# Chapter 15.  Purpose – In this activity, students begin to recognize the relationship between the salinity and density of water and understand that higher.

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Chapter 15

 Purpose – In this activity, students begin to recognize the relationship between the salinity and density of water and understand that higher salinity correlates with higher density.  Materials ◦ 2 – 500ml graduated cylinders ◦ Fresh water ◦ Salt water ◦ Small rubber ball or stopper

 Fill 500 ml graduated cylinders with 400 ml of fresh water and the other with 400 ml salt water.  Gently place small rubber ball in the fresh water. Record the new water level. Remove ball and dry thoroughly.  Gently place small rubber ball in the salt water. Record the new water level. Remove ball and dry thoroughly.

1. What volume of fresh water was displaced by the object? __________ 2. What volume of salt water was displaced by the floating object? ___________ 3. As the density of water increases, the volume of the liquid displaced by the object decreases. Which water is more dense – fresh water or salt water? _______________ 4. How does salinity affect the density of water?

1. What volume of fresh water was displaced by the object? __________ 2. What volume of salt water was displaced by the floating object? ___________ 3. As the density of water increases, the volume of the liquid displaced by the object decreases. Which water is more dense – fresh water or salt water? Salt Water 4. How does salinity affect the density of water? The addition of salt increases the density of water.

15.1 SC.912.N.1.1 SC.912.E.6.5 SC.912.E.7.3

 Identify the units used to express the salinity of ocean water.  List the sources of salt in ocean water.  Recognize the factors that affect the density of ocean water.  Compare and contrast the three main zones of the open ocean.

 Salinity  Thermocline  Density  Pycnocline  Mixed zone

1. What units are used to express the salinity of ocean water? 2. What are the sources of salt in ocean water? 3. What factors affect the density of ocean water? 4. What are the three main zones of the open ocean?

You will need to write down 5 facts from the movie. You will also need to be able to explain why you chose those particular facts.

 Salinity is the total amount of solid material dissolved in water.  Because the proportion of dissolved substances in seawater is such a small number, oceanographers typically express salinity in parts per thousands.  Most of the salt in seawater is sodium chloride, common table salt.

 Chemical weathering of rocks on the continents is one source of elements found in seawater.  The second major source of elements found in seawater is from Earth’s interior.

 Processes that decrease salinity: ◦ Precipitation ◦ Sea ice melting ◦ Icebergs melting ◦ Run off from land  Processes that increase salinity: ◦ Evaporation ◦ Formation of sea ice

Decrease: precipitation, runoff from land, icebergs melting, sea ice melting. Increase: evaporation, formation of sea ice.

 The ocean’s surface water temperature varies with the amount of solar radiation received, which is primarily a function of latitude.

 The thermocline is the layer of ocean water between about 300 meters and 1000 meters where there is a rapid change of temperature with depth.  The thermocline is a very important structure because it creates a barrier to marine life.

Sea surface temperature is highest at the equator and low latitudes because these areas receive the most solar radiation at the highest angle of incidence.

The thermocline is absent in the high latitudes because the temperature of surface water is closer to the temperature of deeper water.

 Density is defined as mass per unit volume. It can be thought of as a measure of how heavy something is for its size.  Factors Affecting Seawater Density ◦ Seawater density is influenced by two main factors: salinity and temperature.

 The pycnocline is the layer of ocean water between about 300 meters and 1000 meters where there is a rapid change of density with depth.

Pycnocline is not present in high latitude waters. This occurs because density and temperature do not vary with depth.

 Oceanographers generally recognize a three-layered structure in most parts of the open ocean: ◦ a shallow surface mixed zone, ◦ a transition zone, ◦ a deep zone.

 Shallow (extends to 300-450 meters)  Zone of mixing  Sun-warmed zone

 Between surface layer and deep zone  Thermocline and pycnocline

 Sunlight never reaches this zone.  Temperatures are just a few degrees above freezing.  Constant high-density water

Salinity is represented by parts per thousand.

Chemical weathering of rocks on continents and Earth’s interior

Temperature and salinity affect the density of water.

The three main zones of the open ocean are surface mixed zone, transition zone, and deep zone.

15.2 SC.912.N.1.1 SC.912.E.6.5, SC.912.E.7.3

 Recognize how marine organisms can be classified.  Differentiate between plankton and nekton.  Describe the area of the ocean in which most benthic organisms live.  List the factors used to divide the ocean into marine zones.

 Plankton  Phytoplankton  Zooplankton  Nekton  Benthos  Photic zone  Intertidal zone  Neritic zone  Oceanic zone  Pelagic zone  Benthic zone  Abyssal zone

1. How can marine organisms be classified? 2. What is the difference between plankton and nekton? 3. In which area do most benthos live? 4. What factors are used to divide the ocean into marine life zones?

 Marine organisms can be classified according to where they live and how they move.

You will read the assigned text. On a sheet of paper you will need: A title At least 3 facts An example (you may draw)

 Plankton include all organisms—algae, animals, and bacteria—that drift with ocean currents.  Phytoplankton are algal plankton, which are the most important community of primary producers in the ocean.  Zooplankton are animal plankton.

 Nekton include all animals capable of moving independently of the ocean currents, by swimming or other means of propulsion.

 Benthos describes organisms living on or in the ocean bottom.

 Three factors are used to divide the ocean into distinct marine life zones: the availability of sunlight, the distance from shore, and the water depth.  Availability of Sunlight ◦ The photic zone is the upper part of the ocean into which sunlight penetrates.

 The intertidal zone is the strip of land where the land and ocean meet and overlap, or the zone between high and low tides.  The neritic zone is the marine-life zone that extends from the low-tide line out to the shelf break.  The oceanic zone is the marine-life zone beyond the continental shelf.

 The pelagic zone is open zone of any depth. Animals in this zone swim or float freely.  The benthic zone is the marine-life zone that includes any sea-bottom surface regardless of its distance from shore.  The abyssal zone is a subdivision of the benthic zone characterized by extremely high pressures, low temperatures, low oxygen, few nutrients, and no sunlight.

 Here seawater seeps into the ocean floor through cracks in the crust.  At some vents, water temperatures of 100 o C or higher support communities of organisms found nowhere else in the world.

Marine organisms can be classified by where they live and how they move.

Nekton are able to move independently of ocean currents. Plankton are not.

Most benthos live on the shallow coastal ocean floor.

The factors dividing the marine life zone are: availability of sunlight, distance from shore, and water depth.

15.3 SC.912.N.1.1 SC.912.E.6.5 SC.912.E.7.3

 List the factors that influence a region’s photosynthetic productivity.  Describe the transfer of energy from one trophic level to another.  Compare and contrast food webs and food chains.

 Primary productivity  Photosynthesis  Chemosynthesis  Trophic level  Food chain  Food web

1. What advantage do organisms in a food web have over those in a food chain? 2. What limits primary productivity in tropical oceans? Why?

 Primary productivity is the production of organic compounds from inorganic substances through photosynthesis or chemosynthesis.  Photosynthesis is the use of light energy to convert water and carbon dioxide into energy-rich glucose molecules.  Chemosynthesis is the process by which certain microorganisms create organic molecules from inorganic nutrients using chemical energy.

 The low availability of solar energy limits photosynthetic productivity in polar areas.

 Productivity in tropical regions is limited by the lack of nutrients.  Solar energy is available year-round but nutrients are trapped in deeper waters because the permanent thermoocline prevents mixing between surface water and deeper water.

 In temperate regions, which are found at mid- latitudes, a combination of these two limiting factors, sunlight and nutrient supply, controls productivity.  Winter ◦ Low productivity ◦ Days are short and sun angle is low.

 Spring ◦ Spring bloom of phytoplankton is quickly depleted. ◦ Productivity is limited.  Summer ◦ Strong thermocline develops so surface nutrients are not replaced from below. ◦ Phytoplankton population remains relatively low.

 Trophic Levels ◦ A trophic level is a nourishment level in a food chain. Plant and algae producers constitute the lowest level, followed by herbivores and a series of carnivores at progressively higher levels.  Transfer Efficency ◦ The transfer of energy between trophic levels is very inefficient.

 A food chain is a sequence of organisms through which energy is transferred, starting with the primary producer.  A food web is a group of interrelated food chains.  Animals that feed through a food web rather than a food chain are more likely to survive because they have alternative foods to eat should one of their food sources diminish or disappear.

You need to read the questions prior to the test so you know what you are listening for. 10 points each. Will be a quiz grade.