic cycle (evaporation, condensation, etc.)
Circulation (Find diagrams, difficult concepts)
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Winds are created by fluids flowing from zones of high to low
pressure (pressure gradient)
Wind direction indicates what direction the wind comes from.
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Global wind circulation
Ekman Spiral: flow pattern driven by Coriolis effect and
frictional drag on water column varying with depth. Net
transport (Ekman transport) 90 degrees to right/left of wind.
Upwelling: rising of bottom water; downwelling: sinking of
surface water.
Langmuir circulation is a complex horizontal helical (spiral)
motion that extends parallel to the wind.
Geostrophic currents: steady flow resulting from a dynamic
balance between pressure gradient and Coriolis deflection.
Because Earth rotates from west to east, water pressed up against
western sides of ocean basins cause western boundary
intensification.
Warm and cold-core rings: large swirling eddies circulating
clockwise and counterclockwise, to the west and east of the Gulf
Stream.
Deep-ocean currents, or thermohaline circulation, is a result of
density differences.
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No need to memorize specific global currents at this stage, but
here they are: http://www.jochemnet.de/fiu/GlobalCurrent.jpg
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Waves
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Progressive waves: move in a direction; standing waves:
oscillate back and forth.
Wave base: depth of ½ wavelength; if water deeper than this
then deep-water wave; else if depth greater than 1/20 of
wavelength intermediate-water wave; else shallow-water wave.
Waves are the undulatory motion of a water surface.
Wave Parameters (missing T, wave period)
Celerity (wave speed) = L/T
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Wave Spectrum
Capillary waves: smallest, water restored by surface tension;
seiche: standing wave; tsunami: seismic sea waves
Wind-generated waves controlled by 4 factors: wind velocity,
wind duration, fetch (area wind blows over), and original sea
state.
Fully developed sea: name says what it means; significant wave
height: average of top 1/3.
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Wave orbitals
Constructive interference: crests coincide; may lead to rogue
waves. Destructive interference: crests and troughs coincide.
Dispersion: process of wave separation
In shallow-water, waves slow down, wavelengths decrease,
heights increase, period remains constant.
Refraction: bending of waves so they hit shoreline orthogonally.
When H/L (steepness of wave) reaches 1/7, the wave collapses
as a breaker. The three types of breakers are spilling, plunging,
and surging.
Standing waves diagram below:
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are progressive, 3. Water always in equilibrium with tidegenerating forces.
Accurate model termed dynamic model of tides. Budges become
rotary waves (like water swirling in cup) in an amphidromic
system (tide rotates about fixed node).
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Flood currents transfer water toward coast, ebb currents away.
Tides
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Tides: waves with very long wavelengths that cause the sea level
to rise and fall daily.
Tidal range: vertical distance between high tide (crest) and low
tide (trough).
Tides can be diurnal (period: 1 day, actually 24 hr 50 min) or
semidiurnal (recur twice daily, 12 hr 25 min), or mixed
When tidal amplitude greatest, it’s called spring tide; when
lowest, it’s called neap tide.
Tides originate from gravitational attraction (mainly Moon) and
centrifugal force
Left bulge from centrifugal, right from moon
Equilibrium (simplified) model of tides assumes: 1. Earth
completely covered with water of infinite depth, 2. Tidal waves
Shorelines
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Coastal Zone
Longshore currents: in surf zone, flow parallel to shoreline.
Rip current: a narrow, swift, seaward flowing current along
show that drains water from surf zone.
Sand budgets: estimates of sand sources and losses; inputs:
longshore transport in, river supply, cliff erosion, and onshore
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transport; outputs: longshore transport out, offshore transport,
wind transportation into dunes; balance: accretion, erosion,
steady-state.
Barrier islands: large deposits of sand separated from the
mainland. Barrier islands are created in many ways including:
sand ridges isolated by rising sea level, sand spits breached
during a storm, and the vertical growth and emergence of
longshore sand bars.
Storm surge: extraordinary high water level that floods and
erodes shore.
Estuary: partially enclosed body of water where freshwater is
mixed with salt-water. They form through various processes
(drowned river valley, fjords, bar-built, tectonic) and can be
categorized into salt-wedge, partially mixed, and well-mixed.
A delta is an accumulation of sediment deposited at the mouth of
a river as it flows into a standing body of water. They can be
river-dominated (Mississippi), wave-dominated (San Francisco),
or tide-dominated (Colorado, Ganges-Brahmaputra).
Human coastal engineering structures include groins, jetties,
breakwaters, and seawalls.
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There are also the light zones: photic, dysphotic (twilight), and
aphotic.
Coastal Habitats
Coral reefs
Habitats
Continental shelf
Open ocean
Deep-sea bottom
Estuaries – crossroads between freshwater
rivers and saltwater oceans; low species
diversity but high carrying capacity, very
fertile.
Salt marshes – plant-covered, intertidal
fringes of coastlines; very productive, serve
as nursery grounds
Mangrove swamps – dense tree growths of
tropical and subtropical shorelines;
mangrove is a large woody, tree-like plant
with thick partially exposed network of
intertwined roots; detritus food chain.
Organic, wave-resistant rock (largely
calcium carbonate / limestone) structures
created by carbonate-secreting animals and
plants, covered with living veneer;
spectacular biodiversity. Hermatypic corals
and zooxanthellae have a mutualistic
relationship. Types: fringing reef  barrier
reef  atoll.
Relatively fertile, neritic (waters) and
sublittoral (shelf bottom) zones
Nutrient poor, sparse life; however, diverse
biota.
No light, very cold, high hydrostatic
pressure, sparse food; life still exists
everywhere.
Biota
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Classified by lifestyle: plankton – drifters; nekton – active
swimmers; benthos – attached/move on seafloor.
Plankton
Biozones
Algae (mostly phytoplankton) form 90% of ocean
plants and photosynthesize.
Nekton
Benthos
Diatoms are encased by frustrules, consisting of the
epitheca and hypotheca, and cause diatom blooms.
As swimmers fish must overcome surface drag +
form drag + turbulent drag (tuna’s shape minimizes
all three). Speed of fish proportial to shape of
caudal (tail) fin. Aspect ratio of fin = H^2/A.
Swimming specialties: cruising, maneuverability,
and rapid acceleration.
Arranged in vertical zonation, consist of epifauna
(live on top of floor) and infauna (live inside
substrate). Deposit feeders process mud to get
mixed in organics.
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Humans
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For a taxonomic table of marine organisms and pictures, see
pages 5-17 of:
www.eos.ubc.ca/courses/eosc112/S07/Lec/EOSC112_BO_2007.
pdf
Ecology
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In ecosystems, temperature is the single most important
regulator.
Salinity necessitates osmoregulation (research how freshwater
and saltwater fish handle differing salinities)
Hydrostatic pressure (weight of water column) also causes
adaptations such as gas-filled deep-ocean inhabitants.
Very general knowledge of following terms assumed:
ecosystem, autotroph, heterotroph, trophic levels (10% energy
passed to each level above), herbivore, carnivore, omnivore,
food chain/web, photosynthesis (takes CO2, produces oxygen),
respiration (inverse of photosynthesis), grazer, predators,
scavengers, filter feeders, deposit feeders, decomposers.
Net primary productivity: amount of carbon fixed by
photosynthesis minus amount demanded by respiration.
Compensation depth: depth below which there is no
photosynthesis; do not confuse with Carbon compensation depth
(CCD): depth below which material composed of calcium
carbonate is dissolved and does not accumulate on the sea).
Least to most productive: open ocean, continental shelves,
upwelling areas/deep estuaries, shallow estuaries/coral reefs.
El Niño: episodic (3-5 years) war current that usually appears
around Christmas off the coasts of Ecuador and Peru which
decimates the indigenous organism populations.
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Pollutants concentrate in three primary areas: seafloor,
pycnoclines, and the surface neuston layer.
Hydrocarbons (oil spills), industrial effluents (sewage, metals,
and artificial biocides such as DDT and PCBs)
Ocean dredging and mining are two examples of human
exploitation of the oceans.
Bioaccumulation: process of chemical substance building up in
an organism; biomagnification: accumulation and amplification
of chemical substances over succeeding trophic levels;
bioremediation: use of organisms (such as bacteria) to clean up
an oil spill.
Eutrophication: process whereby water becomes anoxic because
it is choked with decomposing organic matter (such as that in
sewage).
Additional Reading
For those of you who really want to give former OSB members a run for
their money ;) http://www.amscopub.com/free_downloads.html?CID=11 covers
marine biology more in depth. This will not be emphasized though.