Bellwork 12/15• Answer in notebook:• 1. What is necessary for humans to live? • 2. Where do humans get the things they need to survive? • 3. What sort of impact do you think would happen if any

one thing needed for survival was no longer available? More than one?

• 4. How are nutrients and minerals used by the human body?

• 5. What do ocean creatures need to survive? • 6. What would happen if these nutrients or minerals were

not available? • 7. Is there a connection between humans and living

things in the ocean?

Continental S

lope

Continental Shelf

Abyssal Plain

Sea

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Volcanic Island

New

Jersey

Azores Islands

Portuga

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Con

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tal S

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Abyssal Plain

Seafloor Features

FYI: There is not a trench in the Atlantic Basin because this is a divergent plant boundary

Ocean Zones by Depth

The Sunlight Zone: Surface to 200 meters. Sunlight reaches to the bottom of this zone 90% of all sea life found in this zone.Temperature range depends on latitude (amount of solar energy)Pressure – increase by 1atm every 10m. Increase with depth up to 10atm.

Ocean Zones by DepthThe Twilight Zone: 200 to 1000 meters. Only 5% of the sunlight at the surface reaches

to 260 m.Temp: from 41 to 39 degrees F and decreases with depth.Pressure: increases with depth up to 100atm. The amount of dissolved oxygen in the water is, less than in the sunlit zone.

Ocean Zones by Depth

The Midnight Zone: Below 1000 meters. No sunlight reaches this depth.Temp: on average 4 degrees CPressure: from 100atms increases with depth up to 850atm. The amount of dissolved oxygen in the water is as high as the surface.

Habitat ZonesIntertidal– Region of continental shelf between the high and low tide lineNeritic – Upper 200 meters, over the continental shelf – overlaps with sunlight zoneOpen Ocean – 90%?? Of the ocean habitat is open ocean

Habitat Zones

Finishing yesterday’s notes…

• We’ve already seen the intertidal zone – including estuaries – now let’s move on!

Neritic Zone:

• Neritic Zone: The area of the ocean that extends from the low-tide line out to the edge of the continental shelf. – Includes 2 specialized ecosystems

• Coral Reefs• Kelp Forests

Neritic Zone: Coral Reefs

• Reefs protect coastlines. – Break up the surf– But, reefs can be easily damaged

• Because coral grows only a few millimeters a year, a reef cannot quickly recover.

– Changes in water temperature and clearness affect algae, and therefore, endanger coral reefs.

• Ex. Water becomes too warm, the corals release the algae that live inside them

• Ex. Cloudy water reduces the amount of light that reaches them.

• Without algae, coral animals die

Life in a Coral Reef

Neretic Zone: Kelp Forests

• Kelp forests grow in cold neritic waters where the ocean has a rocky floor – Use the sunlight and

dissolved gases to produce their own food

– Provide a habitat for many organisms

• Gray whales, sea slugs, snails, sea otters

Open Ocean• Open-Ocean Zone: The area of the ocean

beyond the edge of the continental shelf. • At the surface fewer nutrients, therefore

fewer organisms

Open ocean also includes the Twilight and Midnight zones

less or no light = fewer organisms

Open Ocean: Deep Zone – special ecosystems

– Hydrothermal Vent - An opening in the sea floor where super-heated water and other material are discharged into the surrounding seawater.

• Supports many organisms• Water carries gases and minerals from

earth’s interior that bacteria feed on• Giant clams feed on the bacteria• Other organisms found here:

– Crabs– Tube worms

Hydrothermal Vent

Giant tube worms and crabs cluster around a

hydrothermal vent on the ocean floor

Chapter 4 Section 3

Ocean Water Chemistry

Salinity

• On average, one kg of ocean water contains about 35 g of salts (35 parts per thousand)

• Salinity: The total amount of dissolved salts in a water sample.– NaCl makes up most

Worksheet (Practice):

• Ocean water chemistry

Salinity

Salinity• Where is it lower?

– Surface because of precipitation– Near the mouth of large rivers

(brackish water)

• Where is it higher?– Warm areas because of evaporation –

salt is left behind• Ex. Red Sea, has hot and dry climate, the

salinity can be as high as 41 parts per thousand.

– Near the poles – water freezes into ice but the salt doesn’t

Effects of Salinity

• Salt water has a higher density than fresh water. – (Salt water has a higher mass and therefore a

higher density)

• Ocean water does not freeze until the temperature drops to about –1.9°C. – The salt interferes with the formation of ice

crystals.

Temperature

• Warm water is less dense than cold water so it stays on the surface

• The deeper you go, the colder and more dense the water

Temperature

• Lower water temp.—water molecules stay closer together

• Higher water temp.—water molecules spread apart (what happens when they spread apart enough?)

• Therefore in a sample of cold water, you have more water molecules in the same volume so the cold water is more dense

Gases in Ocean Water

• Two gases that ocean organisms use are CO2 and O2.

– CO2 is 60x more plentiful in the ocean than air• Needed by algae for photosynthesis

– O2 is at a lower concentration in seawater than air

• Most common near the surface• Comes from the air and algae• Amount is affected by temp.

– Cold water contain more O2 than warm water

Increasing Pressure

• Water pressure is the force exerted by the weight of water.

• Pressure increases the deeper you go in the ocean.– Because of the high pressure in the deep

ocean, divers can descend safely only to about 40 meters (here the pressure is 4x as much as at the surface).