![]() ![]() Since reef waters tend to be nutritionally poor, corals obtain nutrients through the algae via photosynthesis and also by extending tentacles to obtain plankton from the water. Corals are interesting since they consist of both algae (zooanthellae) and tissues of animal polyp. Naturally, the dominant organisms in coral reefs are corals. They can be found as barriers along continents (e.g., the Great Barrier Reef off Australia), fringing islands, and atolls. Coral reefsĬoral reefs are widely distributed in warm shallow waters. These bacteria are thus the start of the food web as they are eaten by invertebrates and fishes. Chemosynthetic bacteria thrive near these vents because of the large amounts of hydrogen sulfide and other minerals they emit. Mid-ocean ridges (spreading zones between tectonic plates), often with hydrothermal vents, are found in the abyssal zones along the ocean floors. The abyssal zone supports many species of invertebrates and fishes. The water in this region is very cold (around 3° C), highly pressured, high in oxygen content, but low in nutritional content. Flora are represented primarily by seaweed while the fauna, since it is very nutrient-rich, include all sorts of bacteria, fungi, sponges, sea anemones, worms, sea stars, and fishes. Here temperature decreases as depth increases toward the abyssal zone, since light cannot penetrate through the deeper water. The bottom of the zone consists of sand, slit, and/or dead organisms. 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 fauna include many species of fish and some mammals, such as whales and dolphins. The flora in the pelagic zone include surface seaweeds. The pelagic zone is generally cold though it is hard to give a general temperature range since, just like ponds and lakes, there is thermal stratification with a constant mixing of warm and cold ocean currents. ![]() The pelagic zone includes those waters further from the land, basically the open ocean. Waves keep mud and sand constantly moving, thus very few algae and plants can establish themselves the fauna include worms, clams, predatory crustaceans, crabs, and shorebirds.įrom left: mussels, worms, and a spider crab at a hydrocarbon seep community in the Gulf of Mexico a sea fan and brain coral in the Florida Keys National Marine Sanctuary a school of Atlantic amberjack off North Carolina. The intertidal zone on sandier shores is not as stratified as in the rocky areas. ![]() At the bottom of the intertidal zone, which is only exposed during the lowest tides, many invertebrates, fishes, and seaweed can be found. In those areas usually submerged during high tide, there is a more diverse array of algae and small animals, such as herbivorous snails, crabs, sea stars, and small fishes. Where only the highest tides reach, there are only a few species of algae and mollusks. On rocky coasts, the zone is stratified vertically. Because of this, the communities are constantly changing. The intertidal zone is where the ocean meets the land sometimes it is submerged and at other times exposed, as waves and tides come in and out. Some say that the ocean contains the richest diversity of species even though it contains fewer species than there are on land. All four zones have a great diversity of species. Like ponds and lakes, the ocean regions are separated into separate zones: intertidal, pelagic, abyssal, and benthic. The largest of all the ecosystems, oceans are very large bodies of water that dominate the Earth's surface. The evaporation of the seawater provides rainwater for the land. Marine algae supply much of the world's oxygen supply and take in a huge amount of atmospheric carbon dioxide. Marine regions cover about three-fourths of the Earth's surface and include oceans, coral reefs, and estuaries. Reef fish and coral off Eniwetok atoll in the central Pacific. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |