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.
– Temperature and precipitation determine biome
distribution.
• Identified by the dominant plants
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Biomes
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Climatograms
• Climatograms-a graph of the average monthly
rainfall and average monthly temperature from
a given area
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Aquatic Ecosystems
Factors that effect:
• Temperature: ↓ with depth
•affects dissolved gases, rates of chemical reactions, and
where organisms can live
• Light (solar radiation): ↓ with depth
•essential for photosynthesis
• Dissolved oxygen
Varies with temperature, producers, and consumers; essential
for respiration of organisms
• Nutrient availability
Most limiting macronutrients are phosphorus (P) and nitrogen
(N); limiting micronutrients include iron (Fe); essential for
growth of phytoplankton.
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Aquatic Environments
• Saltwater and freshwater cover 71% of earth’s
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surface.
Two types of aquatic environments determined by
salinity (amounts of various dissolved salts)
– Freshwater: <1% salt and only 1% of earth
• Lakes, ponds, streams, rivers, inland marshes
– Saltwater (marine): >70% of earth
• Estuaries, coastlines, coral reefs, costal marshes,
mangrove swamps, and oceans
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- “phyto” =
plant (i.e. diatoms, or
algae)
• Zooplankton- “zoo” =
animal (i.e. 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 (Marine)
Oceans
-All 36 animal phyla are found here (only 10 on land)
-Currents distribute solar heat
-Reservoir for carbon dioxide (CO2)
-Regulates temp of the 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
– Sometimes submerged and at
other times exposed
– Waves and tides come in and out
• Communities are constantly changing
– Types of organisms that live here?
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Pelagic Zone
• Open ocean
• Thermal stratification with a 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 in the epipelagic zone include surface
seaweeds and phytoplankton
• fauna include many species of fish and some
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 food that falls down from above
– 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
• only food is what trickles down from above, or
from eating other animals
• water pressure at this depth is considerable
(~100 – 400 atmospheres)
• most animals are either black or red in color
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Narcomedusa
Vampire Squid
Snake Dragon
Angler Fish
Amphi - crustacean
Ctenophore – voracious predator
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
• home to pretty inhospitable living conditions
– near- freezing temperatures
– crushing pressures
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Deep Water Squid
Basketstar
Sea Pig
Sea Spider
Shrimp
Winged Sea Cucumber
Medussa
Deep Sea Smoker - 648°F
Deep-sea Anemone
Hydrothermal Vent
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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 storms and high 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
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Sediment runoff and effluent
Increased UV radiation
Fishing with cyanide and dynamite
All lead to coral bleaching
Disappearing
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Tidal Environments
• Tidal Marshes and Estuaries – partially
enclosed body of water formed when rivers
and oceans meet
– Brackish water
– Carry rich sediments from downstream
• Estuaries are extremely fertile because nutrients are
brought in by rivers and recycled from the bottom
because of the turbulence.
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Tidal Marshes and Estuaries
• High species diversity and productivity
• Estuaries are sometimes 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
Human Impacts
-World has lost over half of its estuaries and
coastal wetlands
-Percentage lost in the U.S. even higher;
most lost to coastal development
-Causes of degradation urban runoff, sewage
treatment plant effluent, sediment and chemical
runoff from agricultural lands
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Barrier Islands
Barrier Islands- long, thin, low offshore islands of sand that run
parallel to the shore.
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 erosi
-Destroys or disturbs wildlife
habitat (e.g., some
endangered birds nest there)
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-formed when rain, runoff, or groundwater fills
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depressions in the landscape.
May have limited species diversity due to isolation
Four zones based on depth and distance from the
shore:
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Littoral zone
Limnetic zone
Profundal zone
Benthic zone
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Oligotrophic
– Low nutrient supply
– Low primary productivity
– Clear water, few plants and fish
Eutrophic
– Excess supply of nutrients
– High primary productivity
– Murky water, large phytoplankton
population
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Littoral Zone
warmest
sustains a fairly diverse community, which can
include several species of 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
near-surface 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.
Plankton have short life spans—when they die,
they fall into the deep-water part of the lake/pond
nutrients for lower zones
fossil fuels in time
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. Spring
turnover stimulates algae growth!
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Ponds and
Lakes
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Streams and Rivers
• characteristics change during the journey from
the source to the mouth
– At the source, temperature is cooler, water is
clearer with high oxygen levels
– At the middle, width increases, as does
species diversity—numerous aquatic green
plants and algae can be found
– At the mouth, water becomes murky from
all the sediments decreasing the amount of
light that can penetrate through the water
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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
Wetlands- lands covered with fresh water all or part of the
time (not including lakes and streams)
Wetland functions
-Filter sediments and pollutants from runoff , “nature’s
kidneys”
-Flood reduction
-Wildlife habitat, especially for waterfowl and
amphibians
Human impacts
-Some states have lost over 90% of their wetlands
-Major loss because of draining for agriculture
-Some loss because of filling for development
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Wetlands
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Wetland
Organisms
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