Earth Science II (Session 14) Ocean Water Earth Science II (Session 14)

Introduction The oceanic microflora produces most of oxygen that we breath. 90% of the Earth´s Oxygen comes from Marine photosynthesis by phytoplankton and algae. Through the water cycle, the oceans purify the atmosphere and constitute an immense space for marine life.

Origin of the oceans In its beginnings, the Earth was surrounded by great volcanic activity throwing rocks and gases that later gave origin to the atmosphere. With time, the Earth’s surface cooled enough so that the water vapor was condensed and formed water drops that fell on Earth in form of rain during thousands of millions of years. The rain water formed rivers and water streams initiating the formation of oceans.

Properties of ocean water Physical properties Data Salt (Sodium chloride, sodium bromide and fluoride. Calcium potassium, carbonates and magnesium, etc.) 34.5 g/Kg Density 1.026 - 1.028 g/cm³ Dissolved gases (Oxygen and Carbon dioxide) Variable Boling Point More then 100oC Freezing Point Less then 0oC DiSpezio, Michael , et al. (1999)

Marine organisms The organisms that habitat the oceans use substances of the ocean water as nutrients and to obtain energy. Many of these organisms depend on solar light and because of this they need to live on the superficial waters. The density of the ocean water also affects the organisms that live in the ocean.

Distribution of life in the oceans Ocean zones Organism's Euphotic (500 m) also called the Sunlight Zone Seaweed Zooplankton & plants Fish Marine mammals Dysphotic (1,000 m) also called the Twilight Zone Mollusks Aphotic (up to 6,000 m) this latin word mean “no light” Worms Gelationous bodied Gutiérrez, M. (1996)

Distribution of life in the oceans Gutiérrez, M. (1996) Distribution of life in the oceans

In the ocean, the same phenomenon of the food chain as what occurs on the Earth’s surface occurs. Predator fish, eat smaller fish. Small fish eat smaller organisms. Small organisms eat micro organisms…..and so on….

Facts Most of the life in the ocean is found in the Euphotic zone. This layer is also the smallest. Many fish and mammals use countershading to disguise themselves. Their backs are dark and their bellies are light

Things to Think about Dysphotic Zone….there is no photosynthesis here…why? What mechanism do organisms use in to create light? What is the relationship between pressure and temperature in the ocean? What are the factors that affect the oceans density?

Physical Properties The surface zone is heated by solar energy and mixed by the wind. The warmest water and the least dense water is found in the surface zone. Surface water temps can vary from 28°C near the equator or -2° near the poles. http://www.bigelow.org/collaboratory/images/Thermocline.jpg

Thermocline Occur when water temperatures decrease rapidly. Are formed becuase warm surface water floats on top of the colder water The depth of the thermocline can vary due to location or season http://www.bigelow.org/collaboratory/images/Thermocline.jpg

Reading in class From the textbook… Science and Technology: Drinkable Ocean Water. Page 342

Bibliography DiSpezio, M. et al. (1999) Science Insights: Exploring Earth and Space. 1st ed. United States of America: Prentice Hall. Gutiérrez, M. (1996) Ecology: Lets Save the Planet Earth. 1st ed. Mexico: LIMUSA.