The Neritic Zone

1. The Neritic Zone By: Mallory Jayjohn, Hadley Jahnke, Christiana Carr, and Lily Davis

3. About the Neritic Zone • The Neritic zone is the first 200 meters of ocean water which includes the sea shore and most of the continental shelf. • The Neritic zone is a subdivision of the Pelagic zone. • This zone has generally well-oxygenated water, low water pressure, and relatively stable temperature and salinity levels. • Unlike clear blue waters around coral reefs, coastal seas are green, a sign of high productivity. • Neritic waters are penetrated by varying amounts of sunlight, which permits photosynthesis by both planktonic and bottom-dwelling organisms. • The neritic zone covers an area equivalent to about the size of Asia. • It contains only 10% of the ocean’s expanse. • It produces nearly 90% of the world’s annual harvest of fish and shellfish.

4. The continental shelves • Neritic Zone is located above the continental shelf which extends along the coastline of the major land masses of the world. • continental shelfs along the east coast of the US extend more into the ocean because it is located along a passive margin, where as on the west coast it does not extend very far due to the fact that it is on an active margin. The more of a continental shelf there is, the more space there is for the neritic zone. • Continental shelves are commercially exploited for the ores and fossil fuels that can be extracted from them, and the waters above the shelves provide a wealth of seafood.

5. Food Chains • The microscopic photosynthetic organisms form the basis of aquatic food webs • The greatest concentration of marine life exists in the Neritic zone beginning at the low water mark to the edge of the continental shelf. • Phytoplankton and floating sargassum are found in this region along with zooplankton. • Zooplankton- the floating creatures ranging from microscopic diatoms to small fish and shrimp. • Many species of whales feed entirely on the zooplankton, such as the gigantic blue whale and the humpback. • Although fish are found everywhere in the ocean, the abundance found in the neritic zone provides a plentiful source of food for larger animals.

6. Food Chains Because of the abundance of sunlight and nutrients, phytoplankton in coastal seas can reproduce at extremely rapid rates and can therefore support about five times their own biomass in primary consumers. In this generalized pyramid, the size of each box indicates the relative amount of biomass at each trophic level. Quaternary Consumers Tertiary Consumers These primary consumers, which include enormous Secondary Consumers amounts of zooplankton, are in turn a rich food supply for large populations of higher Primary Consumers order consumers. Primary Producers (phytoplankton)

7. Food Chains cont. The neritic zone receives freshwater runoff from the neighboring land, which provides enough nutrients to support the growth of relatively large producers called micro-phytoplankton as well as smaller forms, the nanophytoplankton. Because tiny phytoplankton can be either eaten directly by small zooplankton or filtered from the water by benthic filter feeders such as clams and worms, food chains in coastal seas are frequently two or more steps shorter than those of the open sea. This combination of higher productivity and shorter food chains supports a larger number of high-level consumers.

8. PRODUCTIVITY The most productive of the planktonic ecosystems are located in upwelling zones, where the combination of winds, ocean currents, and shape of the sea floor interact to bring nutrients into the photic zone from the ocean floor. Biologists estimate that about 1/7 of the anchovies caught world wide by humans and seabirds come from Peru’s coastal seas.

9. Bibliography Contrast, By. "Continental Shelf - New World Encyclopedia." Info:Main Page - New World Encyclopedia. Web. 01 Dec. 2010. <http://www.newworldencyclopedia.org/entry/Continental_shelf>.