Chemical and Chemical and Physical Physical

Features of the Features of the World OceanWorld Ocean

To understand the To understand the biology of marine biology of marine

organisms we must organisms we must know something about know something about

the environment in the environment in which they live.which they live.

The Waters of the OceanThe Waters of the Ocean The presence of The presence of waterwater makes our makes our

planet planet uniqueunique. Most other planets . Most other planets have little to no water and the ones have little to no water and the ones that do, have water in the that do, have water in the solidsolid ( (iceice) ) or or gasgas ( (water vaporwater vapor) form) form

The oceans play a crucial role in The oceans play a crucial role in regulating our regulating our climateclimate and and atmosphereatmosphere

Without water LIFE would be Without water LIFE would be IMPOSSIBLEIMPOSSIBLE!!!!!!

Oceans make up about Oceans make up about 75%75% of the of the Earth’s surfaceEarth’s surface

Commonly classified into 4 large basins: Commonly classified into 4 large basins: PacificPacific, , AtlanticAtlantic, , IndianIndian, and , and ArcticArctic

Water makes up Water makes up 80%80% of most marine of most marine organisms. Jellyfish are actually organisms. Jellyfish are actually made up of over made up of over 95%95% water water!!

The States of WaterThe States of Water

Water is the only substance that Water is the only substance that naturally occurs as a naturally occurs as a solidsolid, , liquidliquid, , and and gasgas on earth. on earth.

Phase ChangesPhase Changes

1.1. Evaporation – liquid to a gasEvaporation – liquid to a gas

2.2. Melting – solid to a liquid Melting – solid to a liquid

3.3. Freezing – liquid to a solid Freezing – liquid to a solid

4.4. Condensation – gas to a liquidCondensation – gas to a liquid

As seawater gets colder it gets more As seawater gets colder it gets more dense and therefore tends to sink in dense and therefore tends to sink in the oceanthe ocean

D = M/VD = M/V

Density = mass / volumeDensity = mass / volume

Since water expands as it freezes the water Since water expands as it freezes the water molecules become farther apart making the molecules become farther apart making the solid state less dense than the liquid state solid state less dense than the liquid state

(ice floats on liquid water)(ice floats on liquid water) This is extremely unusual - for a substance’s solid This is extremely unusual - for a substance’s solid

phase to be less dense than its liquid phasephase to be less dense than its liquid phase This unique characteristic is extremely important This unique characteristic is extremely important

for aquatic organisms (both marine and fresh for aquatic organisms (both marine and fresh water)water)

b/c ice floats it acts as an insulating blanket that helps b/c ice floats it acts as an insulating blanket that helps keep water below from rapidly cooling off in cold keep water below from rapidly cooling off in cold weatherweather

This keeps organisms alive beneath the iceThis keeps organisms alive beneath the ice

SeawaterSeawater

The solids dissolved in seawater The solids dissolved in seawater come from 2 main sources:come from 2 main sources:

1.1. Chemical weathering of rocks on land Chemical weathering of rocks on land

2.2. Earth’s interior – ex. Hydrothermal Earth’s interior – ex. Hydrothermal vents or volcanoesvents or volcanoes

Salt CompositionSalt Composition

6 main solutes of seawater 6 main solutes of seawater (98% of solids (98% of solids in the ocean):in the ocean):

1.1. Chloride (Cl)Chloride (Cl)

2.2. Sodium (Na)Sodium (Na)

3.3. Sulfate (SOSulfate (SO44) )

4.4. Magnesium (Mg)Magnesium (Mg)

5.5. Calcium (Ca)Calcium (Ca)

6.6. Potassium (K)Potassium (K)

85%

SalinitySalinity

Salinity is the total amount of salt Salinity is the total amount of salt dissolved in seawaterdissolved in seawater Salinity of water strongly affects the Salinity of water strongly affects the

organisms that live in it.organisms that live in it. Even slight changes in salinity will Even slight changes in salinity will

harm some organismsharm some organisms

Rule of Constant Rule of Constant ProportionsProportions

States that the relative amounts of States that the relative amounts of various ions in seawater are always various ions in seawater are always the samethe same Chloride always = 55% of the ions no Chloride always = 55% of the ions no

matter how much salt is presentmatter how much salt is present Marine organisms don’t have to worry Marine organisms don’t have to worry

about ion ratio changes only total about ion ratio changes only total salinity levelssalinity levels

Salinity, Temperature, and Salinity, Temperature, and DensityDensity

Density of seawater depends on both Density of seawater depends on both temperaturetemperature and and salinitysalinity seawater gets more dense as it gets seawater gets more dense as it gets colder and saltiercolder and saltier

+/OR =Density

TransparencyTransparency One of the most biologically One of the most biologically

important properties of seawater is important properties of seawater is that it is relatively transparentthat it is relatively transparent Sunlight can go fairly deep into the Sunlight can go fairly deep into the

oceanocean Vital to plants that need light for Vital to plants that need light for

photosynthesisphotosynthesis

PressurePressure

Pressure increases as depth Pressure increases as depth increases increases This limits depth range of marine This limits depth range of marine

organisms (gas-filled body structures organisms (gas-filled body structures could shrink or collapse)could shrink or collapse)