Chapter 16 - Marine Ecosystems

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• Choose to view chapter section with a click on
  the section heading.
• Ecology and Ecosystems
• Ecosystems in the Open Sea
• Coastal Ecosystems - Estuaries, Salt Marshes,
  Mangrove Swamps, Seagrasses
• Coastal Ecosystems - Intertidal Zones, Beaches,
  Kelp and Seaweed, Coral Reefs
• Polar Ecosystems
• Deep-Sea Ecosystems

Chapter Topic Menu
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Ecology and Ecosystems
Ecology and Ecosystems
Chapter 16 Pages 16-3 to 16-9
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The Science of Ecology

• With the rise of environmental awareness, the
  term ecology has become a buzzword thrown about
  by the media and politicians.
• You may already have a general idea of what
  ecology is, but to discuss marine ecology clearly
  its important to be precise and specific.

Ecology and Ecosystems
Chapter 16 Page 16-3
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The Science of Ecology

• Ecology is the science that studies how organisms
  relate to each other and their environment.
• Ecology embraces the broad range of disciplines,
  including biology, physics, geology, climatology,
  oceanography, paleontology, and even astronomy.
• Beyond biotic (living) factors, the study of
  ecology considers the abiotic (nonliving) aspects
  of the environment.

Ecology and Ecosystems
Chapter 16 Page 16-3
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The Science of Ecology

• Abiotic aspects include temperature, wind, pH,
  currents, minerals, and sunlight.
• Ecology also examines the biological factors,
  such as the quantity and type of organisms in an
  environment.
• Ecology studies the relationships and
  interactions of the abiotic and biotic aspects of
  the environment.
• The goal is to understand how, through
  relationships and interactions, changes in an
  environment will affect those organisms in the
  environment.
• In marine ecology, the four branches of
  oceanography come together.

Ecology and Ecosystems
Chapter 16 Page 16-3
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Ecology Terminology

• At some level youre probably familiar with the
  concept of an ecosystem.
• Definition A distinct entity usually with
  clearly defined physical boundaries, distinct
  abiotic conditions, an energy source, and a
  community of interacting organisms through which
  energy is transferred.
• No ecosystem exists entirely in isolation (except
  under artificial conditions). The ocean is
  composed of interacting, complex ecosystems.

Ecology and Ecosystems
Chapter 16 Pages 16-3 to 16-5
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Ecology Terminology

• A community is a collection of different
  organisms living and interacting in an ecosystem.
  This includes all species and types of organisms.
• A population is a group of the same species
  living and interacting within a community.
• The interaction is part of the definition because
  sometimes two populations of the same species
  live in a single community.
• Can you think of examples?

Ecology and Ecosystems
Chapter 16 Pages 16-3 to 16-5
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Ecology Terminology

• A habitat includes the area and conditions in
  which you find an organism.
• Some species are adapted to or occur in very
  specific habitats, whereas others range over a
  variety of habitats.
• Chitons, for example, live in the rocky
  intertidal zone, whereas octopuses live in a wide
  depth range and in many different parts of a
  reef. The chiton has a narrowly defined habitat
  compared to the octopus.

Ecology and Ecosystems
Chapter 16 Pages 16-3 to 16-5
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Ecology Terminology

• A microhabitat exists on a very small scale. For
  example, tiny crustaceans and worms live in the
  spaces between sand grains on the sea floor.
• Organisms in this microhabitat are a type of
  infauna called meiofauna.

Ecology and Ecosystems
Chapter 16 Pages 16-3 to 16-5
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Ecology Terminology

• An organisms role in its habitat is called its
  niche.
• Very different species can occupy the same niche.
  On coral reefs, for example, cleaner-shrimp and
  cleaner-fish both survive by feeding on the
  parasites and dead or injured skin of reef fish.
• To avoid confusing habitat and niche, think of
  the habitat is an
  organisms address,
  and the niche
  
  as its job.

Ecology and Ecosystems
Chapter 16 Pages 16-3 to 16-5
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Energy Flow and Nutrient Cycles

• Trophic relationships and nutrient cycles are
  concepts fundamental to ecology.
• They describe how energy and matter form the
  basis for interaction among organisms and between
  organisms and the environment.
• Recall that photosynthesizers and
  chemosynthesizers bring energy from the sun and
  chemicals into the food web.
• This energy transfers up through the food web,
  but most of the energy gets lost as heat in the
  process.
• Only about 10 of the available energy passes
  from one trophic level to the next.

Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Energy Flow and Nutrient Cycles
Energy flow. This illustration shows how energy
flows through a functioning ecosystem.
Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Energy Flow and Nutrient Cycles

• The energy flow through the food web affects an
  ecosystem by determining how much energy is
  available for organisms at higher trophic levels.
  
• In all ecosystems, there are fewer high-level
  predators than low-level prey.
• The amount of primary production shapes the
  ecosystem.
• High primary production creates the potential for
  more organisms at high trophic levels, and the
  potential for more trophic levels.
• Anything that affects energy flow will also
  affect the ecosystem.
• Even with ample primary production the ecosystem
  would lose many of the high-level organisms in
  its community.

Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Energy Flow and Nutrient Cycles
Interrupted energy flow. A substantial decline
in an ecosystems primary consumers disrupts
energy flow to higher trophic levels. Here we see
a reduction of the amount and types of prey
available to killer whales. The whale population
will suffer in this ecosystem unless they move on
to an area with more productivity, or more
primary consumers to transfer energy to higher
trophic levels.
Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Energy Flow and Nutrient Cycles

• Energy flows through an ecosystem, eventually
  being lost as heat into the water, atmosphere,
  and space.
• Nutrients, on the other hand, arent lost.
• Carbon, nitrogen, phosphorus, and other crucial
  elements cycle through the Earths ecosystems.

Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Energy Flow and Nutrient Cycles

• The nitrogen nutrient cycle is thought to be more
  limited in marine ecosystems than in terrestrial
  ecosystems.
• Because Inorganic nitrogen must be fixed into
  organic compounds before it can be used by
  organisms.
• Nitrogen-fixing bacteria that do this live
  primarily in terrestrial ecosystems.
• Seabird droppings, erosion, and runoff carry
  organic nitrogen compounds (and phosphorus) from
  terrestrial environments into the marine
  environment.
• This is an example of how ecosystems dont exist
  entirely in isolation.

Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Energy Flow and Nutrient Cycles
Nitrogen Cycling
Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Energy Flow and Nutrient Cycles

• The ecological significance of nutrient cycles is
  usually greater than that of energy flow.
• Why? Nutrients are usually a limiting factor,
  whereas energy is usually not. Compare many warm,
  tropical marine ecosystems with cold, temperate
  marine ecosystems.
• Tropical ecosystems generally have more energy
  (sunlight) available, yet oceanic conditions
  dont supply as many nutrients to tropical
  regions.
• One of the few highly productive marine
  ecosystems found in tropical waters is the coral
  reef.
• Temperate coastal waters, by comparison, have
  less overall sunlight, but receive far more
  nutrients. For this reason, the most highly
  productive marine ecosystems are found in colder
  water.

Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
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Ecosystems in the Open Sea
Ecosystems in the Open Sea
Chapter 16 Pages 16-10 to 16-14
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Euphotic Zone Ecosystems

• The euphotic zone comprises only 1 of the ocean,
  yet the majority of marine life lives there.
• Extends as deep as 200 meters (656 feet), but in
  coastal waters with more turbidity, light may
  only penetrate to about 30 meters (100 feet).
• The euphotic zone is where photosynthetic
  organisms live, and light energy transfers
  through food webs as chemical energy.

Ecosystems in the Open Sea
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Euphotic Zone Ecosystems

• The neuston are the plankton that live in the
  uppermost layer of the ocean.
• This ecosystem is very thin only a few
  millimeters in many instances.
• It receives the maximum sunlight and because it
  covers about 71 of the Earths surface.

Ecosystems in the Open Sea
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Euphotic Zone Ecosystems

• There have been surprisingly few studies to
  compare the neuston layers to the water layers
  below.
• It is known that the first few millimeters to a
  few centimeters of water differ substantially
  from the water below.
• Generally, neuston layers hold significantly more
  nutrients, chlorophyll a, and carbon compounds.
• Surface tension supports eggs, larvae, and
  microscopic life on the top film of the water.
• Cyanophyte, diatom, and dinoflagellate
  populations in the neuston ecosystem may be
  10,000 times more numerous than in the water just
  a few millimeters deeper.
• This makes the neuston zone an important
  ecosystem for worldwide primary productivity.

Ecosystems in the Open Sea
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Euphotic Zone Ecosystems

• This isnt true globally, however. In some
  places, photosynthesis and primary productivity
  are higher below the neuston ecosystem.
• One reason may be photoinhibition.
  Photoinhibition seems to be prevalent in tropical
  seas.
• Because theres little water to protect neuston
  organisms, ultraviolet light may account for some
  of the photoinhibition.
• If this is true, ozone depletion may make
  photoinhibition worse as even more UV light makes
  it to the Earths surface.

Ecosystems in the Open Sea
Chapter 16 Pages 16-10 to 16-12
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Euphotic Zone Ecosystems

• An important factor reducing primary productivity
  in the neuston ecosystem may be pollutants.
• A variety of pollutants from the atmosphere and
  runoff enter the euphotic zone.
• How pollutants affect the neuston ecosystems
  concerns scientists with respect to global
  climate change.
• The ocean plays an important role in moderating
  global climate - particularly removing CO2.
• Many oil-based chemicals, float on water,
  creating a barrier that slows or stops carbon
  dioxide (and other gases) from dissolving into
  the water below. By affecting the euphotic zone
  ecosystems, these pollutants may contribute to
  global climate change.

Ecosystems in the Open Sea
Chapter 16 Pages 16-10 to 16-12
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Euphotic Zone Ecosystems

• Floating debris, whether natural or
  human-produced, acts as potential shelter and
  attracts marine life.
• This creates distinct neustonic ecosystems that
  thrive around floating material in the water.
• The worlds largest floating ecosystem is the
  Sargasso Sea - a complex community.
• Sargassum mat organisms include tiny fish of many
  species, crustaceans, and other organisms.
• On the other hand, the Sargassum fish is a
  species of frogfish adapted specifically to this
  ecosystem. It blends in with the Sargassum,
  preying on small crustaceans and fish.

Ecosystems in the Open Sea
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Euphotic Zone Ecosystems

• The Sargasso Sea and other euphotic zone
  ecosystems found around floating debris provide
  another example of how ecosystems interact.
• Predatory fish hide under Sargassum or debris,
  feeding on fish and other neustonic organisms
  that live there.
• These predators in turn provide food for pelagic
  fish, sharks, dolphins, and other large predators.

Ecosystems in the Open Sea
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Continental Shelf Ecosystems

• The neritic zone consists of the water between
  the low-tide mark and the edge of the continental
  shelf.
• This zone can range from only a few to several
  hundred kilometers or miles wide.
• The neritic zone is a significant marine
  ecosystem because it is the most productive
  region in the ocean.
• The area tends to keep nutrients in the shallow,
  photic zone and helps retain heat from the sun.
• Being near the shoreline - the neritic zone
  benefits from nutrients in river runoff also.
• Nutrients rising with currents from deep water at
  the shelf edges also make this zone biologically
  rich.
• All of these factors combine to make the neritic
  zone a highly productive ecosystem.

Ecosystems in the Open Sea
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Continental Shelf Ecosystems
Ecosystems in the Open Sea
Chapter 16 Pages 16-12 to 16-14
Neritic Zone Productivity
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Continental Shelf Ecosystems

• Upwelling plays a significant role in the balance
  of coastal ocean ecosystems.
• This is because upwelling brings nutrients from
  deeper water to shallow, more productive depths.
• This is especially significant with respect to
  fecal pellets and other nutrients that sink to
  the relatively less productive bottom in the
  abyssal zone.
• Wind causes upwelling that returns nutrients to
  the upper ocean depths.

Ecosystems in the Open Sea
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Continental Shelf Ecosystems

• The role of upwelling is unmistakable.
• Areas with the highest upwelling activity also
  have the highest nutrient levels.
• These correspond with many of the oceans highest
  productivity regions.
• Examples include the waters offshore of Peru, the
  Bering Sea, the Grand Banks in the Atlantic, and
  the deep water surrounding Antarctica.

Ecosystems in the Open Sea
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Continental Shelf Ecosystems
Ecosystems in the Open Sea
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Areas of Coastal Upwelling
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Coastal Ecosystems - Estuaries, Salt
Marshes,Mangrove Swamps, Seagrasses
Coastal Ecosystems - Part 1
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High Productivity Marine Environments

• Coastal ecosystems are generally highly
  productive ecosystems for several reasons.
• They benefit from nutrient-rich runoff from land.
  Because theyre shallow, the benthic organisms in
  these ecosystems live in the upper photic zone,
  instead of the bottom as in the open sea.
• Salt-tolerant plants can grow in the well-lit
  shallows, providing shelter. These plants act as
  the foundation for several different types of
  ecosystems that cannot exist in the open ocean.

Coastal Ecosystems - Part 1
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High Productivity Marine Environments

• The combination of nutrients, ample light, and
  shelter make coastal ecosystems diverse and rich.
  
• While you dont commonly find large organisms
  here (though there are some), these ecosystems
  provide a haven for juveniles of open ocean
  species.
• Mangrove swamps contribute to the health of coral
  reefs in this way.

Coastal Ecosystems - Part 1
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High Productivity Marine Environments

• Human activities have wide-ranging potential
  effects on coastal ecosystems.
• The effects are varied and immediately at hand.
• People have always tended to live near water,
  putting humans in proximity with these ecosystems
  - this causes problems.
• Agriculture, for example, can alter these
  ecosystems when excess fertilizer washes seaward
  with rain runoff. Can you name more?
• The variety of human activities is so wide we
  cant always anticipate all the consequences to
  ecosystems.

Coastal Ecosystems - Part 1
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High Productivity Marine Environments

• Because the effects are immediately at hand,
  coastal ecosystems may experience the
  consequences more severely.
• Pollutants, for example, often reach coastal
  ecosystems in concentrated form.
• Open ocean ecosystems, by contrast, benefit from
  a diluting effect.

Coastal Ecosystems - Part 1
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High Productivity Marine Environments

• One particular concern with coastal ecosystems is
  eutrophication, which is an overabundance of
  nutrients that causes an ecological imbalance.
• Eutrophication is a stimulus to some species and
  a detriment to others.
• Fertilizer runoff can dump excess nutrients in
  the water, stimulating excessive algae growth or
  algae blooms. When the algae die, degradation of
  biomass consumes available oxygen.
• The depletion of oxygen kills fish and other sea
  life.
• Although there are other causes of harmful algae
  blooms (HABs), eutrophication is the most
  conspicuous.

Coastal Ecosystems - Part 1
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Estuaries

• Estuaries exist where the tides meet rivers.
• Theyre not found where all rivers enter the sea,
  but theyre common where the tidal range is high.
  
• This allows high tide to push well up river,
  often flooding large land areas.
• Estuaries may be large, complex deltas with
  multiple inlets, lagoons, and islets or they may
  be simple wide stretches of river entering the
  sea.

Coastal Ecosystems - Part 1
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Estuaries
Coastal Ecosystems - Part 1
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Estuaries

• Estuaries tend to trap and accumulate runoff
  sediments, so theyre rich with nutrients and
  biologically productive.
• Most of the major North American rivers flowing
  into the Atlantic flow first into estuaries.
• This is why the North Atlantic doesnt have as
  much sediment flowing in to it as other ocean
  basins have with comparable rivers.
• Estuaries trap much of the sediment. This also
  makes estuaries sensitive to eutrophication
  because the same process traps excess nutrients
  such as fertilizer runoff.

Coastal Ecosystems - Part 1
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Estuaries

• Estuaries act as a dumping ground, filter, and
  absorber of nutrients (and pollutants).
• Estuaries are the kidneys of the biosphere
  because of their cleansing function.
• The continuous replenishment of nutrients results
  in ecosystems with high primary productivity from
  algae and halophytes - saltwater plants. These,
  in turn, support a large community of primary and
  secondary consumers.

Coastal Ecosystems - Part 1
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Estuaries

• Some factors limit productivity in estuaries.
• One is that organisms in this ecosystem must
  tolerate wide salinity ranges.
• The osmotic stress caused by the rising and
  falling tides mixing with fresh water proves
  fatal to many organisms.
• Organisms that tolerate wide salinity ranges are
  called euryhaline organisms. Therefore,
  variations in salinity tend to reduce the variety
  of species.

Coastal Ecosystems - Part 1
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Estuaries

• Another productivity limit results from the
  tendency of decomposition to deplete the oxygen
  in the nutrient-rich sediments.
• This limits the benthic organisms that can thrive
  in estuaries.
• The rotten eggs smell common to these areas comes
  from sulfides released by thriving anaerobic
  sulfur bacteria.

Coastal Ecosystems - Part 1
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Estuaries

• Estuaries provide a region of shallow, sheltered
  water and nutrients, making them excellent
  nurseries.
• By providing a rich haven, larvae and juveniles
  of open ocean species can elude predation and
  grow before venturing out to sea.
• Estimates show that estuary ecosystems serve as
  nurseries for more than 75 of commercial fish
  species.

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Estuaries

• Estuaries contribute to the productivity of
  adjacent marine ecosystems in at least two ways.
• First, surviving juveniles migrate from the
  estuaries as they grow and mature. They increase
  the number of individuals that survive the
  hazardous larval and juvenile stages.
• Second, estuaries provide a steady stream of
  nutrients to adjacent marine ecosystems, while
  trapping sediment and other materials in runoff
  from rain and storms.

Coastal Ecosystems - Part 1
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Salt Marshes

• Salt marshes exist in estuaries and along the
  coasts.
• They are found where flat, gently sloping shore
  are washed by the tides with nutrient-rich
  sediments.
• Rivers provide a source of sediments and
  nutrition.
• Conditions within a salt marsh vary, which
  affects the types of organisms inhabiting
  different areas within the ecosystem.
• The upper marsh includes the areas only rarely
  flooded by the tides.
• The lower marsh includes areas flooded by salt
  water as a regular part of the tidal cycle.

Coastal Ecosystems - Part 1
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Salt Marshes
Salt Marsh Plant Community
Coastal Ecosystems - Part 1
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Salt Marshes

• Most plants cant live in seawater because
  osmosis dehydrates them.
• Halophytes, on the other hand, have adaptations
  that allow them to survive in salt water.
• Thanks to these adaptations, halophytes occupy a
  niche with little competition from other plants,
  and become the dominant species.

Coastal Ecosystems - Part 1
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Salt Marshes

• Halophytes in the lower marsh deal with constant
  osmotic stress.
• The hollow reed Spartina sp., called cordgrass,
  is a good example of halophyte adaptation to this
  part of the ecosystem.
• Spartina sp. excludes salt from its tissues and
  moves oxygen it produces by photosynthesis to its
  roots.

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Salt Marshes

• Plants in the upper marsh dont have to deal with
  daily tides.
• In addition, the inflow of fresh water dilutes
  salt water, reducing osmotic stress.
• Organisms thriving in this part of the ecosystem
  adapt differently. One example is Salicornia sp.,
  or pickleweed.

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Salt Marshes

• Pickleweed handles excess salt by storing it in
  sacrificial leaves.
• When the salt load accumulates to a certain
  point, the leaf drops away, taking the salt with
  it.
• Salicornia grows another leaf to take its place.

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Salt Marshes

• Halophytes dominate the salt marsh, yet they are
  not food for many organisms.
• Salt marsh plants are tough and salty, making
  them unsuitable for most herbivores.
• Their root systems hold sediment, which, along
  with the accumulation of dead halophytes, creates
  dense mats of detritus.
• In the salt marsh, detrital mats provide habitats
  for huge communities of invertebrates, water
  birds, juvenile fish, larva, eggs, and other
  organisms.

Coastal Ecosystems - Part 1
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Salt Marshes
Coastal Ecosystems - Part 1
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Food Web
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Mangrove Swamps

• Mangrove swamps include many species.
• They all play an important role in the marine
  environment, especially coral reefs.
• In many respects, mangroves occupy similar niches
  as the halophytes that characterize salt marshes,
  but theyre bigger, tougher, and found in
  tropical climates.
• Mangrove species have variousadaptations that
  allow them tolive in salt water and anaerobic
  mud.

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Mangrove Swamps

• Red mangroves grow above the waterline on
  stilt-like roots. This allows oxygen to reach the
  roots. a. They obtain fresh water by filtering
  seawater through its adapted roots, which exclude
  the salt.
• This is an example of reverse osmosis, which is
  the process of transporting water through a
  semipermeable membrane against the natural
  osmotic pressure gradient.
• This is a form of active transport, which is the
  process of a cell moving materials from areas of
  low concentration to areas of high concentration.

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Mangrove Swamps

• Black Mangroves have roots that grow in the
  sediment below the waterline.
• These mangroves aerate their roots with
  snorkel-like tubes called pneumatophores, which
  carry air from above the surface to the roots.
• Some black mangroves eliminate salt through
  sacrificial leaves, like the pickleweed. Others
  have special salt glands in their leaves.

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Mangrove Swamps

• White mangroves lack such specialized
  adaptations.
• Theyre very saltwater tolerant, but thrive high
  on the tideline where they dont need special
  root adaptations. These mangroves receive
  sufficient freshwater runoff to survive.

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Mangrove Swamps

• Regardless of species or adaptations, mangroves
  share two important characteristics that make
  them the basis of mangrove ecosystems.
• They have strong, tangled roots that provide
  habitats for juvenile fish and invertebrates -
  they are nurseries for nearby marine ecosystems,
  particularly coral reefs.
• They hold the soil well, protecting the habitat
  and coast from erosion due to storm surges,
  waves, and weather.
• Without strong mangrove root systems, tropical
  storms would quickly wash away many tropical
  islands and beaches.

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Mangrove Swamps

• Mangroves trap nutrients, much as estuaries do,
  helping to protect coral reefs and other nearby
  marine ecosystems.
• However, because theyre swampy, sulfide-smelling
  mosquito havens, until relatively recently people
  viewed them as wastelands.
• Today we know theyreecosystems crucial to
  theglobal ecosystem, butmangroves continue to
  vanish.

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Seagrasses

• Seagrass ecosystems are similar to other
  halophyte-based ecosystems in that they stabilize
  sediments and provide shelter and habitats for
  other organisms.
• However, seagrasses differ from other halophytes
  in several important ways that make them and
  their ecosystems distinct.

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Seagrasses

• Seagrasses are rooted, vascular flowering plants
  that live entirely under water except during
  rare, very low tides.
• Some species live as deep as 30 meters (100
  feet).
• Seagrasses can grow as members of a mangrove or
  salt marsh ecosystem.
• Commonly seagrass grow spread across the bottom
  like underwater pastures - they mat the sediment
  below.
• Seagrasses extract oxygen from the water and have
  internal air canals.
• Most species even release pollen into the current
  to reproduce, much like terrestrial plants.

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Seagrasses

• Unlike most halophytes, seagrasses are edible and
  provide food for ecosystem inhabitants.
• They are heavily grazed by microbes,
  invertebrates, fish, turtles, and even manatees
  and dugongs.

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Coastal Ecosystems - Intertidal Zones,
Beaches,Kelp and Seaweed, Coral Reefs
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Intertidal Zones

• When we think of coastal ecosystems, we tend to
  think of mangroves, estuaries, and similar
  ecosystems.
• The numerous complex organisms make their
  productivity conspicuous. However, in every place
  the ocean touches land, youll find a coastal
  ecosystem with rich communities.
• Ecosystems in the worlds intertidal zones exist
  in areas that may be above the waterline at
  times.
• Other portions of intertidal zones reach depths
  of about 10 meters (33 feet).

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Intertidal Zones

• The supralittoral zone is the area only submerged
  during the highest tides.
• The greatest challenges facing organisms that
  live in supralittoral ecosystems are drying and
  thermal stress.
• A constant spray of seawater that evaporates also
  results in high salt levels.

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Intertidal Zones

• Organisms with habitats in the supralittoral zone
  have adaptations that help them retain moisture.
• Unlike many marine organisms, they can either
  obtain oxygen from the air or store sufficient
  oxygen in their tissues to endure many hours out
  of the water.
• They are hardy enough to withstand periodic
  motion and pounding by waves.
• Barnacles, periwinkles, and limpets are examples
  of organisms adapted to life in the
  supralitttoral zone.

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Intertidal Zones

• The rest of the littoral zone (the area between
  high and low tide) faces similar challenges. Life
  here isnt left above the surface for extended
  periods like the supralittoral zone.
• These organisms also face the challenges of
  drying out, thermal stress, and water motion.
• Progressing seaward, the environment becomes less
  stressful with respect to drying out and thermal
  stress, though waves and surge remain challenges.
  
• Organisms that thrive here are seaweeds, starfish
  anemones, and mussels.

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Intertidal Zones

• The lowest part of the littoral zone is rarely
  exposed to air - only at extremely low tides.
• With ample water, nutrients, and sunlight, this
  is a highly productive region in most coastal
  ecosystems.
• One challenge to life here, therefore, is intense
  competition.

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Intertidal Zones
RockyShoreCommunity
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Beaches

• To the untrained eye, the typical sandy beach
  appears nearly devoid of life.
• It looks almost like a desert, with only an
  occasional shell or starfish.
• The reality is that beaches are rich and
  productive ecosystems.
• They also have important roles that affect other
  marine ecosystems.

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Beaches

• Sand results from the energy of waves weathering
  the coast and washing it into the sea with river
  runoff.
• Scientists think that the sands on the worlds
  beaches may have migrated thousands of years
  before washing ashore.
• In addition to minerals, living and dead organic
  material accumulates into the sand mix.

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Beaches

• Sand protects the coastline.
• As a wave comes ashore, it picks up sand. Each
  sand grain dissipates a miniscule portion of wave
  energy.
• That portion times billions and billions of sand
  grains reduces the forces that wear away the
  coastline.
• This is the first way that beaches affect
  ecosystems. They reduce sedimentation caused by
  coastal erosion.

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Beaches

• Beach ecosystems are rich in organisms living on
  the organic material in the sand mix.
• Complex organisms, including worms, mollusks, and
  fish live in the submerged beach sand.
• Called meiofauna - benthic organisms that live in
  the spaces between sand grains are very diverse.
• About a third of all known animal phyla have
  representatives in the meiofauna.
• Additionally, algae and othernon-animal
  organisms liveamong the sand grains.

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Beaches

• The interaction between water motion and the
  meiofauna provides the second way that beaches
  affect other marine ecosystems.
• The physical and organic processes in the beach
  ecosystem break down organic and inorganic
  materials.
• This makes the beach a giant filter that
  processes compounds from runoff to the sea or
  washed up from the sea.

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Kelp and Seaweed Ecosystems

• Seaweed refers to a diverse group of red, green,
  and brown algae.
• All provide the bases for ecosystems among their
  stipes, holdfasts, and blades.
• Among these, kelp ecosystems are probably the
  most diverse.

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Kelp and Seaweed Ecosystems

• You find kelp forests globally in cool water.
  This is because they require the nutrients found
  in a cool ocean.
• The richest and most productive kelp ecosystems
  exist in coastal waters with upwellings.
• In clear water with ample sunlight and nutrients,
  giant kelp can reach 60 meters (196.8 feet) long
  that cover many acres underwater.
• Kelp forests and other seaweed-based ecosystems
  are among the most biologically productive
  ecosystems.
• Their primary production exceeds the primary
  productivity of terrestrial forests and is almost
  equal to the productivity of coral reefs.

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Kelp and Seaweed Ecosystems

• Because of its dependence on sunlight, cool
  water, and nutrients, kelp responds noticeably to
  environmental changes.
• During ENSO events, for example, the coastal
  water temperatures in Southern California rise.
  This often causes massive die offs of kelp,
  disrupting the local ecosystems for a year or
  more.

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Kelp and Seaweed Ecosystems

• Kelp provides a clear example of why its
  important to study ecology, not simply individual
  organisms.
• Until protected, in some areas the sea otter was
  hunted nearly to extinction.
• Amazingly, in these areas the kelp began to die
  off rapidly.

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Kelp and Seaweed Ecosystems

• It turns out that while few organisms eat kelp,
  one that does is the sea urchin.
• These echinoderms graze on the rubbery holdfasts
  that anchor the kelp.
• Sea urchins are also one of the sea otters
  primary foods.
• The energy required by a mammal living in cool
  seawater is considerable, so theaverage sea
  otter eats asubstantial number of sea urchins.

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Kelp and Seaweed Ecosystems

• Killing the sea otters disrupted the kelp
  forests ecological balance by removing the sea
  urchins chief predator.
• This allowed the sea urchin population to rise
  relatively unchecked.
• More sea urchins meant more grazing on kelp
  holdfasts.
• In the end, the sea urchins ate the kelp faster
  than it could grow.
• This is an excellent example of the
  interdependence that exists within an ecosystem.
  It shows that each organism contributes to a
  balance that allows life to thrive there.

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Coral Reefs

• Of all the Earths ecosystems, few compare to the
  coral reef.
• Most scientists believe they are the most
  taxonomically diverse ecosystems in the ocean.
• The Indo-West Pacific area between Papua New
  Guinea and the Sulu and Celebes Seas has the
  worlds highest marine species diversity.
• More than 2,000 species of fish are known, with
  new species discovered every year.
• Scientists think corals and coral reefs
  originated here because the further you go from
  this area, the less diversity you find.

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Coral Reefs

• While supporting immense diversity, coral reef
  ecosystems are also fragile.
• For decades now, scientists, divers, and others
  familiar with coral have been worried about their
  health.
• The conditions coral requires for life are narrow
  and specific. It lives in clear water so that
  dinoflagellates (zooxanthellae) coexisting in the
  polyps have light for photosynthesis.
• It also needs water thats in moderate motion to
  prevent sediments from accumulating on the
  polyps. Particulate matter can clog and smother
  the polyps. It also reduces the light reaching
  the algae inside.

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Coral Reefs

• Coral ecosystems also require water thats
  relatively free of nutrients.
• This may seem odd considering the high
  productivity of this ecosystem.
• However, coral ecosystems efficiently pass on and
  preserve organic material.
• The lack of nutrients in the water actually
  protects coral from competitive organisms.

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Coral Reefs

• This is why eutrophication is one of the biggest
  threats to coral ecosystems.
• A rise in water nutrient levels allows
  competitive algae to overgrow and smother coral
  colonies.
• It also allows plankton to grow, reducing water
  clarity and the amount of sunlight reaching the
  polyps.
• To some extent, these are natural processes, but
  over the last several decades eutrophication
  levels have been rising. Correspondingly, many
  reefs once dominated by corals now have algae
  overgrowing them.

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Coral Reefs

• Besides eutrophication, thermal stress threatens
  coral reef ecosystems.
• A concern is that global warming may raise
  temperatures above corals survival threshold.
• Another threat comes from sedimentation resulting
  from coastal dredging and construction. This
  causes sediment to accumulate on the polyps more
  quickly than water motion can remove it.
• Coral diseases seem to be more common. These are
  attacks by fungi, cyanophytes, bacteria, and
  other competitive algae damaging and displacing
  corals.
• Scientists are still determining the likely
  sources and causes for many of these.

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Coral Reefs

• Regardless of the specific threat, its important
  to apply the principles of ecology to the overall
  picture.
• The concern isnt for the coral alone, but the
  entire coral ecosystem.
• Just as the loss of sea otters threatens kelp,
  the loss of the corals threatens other organisms
  in the ecosystem.

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Coral Reefs

• Parrotfish, for example, feed on coral. If the
  coral dies, the parrotfish will dwindle as they
  lose their primary food source.
• Predators that feed on the parrotfish may
  similarly suffer. Other organisms will not
  survive because the competitive algae dont
  provide the same habitat as a coral reef.
• The decline of coral is likely to have a domino
  effect throughout not just the coral ecosystem
  but the entire marine ecosystem.
• Ultimately, that means the loss of coral will
  affect the global ecosystem in ways that
  ecologists are still trying to predict.

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The Arctic

• The Arctic Ocean is bordered by the shallow
  continental shelves of North America, Greenland,
  Eurasia and Russia. It connects to the rest of
  the ocean at the Bering Straight and the upper
  North Atlantic.
• The Arctic is a deep basin andmuch of this sea
  is a permanentlyfrozen ice cap.

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The Arctic

• Marine ecosystems in the Arctic face the
  challenges of reduced sunlight under the ice and
  water thats barely above freezing.
• For these reasons, divesity of organisms is
  limited under the permanent ice cap.
• Species that do live in these conditions have
  special adaptations. These include antifreezing
  compounds in their blood and extremely low
  metabolisms.

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The Arctic

• At the edge of the ice cap, however, life
  intensifies especially between March and
  September.
• As the sun melts ice in the spring, water flows
  off the ice, sinking into deep water.
• Warm currents from the south interact with the
  cold water at the continental shelf edges.
• This process churns up nutrients from the shelf
  bottom.

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The Arctic

• Extremely high productivity occurs along an arc
  in the North Pacific and across the North
  Atlantic from April to August.
• These waters support massive fisheries, marine
  mammals, and other organisms.
• This ecosystem flourishes from the nutrients
  churned up from the bottom.

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The Antarctic

• Antarctica has a more extreme climate than the
  Arctic.
• Also, the Antarctic differs geographically from
  the Arctic. Antarctica, is a continent, not a
  frozen sea.

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The Antarctic

• Its also not enclosed by the continental shelves
  of other continents. Instead, it has its own
  continental shelf.
• The deepest and broadest ocean ring surrounds the
  Antarctic. For these reasons, the Antarctic
  ecosystem has differences and similarities
  compared to the Arctic.

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The Antarctic

• During the winter, sea ice surrounding Antarctica
  freezes, adding an area about the size of North
  America.
• When summer comes, the melting of this sheet sets
  off an explosion of bioproductivity.
• As the temperature of the seawater drops, water
  molecules join together to form sea ice. When the
  ice forms, the salts become concentrated in the
  remaining seawater.
• This very cold, very salty, very dense water
  flows down the continental margins of Antarctica
  and becomes Antarctic Bottom Water, the most
  dense water in the ocean.
• Winds blowing along the coast result in Ekman
  Transport, which moves water away from the
  continent at the surface, causing upwelling in
  the area.

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The Antarctic

• This nutrient-rich deep water reaches the surface
  at the Antarctic Divergence, an area located at
  approximately 65 to 70 south latitude.
• This is the largest nutrient-rich area on Earth.
• The Antarctic Divergence supports massive
  phytoplankton blooms from November through the
  southern summer.
• The copepod and krill populations are larger than
  any other species population found in any other
  ecosystem.
• Single krill swarms have been estimated as
  exceeding 100 million tons, which is more than
  the worlds annual commercial fish catch.

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The Antarctic

• The productive water zone extends northward until
  it meets the warm Atlantic, Indian, and Pacific
  waters.
• At this point, the cold Antarctic water sinks
  under the warm water. This area is called the
  Antarctic Convergence. It is located at
  approximately 50 to 60 south latitude.
• As in the Arctic, organisms living in the coldest
  Antarctic ecosystems have special adaptations.
• Because the Antarctic is a relatively isolated
  ecosystem, most species are specialized and found
  only in the Antarctic.

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The Abyssal Zone

• In the deep ocean beyond the continental shelves,
  the suns light and warmth never reach the bottom
  and the average temperature is 2C (35.6F).
• Without sunlight, theres no photosynthesis
  consequently, theres no primary productivity in
  most of the deep ocean.

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The Abyssal Zone

• Because theres no primary productivity, most of
  the deep ocean gets its nutrients from marine
  snow.
• Marine snow is the constant fall of sediment,
  dead organisms, fecal pellets, and other
  nutrients from the productive shallow waters
  above.
• Most of the deep ocean is the abyssal zone, which
  covers about 30 of the Earths surface.
• This is one of the smoothest and flattest areas
  on Earth, found at depths between about 3,000 and
  4,000 meters (9,843 and 13,123 feet).
• Without primary productivity, the abyssal zone
  lacks dense life concentrations. However, theres
  a vast species diversity.

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The Abyssal Zone

• Marine snow makes the deep ocean rich in
  nutrients. However, the nutrients are spread out
  evenly.
• Without photosynthesis, theres insufficient
  energy accumulated to support a great abundance
  of multicellular organisms.
• Those that do survive are primarily echinoderms,
  such as sea cucumbers, sea lilies, and brittle
  stars.
• Concentrations of large organisms are rare.
  However, submersibles have seen rattails,
  deep-sea dogfishes, catsharks, crustaceans,
  mollusks, and many species of deep ocean fish.

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The Abyssal Zone

• The greatest diversity in the abyssal zone is
  found in the meiofauna.
• As in beach sand, you can find representatives
  from almost all the animal phyla living in the
  deep ocean mud or sediment.
• The concentrations and populations are lower than
  in shallower seas, but the diversity is not.
• Scientists have explored only a small portion of
  the abyssal zone. It is not unusual for new
  species to be found there. It is one of the last
  frontiers on Earth to be explored.

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Whale Falls

• Although the abyssal plains are typical of most
  of the deep-ocean ecosystems, there are some
  important exceptions, including whale falls.
• A whale fall is exactly what the name says - a
  place where a dead whale comes to rest on the
  deep ocean floor.

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Whale Falls

• Whale carcasses provide a massive concentration
  of nutrients in areas that normally only receive
  diffuse marine snow.
• Scientists think that the result is the
  development of a distinct local ecosystem that
  goes through three distinct stages.
• The first stage is when the scavengers arrive.
• They consume the whales soft tissues in a few
  months. Hagfish, grenadiers, deep-sea spider
  crabs, and sleeper sharks are some of the
  scavengers associated with this stage.

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Whale Falls

• The second stage lasts about a year.
• Worms, small crustaceans, and other small
  organisms feed on the remaining soft tissue and
  the tissue dispersed around the whale as
  detritus.
• Marine biologists are still trying to determine
  exactly how these organisms find their way to the
  whale.
• The current thinking is that the larval stages
  for these animals is widely dispersed, and settle
  on food when it becomes available to complete
  development.

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Whale Falls

• The final stage involves the decay of the whale
  skeleton.
• This can last several years or even decades. The
  bones provide a steady supply of sulfide as
  theyre broken down.
• Chemosynthetic bacteria live on this sulfide,
  creating a food source for tubeworms,
  crustaceans, gastropods, and bivalves.
• These bacteria appear to be the same as those
  associated with hydrothermal vents. It may be
  that whale falls enable the colonization of these
  deep-sea ecosystems.

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Whale Falls

• If this is the case, the effects of whaling on
  these deep ecosystems may be substantial.
• Other large organisms sinking to the deep ocean
  bottom have a similar effect.
• Wood, kelp, Sargassum, and large fish provide a
  nutrient concentration that supports a local
  ecosystem for several months to a year.

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Hydrothermal Vents and Cold Seeps

• Hydrothermal vents are sources of primary
  productivity.
• Around these vents, chemosynthesizing bacteria
  consume sulfides dissolved in the heated water
  emerging from these vents.
• These bacteria act as the base of a trophic
  pyramid for a diverse community living in these
  deep ocean ecosystems.

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Hydrothermal Vents and Cold Seeps

• Similar to hydrothermal vents, cold seeps are
  areas where hydrocarbons and sulfide-rich fluids
  seep from the underlying rock in the ocean floor.
• These are called cold seeps because theyre
  cool compared to hydrothermal vents.
• However, they are heated by geothermal energy
  from inside the Earth.

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Hydrothermal Vents and Cold Seeps

• Like the hydrothermal vents, cold seeps support
  chemosynthetic-based ecosystems.
• The chemosythesizers include the same
  sulfide-consuming bacteria, but other vents and
  seeps rely on microbes that consume methane or
  other hydrocarbons.

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The Hadal Depths - Ocean Trenches

• The hadal zone makes up the deepest ocean depths,
  found in the deep ocean trenches where the
  oceanic plates collide with continental plates.
• Depths in this zone range from about 5,000 to
  6,000 meters (16,400 to 19,700 feet), although
  some spots are deeper than 11,000 meters (36,000
  feet).

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The Hadal Depths - Ocean Trenches

• Scientists know little about the hadal zone
  ecosystems primarily because of the limits of
  technology.
• The extreme pressure makes it expensive and
  difficult to make submersibles or instruments
  capable of observing these depths.
• Only a few submersibles have been built that can
  descend safely into the hadal zone, and only a
  single manned trip has been made to the deepest
  known spot in the ocean.

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The Hadal Depths - Ocean Trenches

• Therefore, what scientists know about life in the
  hadal zone is limited to fleeting glimpses.
• Most of these are from ROVs (Remote Operated
  Vehicles) and brief visits by submersibles.
• These brief observations have found organisms
  even in the Mariana Trench (the deepest known
  place on Earth), but the character and extent of
  the hadal ecosystems remain largely unknown.

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