ABE - Marine Regions (Lesson)

Marine Regions

Marine regions cover about three-fourths of the Earth's surface and include oceans, coral reefs, and estuaries. Marine algae supply much of the world's oxygen supply and take in a huge amount of atmospheric carbon dioxide. The evaporation of the seawater provides rainwater for the land.

Estuaries

Transition areas located between the river and the ocean are called estuaries. The salt content varies within estuaries because of the rise and fall of the tides. Nutrients from rivers make estuaries one of the most productive biomes. They create a complex network of tidal channels, islands, natural levees, and mudflats. The major producers in estuaries are salt marsh grasses and algae. Estuaries support the lives of worms, oysters, crabs, and many fish species. This is a special environment where some creatures have learned to adapt to a mixture of fresh and saltwater. When freshwater, groundwater, and soils are altered by human actions and salinity greatly increases, it can have an extremely detrimental effect on life there. Changes in salinity brought about by human residential, commercial, and industrial activity can kill plant life, aquatic life, and animal life in a given area. Humans have the responsibility to make sure their actions are not causing this type of devastation.

Intertidal Zones

An intertidal zone is periodically submerged and exposed by the tides, twice daily. The oxygen and nutrient levels are usually high. The substrates, which are either rocky or sandy, select for particular behavior and anatomy among organisms. Common animals are clams, crustaceans, sponges, sea anemones, mollusks, and small fishes.

The ocean pelagic biome is a vast realm of open blue water. The oxygen levels are high while the nutrients level is lower than in other coastal waters. This biome covers approximately 70% of the earth's surface. Phytoplankton is the dominant photosynthetic organism. The most abundant animals in this biome are zooplankton. It also includes free-swimming animals, squids, fishes, sea turtles, and marine mammals.

The benthic zone is the area below the pelagic zone but does not include the very deepest parts of the ocean (see abyssal zone below). The bottom of the zone consists of sand, silt, and/or dead organisms. Here temperature decreases as depth increase toward the abyssal zone since light cannot penetrate through the deeper water. Flora is represented primarily by seaweed while the fauna since it is very nutrient-rich, includes all sorts of bacteria, fungi, sponges, sea anemones, worms, sea stars, and fishes.

The deep ocean is the abyssal zone. The water in this region is very cold (around 3° C), highly pressured, high in oxygen content, but low in nutritional content. The abyssal zone supports many species of invertebrates and fishes. Mid-ocean ridges (spreading zones between tectonic plates), often with hydrothermal vents, are found in the abyssal zones along the ocean floors. Chemosynthetic bacteria thrive near these vents because of the large amounts of hydrogen sulfide and other minerals they emit. These bacteria are thus the start of the food web as they are eaten by invertebrates and fishes.

Coral Reefs

Coral Reefs are sensitive to temperatures below 18-20° C and above 30° C. Coral Reefs require high oxygen levels. They are formed from the calcium carbonate skeletons of corals and develop over a long period of time on oceanic levels. Unicellular algae live within the tissue of the corals. Cnidarians are the predominant animals on coral reefs. The fish population is exceptionally high.

 

 

 

 

 

 

 

RESOURCES IN THIS MODULE ARE OPEN EDUCATIONAL RESOURCES (OER) OR CREATED BY GAVS UNLESS OTHERWISE NOTED. SOME IMAGES USED UNDER SUBSCRIPTION.