Transcript Standing-water Ecosystems

Topic 2.4
Aquatic Ecosystems
~Basics~
Important Env. Limiting Factors
• In Terrestrial environments:
– Temperature & Precipitation are limiting factors
– Light is plentiful
• In Aquatic environments:
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Temperature less important
Salinity
Dissolved Oxygen (DO)
Low light
Low levels of essential nutrient minerals
Temperature, pH, presence/absence of
waves/currents
Aquatic Ecosystem Organisms
~Plankton~
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“Free-floating” – Carried by currents
Usually small or microscopic
Can migrate vertically daily or seasonally
Two categories:
– Phytoplankton (plant-like)
• Photosynthetic cyanobacteria & algae
• Producers: base of most aquatic ecosystems
– Zooplankton (animal-like)
• Non-photosynthetic organisms (protozoa, tiny crustaceans,
larval stages of animals)
• Feed on algae & eaten by small aquatic organisms
Aquatic Ecosystem Organisms
~Nekton~
• Larger, stronger-swimming organisms
• Can swim against a current
• Fish, turtles, whales
Aquatic Ecosystem Organisms
~Benthos~
• Bottom-dwelling organisms
– Can move in three ways:
1. Sessile: Fix themselves to one spot
– sponges, barnacles, or oysters
2. Burrow into sand
– Worms, clams, echinoderms
3. Walk around on the bottom
– Crawfish, aquatic insect larvae, brittle stars
Eutrophication
1. Enrichment occurs: excessive addition of
nutrients (primarily nitrogen & phosphorus).
…Possibly from fertilizers, excessive
decomposition, or sewage spills.
2. Nutrients cause algae & plants to bloom,
then bust.
3. Bacteria increases to decompose the dead
algae/plants.
4. Bacteria use oxygen (DO) in high amounts,
decreasing DO in the water.
5. Low DO has potential to kill other aquatic
organisms, like fish.
Eutrophication
1. Enrichment occurs: excessive addition of
nutrients (primarily nitrogen & phosphorus).
…Possibly from fertilizers, excessive
decomposition, or sewage spills.
2. Nutrients
cause
algae
& plants
to into
bloom,
Let’s
break
this
down
then bust.
“buzz words”
3. Bacteria increases to decompose the dead
algae/plants.
4. Bacteria use oxygen (DO) in high amounts,
decreasing DO in the water.
5. Low DO has potential to kill other aquatic
organisms, like fish.
Eutrophication
1.
2.
3.
4.
5.
Enrichment
Algae & plants bloom & die
Bacteria decompose dead algae
Decreasing DO
Fish Kill
Remember: this is IB. You must be able to
explain this, not simply remember a list of five
buzz words.
Eutrophication
Discuss: What is the difference between
Enrichment & Eutrophication?
1.
2.
3.
4.
5.
Enrichment
Algae & plants bloom & die
Bacteria decompose dead algae
Decreasing DO
Fish Kill
FRESHWATER ECOSYSTEMS
2% of Earth’s surface
Recycle precipitation that flows as
surface runoff to the ocean
Large bodies help moderate daily/seasonal
temperature fluctuations on land
Provide habitats
Three Types:
Flowing-Water, Standing-Water, & Freshwater Wetlands
Flowing-Water Ecosystems
Rivers & Streams
Annotate the
diagram to discuss
the following:
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Temperature
DO
Water speed
Salinity
Turbidity
Pollution levels
Eutrophication
present
Light penetration
Types of organisms
present
Source of energy
Productivity (GPP)
Flowing-water Ecosystems
• Source vs. Mouth
• Headwater Streams
– Shallow, cold, less turbid, swiftly flowing, high DO
• Downstream Rivers
– Wider, deeper, more turbid, warmer, slowly flowing,
lower DO
• Groundwater can well up through sediments
– This local input can moderate water temperature
during summer & winter
• Organisms present:
– Faster currents (headwaters or sloped land)
• adaptations w/ suckers or streamlined & muscular bodies
– Slower currents (downstream or flat land)
• organisms similar to those in ponds
Flowing-water Ecosystems
~Energy~
• Where does the energy come from?
– Headwater Streams
• 99% comes from detritus
(leaves carried in by runoff)
– Downstream Rivers
• More producers, therefore lower
dependence on detritus
Flowing-water Ecosystems
~Human Influence~
• Pollution
– Alters physical environment
– Changes biotic component downstream
from the pollution source
• Dams
– Cause water backup & flooding
– Create reservoirs (alters/destroys habitat)
– Downstream river is reduced (alters habitat)
Standing-Water Ecosystems
Lakes & Ponds
Zonation in a Large Lake
TRY TO DESCRIBE THESE WITH A PARTNER!!!
• Littoral Zone: shallow-water area along the shore.
• Limnetic Zone: open water beyond the littoral
zone, away from shore, extends down as far as
sunlight penetrates.
• Profundal Zone: beneath the limnetic zone.
Annotate the
diagram to discuss
the following:
•
•
•
•
•
•
•
•
•
•
•
Temperature
DO
Water speed
Salinity
Turbidity
Pollution levels
Eutrophication
present
Light penetration
Types of organisms
present
Source of energy
Productivity (GPP)
Standing-water Ecosystems
~Zonation: Littoral Zone~
• Most productive zone
– Photosynthesis is greatest here
– Many nutrients from surrounding land
• Plant Life:
– Emergent vegetation (cattails)
– Deeper-dwelling aquatic plants & algae
• Animal Life:
– Tadpoles, turtles, worms, crayfish, insect larvae,
many fishes (perch, carp, bass)
– Surface dwellers (water striders) in calm areas
Standing-water Ecosystems
~Zonation: Limnetic Zone~
• Main organisms = phytoplankton &
zooplankton
• Larger fishes
• Less vegetation than Littoral Zone due to
its depth
Standing-water Ecosystems
~Zonation: Profundal Zone~
• Typically absent in smaller lakes & ponds
• Light cannot penetrate this deep
– No plants & algae
• Food drifts down from other zones
• Bacteria decompose dead organisms here,
using up O2 & liberating nutrient minerals in the
organic material
– Nutrients are not recycled well because there are
no producers to absorb them
• Mineral-rich & anaerobic
Freshwater Wetlands
Marshes & Swamps
Freshwater Wetlands
• Covered by shallow water for at least part of
the year.
• Have characteristic soil and water-tolerant
vegetation.
• Anaerobic & therefore low decomposition.
• Types:
– Marshes (grasslike plants)
– Swamps (woody trees or shrubs)
– Hardwood bottomland forests (along streams &
rivers that periodically flood)
– Prairie potholes (shallow ponds)
– Peat moss bogs (acidic, mossy wetland)
Freshwater Wetlands
Anaerobic!
• Types:
– Marshes (grasslike plants)
– Swamps (woody trees or shrubs)
– Hardwood bottomland forests (along streams &
rivers that periodically flood)
– Prairie potholes (shallow ponds)
– Peat moss bogs (acidic, mossy wetland)
Freshwater Wetlands
• Highly productive
• Ecosystem Services:
– Food sources
– Habitat for migratory birds
– Control flooding
• act as water holding areas, then release water
slowly back
– Groundwater recharge areas
– Cleanse and purify water
Freshwater Wetlands
• Problems protecting wetlands:
– Formerly considered wastelands
• Filled in or drained to create real estate, farms, or
industrial sites.
– Breeding grounds for mosquitoes
• Seen as a nuisance to public health.
• Importance is now widely recognized.
– Some legal protection
– Still threatened by development & pollution
Estuaries
Where freshwater meets saltwater
Estuaries
• Where a freshwater stream or river
meets the salty ocean water.
• Creates BRACKISH water.
• Water level rises & falls with tides.
• Salinity level changes with tidal cycles,
time of year, and precipitation.
– Organisms must tolerate these changes!!
Estuaries
• Among the most fertile & most productive
ecosystems in the world.
• High productivity created by:
1. Nutrients are transported from the land
into rivers/creeks that flow into the estuary.
2. Tides promote rapid nutrient circulation &
helps remove waste products.
3. High light penetration.
4. Many plants provide an extensive
photosynthetic base for the food chain.
Estuaries
• Often contain salt marshes or mangroves.
• Salt Marsh = shallow wetlands dominated by
salt-tolerant grasses.
– Often seen as worthless, and experience similar
problems as other wetlands.
– Also acts as a storm buffer.
• Mangrove Forest = tropical equivalent of salt
marsh.
– Cover 70% of tropical coastlines.
– Ecosystem services:
• Breeding & nesting grounds
• Roots stabilize submerged soil (prevent erosion)
• Storm buffer: actually stronger than concrete seawalls in
dissipating wave energy during tropical storms.
Mangrove Distribution
Mangrove Forest
Mangrove Forest
Marine Ecosystems
Marine Ecosystems are
divided into 3 main zones:
1. Intertidal
2. Benthic (bottom)
3. Pelagic (shallow & open ocean)
Divided into 2 zones based on distance from shore
1. Neritic
2. Oceanic
Pelagic
(Consists of the neritic and oceanic provences)
Continental Margin
(shelf, slope, rise)
Inter-Tidal Zone
Area of shoreline
between high
and low tides
Neriticsurface to
200 m
Oceanic: open ocean overlying ocean floor at depths greater than 200 m
High Tide
Low Tide
~200m
Euphotic Zone: upper part of pelagic- light
penetrates for photosynthesis. Up to 150m
(488ft)
Benthic Environment:
MAJOR
OCEANIC
ZONES
Ocean bottom or floor
(composed of benthic, abyssal,
and hadal)
4000 m
Abyssal Zone: 4000-6000m
Abyssal Plain
>6000m
Hadal Zone
Zones:
1. Intertidal: between high & low tide
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Biologically productive habitat
Stressful for organisms
• The Sandy Beach is constantly changing with each wave.
The Rocky Shore is exposed to wave action (at high tide)
and drying out/temp changes (exposed to air at low tides)
• Organism adaptions to seal in moisture
• closing shell, thick skin , special glands, gummy
coating, burrowing, etc
2. Benthic Zone
– Ocean Floor
– Consists of mostly sediment (sand/mud)
– Bacteria are common
A. Shallow Water
1. Sea grass
2. Kelp
3. Coral
B. Deep Water
1. Abyssal (deep ocean floor)
2. Hadal (inside deep trenches)
Abyssal & Hadal – fun times!
Video: Bill Nye's Hydrothermal Vents!
A. Shallow water Benthic Zone
– Productive with sea grass beds, kelp forests and coral reefs
1. SEAGRASS BEDS
Provide habitat/food for organisms
Roots stabilize sediments
(warm, tropical waters)
Shallow Benthic continued…
2. Kelp Beds
vital primary food producer for the Kelp
forest ecosystem
(cold waters)
Remember Sea Otters? Importance???
Tunicate
Kelp Bed
Marine sponge
Shallow Benthic continued…
3. Coral Reefs
– Built from accumulated layers of CaCO3
– Found in warm (>21C) shallow water
– Most diverse marine environment
– Protect shorelines from erosion
– Grow very slowly
- build on the remains of organisms before them
Note: 2 types of coral!
– Without Zooxanthellae (do not build reefs)
– With Zooxanthellae (do build reefs)
Zooxanthellae = Symbiotic relationship between
coral polyp and algae
(commensalism)
– Daytime: Zooxanthellae photosynthesize for the coral
– Nighttime: Coral polyps feed with tentacles & stingers
– BLEACHING:
Zooxanthellae leave the polyp (they give coral its color) because:
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Water is too cloudy for photosynthesis
Water temperature is too high
Ocean Acidification
Higher UV levels
Coral Bleaching
The coral reef's
zooxanthellae, or symbiotic
algae, give it its color.
When coral is stressed, it
expels the algae and loses
its color in a process
called bleaching.
Coral
Bleaching
Bleaching is not the fatal blow once believed.
– Natural Variation in zooxanthellae
– Corals can lose 75% of zooxanthellae seasonally
without harming the reef
– Corals may hold a “secret reserve” of zooxanthellae
to help them recover
– Corals can use any of several zooxanthella species
May be “rescued” by one species when abandoned by
another.
Coral Reef Global Distribution
Human Impact to Reefs
Threats
– 27% of the world’s coral reefs are in danger
– Of 109 countries with coral reefs, 90 are
damaging them.
(UN)
Asian reefs contain the most diversity and are also
the most endangered reefs in the world.
Coral Damage is caused by…..
Underwater Mining
(for Land Reclamation & Building
Materials)
Tourism
(causes
sediment
pollution & cloudy water)
Hurricane
Damage
Fishing
Oil Spills
with
Dynamite
&
Cyanide
Sewage
Discharge & Boat Grounding
Agricultural
Overfishing
SILT WASHING
DOWNSTREAM
High
Salinity
due
to fresh water diversion
Runoff
The Ganges River forms an extensive delta where it
empties into the Bay of Bengal. The delta is largely
covered with a swamp forest known as the Sunderbans,
which is home to the Royal Bengal Tiger.
Coral Damage is caused by…..
Silt washing downstream
High salinity due to fresh water diversion
Overfishing
Sewage Discharge/Agricultural Runoff
Boat Grounding
Oil Spills
Fishing w/ Dynamite/Cyanide
Hurricane Damage
Land Reclamation
Tourism
Mining for Building Materials
3. Pelagic Zone (shallow & open ocean)
A. Shallow:
Organisms are plankton or nekton
Base of food web?
– Large numbers of phytoplankton
– Photosynthetic
Main Herbivores?
– Zooplankton (and jellyfish, barnacles, urchins & crabs) feed on
phytoplankton
Nekton then eat the zooplankton (sardines,
squid, baleen whales, manta rays)
B. Deep / Open-Ocean Pelagic
Overlies ocean floor at depths >200m
Largest marine environment (75% of ocean)
Cold temps, high hydrostatic pressure,
absence of sunlight
Base of the food chain?
– Organisms depend on MARINE SNOW
(organic debris that drifts down
from the lighted regions)
– Filter feeders, Scavengers & Predators
– Unique adaptations (bioluminescence,
reduced bone/muscle mass)
Impact of Human Activities on the Ocean
Coastal development
– Damages mangrove forests, salt marshes,
sea grass beds, coral reefs
Pollution from land
– (enters via runoff)
Pollution from atmosphere
– (enters via precipitation
Human sewage contaminates seafood
Trash (plastics, fishing nets, packing materials)
Offshore Mining & oil drilling (oily ballast)
Mechanized fishing/Dredging (scallops/shrimp)