Chapter 13 Exploring the Oceans

Chapter 13.1 Major Divisions of the Global Ocean

History of Earth’s Oceans Oceans formed 4.8 bill. yrs ago -The Solar System was only 1 bill. yrs. Old x -Earth was hot rock w/out a trace of water ! -volcano gases & ash formed atmosphere ! - Earth cooled & water vapor condensed ! -Water came from 2 sources: 1. bombardment by comets X 2. gases (ammonia, water vapor, carbon dioxide) in atmosphere which came from volcanic activity ! -Water stayed in gaseous form until surface cooled ! -4.8 bill yrs ago water condensed into rain & collected into low lying areas ! -18,000 yrs ago most of ocean was frozen in glaciers & ice caps X -5 oceans of today formed within last 300 mill yrs !

Properties of Ocean Water -Running water carried dissolved minerals on land to oceans -Evaporation of ocean water leaves solids behind (chlorine, sodium, magnesium, sulfur, potassium, & calcium) -Most abundant solid is sodium chloride (NaCl or SALT) -Salts have been added to ocean for bill of yrs -A measure of the amount of solids in a given amount of liquid is called salinity (measured in grams of dissolved solids per killograms of water

What Affects Salinity? 1. Climate coastal, warm waters have hot, dry climate and high salinity b/c heat increases evaporation coastal, cool waters have low salinity 2. Water movement slow moving water (bays, gulfs, seas) have high salinity 3. Temperature Zones ocean temp decreases as depth & pressure increases *Rainfall decreases salinity near the surface.

The Dead Sea, located between Israel & Jordan, is so dense (35% salinity) that a human can float

The Ocean’s Temperature Zones Pg. 377 Draw a graph of the 3 temp zones -the depth of each zone -the temp of each zone UNDER WATER PRESSURE: -At sea level air pressure is 1 atmosphere (atm) -Under water pressure increases at the rate of 1 atm every 10 m of depth (Ex. at zero m, water pressure is 1 atm; at 10 m, water pressure is 2 atm) Practice: If the ocean’s average depth is 3.8 km, what is the pressure at the bottom of the ocean?

Interactions Between the Ocean & the Atmosphere Water, land, & air interact in the Water Cycle--- (a continuous movement of water) sunlight heats ocean (evaporation) into water vapor rising to the atmosphere where it changes from a gas to a liquid(condensation) & gets heavy enough to fall as precipitation The ocean absorbs & releases thermal energy slowly into the atmosphere thus keeping our weather stable & regulating temp. If not for this, Earth would experience extreme weather conditions. (Ex. 100 degrees C during day & -100 degrees C at night)

Chapter 13.2 The Ocean Floor Technologies for studying the ocean floor: Sonar—sound pulses from ships to ocean floor & back (longer it takes for sound to bounce off ocean & return, the deeper the ocean floor) Scientists calculate depth by multiplying ½ the travel time by speed of sound in water, which is 1500 m/s. Satellites—covers more territory & more accurate than Sonar. Launched Seasat which measured direction & speed of ocean currents & Geosat which measures slight changes in height of ocean surface over underwater features.

Technologies continued Piloted underwater vessels -Alvin—recovers & discovers unique ecosystems (ex. tubeworms) -Deep flight underwater airplane—take pilots to depths of 11,000 m

Technologies continued Robotic vessels Jason II and Medea—pilot on surface guides Medea which is tethered to it & can take pressure of deepest parts of ocean floor.

Two Major Ocean Floor Regions Continental Margin: continental shelf, slope, & rise

Two Major Ocean Floor Regions Deep-Ocean basin: abyssal plain, mid-ocean ridges, rift valleys, sea mounts, ocean trenches

Chapter 13.3 Life in the Ocean 3 Groups of Marine Life Plankton: microscopic animal-like & plant-like float near ocean’s surface Nekton swim actively in open ocean mammals, whales, dolphins Benthos live on/near ocean floor crabs, starfish, coral

2 Major Marine Environments & Their Ecological Zones 1. Benthic environment-region on bottom of ocean floor & all organisms that live on/in it. Intertidal Zone: shallowest zone; located btwn low & high tide ; organisms can live both on land & in water Sublittoral Zone: from low tide to edge of shelf; temp, pressure, sunlight remain constant Bathyal Zone: edge of cont. shelf to abyssal plain; plants scarce, animals include sponges, sea stars, octopuses Abyssal Zone: largest; on abyssal plain; no plants, few animals (worms, crabs, sea cucumbers) Hadal Zone: deepest; floor of trenches, know little about few animals

2 Major Marine Environments & Their Ecological Zones 2. Pelagic environment-near surface & middle depths-beyond sublittoral zone & above abyssal zone Neritic Zone: covers cont. shelf; warm & sunlight; largest concentration of marine life Oceanic Zone: entire ocean beyond the shelf; cold water ; high pressure; marine life spread out; strange animals in dark, deep depths

Chapter 13.4 Resources from the Ocean Ways humans harvest living resources from the ocean Fishing the ocean-75 million tons of fish caught using drift nets Farming the ocean-raise ocean fish, oysters, shrimp & crabs in holding ponds Harvested kelp (seaweed)from the ocean-rich in protein; used as thickener in jellies & ice cream

3 Nonliving Resources in the Ocean Nonrenewal resources: (used up faster than can be replenished naturally) ex. oil & natural gas-must drill under layers of impermeable rock ; use seismic tools to find oil Water-remove salt thru desalination; costly Minerals-nodules on deep ocean floor contain manganese, iron, copper, nickel, cobalt ; costly Tidal energy-renewable (replenished in time) power generated from movement of tide; clean, inexpensive; limited to coastlines with shallow, narrow channels Wave energy-renewable; generates clean electricity in certain areas

Chapter 13.5 Ocean Pollution Nonpoint-source pollution: comes from many sources: oil/gasoline from cars/boats & pesticides/fertilizers from yards/gulf courses leak into sewers/waterways Point-source pollution: comes from 1 source oil tanker/factory/wastewater treatment plant 3 Types of point-source pollution Trash dumping-can affect organisms (plastic materials) Sludge dumping-raw sewage solids can pollute beaches Oil spills-can harm animals, plants, people

Controlling Ocean Pollution International treaties signed by 64 countries-1989 treaty prohibits dumping of metals, plastics, oils, & radioactive waste Volunteer cleanups-1980 citizens organized beach cleanups 1972 U.S. Laws: the Clean Water Act & the US Marine Protection, Research, & Sanctuaries Act