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Chapter 11The Marine Biome

11.2Neritic Zones

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Objectives

Describe the factors that define a neriticzone.

Compare and contras two types of neriticzone ecosystems.

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Neritic ZonesThe edges of continents do not drop

suddenly into the ocean.

Instead, the major landmasses aresurrounded by an area of relativelyshallow water.

The shallow border that surrounds thecontinents is called the continental shelf.

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Neritic Zones

The ocean region between the edge of thecontinental shelf and the low tidemark iscalled the neritic (ne-RIHT-ihk) zone.

Because the continental shelf is usuallyshallow enough to be within the photiczone, it receives enough sunlight forphotosynthesis to occur.

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Neritic Zones

The neritic zone accounts for only about10% of the ocean but is the mostproductive part of the ocean.

Two types of very productive neriticecosystems are reefs and estuaries.

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Coral ReefsA reef is a natural structure built on a

continental shelf.

Reefs are made from products of the reeforganisms.

Reefs are found in warm, tropical waters.

Kelp reefs, also called kelp beds are found incold waters.

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Coral ReefsReefs can be thought of as the tropical

rain forest of the marine biome.

Coral reefs are the breeding and feedinggrounds for many economicallyimportant types of fish.

One-thrid of all ocean fish live on ordepend on coral reefs.

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Coral ReefsThe reef itself protects the shoreline from

erosion.

Many coral reef organisms may havemedicinal value that has not yet beenidentified.

The delicate coral reef ecosystems of theworld are vulnerable to human activities.

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Coral ReefsThe reef is made from the calcium

carbonate skeletons of millions of tinycorals.

Only the top layer of the reef is alive.

Corals depend on a symbioticrelationship with a form of algae, calledzooxanthellae (ZOH-oh-ZAN-thel-ay),that lives inside the tissues of the coral.

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Coral Reefs

The Zooxanthellae algae carry outphotosynthesis and provide corals with food.

These photosynthetic organisms require anadequate amount of sunlight and cannot growbelow a certain depth.

Human activities can harm coral reefs in manyways.

The reef is often blasted with dynamite to makeharbors and shipping channels.

The coral itself is often harvested and sold forjewelry.

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Coral Reefs

Water pollution is also a major cause of coralreef damage.

Silt, sand, and topsoil that wash into the watermake it cloudy and reduce the amount of lightavailable for photosynthesis. As a result, thezooxanthella die. This is called coralbleaching.

When the corals begin to die rapidly, it is a signthat there is something wrong with the qualityof the water.

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Great Barrier Reef,Austrailia

http://video.nationalgeographic.com/video/player/places/parks-and-nature-places/oceans/oceans-barrier-reef.html

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Estuaries

An estuary (ES-tyoo-ayr-ee) is a region where afreshwater source, usually the mouth of a river,meets the salt water of the ocean.

Estuaries are subject to the rise and fall ofocean tides that mix the nutrient rich watersand sediments.

The water in an estuary is usually brackish, butthe salinity varies with depth, time of year, flowrate, and tide.

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Estuaries

Many commercially important food species useestuaries as spawning grounds.

Humans use estuaries for recreationalactivities, such as boating, hunting, andfishing.

Estuaries function as important buffer zones,filtering sediments and pollutants from thewater.

They also ease the effects of storms and floodsby slowing the flow of water.

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Estuaries

The Chesapeake Bay isthe largest estuary in theUnited States.

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Question 1

Where in the ocean does the neritic zonebegin and end?

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Answer

The neritic zone begins at the end of theintertidal zone and ends at the edge of thecontinental shelf.

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Question 2

Continental shelves have been called thebreadbaskets of the ocean. Explain thisstatement.

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Answer

Continental shelves are responsible formuch of the productivity that feeds theentire ocean.