Zones of marine Environment

Tahir

Intertidal,

Ocean ecosystem Marine ecosystems are among the largest of Earth's aquatic ecosystems.

They include oceans, salt marshes, intertidal zones,

estuaries, lagoons, mangroves, coral reefs, the deep sea, and the sea floor.

They can be contrasted with freshwater ecosystems, which have a

lower salt content. Marine waters cover two-thirds of the surface of the Earth.

Such places are considered ecosystems because the plant life supports the

animal life and vice-versa.

Nearly three-quarters of the earth’s surface is covered by ocean with an

average depth of 3,750m and with salinity averaging 35ppt, about 90 per cent

of which is sodium chloride.

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 Any water in a sea or lake that is neither close to the bottom nor

near the shore can be said to be in the pelagic zone. The word "pelagic" is derived from Greek πέλαγος (pélagos), meaning "open sea". The pelagic zone occupies 1,330 million km3 (320 million mi3) with a mean depth of 3.68 km (2.29 mi) and maximum depth of 11 km (6.8 mi). 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 (sunlight)

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 (twilight)

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 (midnight)

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 dumbo octpus.

Abyssopelagic (lower midnight)

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 is the ecological region at the lowest level of a body of water such as an ocean or a lake,

including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos, e.g.

the benthic invertebrate community, including crustaceans and polycheates. The organisms generally live in close

relationship with the substrate bottom and many are permanently attached to the bottom. The superficial layer of

the soil lining the given body of water, the benthic boundary layer, is an integral part of the benthic zone, as it

greatly influences the biological activity which takes place there. Examples of contact soil layers include sand

bottoms, rocky outcrops, coral, and bay mud.

The benthic zone of the ocean is varied. There are mountains, trenches, volcanoes, flat muddy areas,

sandy areas and rocky areas.

There 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

Red snapper

Cobia

Tuna

Few favorite commercial fishes from pelagic zone

salmon