Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 14

Oceanographers have divided the ocean into zones to better understand and describe the physical characteristics of the ocean, the ecosystems (biological communities) in each zone, and the inhabitants of those ecosystems. Zoning can be simple, such as dividing the ocean into two zones — photic and aphotic:

 Photic (light): The top 200-meter (650-foot) layer of the ocean through which enough light penetrates enabling photosynthesis to occur. (Photosynthesis is the process of using the sun’s energy to produce food from carbon dioxide and water.)

 Aphotic (dark): The part of the ocean from 200 meters down to the bottom, where it’s totally dark.

Another simple zoning system involves dividing the ocean into pelagic and benthic layers:

 Pelagic (top): The water above the ocean floor.

 Benthic (bottom): The seafloor and the thick layer of sediments below the seafloor.

In Chapter 4, we cover two more-detailed approaches to zoning the ocean — one that divides it into five horizontal layers (like layers of a cake) based on depth, and another that divides it into three vertical zones from coast to open ocean.