The Marine Biome Section 10

I Can… Locate the major ocean zones based on their relationship to the shore Describe the flow of water through the world ocean and the characteristics of ocean water in different parts of the world.

The World Ocean The ocean may seem infinitely large; too big to be affected by humans and their activities. Oceans have been called the lungs of the Earth, cycling carbon dioxide and oxygen. Oceans moderate temperatures and their changes. Lastly, the oceans are home to many organisms that affect the stability of the Earth and it’s complex food web.

The World Ocean All the water between the continents can be though of as one big ocean, even though people have assigned them different names. Because they are all connected, they can be thought of as one large biome.

The World Ocean We can divide this biome up into zones horizontally and vertically. We discussed the vertical zones in the last chapter: the photic, aphotic and benthic zones. The ocean can also be divided into zones based on distance from the shore: the oceanic, neritic, and intertidal zones.

The World Ocean

The World Ocean The open ocean is considered the oceanic zone. This is the largest zone at over 90% of the surface area of the ocean. The oceanic zone is very deep, ranging from 500m to 11,000m. Sunlight does not penetrate deeply into the oceanic zone.

The World Ocean The photic zone is up to 200m deep at the surface of the ocean. The only producers in the open ocean are phytoplankton. Each year the phytoplankton absorb tons of carbon from the atmosphere. Plankton are a major food source for large animals in addition to zooplankton and smaller animals.

The World Ocean In terms of biomass, the aphotic zone of the ocean can be thought of as the ocean’s desert. The lack of sunlight limits the number of organisms that live there.

The World Ocean Deep ocean organisms have adapted to living without sunlight. Many feed on detritus, or dead organic materials that drift down from the oceans surface. Benthic organisms include: clams, worms and sponges.

The World Ocean Although all the oceans are connected, not all ocean waters are the same. Differences in temperature caused by receiving different amounts of sunlight cause ocean water to vary in salinity and density as well as temp. Where do you think the water is saltier? Why? Where do you think the water is denser? Why?

The World Ocean Water near Earth’s equator receives the most sunlight, so the water is warmer. Warmer water evaporates more rapidly, this tends to increase the salinity in the water nearer the equator.

The World Ocean The water by the poles tends to be fed by melting glaciers and polar ice. This increase in freshwater decreases the salinity near the higher latitudes. The colder water make the water near the poles denser, as well.

The World Ocean Because of this unequal heating the water in the ocean flows in currents. Although some currents change throughout the year with the seasons, some currents are very stable. Ocean currents are driven by winds.

Ocean Currents

The World Ocean Fish and other organisms can travel within specific oceans following the ocean currents long distances. Likewise, with pollutants, they often do not simply dilute in the water, but they get moved around by the currents. Pollutants also get concentrated in fish eaten by humans. The Ocean Dumping Act of 1988 prohibited dumping industrial waste at sea.

I Can… Describe the factors that define a neritic zone. Compare and contrast the two types of neritic zone ecosystems.

Neritic Zone The edges of the continents do not suddenly drop off into the ocean. The are surrounded by a shallow border called the continental shelf. This area is between the shore and approximately 500m below the water’s surface. It does vary by continent and coastline, though

Neritic Zone The ocean region between the edge of the continental shelf and the low tide mark is the neritic zone. The neritic zone is within the photic zone. About 10% of the ocean is neritic zone, but it is the most productive part of the ocean.

Neritic Zone The two most abundant sections of the neritic zone are the coral reefs and the estuaries. Coral reefs are structures built on the continental shelf made from skeletons of coral organisms. Estuaries are regions where freshwater sources meet the saltwater of the ocean.

Coral Reef Estuary

Neritic Zone Coral reefs are found in warm, tropical waters. Kelp reefs, or beds, are common in cooler waters. Coral reefs can be thought of as the tropical rainforests of the ocean. They are extremely productive and home to a huge variety of life.

Neritic Zone Coral reefs are the breeding grounds for many types of fish, including those that are economically important. 1/3 of ocean fish live or depend on the coral reefs. Many organisms may have medicinal value that is yet undiscovered. Like the rainforests, the reef is vulnerable to humans.

Neritic Zone The reef protects the shoreline from erosion, but yet is very fragile. The reef is made of calcium carbonate skeletons of millions of tiny coral. Only the top layer of the reef is alive Has a symbiotic relationship with algae called zooxanthellae.

Neritic Zone The algae carry out photosynthesis within the tissues of the coral and provide the coral with food. Because of the photosynthesis, corals must live where the sun penetrates the water.

Neritic Zone Humans can harm corals in many ways. Removal to make way for shipping and harbors. Corals can be harvested to make jewelry. The beautiful fish are taken for aquariums, and the methods to collect them can damage the corals. Water pollution Chemical, temperature, water clarity, etc.

Neritic Zone Often the coral act as the “canary in the coal mine”; they are the first organism affected when something is wrong with the water quality of the ocean waters.

Neritic Zone An estuary can be thought of as the nursery of the ocean. They are subject to the rise and fall of tides, but this helps mix nutrients into the water and soils for higher nutritional food qualities. The water is usually brackish.

Neritic Zone Estuaries act as buffer zones. They filter out pollutants and sediments from the water. They also help stem flooding and storm surges by absorbing and slowing the flow of water. Humans use estuaries for recreation.

Neritic Zone The productivity of the neritic zone depends on many factors. Sunlight is the most important for photosynthesis. Mineral nutrients. Tides (nutrients and oxygen in, wastes out)

Neritic Zone The effects of tides affect the development of a reef. Reef formation: Fringe reef – grows just off the land Reef grows larger and farther from shore Reef closest to land begins to die because reefs closer to open ocean are using up the resources before they get to the reef closest to land. Channel forms between the reef and the land. Barrier reef is what is left.

I Can… Explain the processes that contribute to the formation of salt marshes and mangrove swamps. List several human activities that damage intertidal habitats.

Intertidal Zones The intertidal zone is the area of the ocean that is affected by tides. It spends part of its time underwater and the other part exposed. Organisms must be adapted to both conditions, plus the pounding of the waves. They could do this by attaching to rocks, burrowing in the sand, etc.

Intertidal Zones The intertidal zones are often where water meets land and are surrounded by wetlands such as swamps and marshes.

Intertidal Zones Salt marshes are muddy, flat wetlands that are influenced by tides. These are most common in the US along the east coast and the shores of the Gulf of Mexico.

Intertidal Zones The role of salt marshes is similar to that of freshwater wetlands. Important for migratory birds Abundant plant life, especially grasses. Much of the lives of shellfish and commercial fish in the US spend part of their lives in salt marshes.

Intertidal Zones Salt marshes form when streams flow into the estuary or other neritic waters. Because the velocity of the water slows, sediments carried by the stream get deposited and can form a delta in some areas (Mississippi river delta). The weight of the sediments can cause subsistence, or sinking of the delta.

Intertidal Zones If the rate of deposition and the rate of subsistence are not stable there will be disruptions in the depth of water, thus affecting the organisms. The Mississippi River has a 5000 year cycle of sediment accumulation, subsistence, and change in the river’s course. This means the delta changes shape!

Intertidal Zones Mangrove swamps are a wetland that occurs only in warmer climates. They must be warm enough to be frost free. The dominant plant is the mangrove, a woody tree or shrub. Only 10 species of mangrove live in the US. (800)

Intertidal Zones The water in mangrove swamps usually has little oxygen. The mangroves adapted to this several ways: Roots that grow up from the bottom of the plant with tips above water Roots that begin above the water line, making the plant appear to be on stilts These root systems trap sediments and allow other plants to grow.

Intertidal Zones Mangrove swamps support ecosystems full of organisms. Swamps are endangered due to human activities. Creation of aquaculture ponds to raise fish and shrimp Coastal construction projects Waste dumping