Environment | flsaqua2015

Deep sea environment

Environment in the deep sea is highly dynamic and unstable as its conditions are continually undergoing environmental changes. So, the environment conditions in the deep sea are not uniformly distributed all over the deep sea zones. Furthermore, deep sea is an excellent example of extreme environment where the extremophiles such as thermophilic, barophilic and psychrophilic thrives.

Several extreme environmental factors that define the deep sea environment are listed as below [1]:

Pressure: pressure increases as the depth of the ocean increases. The pressure will be increased by one atmosphere (1 atm) for every ten meters increment in depth downwards. So the pressure is normally higher in the deep sea zones as compared to the surface marine zone. Marine organisms found in the deep sea are usually pressure-tolerant or pressure-resistant (barophilic).

Temperature: Environment in the deep sea is commonly characterized by cold water temeprature. The water in the bathypelagic zone can reach as low as 2 degree celcius whereas the water surrounded the hydrothermal vents are extremely hot with the highest temperature of 350 degree celcius. Due to extremely high temperature, the water can sometimes exist in a form of supercritical fluid (somewhere between liquid state and gaseous state). Marine organisms found in cold seeps at the abyssal zone are usually psychrophilic whereas the marine organisms live near or at hydrothermal vents are usually thermophilic.

Oxygen: Although cold water of deep sea dissolves oxygen better than warm surface water, there is no oxygen available at some isolated sea basins discovered at the Mediterranean Sea. Moreover, there are some oxygen-deprived environments known as oxygen minimum zones in the intermediate zones of the deep sea in temperate and tropical areas.

Light: Sunlight from the sea surface could hardly reach the deep sea zones and therefore, photosynthetic plants cannot survive here due to the poor sunlight penetration. This leads to adaptations of deep sea organisms with light-producing ability (bioluminescence and fluorescence properties). Alternative way of energy source acquisition process which is known as chemosynthesis is being carried out by bacteria species at the deep-sea hydrothermal vents using hydrogen sulphide or methane

Salinity: The salt content of sea water is relatively high. However, salinity of deep sea water is constant. Marine organisms are usually salt-resistant (halophilic) and they have adapted to high salinity environment.

Due to limitations in exploration equipments and the extreme conditions of the deep sea, exploration of deep sea zones especially from the abyssopelagic zone onwards is hindered.

References

1. Nelson, R 2015, Deep Sea Biome, Untamed Science, viewed 8 May 2015, <http://www.untamedscience.com/biology/biomes/deep-sea-biome/>.