The depth of the waters is closely related to productivity, vertical temperature, light penetration, density, oxygen, and nutrients (Hutabarat and Evans, 2008). The depth of the waters affects the biota are cultivated. This is related to the pressure received in the water, because the pressure increases with increasing depth (Nybakken, 1992). Depth is an important parameter in solving various technical problems of coastal erosion.
Added stability of coastlines, ports and contraction, port, evaluation, storage tides, movement, maintenance, route navigation. Depth also affects the determination of aquaculture technology were carried out at sea or in stagnant or flowing waters. Closely related to the depth Bathymetry which means the study of underwater depth and three-dimensional studies of the ocean or lake floor.
A general bathymetric map showing the coast or inland relief with contour lines (contor lines) is called the depth contour (depth contous or subath). Based on the deep ocean waters can be grouped into four zones, among others:
a) littoral zone
Littoral zone is the area between the line ups and downs line seawater. This region is sometimes dry at low tide and sea water inundated when experiencing ups. Littoral zone is usually found in areas with sloping beaches. Littoral zone is a part of the sea, lake or river close to the beach. In the coastal environment of the coastal zone extends from the high water mark, which is rarely submerged, for coastal areas that are permanently submerged. It always includes intertidaldan this zone is often used to mean the same as the intertidal zone. However, the meaning of “littoral zone” may extend well beyond the intertidal zone.
b) Zone neritik
Neritik zone is a sea zone that has a shallow depth, until kedalaman200 meters. This zone is the zone neritik beautiful belle with a variety of coral reefs and a place bekumpulnya fish. Neritik zone is an area of the sea began tidal zone to depths of 200 meters, this zone is often called a shallow sea area. Neritik zone characteristics include:
(1) The sun’s rays still penetrate the seabed
(2) depth is ± 200 m
(3) The most numerous fish and marine plants
Neritik zone located in the continental shelf which is inhabited by marine life that is different from the oceanic zone because:
(1) The content of nutrients in the zone neritik abundant.
(2) The chemistry is different neritik waters with oceanic waters because of the varied solutes brought into the sea from the mainland.
(3) Water neritik very changeable, both in time and in space, compared to oceanic waters. This can happen because the proximity of this zone to the mainland and the spills of various solutes from land to sea.
(4) The penetration of light, sediment content and physical energy in the water column is different between neritik zone and the oceanic zone.
c) Zone Batial
Bathyal zone (deep sea), is a sea area that has a depth of between 150 and ± 2,000 meters. This region can not penetrate the sun, therefore the life of the organism is not as much as there is in the neritic zone. Batial sea zone starting from the lower limit of the shelf (typically 130-200 m) on the basis of the slope, which is located at the depth of 2000 m This zone is characterized by calm water, the absence of light, the animal life is very poor and weak influence soil processes occur in the environment. With no light there, no plants.
d) abyssal zone
Abyssal zone is a zone in the bottom lautyang very deep, starting from the depths 1000meter to 6000meter. This zone included into the depths of the sea and ocean trenches. Sea water pressure is very big so few marine animals that can live in this zone. Marine animals that can live in these zones tend to be flat and long. Right above the abyssal zone there is a bathyal zone, the last area to get the light where most of the marine life there.
Whereas just below the abyssal zone is the hadal zone, the area covered by eternal darkness. Sedimentation very smooth material, in the form of a kind of lumpuryang reddish and consists of diatomea stampings and radiolarian, because of the depth of about 3000 meters kerangpun before reaching the sea floor has been destroyed and dissolved. Due to the water pressure in the abyssal zone is increased by one atmosphere every depth of 33 feet, the animals in the abyssal zone must be able to withstand tremendous pressure.
This pressure makes it very difficult man to explore the deep sea. Examples of animals that can live in the abyssal zone is the giant squid. The characteristics of this zone, among others, light, pressure, temperature, oxygen, and food. Because it is very deep and dark, abysal layer does not get light. So most of the living creatures in this layer have a body that produce blue-green light (bioluminescence). In addition, they also have a greater eye to capture more light.
According Hutabarat and Evans (1985), the depth of the waters is an indication of the presence of oceanographic parameters. Light intensity decreases rapidly and will disappear at a certain depth, as well as temperature and dissolved oxygen diminishing at a certain depth to the bottom waters. So the dissolved oxygen concentration is strongly associated also with a variable depth of a body of water or pond.
In conducting photosynthesis phytoplankton need sunlight. Radiation of sunlight decreases rapidly with increasing height depth. This is why phytoplankton as primary producers can only be obtained in an area or depth where sunlight can penetrate the water body.