DEEP SEA

Introduction to deep sea

 

As established, the ocean covers up to 71% of earth’s surface whereas deep sea belongs to a part of it. Whilst the ocean is well recognized for harboring a wide diveristy of species, the deep sea where 90% of the marine habitats can be found, is believed to have the highest biodiversity on Earth [1]. There is no a certain definition established for the deep sea to date while it is known traditionally as the zones of ocean from 200 meters deep onwards.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Deep sea constitutes two major zones including the pelagic zone and the benthic zone [2].  

 

• Pelagic zone: the area of open sea where swimming organisms (fish etc.) and floating organisms (phytoplankton etc.) live [2] . This zone of deep water can be further divided into four zones as the following:

 

    * Mesopelagic zone (twilight zone) : 200 - 1000 m in depth

     Limited sunlight penetration. Home to mobile marine species that forays into shallow surface waters at        night for food.

 

    * Bathypelagic zone (midnight zone) :  1000 - 4000 m in depth

     No sunlight penetration. Home to light-producing species and non-migrating fish as well as crusteceans.

 

    * Abyssopelagic zone (abyssal zone) : 4000 - 6000 m in depth

     No sunlight penetration. Home to light-producing species and non-migrating fish as well as crusteceans.

 

    * Hadapelagic zone : 6000-11000 m in depth

     No sunlight penetration. The zone is where the deep ocean trenches are located.

 

• Benthic zone : the area of sediment at the bottom of the deep sea where the benthos live [2].

    This benthic zone of deep sea includes the bathyal zone (continental slopes between 200 - 4000 m), the       abssyal zone (deep ocean seafloor between 4000-6000m where the hydrothermal vents and cold seeps       are located) and the hadal zone (deep trenches between 6000 to 11000m). 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References:

 

1. United Nations Environment Program (UNEP) 2007, Deep-sea biodiversity and ecosystems: a scoping report on their socio-economy,           management and governance, UNEP Regional Seas Reports and Studies No 184, viewed 6 May 2015, <http://www.unep.org/regionalseas/ publications/reports/RSRS/pdfs/rsrs184.pdf>.

 

2. MarineBio Conservation Society 2011, The deep sea, MarineBio Conservation Society, viewed 6 May 2015, <http://marinebio.org/oceans/deep/>.