Transcript Understanding Our Environment

Biomes: Global Patterns of Life
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Terrestrial Biomes
• Biomes - Areas sharing similar climate,
topographic and soil conditions, and roughly
comparable communities.
– Determined by temp and precip
• Identified by the dominant plants
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Biomes
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Climatograms
• Climatograms
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Aquatic Ecosystems
Factors that effect:
• Temperature: ↓ with depth
• Light (solar radiation): ↓ with depth
• Dissolved oxygen
• Nutrient availability
• limiting macronutrients are phosphorus (P) and nitrogen
(N)
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Aquatic Environments
• Cover 71% of earth’s surface
• 2 types determined by salinity
•
– Freshwater: <1% salt and only 1% of earth
– Saltwater (marine)
Hydrologic cycle connects all aquatic environments!
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Sample Food Chain
•Type of organisms determined by their tolerance of
salinity (fresh vs. salt).
•Plankton play a crucial role in the food chain
Starfish
Coral
Octopus
Zooplankton
Moray Eel
Phytoplankton
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Plankton
Plankton
• Phytoplankton– diatoms or algae
• Zooplankton
– protozoans and small crustaceans
Bottom: Diatoms found between ice
sheets in Antarctica
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Aquatic Organisms
4 major types of organisms
– Plankton (zoo- and phyto)
– Nekton (fish, turtles, whales)
– Benthos (bottom-dwellers such as oysters)
– Decomposers (mostly bacteria)
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Saltwater
Oceans
-All 36 animal phyla are found here (only 10 on land)
-Currents distribute solar heat
-Reservoir for carbon dioxide (CO2)
-Regulates temp of land and atmosphere
-Habitat for plants and animals, critical food sources
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Life Zones of the Ocean
• Zones defined by amount of solar radiation penetrating the
water
• Zones:
•Intertidal zone
•Pelagic zone
•Abyssal zone
•Benthic zone
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Oceans
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Intertidal Zone
• Where the ocean meets the land
• Communities are constantly changing
– Types of organisms that live here?
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Pelagic Zone
• Open ocean
• Thermal stratification
– constant mixing of warm and cold ocean currents
• Open ocean is the LEAST productive of aquatic
life zones PER UNIT VOLUME.
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Epipelagic
Mesopelagic
Bathypelagic
Abyssalpelagic
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Epipelagic Zone
• extends down to around 200m
– lowest depth that light can penetrate (photic zone)
• Flora
– surface seaweeds and phytoplankton
• Fauna
– many species of fish and mammals, such as whales
and dolphins
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Mesopelagic Zone
• "twilight zone" of the ocean
– photic zone above
– darkness below
• food becomes scarce – some animals:
– migrate up to the surface at night to feed
– rely on detritus
– eat each other
• sometimes the only things to eat may be bigger than the
hunter
– developed long sharp teeth
– expandable jaws and stomachs
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Big Scale - ambush predator
ctenophore – related to jellyfish
cilia can be illuminated
Firefly squid
three kinds of photophores
Hatchet Fish
only a few inches long
Viperfish
specially adapted hinged skull
Dragonfish - stomachs hold big meals
Snipeel
up to 1.2m
Siphonophores are colonies of animals
related to jellyfish
best known is Portugese Man of War
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http://oceanlink.island.net/oinfo/deepsea/meso.html
Bathypelagic Zone
• extends down from 1000 to 4000m
• only light is from bioluminescent organisms
• food is from detritus or from eating other
animals
• considerable water pressure
• most animals are either black, red, or transparent
– Why?
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Narcomedusa
Vampire Squid
Snake Dragon
Angler Fish
Amphi - crustacean
Ctenophore
Deepstaria very slow swimmers,
no tentacles, close flexible bells
(up to a meter across) around
their prey
Big Red
grows to over
a meter across
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Abyssopelagic Zone - the Abyss
• 4000m to the sea floor
• inhospitable living conditions
– near- freezing temperatures
– crushing pressures
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Deep Water Squid
Basketstar
Sea Pig
Shrimp
Sea Spider
Medussa
Winged Sea Cucumber
Hydrothermal Vent
Deep-sea Anemone
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Coral Reefs
• Coral Reefs –formed by mutualism between polyps
and algae
– Reefs built as colonies of polyps secrete limestone; hard
deposits remain when the polyps die
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Reefs located in coastal zones of tropical oceans
Protect coastlines from currents and waves
Nurseries for many fish species
Highly productive area
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Human Impacts on Coral Reefs
• Vulnerability
– Slow growing
– Easily disturbed
– Thrive only in clear water
• Human Impacts
– All lead to coral bleaching
• Sediment runoff and effluent
• Increased UV radiation
– Fishing with cyanide and dynamite
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Tidal Environments
• Tidal Marshes and Estuaries
– Brackish water
– Carry rich sediments from downstream
• Extremely fertile
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Tidal Marshes and Estuaries
• High species diversity and productivity
• Estuaries called “marine nurseries”
– habitats for many juvenile organisms, especially for fishes
– many fish are born and grow up in estuaries
• 2/3 of all marine fish and shellfish spawn or develop in estuaries
– migrate to the open ocean
• Waterfowl and shorebird breeding areas
• Filter water pollutants
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Estuaries and Tidal Marshes
• Over ½ of estuaries and coastal wetlands are
gone
• Why?
– Degradation from:
• Urban runoff
• Sewage treatment plant effluent
• Sediment and chemical runoff from ag
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Barrier Islands
Importance
-Protect mainland from offshore storms
-Shelter inland bays, estuaries, and wetlands
-Popular recreational and residential areas
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Barrier Islands
Human Impacts
Development of barrier islands
-Destroys dunes and dune
vegetation
-Causes beach erosion
-Destroys or disturbs wildlife
habitat
Protecting barrier islands
-Jetties and seawalls
-Beach replenishment
-Replanting dune vegetation,
controlling development
-**BEST long-term protection:
Allowing development only
behind secondary dunes
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Freshwater
• Lakes
– limited species diversity due to isolation
– Four zones based on depth and distance from the shore:
• Littoral zone
• Limnetic zone
• Profundal zone
• Benthic zone
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Littoral Zone
Fairly diverse
algae (like diatoms), rooted and floating aquatic
plants, grazing snails, clams, insects, crustaceans,
fishes, and amphibians
Insect egg and larval stages found here
Vegetation and animals are food for other
creatures such as turtles, snakes, and ducks
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Limnetic Zone
open water surrounded by the littoral zone
well-lighted (like the littoral zone) and is dominated by
plankton
variety of freshwater fish also occupy this zone
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Profundal and Benthic Zones
Deep open water with no light penetration
Much colder and denser than the other two
Benthic zone -the bottom of a lake; inhabited by
decomposers, clams, and bottom-feeders.
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Lake Temperature
– Varies seasonally
• In summer warm layers on top, colder at bottom, separated
by thermocline-where temp of water changes rapidly with
depth
• In fall water turns over, mixing occurs.
• In winter ice forms – cold at the top, warmer at the bottom.
• In spring another turnover.
– Why is this important?
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Ponds and
Lakes
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Oligotrophic
– nutrient poor
– Low primary productivity
– Clear water, few plants and fish
Eutrophic
– nutrient rich
– High primary productivity
– Murky water, large phytoplankton
population
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Streams and Rivers
• Characteristics change
– Source
• Cool temps, clear water with high oxygen levels
– Middle
• Width increases, as does species diversity—numerous
aquatic green plants and algae can be found
– Mouth
• Murky water becomes murky-why?
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Streams &
Rivers
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Streams and Rivers
Human Impacts
-Pollution
-Sediments
-Dams
-Introduction of exotic
species
-Removal of
vegetation from banks
-Change of flow (more
floods, lower base
flow)
Fig. 8–15
-Channelization
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Wetlands
Functions:
• nature’s kidneys
•Filter sediments and pollutants from runoff
•Recharge groundwater
•Flood reduction
•Wildlife habitat used for migration or breeding
Human impacts
-Some states have lost over 90% of their wetlands
-Drain for agriculture
-Fill in for development
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Wetlands
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Wetland
Organisms
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