Transcript AQUATIC ECOSYSTEMS - Henriksen Science

AQUATIC ECOSYSTEMS
What are the basic needs of
aquatic biota (organisms)?
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CO2
O2
Sunlight
Nutrients- food &
minerals
Types of Aquatic Ecosystems
• Freshwater Ecosystems
– Standing Water- lakes &
ponds
– Moving Water- rivers &
streams
• Transitional Communities
– Estuaries
– Wetlands- bogs/fens,
swamps, marshes
• Marine Ecosystems
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Shorelines
Barrier Islands
Coral Reefs
Open Ocean
Freshwater Ecosystems
• Usually 0.005% salt
– Some exceptions:
• Great Salt Lakes-
5-27% salt
• Dead Sea- 30% salt
• Moving water- high elevations;
cold; high O2; trout; streamlined
plants
• Standing water- lower
elevations; warmer; less O2;
bass, amphibians; cattails,
rushes
• Why would there be less
oxygen in standing water?
Plankton
• Plankton is a general term for
the tiny, free-floating
organisms that live in both
freshwater and saltwater
environments.
• Unicellular algae, or
phytoplankton, are supported
by nutrients in the water and
form the base of many aquatic
food webs.
• Planktonic animals, or
zooplankton, feed on the
phytoplankton.
Transitional Communities
• ESTUARIES
• Where freshwater dumps
into ocean
• Brackish water (less salty
than seawater)
• Has rich sediments that
often form deltas
• Productive & biodiverse
• Organisms adapted to
varying levels of salinity
as tide ebbs & flows
• “Nursery” for larval forms
of many aquatic species
of commercial fish &
shellfish
Delta
Transitional Communities
• WETLANDS
• Land saturated at least part of
the year
• Swamps- have trees like bald
cypress; high productivity
• Marshes- no trees; tall
grasses; high productivity
• Bogs/Fens- may or may not
have trees; waterlogged soil
with lots of peat; low
productivity
Swamp
Marsh
– Fens- fed by groundwater &
surface runoff
– Bogs- fed by precipitation
Bog
Fen
Importance of Wetlands
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Highly productive- get lots of
sunlight, ↑ plants =
↑ animals
• Nesting, breeding ground for migratory
birds
• Slows flooding by absorbing runoff
• Silt settles, making water clearer &
nutrient rich
• Trap & filter water, Bacteria in soil
break down contaminants
= “Nature’s Septic Tank”
• Natural chemical rxns neutralize and
detoxify pollutants
• Gives H2O time to percolate (filter thru
soil) & replenish underground aquifers
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Threats- artificial eutrophication (see
slide 13), draining, sedimentation via
construction
Marine Ecosystems
• Benthic zone lowest level.
Organisms
living in this
zone are called
benthos.
• Photic Zone –
well-lit upper
layer of the
oceans.
• Aphotic Zone permanently
dark layer of
the oceans
below the
photic zone
MARINE ECOSYSTEMS
• CORAL REEFS
• Clear, warm shallow seas
• Made up of accumulated
calcareous (made of calcium)
skeletons of coral animals
• Formation of reefs depends on
light penetration.
• Corals have a symbiotic
relationship with algae
(which are photosynthetic) .
• Very diverse, abundant
(Rainforests of Sea)
• Threats- destructive fishing
(cyanide & dynamite to stun
fish), pet trade; about 75% of
coral reefs have been
destroyed
What factors can alter aquatic
ecosystems?
• Natural Successionnormal cycle of pond
becoming forest
• Artificial Successionhumans add Nitrogen &
Phosphate to water via
fertilizer & sewage
causing succession to
happen faster =
EUTROPHICATION
What factors can alter aquatic
ecosystems?
• Humans!
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Find food
Recreation
Waste disposal
Cooling of power
plants
– Transportation
– Dams, canals