oceanography
DESCRIPTION
Oceanography. http://antwrp.gsfc.nasa.gov/apod/image/earth_1_apollo17_big.gif. The Oceans. Ocean Facts: Covers 71% of the earth’s surface Accounts for 97% of the water on earth (rest in land ice, groundwater, lakes & rivers) Average depth ~ 4,000 meters Average temp ~ 4 o C (only 39 o F) - PowerPoint PPT PresentationTRANSCRIPT
Oceanography
http://antwrp.gsfc.nasa.gov/apod/image/earth_1_apollo17_big.gif
The Oceans
Ocean Facts: Covers 71% of the earth’s surface Accounts for 97% of the water on earth
(rest in land ice, groundwater, lakes & rivers)
Average depth ~ 4,000 meters Average temp ~ 4oC (only 39oF) Average salinity ~ 35‰ = 3.5%
(1 meter = 3.3 feet)
The Oceans
Ocean Zones
Horizontal divisions: Coastal (neritic) = on/over shelf (shallow) Oceanic = beyond continental shelf (deep)
benthicshelf
oceaniccoastal
benthicabyss
Ocean Zones
Vertical divisions: Pelagic = open
water Epipelagic
(0-200m) Mesopelagic
(200-1000m) Bathypelagic+
(1000m+) Benthic = ocean bottom
benthicshelf
oceaniccoastal
benthicabyss
Continental Margins
Continental shelf As narrow as <1 km (0.6 mi) at active
margins (tectonic activity) As wide as >750 km (470 mi) at passive
margins (in middle of plates) Shallow, typically <200 m (600 ft) Only 8% of ocean surface, but biologically
richest part of ocean
Continental Shelf Intertidal zone (between high and low tides) – open, exposed
Sandy shores (Atlantic – Cape Cod and south) Rocky shores (most Pacific, Atlantic – north of Cape Cod)
Continental Shelf Intertidal zone (between high and low tides) – protected, muddy
Salt marshes (temperate) Mangrove forests (tropical)
Tides are affected by both the moon and the sun Tidal day = 24 hours, 50 minutes
Tides
Tides
Continental Shelf Estuaries - any semi-enclosed coastal area where freshwater and seawater meet and mix
Long Island Sound
http://www.epa.gov/region01/eco/lis/facts.html
http://www.estuary.cog.ny.us/index.html
South Shore Bays
http://www.epa.gov/owow/estuaries/programs/studies/pb.gif
http://www.peconicestuary.org/CCMP_PDF/Chpt4.habitat.pdf
Peconic Bay
Continental Shelf Subtidal zone (always underwater)
Soft-bottom (sand, mud) Unvegetated Seagrass beds
NOAA
Continental Shelf Subtidal zone (always underwater)
Hard-bottom Seaweed, kelp forests Coral reefs
Continental Margins
http://oceanexplorer.noaa.gov/explorations/02hudson/background/mapping/mapping.html http://soundwaves.usgs.gov/2005/01/research.html
Deep-Ocean BasinsDeep sea floor features: Averages ~4000m (13,000 ft, 2.5 mi)
http://oceanworld.tamu.edu/resources/ocng_textbook/chapter03/Images/Fig3-6.jpg
Deep Ocean Bottom Soft bottom (most common):
Abyssal plains Silt, clay, biogenic oozes (forams, diatoms, radiolarians)
http://www.deepseascape.org/index.phphttp://earthobservatory.nasa.gov/Study/Paleoclimatology_SedimentCores/Images/ocean_detritus.jpg
Hard bottom: Seamounts Ridges Deep coral reefs
NOAA
http://www.savethehighseas.org/photo_gallery.cfm?Cat=1
Deep Ocean Bottom
Hydrothermal Vents
Hydrothermal Vents
http://www.dfo-mpo.gc.ca/communic/endeavour/photo_e.htm
High temperature High chemical concentrations High acidity
Chemosynthesis – energy from chemicals, not the sun
Chemosynthetic bacteria, archaea:
Outside on rocks Inside some animals (tube worms, mussels, clams)
An oasis of warmth and food for other animals
Hydrothermal Vents
http://www.teara.govt.nz/NR/rdonlyres/E84896E2-2F7E-4D2A-9D46-366B50558303/87497/p5365dop.jpg http://oregonstate.edu/dept/ncs/photos/grazers.jpg
Brine pools: Gulf of Mexico was shallow sea that dried up in Jurassic period Thick layer of salts covered with sediment when seawater returned Salt seeps up through cracks in sediment
NOAA
Cold Seeps
Brine pools: Underwater lakes of super salty water Methane gases also seep out
NOAA
depth 700 m
Cold Seeps
Cold Seeps
NOAA
Chemosynthetic bacteria in mussels An oasis of food
http://dx.doi.org/10.1371/journal.pbio.0030102
Water
Water is unique and critical for life Viscous, thick medium Slow to heat up & cool down, regulates climate Exists in 3 states on earth Maximum density at 4°C, not 0°C (ice floats, insulates) Universal solvent
Seawater
Seawater is a complex solution of dissolved ions and other dissolved solids and gasses
Salinity Salinity = the total amount of dissolved salts in water Average amount = 35 g salt/1000 g seawater = 3.5%
= 35‰ (parts per thousand) Can be 0‰ at river mouths and >40‰ in parts of Red
Sea
Salts in Seawater
major
minor
Temperature
Califo
rnia C
urren
t
Gul
f Str
eam
SargassoSea
The density of water is a function of its temperature and salinity Density increases with lower temperature (until 4°C)
Density
http://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Density_of_ice_and_water_%28en%29.svg/573px-Density_of_ice_and_water_%28en%29.svg.png
← Cold water (max. 1000 at 4°C)
← Warm water (958 at 100°C)
← Solid ice (917 at 0°C)
← Water vapor (1.2)
The density of water is a function of its temperature and salinity Density increases with higher salinity Cold salty water is the densest of all
Density
http://www.marietta.edu/~biol/biomes/physsal.gif
← Salty water (1027)
← Fresh water (1000)
3 stratified layers according to density: Surface mixed layer (epipelagic)
Mixed by wind and waves Warmer and less dense Up to 200m deep
Intermediate transition layer (mesopelagic) Deep stable layer (bathypelagic & beyond)
Colder and denser Below 1000m
Density, Temperature, and Salinity
Density, Temperature, and Salinity
pycnocline
halocline
200 -
Density, Temperature, and Salinity
Dissolved Gasses Most gases easily dissolve in seawater, but ocean proportions differ greatly from atmospheric proportions Carbon dioxide is very soluble (0.039% of atmosphere, 15% of gases in ocean) Oxygen is not very soluble (much less than in atmosphere) Unlike solids, gases dissolve better in cold water, so all gas concentrations are higher in the polar waters than the tropics
Dissolved Gasses
Oxygen minimum zone -
decomposition of organic matter
Highest at surface –mixing with air
High at bottom –deep water formed at surface
Dissolved Gasses
http://longislandsoundstudy.net/wp-content/uploads/2010/08/Hypoxia.jpghttp://www.gulfhypoxia.net/overview/images/image005.png
Hypoxia = low oxygen (<3 mg/l) Anoxia = no oxygen Stressful or deadly for marine life
Dissolved Gasses
Hypoxia in Long Island Sound every summer
http://longislandsoundstudy.net/wp-content/uploads/2010/07/freq-of-hypoxia-2011.jpg
Dissolved Gasses
http://theotherco2problem.files.wordpress.com/2009/11/ocean-chemistry.gif
Increased CO2 in air → more in the ocean Increase in H+ ions makes water more acidic,
pH 8.2→8.1, expected 7.6-7.8 by 2100
Dissolved Gasses
http://www.ucar.edu/communications/Final_acidification.pdf
“Ocean acidification” Bad for organisms with calcium carbonate shells
http://s.ngm.com/2007/11/marine-micro/img/ftr-hdr-acid.jpg
Dissolved Gasses
http://3.bp.blogspot.com/-9MpFK0zekqo/T-s8Mzm9qjI/AAAAAAAAB-c/5zsexadUp8A/s1600/oceanacidification.jpg
Light in the Ocean
Most sunlight does not penetrate very far into the ocean
transparency depends upon suspended matter deeper in tropics, less in coastal
Blocked by scattering and absorption Different colors penetrate to different depths
NOAA
Light in the Ocean
Light in the OceanEpipelagic = photic zone(bright light, all plants/algae)
Mesopelagic = twilight zone(little light, no plants/algae)
Bathypelagic = aphotic zone (no light, no plants/algae)
Pressure in the Ocean
Water is heavier than air Pressure increases with increasing water depth Sea level = 1 atm. of pressure In ocean, each 10m of depth (33ft) you add another atm. of pressure
Pressure in the Ocean
http://www.naturalsciences.org/education/deepsea/images/cups_before_after.jpg
Before and after travelling to 2000 ft