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WHAT IS A BIOME?
BIOME:
A large, relatively distinct terrestrial region
characterized by similar climate, soil, plants and
animals, regardless of where it occurs in the
world.
Key ABIOTIC Factors:
Temperature & Precipitation
Other important abiotic factors include:
Rapid temp changes
Fires
Floods
Droughts
Strong winds
Hiking up a mountain is similar to
traveling towards the North Pole
with respect to the major
ecosystems encountered.
WHY??
As you climb up a
mountain, the
temperature drops
& the types of
organisms that
live there
changes.
Important AquaticLimiting Factors
• In TERRESTRIAL environments:
– Temperature & Precipitation are limiting factors
– Light is plentiful
• In AQUATIC environments:
–
–
–
–
–
–
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
• “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
• Fish, turtles, whales
BENTHOS
• Bottom-dwelling organisms
• Fix themselves to one spot
– sponges, barnacles, or oysters
• Burrow into sand
– Worms, clams, echinoderms
• Walk around on the bottom
– Crawfish, aquatic insect larvae, brittle stars
FRESHWATER
ECOSYSTEMS
2% of Earth’s surface
Recycle precipitation that flows as surface runoff to
the ocean
Large bodies help moderate
daily/seasonaltemperature fluctuations on land
Provide habitats
Three Types:
Flowing-Water, Standing-Water, &
Freshwater Wetlands
1. FlowingWater
Ecosystem
Rivers &
Streams
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)
STANDINGWATER
ECOSYSTEMS
Lakes & Ponds
Zonation in a Large Lake
• 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.
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
Standing-water Ecosystems
~Thermal Stratification~
• Caused by light
penetrating to
different depths
• Temperature
changes sharply
with depth
4°C, Thermocline, Density, Fall & Spring Turnover
Standing-water Ecosystems
~Thermal Stratification~
• How it works: SUMMER
• Sun warms surface waters, making them
less dense.
– Density of water is greatest at 4°C
– Less dense above & below 4°C
• Cooler, denser water remains at bottom
• Thermocline: abrupt temp change
Standing-water Ecosystems
~Thermal Stratification~
• How it works: FALL
• Falling temps cause layers to mix.
– Called the Fall Turnover
• Surface water cools (density increases) &
displaces the less-dense, warmer, mineral-rich
water below.
• Warm water rises, where it again cools & sinks.
• Cycling continues until the lake has a uniform
temperature throughout.
Standing-water Ecosystems
~Thermal Stratification~
• How it works: WINTER
• Surface water cools below 4°C
–
 4°C has greatest density!
• As it cools below 4°C, it becomes less
dense, and can even form ice, which
will form on the surface.
• Water on the lake bottom is warmer
than the ice on the surface.
Standing-water Ecosystems
~Thermal Stratification~
• How it works: SPRING
• Ice melts, warming surface to 4°C
– Surface water, now denser, sinks.
– Bottom water, now less dense, rises.
• Layers mix again
– Called Spring Turnover.
• Thermal stratification occurs again in the
summer, continuing the cycle.
Standing-water Ecosystems
~Effects of Fall & Spring Turnover~
• Turnovers bring:
– Essential nutrients to the surface
– Oxygenated water to the bottom
• These nutrients encourage the growth of
large algal & cyanobacteria blooms!
– Causes Eutrophication, red tides, etc.
Standing-water Ecosystems
~Thermal Stratification~
• Where are the fish all this time?
• There is varying seasonal
distribution of temperature & O2
– We know how temps change.
– How does O2 change?
• Cooler water holds more DO
• Fish follow these distributions
according to their individual
tolerance levels!
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
• 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
• Usually 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.
Marine
EcosystemsOCEANS
Marine Ecosystems
Oceans differ from streams/lakes in
several ways:
1. Depth
(up to 6 km or 3.6 miles)
2. Tides (gravitational pull of the moon)
3. Currents (surface & density)
Marine Ecosystems are
divided into 3 main zones:
1. Intertidal
2. Benthic
3. Pelagic
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
•
•
Biologically productive habitat
Stressful for organisms
• The Sandy Beach is constantly changing. Organisms must
continuously burrow and follow the tides up and down on
the beach (must avoid drying out- no adaptations)
• 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
Two kinds of benthic zones
A. Shallow Water
1. Sea grass
2. Kelp
3. Coral
B. Deep Water
1. Abyssal
2. Hadal
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)
2. Kelp Beds
vital primary food producer for the Kelp
forest ecosystem
(cold waters)
Remember Sea Otters? Importance???
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:
– Water is too cloudy for photosynthesis
– Water temperature is too high
Types of Coral Reefs & Their Formation
FRINGING

BARRIER

ATOLL
Reef begins attached to land, then as the land subsides
below the surface, the coral continues to grow vertically.
Largest Barrier Reef????? (1200mi long, 62mi wide)
Great Barrier Reef!
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…..
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
B. DEEP SEA BENTHIC ZONES
1. Abyssal Benthic Zone: Bottom
~4,000-6,000m
2. Hadal Benthic Zone: Trenches
> 6,000m to bottom
3. Pelagic Zone – two parts: Neritic & Oceanic
A. Neritic Province: shallow waters
Open ocean: shoreline  depth of 200m
Organisms are floaters or swimmers
Large numbers of phytoplankton
– produce food
– are the base of the food web
diatoms & dinoflagellates
Zooplankton (and jellyfish, barnacles, urchins & crabs) feed
on phytoplankton and then are consumed by planktoneating nekton (sardines, squid, baleen whales, manta rays)
B. Oceanic Province: open ocean zone
Part of the pelagic zone
Overlies ocean floor at depths >200m
Largest marine environment (75% of
ocean)
Cold temps, high hydrostatic pressure, absence
of sunlight
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)