Aquatic Zonation

In general, the deep sea is considered to start at the aphotic zone, the point where sunlight loses its power of transference through the water.[citation needed] Many life forms that live at these depths have the ability to create their own light a unique evolution known as bio-luminescence.

Marine life also flourishes around seamounts that rise from the depths, where fish and other sea life congregate to spawn and feed. Hydrothermal vents along the mid-ocean ridge spreading centers act as oases, as do their opposites, cold seeps. Such places support unique biomes and many new microbes and other lifeforms have been discovered at these locations .[citation needed]

Open oceanMain article: Pelagic zoneThe open ocean is relatively unproductive because of a lack of nutrients, yet because it is so vast, in total it produces the most primary productivity. Much of the aphotic zone's energy is supplied by the open ocean in the form of detritus. The open ocean consists mostly of jellyfish and its predators such as the mola mola.

Intertidal and shore

Intertidal zones, those areas close to shore, are constantly being exposed and covered by the ocean's tides. A huge array of life lives within this zone.Shore habitats span from the upper intertidal zones to the area where land vegetation takes prominence. It can be underwater anywhere from daily to very infrequently. Many species here are scavengers, living off of sea life that is washed up on the shore. Many land animals also make much use of the shore and intertidal habitats. A subgroup of organisms in this habitat bores and grinds exposed rock through the process of bioerosion.

A black smoker, a type of hydrothermal vent

Aquatic biomesOccupy largest part of biosphere. Two major categories of aquatic biomesFreshwatersalt concentration of

Vertical stratificationBased on physical and chemical variables, such asLight

is absorbed by organisms and the waterintensity decreases rapidly with depth

ecologists distinguish between 2 zones based on light penetrationphotic zone zone through which light penetrateslight is sufficient for photosynthesis aphotic zone (profundal)very little light can penetrateinsufficient for photosynthesis

Temperature.Light-penetrated layerwarmed by heat energy from sunlightThermoclinenarrow stratum of rapid temperature change separates a more uniformly warm upper layer from more uniformly cold deeper watersDeep watersbeyond penetration of lightare uniformly cold

Benthic zone bottom of any aquatic biome the substrate, made up ofsandorganic and inorganic sedimentscontains detritusdead organic matteroccupied by communities of organisms collectively called benthosfor whom a major source of food is detritusrains down from waters of photic zone

Often classified according to their production of organic matter into three general categories1. Oligotrophic deepcoldsmall surface area relative to depthnutrient-poor phytoplankton are sparse, not very productivedont contain much lifewaters often very clearsediments low in decomposable organic matterexample: Lake Baikal, Siberia

2. Eutrophic shallowwarmlarge surface area relative to depthnutrient-richphytplankton more plentiful and productivewaters often murkyhigh organic matter content in benthosleads to high decomposition rates and potentially low oxygen

Eutrophicationprocess in which some oligotrophic aquatic ecosystems become eutrophic occurs over long periods of timeThe ecosystem pass from oligotrophic to mesotrophic to eutrophicoccurs as runoff brings in nutrients and siltpollution from fertilizers can cause explosions in algae population and cause a decrease in oxygen content

3. Mesotrophicmoderate nutrient contentmoderate amount of phytoplankton, reasonably productive.

Estuaries areas where freshwater (stream or river) merges with oceanfreshwater meets salt watersalinity varies from that of fresh water to that of ocean waterspatially (based on location)temporally (due to tidal activity)one of most productive biomes on earth due to nutrients delivered by riversmajor producers are salt marsh grasses, algae, phytoplanktonsupport diverse communitiesare crucial feeding areas for many types of water fowlthreatened by same types of activities as wetlands

Marine biomessalt concentration of ~ 3% cover ~ 75% of the earths surfacehave enormous impact on planets climateevaporation of seawater provides most rainfallocean temperatures affect wind patterns, distribution of energy to land via currentssupply substantial portion of worlds oxygen

photosynthesis by marine algae & photosynthetic bacteriaconsume huge amounts of atmospheric carbon dioxideresult of photosynthesis by marine algae and photosynthetic bacteriacommunities are distributed through several zonesbased ondepth of waterdegree of light penetrationdistance from shoreopen water versus bottom

There are 5 general zones in marine communitiesintertidal zoneneritic zoneoceanic pelagic zonebenthic zoneabyssal zone

Ad 1. Intertidal zonewhere land meets wateris alternately submerged and exposed twice daily die to tidescommunities are subjected to huge daily variations in availability of saltwatertemperatureorganisms are subject to mechanical forces of wave actioncan be rocky or sandyare often destroyed by pollution and human activity

vertical zonationbased on percentage of time spent submergeduppermost zonemiddle zonebottom zone

uppermost zonesubmerged only during highest tideshave adaptations that prevent dehydration and overheatinginhabited by grazing mollusks, suspension-feeding barnacles, a few algae

middle zonesubmerged at high tideexposed at low tideinhabited by array of algae, sponges, sea anemones, mollusks, crustaceans, echinoderms, small fishesbottom zoneexposed only during lowest tidesinhabited dense cover of seaweeds, diver community of invertebrates and fishes

Ad 2. Neritic zonebeyond intertidalincludes shallow regions over the continental shelvesin warm tropical waters, this region containscoral reefsdominated by structure of coral itselfformed by diverse group of cnidarians that secrete hard external skeletons made of calcium carbonatecerates a substrate upon which other corals, sponges, algae grow

include a very diverse assortment of vertebrates and invertebrates very productive currents and waves constantly renew nutrientslight penetrates to ocean floor allowing photosynthesiseasily degraded bypollutiondevelopmenthigh water temperatures

Ad 3. Oceanic pelagic zoneextends past continental shelves, can be very deep, is the open waterincludes most of the oceans water.water is constantly mixed by ocean currentsplankton live in photic zone and are producers for this biomenutrient concentrations generally lower than in coastal areasincludes a great variety of free swimming animals (fish, large squid, sea turtles, marine mammals )

Ad 4. Benthic zoneocean bottom below neritic and oceanic pelagic zones.Substrate and temperature are very important characteristics in determining community developmentnutrients "rain" down from above in form of detrituscommunities consist of bacteria, fungi, seaweed and filamentous algae, numerous invertebrates, and fish.

Ad 5. Abyssal zonevery deep benthic communitiesorganisms are adapted to continuous cold.high pressurelow to no lightlow nutrientsdeep-sea hydrothermal vents of volcanic origin found here.dark, hot, oxygen-deficient environmentproducers are chemoautotrophs