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Lake Ouachita
Map
What is a pelagic fish?
Fish that live in pelagic zones are typically mobile and migratory
species that are not closely associated with permanent structures. This
behavior makes pelagic fish difficult to study and understand because it is
often impossible to observe them using Scuba gear typically employed by
marine biologists. Therefore, it is useful to combine a variety of methods,
including the vast knowledge of experienced fishermen, to learn about these
important fish.
The pelagic zone:
The part of the lake which is located in the open water
column, that is the part of the The pelagic zone is further divided into
sections creating a number of sub-zones based on their different
ecological characteristics. These characteristics are roughly a function
of depth and generally do not apply to fresh water Lakes.
- Epipelagic Zone:
The illuminated surface zone where there is enough light
for
photosynthesis. From the surface down to around
650ft.
- Mesopelagic Zone:
The twilight zone. Although some light penetrates this
deep, it is insufficient for photosynthesis. From 651ft
down to around 3,280 ft.
Bathypelagic Zone:
By this depth the water is almost entirely dark (with only the
occasional
bioluminescent organism). There are no living plants. From
3281ft down to around 13,100ft.
- Abyssopelagic Zone:
No light whatsoever penetrates to this depth
- Hadopelagic Zone:
From 13,100ft down to above the ocean floor.
The photic zone or euphotic zone:
The depth of the water in a lake that is exposed to sufficient sunlight
for photosynthesis to occur. The depth of the euphotic zone can be
greatly affected by seasonal turbidity.
It extends from the surface to a depth where light intensity falls to 1%
of that at the surface (also called euphotic depth), so its thickness
depends on the extent of light attenuation in the water column. Typical
euphotic depths vary from only a few centimetres in highly turbid
eutrophic lakes, to around 200 metres in the open ocean.
Since the euphotic zone is the only zone of water where primary
productivity occurs, an exception being the productivity connected with
abyssal hydrothermal vents along mid-oceanic ridges, the depth of the
photic zone is generally proportional to the level of primary
productivity that occurs in that area of the ocean.
The Aphotic Zone:
Is the portion of a lake or ocean where there is little or no
sunlight.
It is formally defined as the depths beyond which less than 1% of
sunlight penetrates. Consequently, bioluminescence is essentially the
only light found in this zone. Most food comes from dead organisms
sinking to the bottom of the lake or ocean from other zones.
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