Properties of Properties of WaterWater

Marine and Marine and FreshwaterFreshwater

1. Temperature1. Temperature

THE most important limiting THE most important limiting factor.factor.

A change in temperature can A change in temperature can change other parameters.change other parameters.

Surface water is heated by the Surface water is heated by the sun and changes seasonally.sun and changes seasonally.

A narrow zone called a thermocline A narrow zone called a thermocline separates warm surface water from separates warm surface water from cool bottom water.cool bottom water.

Divers can feel temperature Divers can feel temperature differences as they go through this differences as they go through this zone.zone.

Whales use this zone for long distance Whales use this zone for long distance communication…this channel is called communication…this channel is called the sofar channelthe sofar channel

THERMOCLINETHERMOCLINE

Sofar channelSofar channel

Most marine animals are ectothermic. Most marine animals are ectothermic. Warmer water temperature increases Warmer water temperature increases their metabolism.their metabolism.

However, warm water holds less However, warm water holds less OxygenOxygen

Mammals and a few fish are Mammals and a few fish are endothermic…can usually maintain a endothermic…can usually maintain a constant body temp, but can suffer constant body temp, but can suffer from hypothermia like we can.from hypothermia like we can.

Sea surface temperatureSea surface temperature

Evaporation and condensation provide Evaporation and condensation provide energy to run the hydrologic cycle; energy to run the hydrologic cycle; this energy reduces the possibility of this energy reduces the possibility of freezing in marine organisms’ tissues.freezing in marine organisms’ tissues.

Water also has a high heat capacity Water also has a high heat capacity that allows it to absorb or release that allows it to absorb or release large quantities of heat with little large quantities of heat with little temp change; this helps to moderate temp change; this helps to moderate climates.climates.

2. Salinity2. Salinity

Is the amount of dissolved solids in Is the amount of dissolved solids in waterwater Ions of chloride, sodium, sulfate, Ions of chloride, sodium, sulfate,

magnesium, calcium or potassiummagnesium, calcium or potassium The first 4 ions listed are remarkably The first 4 ions listed are remarkably

constant in seawater. If chloride ions constant in seawater. If chloride ions are measured, then the other ions can are measured, then the other ions can be calculated from it.be calculated from it.

Units are in parts per thousand (ppt)Units are in parts per thousand (ppt)

Surface salinity is Surface salinity is GREATLY GREATLY influenced by influenced by temperature. High temperature. High temperatures temperatures cause increased cause increased evaporation rates evaporation rates and increase and increase salinity.salinity.

The halocline is a zone where The halocline is a zone where fluctuating surface salinity is fluctuating surface salinity is divided from the constant divided from the constant salinity of deeper water.salinity of deeper water.

3. Density3. Density Density = mass (g) / volume (ml)Density = mass (g) / volume (ml) Density is affected by temperature Density is affected by temperature

and salinity.and salinity. Water is 800 times more dense than Water is 800 times more dense than

air. Sea water is more dense than air. Sea water is more dense than fresh water.fresh water.

Above the freezing point, the density Above the freezing point, the density of water is 1 gram/cubic centimeter. of water is 1 gram/cubic centimeter. When water freezes, its density When water freezes, its density decreases because the volume decreases because the volume increases.increases.

Ice has a Ice has a density of .92 density of .92 g/cmg/cm33 so it so it floats in floats in water.water.

Any object will Any object will float in water float in water if its density is if its density is less than the less than the density of density of water it is water it is floating in.floating in.

Chemical Properties of Chemical Properties of WaterWater

1. pH in sea water is closely 1. pH in sea water is closely associated with dissolved COassociated with dissolved CO22

COCO22 is a reactant in photosynthesis is a reactant in photosynthesis and a product of respiration. It and a product of respiration. It dissolves easily in sea water and is dissolves easily in sea water and is stored in marine shells and sediments.stored in marine shells and sediments.

HH22O + COO + CO2 2 = H = H22COCO33 Carbonic Acid Carbonic Acid—lowers the pH of the water—lowers the pH of the water

Enzyme activities and the shapes of Enzyme activities and the shapes of vital proteins require a stable pH.vital proteins require a stable pH.

Since mollusk’s shells are calcium Since mollusk’s shells are calcium carbonate, a decrease in pH could carbonate, a decrease in pH could dissolve shells.dissolve shells.

Dissolved GassesDissolved Gasses

2. Dissolved nitrogen is the most 2. Dissolved nitrogen is the most common gas in the ocean because it common gas in the ocean because it dissolves from the atmosphere dissolves from the atmosphere where there is 78%.where there is 78%. It can’t be used by organisms until it is It can’t be used by organisms until it is

attached to oxygen—nitrogen fixationattached to oxygen—nitrogen fixation Nitrogen fixation happens because of Nitrogen fixation happens because of

blue-green algae.blue-green algae.

3. Dissolved oxygen comes mostly 3. Dissolved oxygen comes mostly from photosynthesis of marine plants from photosynthesis of marine plants and algae.and algae.

They produce over 50% of the total They produce over 50% of the total atmospheric oxygen.atmospheric oxygen.

Marine animals need OMarine animals need O2 2 for for respiration.respiration.

Below the thermocline, there is very Below the thermocline, there is very little oxygenlittle oxygen

4. Carbon dioxide is highly soluble 4. Carbon dioxide is highly soluble in sea water…which contains about in sea water…which contains about 50x more CO50x more CO22 then the atmosphere. then the atmosphere.

Effects of LightEffects of Light

Marine plants (autotrophs) make Marine plants (autotrophs) make their own food by photosynthesis.their own food by photosynthesis.

Marine food webs depend on light Marine food webs depend on light that either is absorbed or reflected that either is absorbed or reflected as it enter the water.as it enter the water.

About 65% of the light energy is About 65% of the light energy is absorbed in the first 5 feet and can’t absorbed in the first 5 feet and can’t be used by autotrophs.be used by autotrophs.

Red light is absorbed first.Red light is absorbed first. Blue light is transmitted bestBlue light is transmitted best

Light is inversely proportional to Light is inversely proportional to depth…as you increase depth, you depth…as you increase depth, you decrease light.decrease light.

The lighted layer is called the photic The lighted layer is called the photic zone…only about 10% of the oceanzone…only about 10% of the ocean

The dark layer is the aphotic zone…The dark layer is the aphotic zone…90% of the ocean is dark90% of the ocean is dark

TurbidTurbidityity

Is the measure of the Is the measure of the suspended or suspended or dissolved solids.dissolved solids.

The more sediments, The more sediments, the less light the less light penetration and the penetration and the poorer the visibility. poorer the visibility. Photosynthesis is Photosynthesis is reduced by turbidity.reduced by turbidity.

Turbidity can be Turbidity can be measured with a measured with a secchi disk.secchi disk.

PressurePressure

Pressure at sea level is the weight of Pressure at sea level is the weight of air (14.7 lb/inair (14.7 lb/in3 3 ) )