Lecture 5: Oceans & Tides Corresponding Reading Material ~ Levinton: chapters 2 and 3

The Oceanic Environment Notes for Marine Biology: Function, Biodiversity, Ecology By Jeffrey S. Levinton ©Jeffrey S. Levinton 2001

The Ocean and Marginal Seas The worlds oceans: oceans and marginal seas The worlds oceans: oceans and marginal seas Oceans cover 71% of earth’s surface Oceans cover 71% of earth’s surface Southern hemisphere 80%, Northern hemisphere 61% Southern hemisphere 80%, Northern hemisphere 61% 84% deeper than 2000m 84% deeper than 2000m Greatest depth ~ 11,000 m in Marianas Trench Greatest depth ~ 11,000 m in Marianas Trench

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

Marginal Seas 2 Often have recent history of major change Often have recent history of major change Mediterranean: completely dry a few million years ago Mediterranean: completely dry a few million years ago Baltic Sea: less than 11,000 years old Baltic Sea: less than 11,000 years old

Topographic Features Continental shelf (1° slope) Continental shelf (1° slope) Continental slope (2.9° slope) Continental slope (2.9° slope) Continental Rise Continental Rise Abyssal Plain Abyssal Plain Submarine Canyons Submarine Canyons Oceanic Ridge Systems Oceanic Ridge Systems

Topographic Features 2 Coastal plain Shelf Slope Continental rise Abyssal plain Seamount Mid-ocean ridge Abyssal plain Trench Volcanic island Marginal sea Depth (miles) Depth (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 ridges, moved laterally, and destroyed by subduction, which forms trenches Intermediate, deep- focus earthquakes Continental crust Inactive fault Oceanic crust Ridge Fault Continent Continental Crust Mantle Trench

Evidence of Plate Tecontics Fossils from different continents of same species or similar species Fossils from different continents of same species or similar species Sonar data of sea floor Sonar data of sea floor Magnetic field reversals and age of rocks near sea floor spreading centers Magnetic field reversals and age of rocks near sea floor spreading centers Seismic waves and how they move through liquids and solids Seismic waves and how they move through liquids and solids

Properties of Water Water has a high heat capacity (specific heat) Water has a high heat capacity (specific heat) ~ Heat Capacity = measure of the heat required to raise the heat required to raise the temperature of 1 gram of temperature of 1 gram of substance 1°C substance 1°C This means water can absorb (or release) large amounts of heat while changing relatively little in temperature Due to the lattice structure of water when it changes from a liquid to a gas, the solid ice floats on the liquid water. Due to the lattice structure of water when it changes from a liquid to a gas, the solid ice floats on the liquid water.

Properties of Water The water molecule was a high dissolving power The water molecule was a high dissolving power ~ The water molecule is polar ~ Water molecules can form hydrogen bonds hydrogen bonds

Salinity Definition: g of dissolved salts per 100g of seawater; units are o/oo or ppt Definition: g of dissolved salts per 100g of seawater; units are o/oo or ppt Controlled by: Controlled by: + evaporation, sea-ice formation - precipitation, river runoff Salinity in open ocean is o/oo

Important elements in seawater Chlorine (19,000 mg/l) Chlorine (19,000 mg/l) Sodium (10,500 Sodium (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 Ratios Ratios between many major elements are constant all over the ocean, even though salinity varies Ratios between many major elements are constant all over the ocean, even though salinity varies

Light What happens when light passes through water? What happens when light passes through water? 1. Scattering = occurs as light is bounced between air of water molecules, dust particles, water droplets, or other objects before being absorbed 2. Absorption = water molecules vibrate and the light’s electromagnetic 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. Photic Zone = illuminated zone of the ocean’s surface Photic Zone = illuminated zone of the ocean’s surface ~ Open Ocean: Water absorbs most light by 200 m ~ Coastal Zone: Due to suspended particles most light is absorbed in m Apothic Zone = lightless zone beneath the surface Apothic Zone = lightless zone beneath the surface

Temperature Oceanic range ( °C) less than terrestrial range ( °C) Oceanic range ( °C) less than terrestrial range ( °C) Deep ocean is cold (2 - 4) degrees Deep ocean is cold (2 - 4) degrees

The Ocean Circulation in the Ocean ©Jeffrey S. Levinton 2001

Coriolis Effect - Earth’s Rotation Latitude Eastward Velocity (km/h)Equator ° N. latitude ° N. latitude 830

Coriolis Effect - Movement of fluids, in relation to earth beneath, results in deflections North South Equator No deflection Increasing deflection of moving water parcel to the right Increasing deflection of moving water parcel to the left

Ocean Circulation  Circulation of surface waters are driven by winds  Coriolis Effect = deflection of moving air or water caused by the rotation of the Earth  The circulation of deep water is driven by density differences.  The deep ocean is layered with the densest water on the bottom and the lightest on top.  Water tends to move horizontally in throughout the deep ocean (along the lines of equal density)

Wind-driven Circulation 3 Wind systemsSurface currents Westerlies NE Tradewinds Doldrums SE Tradewinds Westerlies Subpolar gyre Subtropical gyre Subtropical gyre West wind drift

Coriolis Effect and Deflection Surface winds move over water Surface winds move over water Coriolis effect causes movement of water at an angle to the wind (to right in northern hemisphere) Coriolis effect causes movement of water at an angle to the wind (to right in northern hemisphere) Water movement drags water beneath, and to right of water above Water movement drags water beneath, and to right of water above Result: Shifting of water movement - Ekman Spiral (actually friction binds water together and all water moves at a right angle to wind (right of wind in n. hemisphere) Result: Shifting of water movement - Ekman Spiral (actually friction binds water together and all water moves at a right angle to wind (right of wind in n. hemisphere)

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

Coastal Winds + Coriolis Effect = Upwelling Nutrient-rich water Surface water movement Peru WIND Southern hemisphere: water moves to the left of wind

Oceanic Circulation Surface currents are controlled by the interaction of the planetary wind system and the earth’s rotation. Surface currents are controlled by the interaction of the planetary wind system and the earth’s rotation. Winds and Coriolis effect combine to cause upwelling, which bring s nutrient rich cold waters from the deep ocean to the coastal regions Winds and Coriolis effect combine to cause upwelling, which bring s nutrient rich cold waters from the deep ocean to the coastal regions Pages 25 through 29 in your textbook. Pages 25 through 29 in your textbook.

The Oceanic Environment: Ecological terms

Habitats Intertidal Intertidal Subtidal Subtidal Continental shelf or Neritic - waters and bottoms on the continental shelf Continental shelf or Neritic - waters and bottoms on the continental shelf Oceanic or Pelagic - waters and bottoms seaward of the shelf Oceanic or Pelagic - waters and bottoms seaward of the shelf Epipelagic zone - upper 150 m of water depth Epipelagic zone - upper 150 m of water depth Mesopelagic zone m m depth Mesopelagic zone m m depth Bathypelagic zone m m depth Bathypelagic zone m m depth Abyssopelagic zone m m depth Abyssopelagic zone m m depth Hadal - trench environments Hadal - trench environments

Life Habits Plankton Plankton Nekton Nekton Benthos Benthos Infaunal versus epifaunal (epibenthic) Infaunal versus epifaunal (epibenthic) Semi-infaunal Semi-infaunal Boring Boring

What are the Tides??

What Are the Tides? Tides = periodic, short-term changes in the height of the ocean surface at a particular placed Tides = periodic, short-term changes in the height of the ocean surface at a particular placed Are the longest of the waves Are the longest of the waves Are huge shallow-water waves Are huge shallow-water waves Causes of the Tides: Causes of the Tides: Combination of the gravitational force of the moon and the sun, rotation of the Earth, and the shape of oceanic basins.

High Tide Low Tide

What Causes the Tides?

Spring Tides vs. Neap Tides During each phase of the new moon and full moon the earth, sun, and moon come into alignment creating spring tides. When they are not in alignment neap tides occur. During each phase of the new moon and full moon the earth, sun, and moon come into alignment creating spring tides. When they are not in alignment neap tides occur. Spring Tide- A tide which results in the greatest range between high and low tide Spring Tide- A tide which results in the greatest range between high and low tide Neap Tide- A tide which results in the least tidal range between high and low tide Neap Tide- A tide which results in the least tidal range between high and low tide

Tides Sun E E Spring Tide Neap Tide E = Earth m m m m m = Moon

Tides Tidal height (cm) Day Connecticut Washington State

Types of Tides Semidiurnal 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.Estuary of the River Severn 3.Puerto Punta Peñasco, Sonora, Mexico

Bay of Fundy The Bay of Fundy is located on the west coast of Novia Scotia The Bay of Fundy is located on the west coast of Novia Scotia It has the largest tidal range in the world of 53 ft. (16 m) It has the largest tidal range in the world of 53 ft. (16 m) 100 billion tons of water flow into and out of the bay on and average tide. 100 billion tons of water flow into and out of the bay on and average tide. ~ creates strong rip currents, swirling whirlpools, and up-wellings. The energy created by this great movement of water can be used as a clean renewable energy source. The energy created by this great movement of water can be used as a clean renewable energy source. Why is the tidal range so large at the Bay of Fundy? Why is the tidal range so large at the Bay of Fundy?

Bay of Fundy

Estuary of the River Severn Has the second largest tidal range in the world Has the second largest tidal range in the world Average height difference between low and high tides is 47 ft. Average height difference between low and high tides is 47 ft. Located in Britain Located in Britain Pictures of Clevedon Pier on the River Severn Pictures of Clevedon Pier on the River Severn

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??