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The Marine Biome
Environmental Science
Chapter 11
The Oceanic Hydrosphere
• All of the water that exists between the lithosphere (continents) can be thought of as ONE BIG OCEAN
• Even despite having several names, all of the worlds oceans are interconnected
• It is essentially one MASSIVE biome with many ecosystems & habitats
• It consists of all of the worlds interconnected saline (salt) water
The Open Ocean
• Another name for the “open ocean” is the oceanic zone or The DEEP– This is by far the largest zone in the ocean
– Makes up about 90% of the total ocean biome
• This is an extremely deep biome that ranges from 200m deep along the coast, all the way to 11,000m deep.
• Most of the oceanic zone receives little to no sunlight
Ocean Producers• Because the vast majority of area in the open
ocean has no access to the ocean floor, any and all producers must be able to float or swim
• The producers that do this, and make up the primary level of the oceanic food web, are microscopic organisms called phytoplankton
• These microscopic Protists and algae carry out the same photosynthesis that terrestrial plants do, converting carbon dioxide into essential sugars and food for other organisms
Sometimes, water
pollution can cause so many phytoplankton
to grow that the colony is
actually visible.
The photic zone
• In the open ocean, the top 200m of water receives enough sunlight to support photosynthetic organisms– This area is called the photic zone
• This area has the largest amount of life and diversity and a large amount of available biomass
• This area of the ocean is also the largestremover of carbon dioxide from the atmosphere
Beyond the Photic Zone
• Any area below the photic zone (deeper than 200m) is called the aphotic (no light) zone.
• Because there is no sunlight available, there is no potential for photosynthesis
• No photosynthesis means no producers, which means very little biomass
• This makes life difficult and causes there to be MUCH LESS diversity here
• Most organisms here must feed on pieces of dead organic matter and waste that float down form above called Detritus
Its all the same… Kind of…• Because the oceans of the world are all
interconnected, often its is said that it has the same characteristics throughout
• However, this is not totally true– The ocean waters are all affected by temperature,
sunlight intensity, salinity, and dissolved minerals
– Because the sunlight intensity near the equator is the strongest it causes the water to be warmer, and the increased evaporation causes for higher salt and dissolved mineral concentrations
– The poles receive substantially less sunlight for evaporation, and are often receiving melted freshwater from glaciers which make them less saline
Continental Shelf• The continents do not just suddenly drop off into
deep ocean.
• Most continents are surrounded by a shallow border that surrounds the land mass and slowly slants deeper into the ocean
• This area is photic (receives a lot of sunlight) and is considered to extend from the shoreline down to about 200m deep.
• This area usually has a diverse biomass do to the available sunlight and ability to photosynthesize
Neritic Zones
• Within the continental shelf is another division called the neritic zone
• The neritic zone is the area that stretches from the edge of the continental shelf and runs to the edge of the “low tide mark”
• The low tide mark is the lowest point that the tide recedes to during low tide
– This area is therefore always covered in water
Coral Reefs• Continental shelf zones have a
spectacularly diverse and unique ecosystem called a coral reef
• The reef system is composed of large structures of living and once living organisms
• These reef organisms form hard structures out of calcium carbonate
– As these organisms die, their skeletons form structure for other living organisms to inhabit and grow on
Coral Reefs
• Most of the animals on a coral reef are either filter feeders who remove carbon material from the water for food
• Or they are animals that have a symbiotic relationship with a bacteria called zooxanthellae
– The zooxanthellae bacteria are able to carry out photosynthesis to make sugars which it shares with the coral organisms
zooxanthellae
Protecting the Coral
• Coral reefs are extremely fragile ecosystems
• When humans are careless with building harbors, fishing, and coral harvesting they can permanently damage
• Warming of ocean waters and water pollution have caused entire reefs to die (often called coral bleaching), destroying the entire ecosystem
• These ecosystems are great indicators of ecosystem health
Estuaries
• The area where freshwater meets saltwater is called a estuary
• These usually occur at the mouths of rivers where they dump into the ocean.
• Because of the mixing of fresh and salt water these areas are usually brackish (less salty than ocean water but more saline then fresh water)
• These unique ecosystems have brackish water inhabitants that can not survive in salt or freshwater
Intertidal Zones
• The ocean tides are the ocean waters reaction to the gravitational pull of the moon.
• Twice a day the tides change in intertidal zones
• This means that the organisms who live in these zones must be able to survive being submersed in water for a time and then exposed to dry air
• Often times, these areas are surrounded by wetlands
Salt Marshes• Intertidal areas that are flat, muddy wetlands
that are often surrounded by estuaries, bays, and lagoons
• The salty water is usually very affected by the tides
• These areas area still used as massive filters to clean water as it leaves the various ecosystems
• These areas are great for resting and feeding areas for migratory birds & are unique in their niches
Mangrove Swamps
• A special type salt marsh that is dominated by a special tree called a mangrove tree or shrub
– These are found only in warmer, coastal climates
• The waters in a mangrove swamp are usually low in oxygen, so in order to get the needed oxygen, Mangrove roots grow up out of the water
• These roots catch sediment which forms dirt clusters and allows other plants to grow
• These ecosystems are unique and have very specialized niches and organisms
Specialized = Endangered• Many of these oceanic ecosystems that we have
recently discussed are extremely unique and have niches that exist nowhere else
• This causes specialized niches which in turn cause specialized pressures
• For this reason, these ecosystems have small numbers of VERY specialized organisms that can live nowhere else
• Any changes to these ecosystems usually have major ramifications and for this reason, most of the organisms found here are threatened or endangered
