Bell Ringer Name the ocean-mapping technology. Maps as it orbits the Earth Maps from a ship using sound waves Maps by diving deep in the ocean Topex/Poseidon SONAR submersibles

Saltwater Properties

Ocean Water Nutrients Dissolved minerals Dissolved gases Oceans contain 97.5% of water found on Earth (saltwater) What else is in ocean water? Nutrients Dissolved minerals Dissolved gases Microscopic life forms All of these combined make the ocean a thriving ecosystem for the organisms that live there

Ocean Water The Arctic and Antarctic Oceans are covered by sea ice

Ocean Water Icebergs – large masses of ice formed when ice crystals build on each other

Ocean Water As the Earth’s global temperatures continue to increase, sea ice is melting, changing the saltiness of the water as well as the sea levels Sea Level – the average level for the surface of Earth’s oceans Serves as a reference for elevation (ex: Raleigh is 315 feet above sea level)

Ocean Water As sea levels rise, coastlines around the world will change as low-lying land is covered in water

Ice floats because it is less dense than water Ocean Water Density = mass / volume Things that are denser [rise above / sink below] things that are less dense. Sea ice floats, so it is [more / less] dense than water Ice floats because it is less dense than water

Ocean Water The density of ocean water depends on two things: salinity and temperature

Salinity Seawater is a solution of about 96.5% water and 3.5% dissolved salts The most abundant salt in sea water is sodium chloride (NaCl, table salt)

Salinity Salinity – the amount of dissolved salts in seawater Salt adds weight (mass) to water, so saltwater is denser than freshwater

Salinity Adding salt to water lowers its freezing point So the higher the salinity, the colder the water can be and still be a liquid This is why we put salt on roads in winter to prevent them from freezing

Salinity The average ocean salinity is 35 ppt (parts per thousand) Salinity stays relatively constant in the ocean because sea salts are removed at the same rate they are added

Salinity How are salts removed from ocean water? Marine organisms remove salt from the water to build their shells, bones, and teeth Salts can precipitate from (drop to the bottom of) seawater in dry and coastal regions

Salinity Salinity is controlled by a balance between freshwater removed by evaporation and added by rivers and rain Evaporation: removes freshwater, leaving salt behind Precipitation: adds additional freshwater

Salinity ____ Salinity – places with lots of evaporation but little precipitation Example: Mediterranean Sea in Europe (>38ppt) It is nearly closed off from the ocean and there is more evaporation than rain/freshwater High

Salinity Low _____ Salinity – places with lots of rain that dilutes the water

Salinity Low _____ Salinity – places where freshwater streams empty into the ocean (___________) Example: Baltic Sea in Europe (10 ppt) It’s nearly closed off from the ocean and has hundreds of rivers that empty into it estuaries

Salinity ____ Salinity – polar regions near melting ice caps Example: Arctic Ocean (30 ppt) Low

Temperatures Average ocean temperature is 15oC (59oF) Equatorial waters are warmest, averaging 30oC Polar waters are coldest, averaging -2oC Freshwater freezes at ___oC. So how is the water still liquid? Remember, saltwater freezes at a lower temperature than freshwater

Temperatures Density is temperature-dependent, so ocean temperatures also vary based on depth Cold water – dense Warm water – less dense Cold water sinks to the lower parts of the ocean while warm water remains near the surface Review: Convection: warm material _______ and cold material _______! rises sinks

Temperatures The ocean is divided into three temperature-based layers: Surface Layer Thermocline Deep Water

Temperatures Surface layer – 100m thick, relatively warm water Only layer lit by the Sun; the rest of the ocean is very dark! Nearly 90% of all ocean organisms live in the surface layer Surface Layer

Temperatures Thermocline - rapid decline in temperature with depth (thermo = temperature, cline  decline) Surface layer

Temperatures Deep water –dark (nearly pitch-black) and cold (very close to freezing) Surface layer

Temperatures Relatively few organisms live in the deep Those that do are some of the most unique organisms on Earth, adapted to live in the cold and dark

Temperatures Hydrothermal vents – openings in the seafloor which erupt with magma-heated fluids Typically located along the mid-ocean ridges

Temperatures Water can reach 750°F! Lots of organisms in comparison to the rest of the deep water These organisms are specially adapted to survive the hot temperatures and chemicals that come out of the vents Example: Giant Tube Worms

Salinity and Temperature Salinity: Salt water is [more / less] dense than freshwater. Therefore, salt water would [rise above / sink below] fresh water. Temperature: Cold water is [more / less] dense than warm water. Therefore, cold water would [rise above / sink below] warm water. Question: Which of the four types of water would float above all the others? A. warm, salty B. warm, fresh C. cold, salty D. cold, fresh

Get out a sheet of notebook paper Adaptation – inherited characteristics (characteristics you are born with) that help an organism survive its environment Example: Where does a polar bear live? What are some characteristics that help it live there?

How would you describe deep ocean water? Warm or cold? Sunny or dark? Deep sea creatures have to adapt to live in this environment. We’re going to watch a video about deep sea creatures. As you are watching, write down 5 specific (different from each other) adaptations these creatures have developed that enables them to live in the deep ocean water. No phones, sleeping, or work from other classes. No cheating! If your tablemate chooses to be off-task during the video while you pay attention, don’t let them copy your paper! Turn in after video.