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Chapter 16 - Marine Ecosystems

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Title: Chapter 16 - Marine Ecosystems


1
  • 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
2
Ecology and Ecosystems
Ecology and Ecosystems
Chapter 16 Pages 16-3 to 16-9
3
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
4
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
5
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
6
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
7
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
8
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
9
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
10
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
11
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
12
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
13
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
14
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
15
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
16
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
17
Energy Flow and Nutrient Cycles
Nitrogen Cycling
Ecology and Ecosystems
Chapter 16 Pages 16-6 to 16-8
18
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
19
Ecosystems in the Open Sea
Ecosystems in the Open Sea
Chapter 16 Pages 16-10 to 16-14
20
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
Chapter 16 Pages 16-10 to 16-12
21
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
Chapter 16 Pages 16-10 to 16-12
22
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
Chapter 16 Pages 16-10 to 16-12
23
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
24
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
25
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
Chapter 16 Pages 16-10 to 16-12
26
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
Chapter 16 Pages 16-10 to 16-12
27
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
Chapter 16 Pages 16-12 to 16-14
28
Continental Shelf Ecosystems
Ecosystems in the Open Sea
Chapter 16 Pages 16-12 to 16-14
Neritic Zone Productivity
29
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
Chapter 16 Pages 16-12 to 16-14
30
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
Chapter 16 Pages 16-12 to 16-14
31
Continental Shelf Ecosystems
Ecosystems in the Open Sea
Chapter 16 Pages 16-12 to 16-14
Areas of Coastal Upwelling
32
Coastal Ecosystems - Estuaries, Salt
Marshes, Mangrove Swamps, Seagrasses
Coastal Ecosystems - Part 1
Chapter 16 Pages 16-15 to 16-22
33
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
Chapter 16 Pages 16-15
34
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
Chapter 16 Pages 16-15
35
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
Chapter 16 Pages 16-15
36
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
Chapter 16 Pages 16-15
37
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
Chapter 16 Pages 16-15
38
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
Chapter 16 Pages 16-16 to 16-17
39
Estuaries
Coastal Ecosystems - Part 1
Chapter 16 Pages 16-16 to 16-17
40
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
Chapter 16 Pages 16-16 to 16-17
41
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
Chapter 16 Pages 16-16 to 16-17
42
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
Chapter 16 Pages 16-16 to 16-17
43
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
Chapter 16 Pages 16-16 to 16-17
44
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-16 to 16-17
45
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
Chapter 16 Pages 16-16 to 16-17
46
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
Chapter 16 Pages 16-17 to 16-19
47
Salt Marshes
Salt Marsh Plant Community
Coastal Ecosystems - Part 1
Chapter 16 Pages 16-17 to 16-19
48
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
Chapter 16 Pages 16-17 to 16-19
49
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-17 to 16-19
50
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-17 to 16-19
51
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-17 to 16-19
52
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
Chapter 16 Pages 16-17 to 16-19
53
Salt Marshes
Coastal Ecosystems - Part 1
Chapter 16 Pages 16-17 to 16-19
Food Web
54
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 various adaptations that
    allow them to live in salt water and anaerobic
    mud.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-19 to 16-21
55
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-19 to 16-21
56
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-19 to 16-21
57
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-19 to 16-21
58
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-19 to 16-21
59
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 theyre ecosystems crucial to
    the global ecosystem, but mangroves continue to
    vanish.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-19 to 16-21
60
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-21 to 16-22
61
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.

Coastal Ecosystems - Part 1
Chapter 16 Pages 16-21 to 16-22
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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,
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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
Rocky Shore Community
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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 other non-animal
    organisms live among 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 the average sea
    otter eats a substantial 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
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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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Polar Ecosystems
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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 and much of this sea
    is a permanently frozen 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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Deep-Sea Ecosystems
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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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