Lecture 5: Oceans Lecture 5: Oceans & Tides& Tides

Corresponding Reading Corresponding Reading MaterialMaterial

~ Levinton: chapters 2 ~ Levinton: chapters 2 and 3and 3

The Oceanic The Oceanic EnvironmentEnvironment

Notes for Notes for Marine Biology: Marine Biology: Function, Biodiversity, Function, Biodiversity,

EcologyEcology

By By Jeffrey S. LevintonJeffrey S. Levinton

©Jeffrey S. Levinton 2001

The Ocean and Marginal The Ocean and Marginal SeasSeas

The worlds oceans: oceans and The worlds oceans: oceans and marginal seasmarginal seas

Oceans cover 71% of earth’s Oceans cover 71% of earth’s surfacesurface

Southern hemisphere 80%, Southern hemisphere 80%, Northern hemisphere 61%Northern hemisphere 61%

84% deeper than 2000m84% deeper than 2000m Greatest depth ~ 11,000 m in Greatest depth ~ 11,000 m in

Marianas TrenchMarianas Trench

Marginal SeasMarginal Seas

Examples: Gulf of Mexico, Examples: Gulf of Mexico, Mediterranean SeaMediterranean Sea

Affected strongly by regional Affected strongly by regional climate, precipitation-climate, precipitation-evaporation balance, river input evaporation balance, river input of fresh water and dissolved of fresh water and dissolved solids, often with limited solids, often with limited exchange with the open ocean exchange with the open ocean (e.g., sill partially cutting (e.g., sill partially cutting Mediterranean from Atlantic)Mediterranean from Atlantic)

Marginal Seas Marginal Seas 22

Often have recent history of Often have recent history of major changemajor change

Mediterranean: completely dry a Mediterranean: completely dry a few million years agofew million years ago

Baltic Sea: less than 11,000 years Baltic Sea: less than 11,000 years oldold

Topographic FeaturesTopographic Features

Continental shelf (1° slope)Continental shelf (1° slope) Continental slope (2.9° slope)Continental slope (2.9° slope) Continental RiseContinental Rise Abyssal PlainAbyssal Plain Submarine CanyonsSubmarine Canyons Oceanic Ridge SystemsOceanic Ridge Systems

Topographic Features Topographic Features 22

Coa

stal

pla

in

She

lf

Slo

pe

Co n

t in e

ntal

ris

e

Aby

ssal

pla

in

Sea

mou

nt

Mid

-oce

an r

idge

Aby

ssal

pla

in

Tre

nchVol

cani

c is

land

Mar

gina

l sea

Depth (m

iles)Dep

th (

km)

Earth’s surface is divided into plates: borders are ridge systems, faults

American

Eurasian

Pacific

Philippine

Cocos

American

Antarctic

African

Eurasian

Arabian

Nazca

Caribbean

The Oceanic Crust: Crust is formed at The Oceanic Crust: Crust is formed at ridges, moved laterally, and destroyed by ridges, moved laterally, and destroyed by

subductionsubduction, which forms , which forms trenchestrenches

Intermediate, deep-focus earthquakes

Continentalcrust Inactive fault

Oceaniccrust

Ridge Fault

Continent

ContinentalCrust

Mantle

Trench

Evidence of Plate Evidence of Plate TeconticsTecontics

Fossils from different continents of Fossils from different continents of same species or similar speciessame species or similar species

Sonar data of sea floorSonar data of sea floor Magnetic field reversals and age of Magnetic field reversals and age of

rocks near sea floor spreading rocks near sea floor spreading centerscenters

Seismic waves and how they move Seismic waves and how they move through liquids and solidsthrough liquids and solids

Properties of Properties of WaterWater

Water has a high heat capacity Water has a high heat capacity (specific heat)(specific heat)

~ ~ Heat CapacityHeat Capacity = = measure of the measure of the

heat required to raise heat required to raise the the

temperature of 1 gram temperature of 1 gram of of

substance 1°Csubstance 1°C

This means water can absorb (or This means water can absorb (or release) large amounts of heat release) large amounts of heat while changing relatively little in while changing relatively little in temperaturetemperature

Due to the lattice structure of Due to the lattice structure of water when it changes from a water when it changes from a liquid to a gas, the solid ice floats liquid to a gas, the solid ice floats on the liquid water.on the liquid water.

Properties of Properties of WaterWater

The water molecule was a The water molecule was a high dissolving powerhigh dissolving power

~ The water molecule ~ The water molecule is polaris polar

~ Water molecules ~ Water molecules can form can form

hydrogen bondshydrogen bonds

SalinitySalinity

Definition: g of dissolved salts Definition: g of dissolved salts per 100g of seawater; units are per 100g of seawater; units are o/oo or ppto/oo or ppt

Controlled by:Controlled by:+ evaporation, sea-ice formation+ evaporation, sea-ice formation- precipitation, river runoff- precipitation, river runoff

Salinity in open ocean is 32-38 Salinity in open ocean is 32-38 o/ooo/oo

Important elements in Important elements in seawaterseawater

Chlorine (19,000 mg/l)Chlorine (19,000 mg/l) Sodium (10,500Sodium (10,500 Magnesium (1,300)Magnesium (1,300) Sulfur (900)Sulfur (900) Calcium (400)Calcium (400) Potassium (380)Potassium (380) Bromine (65)Bromine (65) Carbon (28 - variable)Carbon (28 - variable)

Principle of Constant Element Principle of Constant Element RatiosRatios

Ratios between many major Ratios between many major elements are constant all elements are constant all over the ocean, even though over the ocean, even though salinity variessalinity varies

LightLight What happens when light passes through water?What happens when light passes through water?

1. 1. ScatteringScattering = occurs as light is bounced between air of = occurs as light is bounced between air of water molecules, dust particles, water droplets, or other objects water molecules, dust particles, water droplets, or other objects before being absorbedbefore being absorbed

2. 2. AbsorptionAbsorption = water molecules vibrate and the light’s = water molecules vibrate and the light’s electromagnetic energy is converted to heatelectromagnetic energy is converted to heat

Each color in the visible spectrum of light has a different wavelength.Each color in the visible spectrum of light has a different wavelength. The longer the wavelength the easier the color is scattered.The longer the wavelength the easier the color is scattered.

~ This means the color red is absorbed first and violet last.~ This means the color red is absorbed first and violet last. Photic ZonePhotic Zone = illuminated zone of the ocean’s surface = illuminated zone of the ocean’s surface

~ Open Ocean: Water absorbs most light by 200 m~ Open Ocean: Water absorbs most light by 200 m~ Coastal Zone: Due to suspended particles most light is ~ Coastal Zone: Due to suspended particles most light is

absorbed in 10-50 mabsorbed in 10-50 m Apothic ZoneApothic Zone = lightless zone beneath the surface = lightless zone beneath the surface

TemperatureTemperature Oceanic range (1.9 - 40 °C) Oceanic range (1.9 - 40 °C)

less than terrestrial range (-less than terrestrial range (-68.5-58 °C)68.5-58 °C)

Deep ocean is cold (2 - 4) Deep ocean is cold (2 - 4) degreesdegrees

The OceanThe Ocean

Circulation in the OceanCirculation in the Ocean

©Jeffrey S. Levinton 2001

Coriolis Effect - Earth’s RotationCoriolis Effect - Earth’s RotationLatitudeLatitude Eastward Eastward

VelocityVelocity

(km/h)(km/h)

EquatorEquator 16701670

30° N. latitude30° N. latitude 14401440

60° N. latitude60° N. latitude 830830

Coriolis Effect - Movement of fluids, in Coriolis Effect - Movement of fluids, in relation to earth beneath, results in relation to earth beneath, results in

deflectionsdeflectionsNorth

South

EquatorNo deflection

Increasing deflectionof moving waterparcel to the right

Increasing deflectionof moving waterparcel to the left

Ocean Ocean CirculationCirculation

Circulation of surface waters Circulation of surface waters are driven by windsare driven by winds

Coriolis EffectCoriolis Effect = deflection of = deflection of moving air or water caused by moving air or water caused by the rotation of the Earththe rotation of the Earth

The circulation of deep water is The circulation of deep water is driven by density differences.driven by density differences. The deep ocean is layered with The deep ocean is layered with the densest water on the bottom the densest water on the bottom and the lightest on top.and the lightest on top. Water tends to move horizontally Water tends to move horizontally in throughout the deep ocean in throughout the deep ocean (along the lines of equal density)(along the lines of equal density)

Wind-driven Circulation Wind-driven Circulation 33Wind systems Surface currents

Westerlies

NE TradewindsDoldrums

SE Tradewinds

Westerlies

Subpolargyre

Subtropicalgyre

Subtropicalgyre

West wind drift

Coriolis Effect and DeflectionCoriolis Effect and Deflection Surface winds move over waterSurface winds move over water Coriolis effect causes movement of Coriolis effect causes movement of

water at an angle to the wind (to right water at an angle to the wind (to right in northern hemisphere)in northern hemisphere)

Water movement drags water beneath, Water movement drags water beneath, and to right of water aboveand to right of water above

Result: Shifting of water movement - Result: Shifting of water movement - Ekman Spiral (actually friction binds Ekman Spiral (actually friction binds water together and all water moves at a water together and all water moves at a right angle to wind (right of wind in n. right angle to wind (right of wind in n. hemisphere)hemisphere)

Circulation RecapCirculation Recap

Coriolis effectCoriolis effect - rotation of - rotation of Earth, prop. to sine of latitude, Earth, prop. to sine of latitude, Right deflection in N. Right deflection in N. hemisphere, Left deflection in hemisphere, Left deflection in S. hemisphere - S. hemisphere - upwelling, upwelling, deflection of currentsdeflection of currents

Coastal Winds + Coriolis Effect Coastal Winds + Coriolis Effect = Upwelling= Upwelling

Nutrient-rich water

Surface water movement Peru

WIND

Southern hemisphere: water moves to the left of wind

Oceanic CirculationOceanic Circulation

Surface currents are controlled by Surface currents are controlled by the interaction of the planetary wind the interaction of the planetary wind system and the earth’s rotation.system and the earth’s rotation.

Winds and Coriolis effect combine Winds and Coriolis effect combine to cause upwelling, which bring s to cause upwelling, which bring s nutrient rich cold waters from the nutrient rich cold waters from the deep ocean to the coastal regionsdeep ocean to the coastal regions

Pages 25 through 29 in your Pages 25 through 29 in your textbook.textbook.

The Oceanic Environment:

Ecological terms

HabitatsHabitats IntertidalIntertidal SubtidalSubtidal Continental shelf or NeriticContinental shelf or Neritic - waters and bottoms - waters and bottoms

on the continental shelfon the continental shelf Oceanic or PelagicOceanic or Pelagic - waters and bottoms seaward - waters and bottoms seaward

of the shelfof the shelf EpipelagicEpipelagic zone - upper 150 m of water depth zone - upper 150 m of water depth MesopelagicMesopelagic zone - 150 m - 2000 m depth zone - 150 m - 2000 m depth BathypelagicBathypelagic zone - 2000 m - 4000 m depth zone - 2000 m - 4000 m depth AbyssopelagicAbyssopelagic zone - 4000 m - 6000 m depth zone - 4000 m - 6000 m depth HadalHadal - trench environments - trench environments

Life HabitsLife Habits

PlanktonPlankton NektonNekton BenthosBenthos Infaunal versus epifaunal (epibenthic)Infaunal versus epifaunal (epibenthic) Semi-infaunalSemi-infaunal BoringBoring

What are the What are the Tides??Tides??

What Are the Tides?What Are the Tides?

Tides Tides = periodic, short-term changes in the height of the ocean = periodic, short-term changes in the height of the ocean surface at a particular placedsurface at a particular placed

Are the longest of the wavesAre the longest of the waves Are huge shallow-water wavesAre huge shallow-water waves Causes of the Tides:Causes of the Tides:

Combination of the gravitational force of the moon and Combination of the gravitational force of the moon and the sun, rotation of the Earth, and the shape of oceanic basins.the sun, rotation of the Earth, and the shape of oceanic basins.

High Tide

Low Tide

What Causes the Tides?What Causes the Tides?

Spring Tides vs. Neap Spring Tides vs. Neap TidesTides

During each phase of the new moon and During each phase of the new moon and full moon the earth, sun, and moon come full moon the earth, sun, and moon come into alignment creating spring tides. into alignment creating spring tides. When they are not in alignment neap When they are not in alignment neap tides occur.tides occur.

Spring Tide-Spring Tide- A tide which results in the A tide which results in the greatest range between high and low tide greatest range between high and low tide

Neap TideNeap Tide- A tide which results in the - A tide which results in the least tidal range between high and low least tidal range between high and low tide tide

Tides Tides

Sun

Sun

E

E

SpringTide

NeapTide

E = Earth

mm

m

m

m = Moon

Tides Tides T

idal

hei

ght (

cm)

Tid

al h

eigh

t (cm

)

Day Day

Connecticut Washington State

Types of TidesTypes of TidesSemidiurnal Tides = the coastline experiences two high tides and two low tides of nearly equal level each lunar day. This type is more likely to occur when the moon is over the equator. Mixed semidiurnal tides = the coastline experiences successive high tides or low tides that are significantly different heights through the cycle. These tides also tend to occur as the moon moves furthest north or south of the equator. Diurnal Tides = the coastline experiences one high tide and one low tide each lunar day. This tends to occur in certain areas when the moon is at its furthest from the equator.

Three largest tides in the

world:

1.Bay of Fundy

2.2.Estuary of the Estuary of the River SevernRiver Severn

3.Puerto Punta Peñasco, Sonora,

Mexico

Bay of FundyBay of Fundy The Bay of Fundy is located The Bay of Fundy is located

on the west coast of Novia on the west coast of Novia ScotiaScotia

It has the largest tidal range It has the largest tidal range in the world of 53 ft. (16 m)in the world of 53 ft. (16 m)

100 billion tons of water flow 100 billion tons of water flow into and out of the bay on and into and out of the bay on and average tide.average tide.

~ creates strong rip ~ creates strong rip currents, swirling whirlpools, currents, swirling whirlpools, and and up-wellings.up-wellings.

The energy created by this The energy created by this great movement of water can great movement of water can be used as a clean renewable be used as a clean renewable energy source.energy source.

Why is the tidal range so Why is the tidal range so large at the Bay of Fundy?large at the Bay of Fundy?

Bay of Bay of FundyFundy

Bay of FundyBay of Fundy

Estuary of the River Estuary of the River SevernSevern

Has the second largest Has the second largest tidal range in the worldtidal range in the world

Average height Average height difference between low difference between low and high tides is 47 ft.and high tides is 47 ft.

Located in BritainLocated in Britain Pictures of Clevedon Pictures of Clevedon

Pier on the River Pier on the River SevernSevern

•From one high tide to to the next high tide takes 12 hours and 25 minutes.

•A tidal day takes 24 hours and 50 minutes, not 24 hours.

•WHY??