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The textbook I have chosen to use for our course is called Oceanography sixth edition by M. Grant

Gross. There are 16 chapters in the book and I plan to cover a chapter each week. That puts us on pace

to finish the book by the end of the semester. That would leave the entire second semester open to

more creative activities,

Chapter 12: Life in the Ocean (because chapter 1 is boring)

We have 4 Goals in this section:

1.

Understand the main parts of oceanic ecosystems

2.

Understand primary and secondary production in the ocean

3.

Be able to explain how organisms affect the composition of seawater

4.

Describe and explain the distribution of primary production in the ocean

Many of the same rules apply to oceanic ecosystems and terrestrial (land) ecosystems. The primary

source of energy in the ocean is the sun. The energy from the sun is absorbed by producers, which in

turn use that energy to grow and reproduce. These producers are then eaten by primary consumers.The primary consumers are eaten by secondary consumers. And so on

Its important to understand that the different animals and plants in the ocean depend on each other for

a variety of reasons. Lets review some of the classifications of organisms according to how they obtain

food and energy:

Autotrophic organisms obtain their energy through sunlight by using photosynthesis to manufacture

sugar. Most plants are autotrophic. The majority of the plants in the ocean are very small. In fact, they

are only one cell! They are called phytoplankton live at the surface of the ocean so that they can receive

sunlight and CO2, which is used to make sugar with the help of chlorophyll.

Animals eat the sugars produced by the phytoplankton. They combine the sugar with oxygen. This

creates miniature explosions in their cells which is harnessed for energy. The process is called cell

respiration. Cell respiration and photosynthesis are the same process the only difference is the

direction of the chemical reactions.

Some organisms are autotrophic even though they do not use photosynthesis. There are many species

of bacteria that use a process called chemosynthesis. They are very important to the ocean because

they are able to feed on certain chemicals. This converts these chemicals into different chemicals that

are needed by other organisms. Chemosynthesis is needed is places where there is very little or no

sunlight. These bacteria may live in large colonies which other organism will feed on or they mayactually live inside of other deep-sea organisms in a symbiotic relationship.

Heterotrophic organisms get their energy by consuming other organisms.

Decomposers break down the dead tissues of other organisms. This is an important process which helps

to recycle materials that are needed for other organisms to live and grow.

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Trophic levels

Each time an organism is eaten, only 10% of its energy is passed on to the consumer.

Carnivores, Herbivores, Omnivores, and Detritivores

While matter is often recycled, energy is a one way street. Luckily, the sun continues to restore that

energy to the ocean ecosystems through the producers.

Review Food Webs

Biomass is the total amount of plants and animals divided by the volume of water that they live in.

Sometimes we can also divide the mass by the area of the ocean floor below them. Think of it as

Population Density.

Production is similar concept to biomass. Instead of measuring the total amount of organism in an area,

we measure how much energy those organism can produce.