Zones of marine Environment. Sadia Tahir. intertidal, . Ocean ecosystem. Nearly three-quarters of the earth’s surface is covered by ocean with an average depth of 3,750 m and with salinity averaging 35 ppt (parts per thong), about 90 per cent of which is sodium chloride.
Zones of marine Environment SadiaTahir
Ocean ecosystem • Nearly three-quarters of the earth’s surface is covered by ocean with an average depth of 3,750 m and with salinity averaging 35 ppt (parts per thong), about 90 per cent of which is sodium chloride. • Marine ecosystems are of singular ecological significance. Concentration of the nutrients in the ocean is low. • Oceans into zones. The divisions are based on things such as water depth, the amount of sunlight, and water temperature. • The major zones in marine ecosystem are littoral, neurotic, pelagic and benthic. The littoral zone is the
The intertidal zone • The intertidal zone, also known as the foreshore and seashore and sometimes referred to as the littoral zone, is the area that is above water at low tide and under water at high tide. • This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral. The well known area also includes steep rocky cliffs, sandy beaches, or wetlands (e.g., vast mudflats). • The area can be a narrow strip, as in Pacific islands that have only a narrow tidal range, or can include many meters of shoreline where shallow beach slopes interact with high tidal excursion.
The intertidal zone • Organisms in the intertidal zone are adapted to an environment of harsh extremes. Water is available regularly with the tides but varies from fresh with rain to highly saline and dry salt with drying between tidal inundations. • The action of waves can dislodge residents in the littoral zone. With the intertidal zone's high exposure to the sun the temperature range can be anything from very hot with full sun to near freezing in colder climates. • Some microclimates in the littoral zone are ameliorated by local features and larger plants such as mangroves. • Adaptation in the littoral zone allows the use of nutrients supplied in high volume on a regular basis from the sea which is actively moved to the zone by tides.
The intertidal zone • A typical rocky shore can be divided into a spray zone or splash zone (also known as the supratidal zone), which is above the spring high-tide line and is covered by water only during storms and the intertidal zone, which lies between the high and low tidal extremes. • Along most shores, the intertidal zone can be clearly separated into the following subzones: high tide zone, middle tide zone, and low tide zone. • The intertidal zone is one of a number of marine biomes or habitats, including estuaries, neritic, surface and deep zones. • The Intertidal Zone Sea grasses, periwinkle snails, and herons are common in an intertidal mudﬂat. • Sea stars and anemones often live on rocky shores, while clams, crabs, snails, and conchs are common on sandy beaches The intertidal is also home to marine vertebrates, some of whom prey on intertidal animals, such as fish, gulls and seals..
Challenges in the Intertidal Zone: • Moisture: There are usually two high tides and two low tides each day. Depending on the time of day, different areas of the intertidal zone may be wet or dry. Organisms in this habitat must be able to adapt if they are left “high and dry” when the tide goes out. Sea snails such as periwinkles have a “trap door” called an operculum that they can close when they are out of water to keep moisture in. • Waves: In some areas, waves hit the intertidal zone with force, and marine animals and plants must be able to protect themselves. Kelp, a type of algae, has a root-like structure called a “holdfast” that it uses to attach to rocks or mussels, thus keeping it in place.
Salinity: Depending on rainfall, the water in the intertidal may be more or less salty, and tide pool organisms must adapt to increases or decreases in salt throughout the day. • Temperature: As the tide goes out, tide pools and shallow areas in the intertidal will become more vulnerable to temperature changes that could occur from increased sunlight or colder weather. Some tide pool animals hide under plants in the tide pool to find shelter from the sun.
The pelagic zone • The pelagic zone can also be called the open-ocean zone. The pelagic zone can be divided into sections making several sub-zones based on the different ecological characteristics. They are mostly divided by depth. Epipelagic • The epipelagic zone is located from the surface of the water down to around 200 meters. This zone is known for many varieties of photosynthetic life because of the abundant sunlight. This zone is where there are a large concentration of fish including tuna, sharks, and dolphin . Jellies are also very abundant in this location because of the large amount of other fish in the area. • Mesopelagic • The mesopelagic zone is located from about 200meters to around 1,000 meters. Some light does make it down this far but it is not sufficient enough for photosynthetic animals to thrive. Animals that are located here include swordfish, squid, and a few species of cuttlefish. Some other creatures can also be found here.
Bathypelagic • The Bathypelagic zone is located from 1,000 meters to about 4,000 meters. This zone of the ocean is almost entirely in the dark because the light cannot penetrate this deep. Many of the animals that live in this zone have adapted to the enviroment by having bioluminescent structures on their body. An example of such a creature is a lanternfish. • Most of the animals that are located here are carnivores or feed on the dead material that falls down from the other parts of the pelagic zone. Giant squid are also known to live in this zone as well as the dumbooctpus. • Abyssopelagic • The abyssopelagic zone is located from about 4,000 meters to just above the ocean floor. This zone is completely dark because no light is able to penetrate to this depth. • Most creatures in this zone are blind and colorless or shades of red. The organisms are red because no red light is able to penetrate down making them well camouflaged in the dark. .
Hadopelagic The hadopelagic zone is located in deep water in ocean trenches. Little is known about this zone and very few species are known to live there. Many of the organisms that do live here are located near hydrothermal vents. Some organisms that live here include Giant tube worms
The benthic zone • The benthic zone of the ocean is varied. There are mountains, trenches, volcanoes, flat muddy areas, sandy areas and rocky areas. T • here is a wide variety of life that makes its home on the ocean floor. Some organisms live in the mud, some crawl or swim along the bottom and some anchor themselves to the ocean floor. • Life in the benthos region is organized by size. Macrobenthos are organisms that are larger than one millimeter like oysters, starfish, lobsters, sea urchins, shrimp, crabs and coral. Meiobenthos are between one tenth and one millimeter in size. Organisms in this group include diatoms and sea worms. • Microbenthos are very tiny organisms like diatoms, ciliates and bacteria. They are smaller than one tenth of a millimeter.
A lot of the marine fish we eat come from pelagic fisheries. Some commercially important species of fish that are fished are Pacific mackerel, jack mackerel, Pacific sardine and Blue-fin tuna. Unfortunately toady, many fish stocks have been over-exploited and some species, such as many shark species, even face extinction due to over fishing. On top of this many pelagic animals that are not targeted by the fishing boats, such as dolphins and turtles, sometimes also get affected by negative fishing methods. jack mackerel Sardine
Few favorite commercial fishes from pelagic zone Red snapper Tuna salmon Cobia