Ocean Bottom

The Water Planet Global ocean is consists of all the oceans on the Earth A sea is a smaller body of ocean water that may be surrounded by land

Oceanography Oceanography began when Matthew Maury aboard the HMS Challenger explored the oceans with limited technology from Today with modern technology ships like the JOIDES Resolution and the CHIKYU, both drill the ocean bottom finding out more about the workings of plate tectonics and sediment of the ocean. sediment of the ocean.

Sonar Sound Navigation and Ranging is a system that uses sound to determine the depth and features of the ocean bottom. Side scan radar is used to map the bottom of the ocean Under water Submersibles are used to explore the depth, some with robots to collect samples.

Continental slope is at the edge of the continental shelf where the sea floor may plunge steeply 4-5 kilometers Marks the boundary between the continental crust and the oceanic crust

Continental rise is the area between the continental slope and the ocean floor It is made of sediments that wash down from the continental shelf Turbidity current carry large amounts of these sediments in masses of moving water, it is like an underwater avalanche

Submarine canyons are deep V shaped valleys cut through the continental shelf and slope

Features of the Ocean Floor

Abyssal Plain Large flat areas on the bottom of the ocean Atlantic and Indian oceans have largest abyssal plains because almost all the worlds major rivers flow into them producing a large amount of sediment deposits in the plains

Seamounts and Guyots Seamounts are underwater volcanic mountains They have steep sides and narrow summits and rise more than 1000 meters above the sea floor When seamounts rise above the surface of the ocean they become islands Guyots are seamounts that do not rise to a peak or have eroded tops

Mid-ocean Ridges Largest mountain ranges on the Earth These are formed where the plates are pulling apart Rift valleys run along the middle of the mid-ocean ridges

Trenches The deepest part of the ocean found along edges of sea floor Long narrow crevices that can be 11,000 meters deep Deepest trench is the Mariana Trench in the Pacific Ocean that is more than 11,000 meters deep

Hydrothermal Vents Openings into the mantle of the Earth where sea water seeps down and returns to the ocean

Reefs Reefs are large masses and ridges of limestone rocks produced by the shells of animals There are three types of coral reefs: fringing reefs touch the shoreline of a volcanic island

Coral Reefs (cont) Barrier reefs that are separated from the shore by an area of shallow water called a lagoon

Coral Reefs (cont) And an atoll that is a ring of coral reef that surrounded an island that has been worn away or sunk

Properties of Ocean Water Ocean water is a mixture of gases and solids dissolved in pure water Oceanographers believe that ocean water contains all of the natural elements found on Earth All but 5 have been found

Gases in Ocean Water Nitrogen, carbon dioxide (60 times more than in atmosphere), and oxygen are the most abundant gasses found in ocean water cold water has more dissolved gases in it Oxygen and carbon dioxide are essential for plant growth There is more gas found at the surface of the water where plant growth occurs

Gases and Ocean Facts Colder temperatures hold more gas. The ocean contains 60 times more carbon that the atmosphere does. The oceans are the most important factor in regulating climate.

Salts in Ocean Water Salinity is the amount of dissolved salts in ocean water Sodium Chloride is the most common salt Average salinity of the ocean is 35 o/oo Salt comes from volcanic activity, erosion of the land, and wave erosion of beaches Sea salts Parts per Thousand chloride19.3 o/oo sodium10.7 o/oo sulfate2.7 o/oo magnesium1.3 o/oo calcium0.4 o/oo potassium0.4 o/oo bicarbonate0.15 o/oo bromide0.07 o/oo other0.06 o/oo Total Salinity o/oo

Salinity Salinity can be greater or less than the average of 35 o/oo Lower salinity where freshwater rivers enter the ocean Salinity is higher where there is greater evaporation and in polar regions where only fresh water freezes Animals using certain salts to build their shells can lower salinity

Deep Cold Water Cold water holds more gas than warm water When the colder denser water sinks to the bottom it carries oxygen rich water that aids in the survival of deep water species

Temperature of Ocean Water The sun is the major source of heat for the ocean Surface zone meters deep, temperature fairly constant, waves and surface winds mix the water and transfer the heat downward

Temperatures (cont) Thermocline- found directly under the surface zone, temperature drops rapidly, less dense warm water floats on top of the more dense cold water

Temperature (cont) Deep zone- has extremely cold water, extends from the thermocline to depths of 4000 meters or more, temperature decreases only slightly Temperature below 1500 meters is only 4°

Temperature The three ocean zones are not found in the Arctic or Antarctic The surface temperatures are always very cold

Density and Color The density of the water gets greater the deeper and colder the water is. Blue wavelengths of light are reflected Phytoplankton can affect the color of the ocean can show the health of the ocean

Upwelling The movement of deep, cold, and nutrient rich water to the surface to support life.

Ocean Life Zones Plant and animal life in the ocean is affect by three factors: amount of sunlight, temperature, and pressure Plants and animals can be classified into three major groups according to their habitats of the water in which they live

Plankton Largest group of animals and plants that float at or near the surface These get the most sunlight Found at depths of 1 to 200 meters deep Very small organisms (plankton that whales eat)

Nekton Contains all forms of organisms that swim around They can actively search for food, prey or predators These are found in all areas of the ocean

Benthos Organisms that live on the ocean floor Benthic plants live in shallow water so they can get the necessary sunlight Oysters, crabs, starfish are all benthic Some even live in the deepest parts of the ocean

Ocean Environments (Zones) The classification of the ocean into life zones is based on the conditions of the ocean- conditions that vary widely

Intertidal Zone (Benthic Zone) The region that lies between low and high tide Organisms must be able to live without water some of the time They must find someway to attach so they are not washed out when tide goes out Includes anemones, crabs, mussels, and plants

Neritic Zone (Pelagic Zone) Extends from the low tide line to the edge of the continental shelf Depth of about 200 meters Receives plenty of sunshine Pressure is low and temperature is constant Plankton, nekton, and benthos plants and animals are found here Riches part of the sea: contains fish, clams, snails, some smaller whales, and lobsters Much of the seafood we eat is found here!

Open-Ocean Zones Bathyal zone begins at the continental slope and ends about 2000 meters Sunlight cannot penetrate to the bottom Squid, octopus, and large whales are found here Abyssal zone extends to over 6000 meters No sunlight can penetrate, high pressure and low temperatures Most animals are small and strange!