11-2 Neritic Zones Where the edges of the continents meet the oceans. The water is relatively shallow here. The continental shelf is the shallow border that surrounds the continent. It extends about 500m below the surface of the water. The neritic zone is the ocean region between the edge of the continental shelf and the low tidemark. These waters are in the photic zone so photosynthesis occurs. They account for about 8% of the total ocean waters. These waters are the most productive parts of the oceans.

Continental Shelf

2 Types of Neritic Ecosystems Reefs Estuaries

Reefs A natural structure built on a continental shelf. Coral reefs are found in warm tropical waters. Kelp reefs (kelp beds) are found in colder waters. Barrier reefs are reefs in areas of reduced oxygen and nutrients.

Coral Reefs The rain forests of the marine biome. Very productive ecosystems. Home to huge variety of organisms. ( 1 main importance) breeding and feeding grounds of many types of fish. 1/3 of all fish in the ocean live on or depend on the coral reef. (Another importance) protects shoreline from erosion. (Another importance) many coral reef organisms have medicinal value. Made up of calcium carbonate skeletons of millions of coral animals.

Coral Reefs Only top layer is alive. Depend on symbiotic relation with alga called zooxanthelle. This alga carries out photosynthesis and provides food for the coral reef.

Human Impact on Coral Reefs Blasted to make harbors and shipping channels. Coral is harvested and sold as jewelry. When colorful fish are collected for home aquariums, the coral reef (where these fish are found) is damaged. Water pollution is also a damaging cause. When coral reefs are affected by chemicals, they show rapid death. This is one reason why coral reefs are a good indicator of pollutions.

Estuaries A region where a freshwater source, usually the mouth of a river, meets the saltwater of the ocean. Subject to the rise and fall of the tides. Water is brackish. Used as spawning grounds for many organisms. Humans use estuaries for boating, hunting and fishing. Estuaries act as buffer zones, filtering sediments and pollutants from the water. They also ease the effects of storms and floods by slowing the flow of water.

Estuaries

Neritic Zone Productivity Since the water is shallow, the sunlight reaches the benthic community. Photosynthesis takes place in all zones. Water is high in minerals.