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Earths Ecosystems
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Ecology
Ecology:
Scientific study of the interactions between organisms and the environment
Rediscovery of the nearly extinct harlequin toad in Costa Rica raises many ecological questions
What environmental factors limit their geographic distribution?
What factors (food, pathogens) affect population size?
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Ecological Research Areas of Ecological Research:
Global Ecology:examines the influence of energy and materials on organisms across the
biosphere
Landscape Ecology:focuses on the exchanges of energy, materials, and organisms across
multiple ecosystems
Ecosystem Ecology:emphasizes energy flow and chemical cycling among the various biotic
and abiotic components
Community Ecology:deals with the whole array of interacting species in a community
Population Ecology:focuses on factors affecting population size over time
Organismal Ecology:studies how an organisms structure, physiology, and (for animals)
behavior meet environmental challenges
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Figure 52.2
Global ecology
Landscape ecology
Ecosystem ecology
Community ecology
Population ecology
Organismal ecology
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Weather vs. Climate
Weather:
Local areas short term temperature, precipitation, humidity, wind, cloud cover andother physical conditions of the atmosphere measured over hours or days
Climate:
Long-term prevailing weather conditions in an area
Major components of climate are temperature, precipitation, sunlight, and wind
Macroclimate:
Consists of patterns on the global, regional, and landscape (multiple ecosystems) level
Microclimate: Consists of very fine patterns, such as those encountered by the community of organisms
underneath a fallen log
Determined by fine-scale differences in the environment that affect light and wind patterns
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Water Currents Affect Climate
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Air Circulations Affect Climate
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Rain Shadow Effect
The Earths surface affects climate.
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Biomes
Biomes:
Major life zones characterized by vegetation type (terrestrial biomes) or physical environment
(aquatic biomes)
Climate is very important in determining why terrestrial biomes are found in certain areas
Climate affects the latitudinal patterns of terrestrial biomes
Biomes are affected not just by average temperature and precipitation, but also by the patternof temperature and precipitation through the year
Leads to formation of tropical (hot), temperate (moderate) and polar (cold) regionsdeserts,
grasslands and forests
Terrestrial Biomes:
Often named for major physical or climatic factors and for vegetation Characterized by distribution, precipitation, temperature, plants, and animals
Usually grade into each other, without sharp boundaries which may be wide or narrow
Climb a tall mountain from its base to the summit, youll see changes as you might as you
travel from the equator to the poles
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Tropic ofCancer
30
N
30
S
Tropic of Capricorn
Equator
Tropical forest
Savanna
Desert
Chaparral
Temperate grassland
Temperate broadleaf forest
Northern coniferous forest
Tundra
High mountains
Polar ice
Figure 52.9
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Biomes Based on Elevation
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Biomes
Similar characteristics can arise in distant biomes through Convergent Evolution
For example, cacti in North America and euphorbs in African deserts appear similar butare from different evolutionary lineages
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Tropical Rain Forest
Tropical Rain Forests:
Hot temperature, moisture laden air rises resulting in constant rainfall (200 inches per year)
Temperature is high year-round (2529C) with little seasonal variation
High Biodiversity: home to millions of animal species, including an estimated 530 million stillunknown species of insects, spiders, and other arthropods
2% of the land but of worlds species; single tree can have several thousand insect species
Dominated by broadleaf evergreen plants; their dense tops block out most of the sun notreaching the forest floor
Ground has little vegetation (those that do have large leaves); vines (lianas) grow on trees toreach the sun
Little wind because of the dense vegetation; plants depend on bats, birds, bees and otherspecies for pollination
Rapid human population growth is now destroying many tropical forests
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Tropical Rain Forests
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Olinguito
New mammal species in the cloud forests lining the Andes Mountains of South
America - Olinguito and classified it in the Procyonidae family, the same as raccoons.
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Temperate Rain Forest
Coastal Coniferous Forest or TemperateRain Forests:
Found in scattered coastal temperate
areas that have ample rainfall ormoisture from dense ocean fogs
Douglass firs and redwoods
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Deserts
Desert:
Annual precipitation is low; often scattered unevenly throughout the year
Heat of day bakes the earth causing evaporation of water from leaves and soil
Soils have little vegetation and moisture to store the heat so you can roast during the day andfreeze at night
Tropical Deserts:
Hot and dry most of the year; few plants and a hard wind blown surface of rocks and somesand
Temperate Deserts:
Daytime temperatures are high in the summer and low in winter; more precipitation than in thetopical deserts; drought resistance vegetation - cacti
Cold Deserts:
Vegetation is sparse; winters are cold; summers warm or hot and precipitation is low; plantsand animals have adapted to stay cool and get enough water
Fragi le Ecosys tem: slow plant grow th; low sp ecies diversi ty; slow nutr ient recycl ing and lack
of w ater
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Deserts
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Deserts
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Savannah
Savannah
Equatorial and subequatorial regions
Warm temperatures year round with wet and dry seasons
Precipitation is seasonal
Temperature averages (2429C) but is more seasonally variable than in the tropics
Contains widely scattered clumps of trees (aracia with thorns to prevent being eaten)
Grasses and make up most of the ground cover; fire-adapted and tolerant of seasonal drought
Plants have adapted to survive drought and extreme heat
Grazing animals (grass and herb eating; wildebeest) and browsing animals (twig and leaf
eating; giraffe) along with predators (lion)
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Savannah
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Chaparral
Chaparral:
Occurs in mid-latitude coastal regions on several continents
Summer is hot (30C+); fall, winter, and spring are cool (1012C)
Close to sea provides a slightly longer winter rainy season than nearby temperate deserts
Precipitation is highly seasonal with rainy winters and dry summers
Fogs in the spring and fall reducing evaporation Consist of dense growth of low growing evergreen shrubs and occasional small trees with
leathery leaves to reduce evaporation
Dominated by shrubs, small trees, grasses, and herbs; adapted to fire and drought
Prone to fires in the dry season
Many plants produce seeds that only germinated after a wildfire
Animals include amphibians, birds, reptiles, insects, small mammals, and browsing mammals
People like to live here because of its moderate, sunny climate with mild wet winters and warm drysummers; risk losing their homes to frequent fires and mud slides
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Chaparral
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Chaparral
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Temperate Grasslands
Temperate Grassland
Found on many continents
Precipitation is highly seasonal
Winters are cold (often below10C) and dry; summers are hot (often near 30C) and dry
Dominant plants are grasses and adapted to droughts and fire
Little tree growth
Large grazers such as bison and wild horses and small burrowers such as prairie dogs
Most grasslands have been converted to farmland (Midwest)
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Temperate Grassland
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Mountains Mountains:
Some of the worlds most spectacular environments are high on Mountains, steep or high
lands that cover of the Earths surface; dramatic changes in altitude, slope, climate, soil and
vegetation occur in a very short distance
1.2 bil people (18% of the worlds population) live on them or their edges; 4 bil (59%) dependon mountain systems for all or some of their water
Majority of the worlds forests; habitats for biodiversity and contain endemic species found no
where on Earth
Help regulate the earths climate: mountains covered in ice and snow help to reflect solar
radiation back into space helping to cool the plant and offset global warming
Can affect sea levels: storing or releasing water in glaciers; as the earth warms, water can be
released in oceans causing them to rise Major storehouses of water
Despite their signif icance, mou ntain ecosystems are not a high p rior i ty for go vernments
and/or environm ental groups
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Mount Rainier National Park
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Forests
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Northern Coniferous Forest
Northern Coniferous Forest or Taiga:
Spans northern North America and Eurasia and is the largest terrestrial biome on Earth
Cold forests are often found just south of Artic tundra and above certain altitudes in the HighSierras or Rockies
Precipitation varies; some have periodic droughts and others, especially near coasts, are wet
Winters are cold; summers may be hot (Siberia ranges from50C to 20C) Subarctic climate: winters are long, dry and extremely cold; sunlight may only be available 6-8
hrs; summers are short, with cool to warm temperatures; sun shines 19 hrs
Plant diversity is low as few species can survive the winters when soil moisture is frozen
Conifers such as pine, spruce, fir, and hemlock dominate; conical shape of conifers preventstoo much snow from accumulating and breaking their branches
Migratory and resident birds; large mammals such as moose, brown bears, and Siberian tigers
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Northern Coniferous Forest
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Temperate Broadleaf Forest
Temperate Broadleaf Forest:
Found at midlatitudes in the Northern Hemisphere, with smaller areas in Chile, South Africa,Australia, and New Zealand
Significant amounts of precipitation fall during all seasons as rain or snow
Winters average 0C; summers are hot and humid (near 35C)
Long warm summers, cold but not severe winters and abundant moisture, often fairly spreadthroughout the year
Dominated by deciduous trees in the Northern Hemisphere; evergreen eucalyptus in Australia
Broad-leaf trees: oak, hickory, maple and beech; survive cold winters by dropping their leavesin the fall and becoming dormant; each spring, new leaves form and turn colors in the fall
Mammals, birds, and insects make use of all vertical layers in the forest
Eastern US were home to bears, foxes and pumas (many have been killed) and the dominant
mammal often is deer In the Northern Hemisphere, many mammals hibernate in the winter
Impact of human activities: disturbed more than any other for growing of crops, wood or cities;within 100-200 years after its left undistributed, it can return to forest
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Temperate Broadleaf Forest
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Tundra
Tundra:
Covers expansive areas of the Arctic; alpine tundra exists on high mountaintops at all latitudes
Precipitation is low in arctic tundra and higher in alpine tundra
Winters are cold (below30C); summers are relatively cool (less than 10C)
Treeless and bitterly cold
Swept by cold winds and covered by ice and snow
Winters are long and dark
Little precipitation
Permafrost, a permanently frozen layer of soil, prevents water infiltration
Vegetation is herbaceous (mosses, grasses, forbs, dwarf shrubs and trees, and lichen) andsupports birds, grazers, and their predators; alpine can be flowers
Most of the growth occurs in the 7-8 week summer when the sun shines almost 24 hrs
Mammals include musk oxen, caribou, reindeer, bears, wolves, and foxes; many migratorybird species nest in the summer
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Tundra
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Water
Earth is covered with water - known as the Water Planet
Saltwater covers 71% of the Earth
Freshwater 2.3%
Aquatic Life Zones:determined by the amount of salinityamount of salt (NaCl) in the water
Saltwater:
Marine:brackish which is a combination of salt and freshwater and are considered to besaltwater and include
Global ocean is a single and continuous body of water
4 oceans: Atlantic, Arctic, Indian and Pacific; Antarctic
Oceans and estuaries, coastlands and shorelines, coral reefs and mangrove forests
Freshwater
Lakes, rivers and streams and inland wetlands
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Water Planet
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Aquatic Biomes
Aquatic Biomes:
Account for the largest part of the biosphere in terms of area
Marine biomes have salt concentrations of about 3%
Largest marine biome is made of oceans, which cover about 75% of Earths surface andhave an enormous impact on the biosphere
Freshwater biomes have salt concentrations of less than 0.1%
Freshwater biomes are closely linked to soils and the biotic components of the surroundingterrestrial biome
Stratified into Zonesor layers defined by light penetration, temperature, and depth:
Pelagic Zone:
Photic Zone has sufficient light for photosynthesis; most animals live here
Aphotic Zonereceives little light; extensive with little life
Deep in the Aphotic Zone lies the Abyssal Zonewith a depth of 2,000 to 6,000 m Benthic Zone:
Organic and inorganic sediment at the bottom of all aquatic zones
Communities of organisms are collectively called the Benthos
Detritus:
Dead organic matter, falls from the productive surface water; important source of food
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Aquatic Biomes
Figure 52.15
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Tropic ofCancer
Tropic ofCapricorn
30
N
30
S
Equator
Oceanic pelagic and benthic zones
Intertidal zones
Estuaries
Coral reefs
Rivers
Lakes
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Lakes
Lakes:
Natural bodies of freshwater formed from precipitation, runoff or groundwater that fill indepressions in the surface caused by glaciers (Bear Mountain), volcanoes (Crater Lake) orother ways such as supplied with water from rain (precipitation) or streams
Size varies from small ponds to very large lakes
Oligotrophic Lakes:
Nutrient-poor and generally oxygen-rich
Small supply of plant nutrients
Generally deep with steep banks; fed by glaciers and mountain streams with little sediment;crystal clear
Eutrophic Lakes:
Nutrient-rich and often depleted of oxygen if ice covered in winter
Rooted and floating aquatic plants live in shallow and well-lighted area close to shore
Water is too deep to support rooted aquatic plants; small drifting animals called zooplanktongraze on the phytoplankton
Invertebrates live in the benthic zone; Fishes live in all zones with sufficient oxygen
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Lakes
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Lakes
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Wetlands Surface Water: precipitation that does not sink into the ground or evaporate
Runoff: precipitation that runs into a stream
Watershed, Drainage Basin: land that delivers runoff, sediment and dissolved substances into astream; small streams form rivers and rivers flow downhill to the ocean
Aquatic Life Zones: Source Zone:
Headwaters or mountain highland streams; usually shallow, cold, clear and swift flowing;waterfalls and rapids
Not productive because of lack of nutrients and producers; food is from decomposition;algae; fishes
Transition Zone:
Middle; become wider, deeper and warmer; slower; more turbid (cloudier) Producers; both cold and warm water fish (black bass)
Floodplain Zone:
Over time, they shape the land including leveling or cutting through mountains formingcanyons; streams can join others, forming wider and deeper rivers
Large amount of producers and fish; rivers end in a mouth or delta; absorb the floodwatersand add nutrient rich land
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Human Activity
Human activities are disrupting and degrading many of the ecological and economic services providedby fresh water rivers, lakes and wetlands:
Dams and Canalson rivers fragment about 40% of the worlds 237 large rivers
Alter or destroy aquatic wildlife habitats by reducing water flow and increasing damage fromcoastal storms
Flood Control Levees and Dikes:
Built along rivers and disconnect the rivers from their floodplains
Destroy aquatic habitats and alter or reduce the function of nearby wetlands
Hinders the spawning cycle of fishes and birds and can disrupt food chains; species are lostand the biodiversity is threatened
Interrupts sediment flow and distribution
Pollutantsfrom cities and farms add excess nutrients causing algal explosions (blooms) anddepleting the oxygen
Wetlandshave been drained or filled to grow crops or covered to build buildings or roads
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Wetlands
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Wetlands
Wetlands
Habitat that is inundated by water at least some of the time and that supports plants adaptedto water-saturated soil
High organic production and decomposition and have low dissolved oxygen content
Can develop in shallow basins, along flooded river banks, or on coasts of large lakes and seas
Wetlands are among the most productive biomes on Earth
Plants include lilies, cattails, sedges, tamarack, and black spruce
Wetlands are home to diverse invertebrates and birds, as well as otters, frogs, and alligators
Humans have destroyed up to 90% of wetlands; wetlands purify water and reduce flooding
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Wetlands
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Restoration of Wetlands
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Streams and Rivers
Streams and Rivers:
Most prominent physical characteristic of streams and rivers is current
Headwaters are generally cold, clear, turbulent, swift, and oxygenrich; they are often narrow
and rocky
Downstream waters form rivers and are generally warmer, more turbid, and more oxygenated;they are often wide and meandering and have silty bottoms
May contain phytoplankton or rooted aquatic plants
Diversity of fishes and invertebrates inhabit unpolluted rivers and streams
Damming and flood control impair natural functioning of stream and river ecosystems
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Streams and Rivers
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Coastal Wetlands
Estuaries:
Where rivers meet the sea; partially enclosed bodies of water where sea water mixes withfresh water as well as nutrients from streams, rivers and runoff from the land
Coastal Wetlands:
Coastal land areas covered with water all or part of the year
Combined with Estuaries, they are some of the Earths most productive ecosystems becauseof nutrients, rapid flow of water and ample sunlight:
Estuaries and Coastal Wetlands: include river mouths, inlets, bays, sounds, salt marshes andmangrove forests
Seagrass Beds:
Species of plants that grow underwater in shallow marine and estuaries along the coastline
Highly productive and support a variety of marine species
Stabilize shorelines and reduce wave impact
Life is harsh; adapt to daily and seasonal changes in tidal and river flow; water temperatures andsalinity; and runoff from the land including soil sediment and pollutants; because of this, they mayhave low plant diversity but high productivity
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Coastal Wetlands
Mangrove Forests:
Found along 70% of gently sloping sandy and silt coastlines in the tropics and sub-tropics
Grow in salt water and have extensive root systems that can support during changes in waterlevels
Coastal Aquatic Systemsprovide important ecological and economic services:
Maintain water quality by filtering toxic pollutants, excess plant nutrients, sediments andabsorb other pollutants
Provide food, habitats and nursery sites
Reduce storm damage and coast erosion by absorbing waves and storing excess waterproduced by storms and tsunamis
Provide timber and wood for fuel
UN estimates that between 1980 and 2005 at least 1/5 of the mangrove forests were lost duemainly to human coastal development
Loss of mangroves can lead to polluted drinking water caused by inland intrusion of saltwater intofresh water aquifers used to supply drinking water
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River Delta
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Estuaries
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Mangrove Trees
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Life in Coastal Wetlands
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Coastal Shoreline
Intertidal Zone:
Area between high and low tides (gravitational pull of the moon and sun)
Organisms must adapt to movement of water; high tides to drying out at low tides
Oxygen and nutrient levels are high
Deal with daily salinity and moisture changes
Organisms need to hold on:
Rocky Shores:
Pounded daily by waves
Numerous pools and other habitats with a great variety of species; marine algae
Animals have adapted to attach themselves to the hard surface
Sandy Shores:
Barrier beaches
Many organisms are hidden from view by burrowing, digging or tunneling in the sand;home to shore birds that feed on crustaceanssea grass and algae
Barrier Islands:
Narrow islands that form offshore parallel to the coast
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Intertidal Zones
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Life Along the Coast
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Importance of Sand Dunes
Importance of Sand Dunes:
Sand is held in place by plant roots
1stline of defense against the sea
Often removed by developers; and when large storms hit and cause damage, they areincorrectly called Natural Disasters
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Oceanic Pelagic Zone
Oceanic Pelagic Zone:
Constantly mixed by wind-driven oceanic currents
Oxygen levels are high
Turnover in temperate oceans renews nutrients in the photic zones; year-round stratificationin tropical oceans leads to lower nutrient concentrations
Biome covers approximately 70% of Earths surface
Phytoplankton and zooplankton are the dominant organisms in this biome; also found arefree-swimming animals
Zooplankton includes protists, worms, copepods, krill, jellies, and invertebrate larvae
Other animals include squids, fishes, sea turtles, and marine mammals
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Oceanic Pelagic Zone
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Coral Reefs
Coral Reefs:
Worlds oldest, most diverse and most productive ecosystem
Known as Natural Wonders
Biodiversitymarine equivalent of Tropical Rain Forests
Formed by tiny animals known as polypsjellyfish; calcium carbonate
Occupy only 0.2% of the oceans floor
15% have been destroyed and another 20% damaged
They provide important ecological and economic services;
Moderate atmospheric temperatures
Act as natural barriers protecting coasts from erosion
Provide habitats
Support fishing and tourism businesses Provide jobs and building materials
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Coral Reefs
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Life on a Coral Reef
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Death of a Coral Reef
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Marine Benthic Zone
Marine Benthic Zone:
Consists of the seafloor below the surface waters of the coastal zone
Organisms in the very deep benthic zone are adapted to continuous cold and extremely highwater pressure
Mainly soft sediments; some areas are rocky Shallow areas contain seaweeds and filamentous algae
Deep-sea hydrothermal vents of volcanic origin on mid-oceanic ridges are surrounded byunique chemoautotrophic prokaryotes, as well as echinoderms and arthropods
Benthic communities include invertebrates and fishes
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Marine Benthic Zone
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