Oceans, Waves and TidesOceans, Waves and Tides

Marine BiomeMarine Biome

Marine BiomesMarine Biomes

Scientists divide the ocean Scientists divide the ocean intointo

zones HORIZONTALLY andzones HORIZONTALLY and

VERTICALLY.VERTICALLY.

VerticalVertical

• Photoic, Aphotic, and Benthic zones Photoic, Aphotic, and Benthic zones (same as with lakes) (same as with lakes)

• Aphotic zone of open ocean = desert Aphotic zone of open ocean = desert of marine biome in terms of biomass; of marine biome in terms of biomass; absence of sunlight limits diversityabsence of sunlight limits diversity

Horizontal Horizontal

• Neritic ZoneNeritic Zone

• Continental ShelfContinental Shelf

• Intertidal ZoneIntertidal Zone

• Oceanic ZoneOceanic Zone

Neritic ZoneNeritic Zone

• Region between the continental shelf and Region between the continental shelf and the surface of the water = 8% of world the surface of the water = 8% of world ocean.ocean.

• Ecosystems in this zone--reefs & estuariesEcosystems in this zone--reefs & estuaries

• Here sunlight reaches the benthic zone of Here sunlight reaches the benthic zone of the continental shelf = photosynthesisthe continental shelf = photosynthesis

• High in mineral nutrientsHigh in mineral nutrients

• Location determined by location of Location determined by location of continental shelf.continental shelf.

Continental ShelfContinental Shelf

• Shallow border that surrounds the continentsShallow border that surrounds the continents

• Between the shore and about 500m below Between the shore and about 500m below the surface of the waterthe surface of the water

• Reefs are a natural structure built on a Reefs are a natural structure built on a continental shelfcontinental shelf

• Estuary is region of water where a Estuary is region of water where a freshwater source, usually mouth of river, freshwater source, usually mouth of river, meets salt water of ocean. (brackish); meets salt water of ocean. (brackish); estuary from Latin for tideestuary from Latin for tide

Swamps and MarshesSwamps and Marshes

• Compared to a temperate deciduous Compared to a temperate deciduous forest of same size, a swamp is twice forest of same size, a swamp is twice as productive.as productive.

• Sediment accumulation contribute to Sediment accumulation contribute to formation of salt marshes and formation of salt marshes and mangrove forestsmangrove forests

• Mangrove swamp – shores of FloridaMangrove swamp – shores of Florida

ReefsReefs

• Coral Reefs are made of calcium Coral Reefs are made of calcium carbonate – skeletons of millions of tiny carbonate – skeletons of millions of tiny coralscorals

• Topsoil washes onto a coral reef making Topsoil washes onto a coral reef making water cloudier limiting photosynthesis water cloudier limiting photosynthesis

• Coral Reefs are very sensitive to pollutionCoral Reefs are very sensitive to pollution• Like rainforest-very productive & huge Like rainforest-very productive & huge

variety of organismsvariety of organisms• One-third of all ocean fish live on or One-third of all ocean fish live on or

depend on coral reefsdepend on coral reefs

Intertidal ZoneIntertidal Zone

• Alternates between periods of exposure and Alternates between periods of exposure and periods of submersion twice a day due to tides.periods of submersion twice a day due to tides.

• Specialized organismsSpecialized organisms

• Salt Marshes & mangrove swamps also known Salt Marshes & mangrove swamps also known as coastal wetlands developed by subsidenceas coastal wetlands developed by subsidence

--weight of accumulated sediments causing --weight of accumulated sediments causing delta to sink under the water.delta to sink under the water.

25% of world’s mangrove species found in USA25% of world’s mangrove species found in USA

Oceanic ZoneOceanic Zone• Open Ocean – largest zone – making up Open Ocean – largest zone – making up

more than 90% of the surface area of the more than 90% of the surface area of the world ocean.world ocean.

• Ranging from 500m along continental slopes Ranging from 500m along continental slopes to a depth of 11,000m to a depth of 11,000m

• Detritus (dead organic materials) provide Detritus (dead organic materials) provide feedfeed

• Mainly aphotic zone (no sunlight)Mainly aphotic zone (no sunlight)• Main producers of open oceans are Main producers of open oceans are

phytoplankton (photic zone)phytoplankton (photic zone)• Benthic organisms – clams, worms, spongesBenthic organisms – clams, worms, sponges

Ocean CurrentsOcean Currents

• Energy from sun – temperature, Energy from sun – temperature, salinity and densitysalinity and density

• Increased radiation along equator Increased radiation along equator make more saline seawatermake more saline seawater

• Water in ocean flows in patterns Water in ocean flows in patterns called ocean currentscalled ocean currents

Wind-drive ocean surface Wind-drive ocean surface currentscurrents

Wind driven surface currents

• How fast? A few miles/hr (Gulf Stream off of Miami = 4.5 mph)

• How much? Total water in ocean surface circulation = about 100 Amazon Rivers (20 million m3/s).

WavesWaves

•A A WaveWave is a is a rhythmicrhythmic movementmovement that carries that carries energyenergy through matter or through matter or space.space.

•In oceans, waves move In oceans, waves move through through seawaterseawater

WavesWaves

Caused byCaused by::

•WindWind

•EarthquakesEarthquakes

•Gravitational force of the Gravitational force of the Moon and Sun.Moon and Sun.

Parts of a WaveParts of a Wave

•CrestCrest – highest point of a wave – highest point of a wave

•Trough Trough – lowest point of a wave– lowest point of a wave

•Wave HeightWave Height – vertical distance – vertical distance between the crest and the troughbetween the crest and the trough

•WavelengthWavelength – horizontal distance – horizontal distance between two crests or two troughsbetween two crests or two troughs

Wavelength

Wave Height

Crest

Trough

Still Water

Wave Parts

Wave MovementWave Movement

•When a wave passes through When a wave passes through the ocean, the ocean, individual water individual water molecules move up and down molecules move up and down but they do not move forward but they do not move forward or backward.or backward.

Wave MovementWave Movement

•When a wave breaks against When a wave breaks against the shore, the shore, the crest outruns the the crest outruns the trough and the crest collapses.trough and the crest collapses.

•Called aCalled a breaker. breaker.

•In this case, water does move In this case, water does move forward and backward.forward and backward.

Waves Caused by WindWaves Caused by Wind

•When wind blows across a body of When wind blows across a body of water, water, frictionfriction causes the water to causes the water to move along with the wind.move along with the wind.

•Wave Height depends on – Wave Height depends on – – Wind speedWind speed– Distance over which the wind blowsDistance over which the wind blows– Length of time the wind blowsLength of time the wind blows

TidesTides

•The rise and fall in sea level is The rise and fall in sea level is called a called a tidetide..

•Caused by a Caused by a giant wavegiant wave..•One low-tide/high-tide cycle takes One low-tide/high-tide cycle takes

about 12 hrs and 25 min.about 12 hrs and 25 min.•Tidal rangeTidal range is the is the difference in difference in

ocean levelocean level between high-tide and between high-tide and low-tidelow-tide

What is the Tidal Range?What is the Tidal Range?

•HT = 30 ft, LT = 20 ftHT = 30 ft, LT = 20 ft

•HT = 20 ft, LT = 12 ftHT = 20 ft, LT = 12 ft

•HT = 50 ft, LT = 20 ftHT = 50 ft, LT = 20 ft

Gravitational Effect of the Gravitational Effect of the MoonMoon

•Two big bulges of water form Two big bulges of water form on the Earth:on the Earth:– one directly under the moon one directly under the moon – another on the exact opposite another on the exact opposite

sideside

•As the Earth spins, the bulges As the Earth spins, the bulges follow the moon.follow the moon.

Gravitational Effect of the Gravitational Effect of the SunSun

•Spring TidesSpring Tides– Earth, Moon, and Sun are lined Earth, Moon, and Sun are lined

upup– High Tides are higher and Low High Tides are higher and Low

Tides are lower than normalTides are lower than normal

Gravitational Effect of the Gravitational Effect of the SunSun

•Neap TidesNeap Tides– Earth, Moon, and Sun form Earth, Moon, and Sun form

right anglesright angles– High Tides are lower and Low High Tides are lower and Low

Tides are higher than normalTides are higher than normal

The EndThe End