The Classification of Marine Communities

To first understand the classification of marine communities we must first understand the two groups of organisms within each community or zone. Castro & Huber (2007) explain that there are two levels of organisms, those that live buried in or on top of the bottom sediment, and those that reside away from the bottom and up in the water (p. 223). The organisms that live on or below the sediment are called Benthic organisms or benthos, while the ones that live in the higher levels of the water are called Pelagic organisms (Castro & Huber, 2007, p. 223). Castro & Huber (2007) note that marine environments are generally based around the distance from land, the depth of the water, and a determination of whether the organisms in question are Benthic or Pelagic (p. 224).

Benthic organism's environmental zones directly relate to the waters continental shelf and how deep the water is (Castro & Huber, 2007, p. 224). The first zone in which a Benthic organism may reside is called the intertidal zone, also known as littoral zone (Castro & Huber, 2007, p. 224). The intertidal zone is made up of the area of the continential shelf that may be exposed during low tide and hidden during high tide, it is considered the shallowest part of the shelf (Castro & Huber, 2007, p. 224). The zone directly below the intertidal zone is called the subtidal zone, also known as sublittoral zone. Following this zone the Benthic organism's habitat is moved away from the continental shelf and is then organized based on the waters depth (Castro & Huber, 2007, p. 224). Castro & Huber (2007) explain the zone in terms of three different depths called the bathyal, abyssal, and hadal zones, which are typically grouped together and titled the "deep-sea floor" (p. 224). Many different levels dealing with the continental shelf equally divide the Pelagic organism's waters (Castro & Huber, 2007, p. 224).

The first zone is called the neritic zone and refers to the waters that cover the shelf itself (Castro & Huber, 2007, p. 224). Directly past the shelf break is a new zone of waters called the oceanic zone (Castro & Huber, 2007, p. 224). Castro & Huber (2007) note, beyond these two zone the ones that follow are divided in a different way than those of the benthic organism's zones; the zones are separated by depth to directly relate to the light each level will get (p. 224). The first zone, which is also the most shallow, is called the epipelagic zone; this zone is the most productive in photosynthesis and has an abundance of health nutrients to support life (Castro & Huber, 2007, p. 224). Directly below the epipelagic zone, past the shelf is a zone called mesopelagic zone (Castro & Huber, 2007, p. 224). This zone allows less light to pass through the water, as such photosynthesis does not occur at this level (Castro & Huber, 2007, p. 224). The deepest zones of the Pelagic organisms environment are those that light from above does not reach, these zones are called bathypelagic, abyssopelagic, and hadopelagic (Castro & Huber, 2007, p. 224). Each one of these zones offer unique communities of organisms designed for life at these level, collectively these zone are called "deep-sea environment" (Castro & Huber, 2007, p. 224).

References:Castro, P. & Huber, M.E. (2007). Marine biology (6th ed.). New York: McGraw-Hill Higher Education.