User:Megan Fanelli/Pelagic zone

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Note to peer reviewer: Everything in bold is what I've added, and most of the references are ones that I put in. Please refer to the original article for comparison.

Epipelagic (Sunlight Zone)

See also: Photic zone and Epipelagic fish

From the surface (MSL) down to around 200 m (660 ft)

The illuminated zone at the surface of the sea, and the only zone with sufficient light for photosynthesis. This zone is just above the continental shelf and has the lowest atmospheric pressure on the oceans surface, at 1 atm for every 10 meters. Nearly all primary production in the ocean occurs here, and about 90% marine life is concentrated in this zone, including: plankton, floating seaweed, jellyfish, tuna, whales, sharks,dolphins, and many more diverse species.

Mesopelagic (Twilight Zone)

See also: Mesopelagic zone and Pelagic fish § Mesopelagic fish

From 200 m (660 ft) down to around 1,000 m (3,300 ft)

The thermocline serves as the boundary from the warmer top zone to the much colder mesopelagic zone, which is also located right under the continental shelf. This zone contains a very trace amount of sunlight and has a pressure of about 20 - 100 amt. A variety of creatures live in this zone, including species of swordfish, squid, wolffish and some species of cuttlefish. Many organisms living here have evolved adaptations, such as bioluminescence, due to the lack of sunlight. Some mesopelagic creatures rise to the epipelagic zone at night to feed. Heterotrophic bacteria are among the more abundant organisms in this zone, and they primarily feed and break down falling matter from the upper zone.

Bathypelagic (Midnight Zone)

See also: Bathyal zone and Pelagic fish § Bathypelagic fish

From 1,000 m (3,300 ft) down to around 4,000 m (13,000 ft)

The name stems from Ancient Greek βαθύς 'deep'. In this zone, the environment is pitch black at this depth and contains no trace of sunlight, apart from occasional bioluminescent organisms, such as anglerfish. The temperature and salinity of this zone is stable.No plants live here. Most creatures survive on detritus known as "marine snow" falling from the zones above or, like the marine hatchetfish, by preying on other inhabitants of this zone. Other examples of this zone's inhabitants are giant squid, smaller squid, viperfish, gulper eel, razorfish, dragonfish, and dumbo octopus.

Abyssopelagic (Abyssal Zone)

Main article: Abyssal zone

From around 4,000 m (13,000 ft) down to above the ocean floor at around 6,000 m (20,000 ft)

The name is derived from Ancient Greek ἄβυσσος 'bottomless'. The ocean floor is next to this zone, and it forms volcanos, mountains, and vents from the movement of the tectonic plates. Among the very few creatures living in the cold temperatures, high pressures and complete darkness there are several species of squid; echinoderms including the basket star, swimming cucumber, and the sea pig; and marine arthropods including the sea spider. Many species at these depths are transparent and eyeless.

Hadopelagic (Hadal Zone)

Main article: Hadal zone

The name is derived from the realm of Hades, the Greek underworld. This is the deepest part of the ocean at more than 6,000 m (20,000 ft) . Such depths are generally located in trenches.This zone contains 13 short narrow troughs and 33 trenches. The deepest trenches stretch to 10,924 m deep, while average trenches are usually 50-100 kilometers deep. This zone can have an atmospheric pressure of 1,100 atm. In this zone, there is an increase in temperature from adiabatic heating. Very few creatures live in this zone. Some of the recorded species are Coelenterate, Polychaetas, amphipods, echinoderms, and mollusks.

Observing and Sampling Methods

Exploring and learning more about the ocean is a main factor to ocean resource management, which sustainably manages how much and how fast we use the oceans resources. Ocean exploration also observes patterns in the oceans weather and climate, and the means why which they were affected. Researchers are better able to understand and see natural phenomena such as earthquakes and tsunamis and react accordingly. Scientists and researchers have developed many methods to sample the ocean biome, and pelagic fish.

Trawling

Main article: Trawling

This method uses a mesh net from a boat to captures deep pelagic fish. The net is dropped at several different depths which collects and records the fish captured. This method produces the largest quantity of specimen to study and is one of the most used strategies for collecting data on deep pelagic fish. This method is very costly, time consuming, and mostly used by research groups with a lot of support and funding. There are also many fish that are able to out swim the net, which limits data.

Active Acoustics

Main article: Sonar

This method analyzes fish that are detected or present in sound pulses that are emitted from the surface, where the pelagic fish' biomass in the reflected single is analyzed. This method of sampling cannot reach deep depths in the ocean. The pulses cover a broad area of the ocean and causes little harm or distress. The received data from this method is complicated to interpret, due to specific variations of swim bladders in fish, such as having little gas or not having a swim bladder.

Remotely Operated Vehicles (ROV)

Main article: Remotely operated underwater vehicle

A submerged ROV on the ocean floor used to observe the deep sea environment.

A remotely operated vehicle is used as a method of sampling that is suitable for deep sea discovery and analysis, where other methods of sampling cannot reach. An ROV is an unoccupied machine which is equipped with lights, cameras, sensors, or arms, which allows for a detailed and live observation of the surroundings, and of the pelagic fish. It is able to conduct experiments and collect samples.This machine is limited in its ground coverage, as well as expensive and hard to control, so very few research groups use it. This machine is also very loud, bright, and big, which causes the organisms to avoid it.

Additional Methods

Some other sampling and observation methods are: predator gut examinations, analysis of environmental DNA, Organisms that get washed up on shore from upwelling, Analyzing the sediments core, and pelagic longline fishing.

Pelagic fish

Main article: Pelagic fish

Pelagic fish live in the water column of coastal, ocean, and lake waters, but not on or near the bottom of the sea or the lake. They can be contrasted with demersal fish, which do live on or near the bottom, and coral reef fish.

Pelagic fish are often migratory forage fish, which feed on plankton, and the larger predatory fish that follow and feed on the forage fish. Migratory fish come up to the more dense prey areas of the pelagic zones to feed, and then descend at night to avoid predators. Examples of migratory forage fish are herring, anchovies, capelin, and menhaden. Examples of larger pelagic fish which prey on the forage fish are billfish, tuna, and oceanic sharks.

Pelagic reptiles

The yellow bellied sea snake as it glides across the surface of the ocean.

Hydrophis platurus, the yellow-bellied sea snake, is the only one of the 65 species of marine snakes to spend its entire life in the pelagic zone. It bears live young at sea and is helpless on land. The species sometimes forms aggregations of thousands along slicks in surface waters. The yellow-bellied sea snake is the world's most widely distributed snake species.

Many species of sea turtles spend the first years of their lives in the pelagic zone, moving closer to shore as they reach maturity.

Pelagic birds

See also: Seabird

The pelagic wandering albatross (Diomedea exulans) ranges over huge areas of ocean and can circle the globe.

Pelagic birds, also called oceanic birds or seabirds, live on open seas and oceans rather than inland or around more restricted waters such as rivers and lakes. These birds have very long wings which give them the ability to fly for long periods of time. Some pelagic birds dive deep into the water to catch prey. Pelagic birds feed on planktonic crustaceans, squid and forage fish. Examples are the Atlantic puffin, macaroni penguins, sooty terns, razorbills, shearwaters, and Procellariiformes such as the albatross, Procellariidae and petrels.