1. Spring 2014

2. Properties of Ocean Water  Physical properties of ocean water Temperature Density Color  Chemical Properties Determine its composition Enable the ocean to dissolve other substances

3. Properties of Ocean Water  Composition of Ocean Water Salts enter the ocean from rivers and streams Gases enter the ocean from rivers, streams, & directly from the atmosphere Elements in Ocean Water ○ 95.6% pure water ○ 75 chemical elements 6 most abundant: chlorine, sodium, magnesium, sulfur, calcium, & potassium

4. Properties of Ocean Water  Dissolved Gases 3 most common ○ Nitrogen ○ Oxygen ○ Carbon dioxide Higher temperature= less dissolved gases Lower temperature= more dissolved gases Exchange of gases between the atmosphere & the ocean is a constant thing

5. Properties of Ocean Water  Salinity The number of grams of dissolved solid per volume of liquid ○ Called salinity most dissolved solids are salts 78% of the dissolved salt in the ocean is NaCl (sodium chloride) Increased by both evaporation & freezing Salinity varies by depth Because the ocean is constantly mixing the average salinity is similar all over the globe

6. Properties of Ocean Water  Temperature Surface Temperture ○ Movement of water throughout the ocean thoroughly mixes the warmed surface water Distributes heat downward (100m – 300m) Temperature of this zone is relatively constant ○ Temperature decreases with increasing latitude Poles have colder surface temp than the middle latitudes -Ice pack- floating layer of sea ice that covers the surface of the ocean in both the Arctic & Antarctic during parts of the year

7. Properties of Ocean Water  Temperature Thermocline ○ Zone of rapid temperature change ○ Exists because water near the surface that is heated by the sun is less dense than the colder deeper water ○ Changing temperature or shifting currents may alter the depth or cause it to disappear completely

8. Properties of Ocean Water  Density Mass of a substance per unit of volume 2 factors affect the density of ocean water: ○ Salinity The large amount of dissolved solids in ocean water makes it more dense than fresh water ○ Temperature Water becomes more dense as it get colder ***Affects density more than salinity

9. Properties of Ocean Water  Color of Ocean Water Color is determined by the way it absorbs or reflects sunlight Only blue wavelengths tend to be reflected ○ Only the upper regions show color; the lower region is in total darkness

10. Life in the Ocean  Most marine organisms depend on 2 factors for their survival: Essential nutrients available in ocean water Sunlight

11. Life in the Ocean  Ocean Chemistry & Marine Life Animals & plants living in the ocean help maintain the chemical balance of ocean water Nearly all life is regulated by the life processes of plants Elements nitrogen, phosphorus, & silicon are critical nutrients for the growth of plants

12. Life in the Ocean  Ocean Chemistry & Marine Life cont… Marine plants & animals absorb & store the substances they need for life. All of the elements necessary to marine life are consumed by marine plants & animals near the surface but released at great depths through decay Upwelling- occurs when wind blows steadily parallel to the shore along a coastline, surface ocean water is moved farther offshore causing deep water to then move up

13. Life in the Ocean  Sunlight & Marine Life All marine plants & animals require sunlight in addition to the nutrients from water ○ Plant growth is limited to the upper 100m of water Plankton- free floating microscopic marine plants & animals ○ 2 main types of plankton Phytoplankton- plants & other photosynthetic organisms Zooplankton- non-photosynthetic animals Nekton- eat plankton, forms of ocean life that swim Benthos- organisms that live on the ocean floor

14. Life in the Ocean  Ocean Environments 2 general environments ○ Benthic- bottom Divided into 5 zones ○ Pelagic- water Divided into 2 zones ○ **The amount of sunlight, temperature, & water pressure determine the distribution of marine life within these zones

15. Life in the Ocean  Ocean Environments Benthic Environments ○ Intertidal zone- lies between low tide and high tide lines Crabs, clams, mussels, sea anemones, & seaweed live here ○ Sublittoral zone- shallow & completely submerged; located on the continental shelf; contains the largest number of benthos Sea stars, brittle stars, & sea lilies

16. Life in the Ocean  Ocean Environments Benthic Environments ○ Bathyal zone- starts at the continental slope & ends at a depth of 4000m Octopuses, sea stars, & brachiopods Very little plant life ○ Abyssal zone- 4000m to 6000m of depth Sponges, worms, & sea cucumbers No light at all ○ Hadal zone- inside ocean trenches; deeper than 6000m Virtually unexplored; life is sparse

17. Life in the Ocean  Ocean Environments Pelagic Zones ○ Neritic zone- above continental shelves Abundant sunlight, moderate temperatures, low pressure Ideal for marine life Much of the seafood & fish that we eat lives here ○ Oceanic zone- extends into the deep ocean & open ocean waters beyond the continental shelf Divided into 4 zones based on depth -Epipelagic,Mesoplagic, bathypelgaic, abyssopelagic Marine life decreases with increasing depth

18. Ocean Resources  Fresh Water from the Ocean 2 ways in which the need for fresh water can be met: ○ Fresh water now available can be conserved to avoid waste ○ Amount of available fresh water can be increased Can be done by finding a way to convert ocean water to fresh water for a reasonable cost

19. Ocean Resources  Fresh Water from the Oceans Desalination- the removal of fresh water from salt water ○ Distillation- heating ocean water to remove the salt Problem: evaporating liquid water requires a large amount of expensive heat energy ○ Freezing The first ice crystals that form are free of salt Chunks of ice can be melted & used as fresh water ○ Use of membranes (reverse osmosis) Allow water under high pressure to pass through while blocking the dissolved salts

20. Ocean Resources  Minerals from the Ocean Nodules ○ Valuable source of manganese which is used making some types of steel ○ Also contain iron, copper, nickel, & cobalt ○ Problem: expensive & difficult to retrieve Minerals ○ Salt ○ Magnesium ○ Bromine Petroleum is the most valuable mineral found beneath the ocean floor ○ Most comes from the continental shelves ○ Productive offshore wells are located in the Gulf of Mexico, the North Sea, the Persian Gulf, & off the coasts of California, Alaska, & Australia

21. Ocean Resources  Food from the Ocean Protein rich fish is an important part of the human diet Aquaculture- farming of the ocean ○ Developing & raising species of marine animals & plants that yield large amounts of food ○ Successful in growing catfish, salmon, oysters, & shrimp

22. Ocean Resources  Ocean-Water Pollution Oceans have been historically used as dumping grounds ○ Garbage, sewage, nuclear wastes Productive coastal waters are in the most danger