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 oceanic Horizontal divisions: Coastal (neritic) = on/over shelf (shallow) Oceanic = beyond continental shelf (deep) benthic shelf benthic abyss

Ocean Zones Vertical divisions: Pelagic = open water Epipelagic coastal oceanic Vertical divisions: Pelagic = open water Epipelagic (0-200m) Mesopelagic (200-1000m) Bathypelagic+ (1000m+) Benthic = ocean bottom benthic shelf benthic abyss

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 Tides are affected by both the moon and the sun Tidal day = 24 hours, 50 minutes

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

South Shore Bays http://www.estuary.cog.ny.us/index.html

Peconic Bay http://www.epa.gov/owow/estuaries/programs/studies/pb.gif http://www.peconicestuary.org/CCMP_PDF/Chpt4.habitat.pdf

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 Basins Deep 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://earthobservatory.nasa.gov/Study/Paleoclimatology_SedimentCores/Images/ocean_detritus.jpg http://www.deepseascape.org/index.php

Deep Ocean Bottom Hard bottom: Seamounts Ridges Deep coral reefs NOAA http://www.savethehighseas.org/photo_gallery.cfm?Cat=1

Hydrothermal Vents

Hydrothermal Vents High temperature High chemical concentrations High acidity http://www.dfo-mpo.gc.ca/communic/endeavour/photo_e.htm

Hydrothermal Vents 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 http://www.teara.govt.nz/NR/rdonlyres/E84896E2-2F7E-4D2A-9D46-366B50558303/87497/p5365dop.jpg http://oregonstate.edu/dept/ncs/photos/grazers.jpg

Cold Seeps 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 depth 700 m NOAA

Cold Seeps Chemosynthetic bacteria in mussels An oasis of food NOAA 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 Gulf Stream Sargasso Sea California Current

Density The density of water is a function of its temperature and salinity Density increases with lower temperature (until 4°C) ← Cold water (max. 1000 at 4°C) ← Warm water (958 at 100°C) ← Solid ice (917 at 0°C) ← Water vapor (1.2) 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

Density 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 ← Salty water (1027) ← Fresh water (1000) http://www.marietta.edu/~biol/biomes/physsal.gif

Density, Temperature, and Salinity 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 200 - pycnocline halocline

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

decomposition of organic matter Dissolved Gasses Highest at surface – mixing with air Oxygen minimum zone - decomposition of organic matter High at bottom – deep water formed at surface

Dissolved Gasses Hypoxia = low oxygen (<3 mg/l) Anoxia = no oxygen Stressful or deadly for marine life http://www.gulfhypoxia.net/overview/images/image005.png http://longislandsoundstudy.net/wp-content/uploads/2010/08/Hypoxia.jpg

Dissolved Gasses Hypoxia in Long Island Sound every summer http://longislandsoundstudy.net/wp-content/uploads/2010/07/freq-of-hypoxia-2011.jpg

Dissolved Gasses 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 http://theotherco2problem.files.wordpress.com/2009/11/ocean-chemistry.gif

Dissolved Gasses “Ocean acidification” Bad for organisms with calcium carbonate shells http://s.ngm.com/2007/11/marine-micro/img/ftr-hdr-acid.jpg http://www.ucar.edu/communications/Final_acidification.pdf

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 Ocean Epipelagic = 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 Pressure increases with increasing water depth 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 Before and after travelling to 2000 ft http://www.naturalsciences.org/education/deepsea/images/cups_before_after.jpg