Part 1

Aspects of a Marine Environment Wind Waves Tides Currents Temperature Salt and salinity **Take a minute and write what you know already about each of these terms**

Significance of Water Where organisms are found in a marine environment is determined by chemical and physical factors Marine organisms are made mostly of water In most cases, 80% or more of body weight is from water Water makes life possible both on land and in waters

Special Characteristics of Water Water molecules stick together because of their polarity Hydrogen atoms are positive Oxygen atoms are negative Water molecules contain hydrogen bonds Makes water different from any other substance on Earth

More Special Characteristics Temperature is a reflection of the average speed of the molecules Faster they move  higher the temperature Slower they move  lower the temperature As water cools, the molecules pack closer together and become more dense Water becomes more dense until is reaches 4°C After 4°C, water becomes less dense as the temperature drops

Self Check If water molecules are vibrating slowly, is the temperature going to be cool or warm? How do you know this? Cool because the speed of the molecules vibrating determines the temperature of water Is water at 1°C more or less dense than water at 4°C? How do you know this? Water at 1°C will be more dense than water at 4°C because water becomes dense after 4°C

More Special Characteristics Water molecules spaced out farther in ice than in liquid water Allows ice to float on top of water Why does water float on top of water? Because it is less dense than liquid water Ice insulates water below and makes life in the water possible

Latent Heat of Melting Definition: amount of heat required to melt a substance Takes a large amount of heat to melt ice Why do you think this?

Heat Capacity Definition: how much heat that a substance can absorb Water has one of the highest heat capacities of any substance Importance: most marine organisms are not exposed to the dramatic temperature changes that occur on land Why is this important to marine organisms?

Seawater Characteristics are due to both the nature of pure water and the material dissolved in it Dissolved materials: Oxygen Solids  comes from the chemical wearing away of rocks on land that is carried to the sea by rivers Solids can also come from hydrothermal vents and volcanoes What makes up these solids?

Salinity Definition: amount of salt dissolved in seawater Calculated by the number of grams of salt left behind when 1,000 grams of seawater are evaporated Expressed in parts per thousand (ppt) Importance: greatly affects marine organisms How? Slight changes can harm them Most can’t survive in pure water

Salinity of the Oceans What are some factors that affect the salinity of these oceans?

Salinity, Temperature, and Density Higher salinity of water = more dense Lower salinity of water = less dense Colder water = more dense Warmer water = less dense

Temperature Profile Definition: a graph that shows the temperature at different depths in the ocean Different depths of the ocean in a vertical shaft of water make up the water column

Dissolved Gases Gases are dissolved in seawater as well as solid materials 3 most important gases: Oxygen (O 2 ) Carbon dioxide (CO 2 ) Nitrogen (N 2 ) Found in the atmosphere and dissolve at the sea surface Which do of the gases do you think is most important to marine life? Why?

Dissolved Gases cont. Gases dissolve better in cold than in warm water Dissolved gas concentrations are higher in polar waters than in the tropics Cold water has _________ dissolved O 2 Warm, tropic water has _____________ dissolved O 2

Circle the regions that have the least amount of dissolved O 2 Star the regions that have higher concentrations of dissolved O 2

Transparency Definition: how much sunlight can penetrate into the ocean Most biologically important property of water Allows for photosynthesis to occur Not all colors go through seawater as far as others Blue penetrates the farthest Red penetrates the least Why do you think transparency is the most biologically important property?

Turbidity Definition: a measure of water clarity and how much the material suspended in the water decreases the passage of light through water Suspended materials: Soil particles (clay, silt, sand) Algae Plankton Microbes- a tiny organism that causes disease Higher turbidity = higher water temperature Why does an increase in turbidity increase the temperature of the water?

Pressure Definition: continuous physical force exerted on an object With each 10 m of increased depth another atmosphere of pressure (atm) is added As pressure increases, gases become more compressed Limits range of organ function Ex. swim bladder becomes enlarged and can come out of fish’s mouth if brought up to the surface too quickly from a deep depth

Three dimensional structure of the sea is controlled by the density of water

Stability and Overturn Densest water sinks  ocean is usually layered (stratified) Deep water = cold and dense Surface water = warm and light Is the water that we swim in at the beach deep water or surface water? Why?

Water Column Stability What is a water column? A vertical shaft of water with different depths Stable water column- less dense water on top, dense water on bottom Low stability- surface water is only slightly less dense than deep water Highly stable- large density difference between layers Unstable- surface water is more dense than bottom water

Downwelling- when surface water sinks to the bottom Overturn- when dense surface water relocates deeper water Occurs in temperate and polar regions during the winter when surface water cools

Thermohaline Circulation Driven by changes in density What determines water’s density? Temperature and salinity Extended throughout the ocean depths Regulates earth’s climate Mixes the oceans Brings dissolved oxygen to the deep sea Why is it important that dissolved oxygen is brought to the deep sea?