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UNIT 3- BIODIVERSITY AND CONSERVATION
Transcript of UNIT 3- BIODIVERSITY AND CONSERVATION
BIODIVERSITY AND CONSERVATION
Does climate dictate biodiversity?
Ch 7: Climate & Terrestrial Biodiversity
It is not random placement that has led to the global distribution of biomes. It is differences in climatic patterns like temperature and precipitation.
- local area's short term temperature, precipitation, humidity, etc.
- area's general pattern of atmospheric conditions over long periods of time
Terrestrial climates vary across the earth due to
patterns in global air circulation and ocean currents
that unevenly distribute heat and precipitation.
3 factors that affect how heat and moisture are distributed:
Properties of air, water, and land
- Solar energy creates continuous evaporation from ocean water, especially at the equator, which transfers heat from the ocean to the atmosphere. This creates cyclical
convection cells that circulate air, heat, and moisture
across the earth
Uneven heating of the earth's surface
- Since the shape of the earth is a sphere, solar radiation is not equally distributed. Sunlight is more direct at the equator, whereas at the poles the sunlight comes in at an angle. This unevenness also creates our wind patterns.
Rotation of the earth on its axis:
As the earth rotates on its axis, heated air masses begin rising above the equator and are deflected to the west and east. This creates
which gives us our prevailing wind patterns.
Due to the
, the earth's rotation causes wind to be deflected clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere!
Atmosphere and Ocean: Interactions that Influence Climate
The atmosphere and ocean are strongly linked.
The heat from the ocean impacts atmospheric circulation just as atmospheric winds affect ocean currents.
Prevailing winds and the rotation of the earth produce earth's major ocean currents.
Warm water and cold water currents are created as the ocean absorbs heat from the atmosphere, primarily in tropical waters.
The differences in water temperature (THERMOCLINE) also create water density differences that can fuel
Upwelling occurs when winds blowing along the coast push warmer surface water away from land and draw up deep cold, nutrient-rich water from the bottom to the top.
SEE YOUR READING GUIDE FOR BIOME SUMMARIES!
71% of the earth's surface is covered with saltwater
1. Atlantic Ocean
2. Pacific Ocean
3. Indian Ocean
4. Arctic Ocean
CH 8- AQUATIC ECOSYSTEMS
Abiotic Factors that influence the presence of life in aquatic systems:
Turbidity- cloudiness of the water
Why does that matter?
Salinity- concentration of dissolved salts
Why does that matter?
OCEAN AS NATURAL CAPITAL
1. Habitats and Nursery Areas
2. Moderates Climate
3. Absorbs CO2
4. Reduces Storm Impact (estuaries, mangoves)
1. Food Resources
2. Oil, Natural Gas, and Mineral Resources
3. Transportation Routes
4. Provides Areas for Recreation
Marine Life Zones Include:
-high tide mark to edge of continental shelf
-warm water, rich in nutrients
-ample sunlight, so high primary productivity
-90% of all marine species
Dominant Primary Producer in Marine Ecosystems=
-free floating single celled algae
-populations limited by sunlight
= drifting herbivores, primary consumers
single celled protozoa, crustaceans, krill, copepods
= stronger swimming organisms like fish
= bottom-dwelling organisms found in marine sediments or the ocean floor
oysters, clams, worms, crabs, lobsters
Coral Reef Acidification
Scenes from Finding Nemo! Which area of the ocean are they in?
-life in this zone is influenced by the rising and
falling tides every 6 hours
-some are gently sloping, some are rocky crevices
-organisms here have adaptations to withstand wind
by burrowing, attaching to rocks, or retreating into
-slow growing, highly diverse occur mostly along
equator in warm tropical water
-very sensitive to salinity, pH, and temperature
-require sunlight so that photosynthetic algae
(zooxanthellae) can provide nutrients
Open Ocean and Sea Floor
-extends off the continental shelf
-defined by sunlight penetration and temperature
changes as dept increases
-freshwater meets saltwater
-bays, inlets, sounds, salt marshes, mangrove forests
-highly productive due to large inputs of nutrients
from rivers and ample sunlight
-organisms that live here must be able to tolerate
variations in temperature and salinity
-natural filter to prevent toxins, excess nutrients,
-natural buffer from storms
a very limited resource!
Two categories of freshwater
Lentic or Lotic?
Lentic or Lotic?
Lentic or Lotic?
-form as surface water runoff,
rainfall fill depressions
-depressions in the land can
or volcanic activity) or
(reservoirs or dams)
Flathead Lake, Montana
Lake Lanier, Georgia
*Shallow zone closest to the shore
*Lots of sunlight and nutrients
*Submergent (underwater) plants
*Emergent (rooted in water, yet sticking out of the water) plants
*Home to a variety of species
*Upper layer of the lake away from the shore
*Lots of sunlight
*Lots of phytoplankton
*Lots of dissolved oxygen
*Receives little sunlight
*Low in nutrients and dissolved oxygen
*Organisms adapted to colder water
Lakes are classified by their
concentration of nutrients
primary productivity rates
1. Oligotrophic Lake- clear, deep lakes
*low nutrient levels
*low primary productivity
*cold water, high dissolved oxygen (DO)
Over time, lakes naturally increase in nutrients from runoff. The added nutrients will result in higher primary productivity.
2. Eutrophic Lake- murky
*high levels of nutrients
*high primary productivity
Humans can cause eutrophication of a lake when large amounts of nutrients are added from fertilizer runoff
= CULTURAL EUTROPHICATION
Inland wetlands= swamps, marshes, flood plains, and bogs
*abundance of biodiversity
*numerous ecosystem services:
1. natural recharge to groundwater
2. habitat (ex: beavers, fish, otters)
3. nursery and spawning area
4. filters toxins and excess nutrients
5. reduces flooding and erosion
Simple Steps of Cultural Eutrophication:
1. Excessive nutrients are added to the system
2. Uninhibited algae growth blocks sunlight
3. Producers run out of nutrients and die
4. Aerobic decomposers break down dead organisms
5. Dissolved oxygen is depleted in the lake
6. Fish run out of oxygen and food and die.
Rivers- get their input or recharge from runoff of precipitation
What is the water picking up as it travels along each of these zones?
The land area that delivers this runoff to the rivers or tributaries=
fast moving, shallow, cold, low nutrients, high DO
turbid water due to increase in sediments, deeper, slower moving, less DO
warm, slow moving, lots of silt and sediments
Ch 9: Sustaining Biodiversity
Do you ever ask yourself...
Why Should I Care About One Species?
As you read Ch 9's
Core Case Study
, think about the following questions:
1. How long did it take to go from “most abundant” to extinct (roughly)?
2. Think about your “favorite” endangered species, about how long has it been in peril ?
3. What characteristics of the bird made it vulnerable to extinction?
4. What other species (still alive) have similar characteristics – making them vulnerable?
5. What actions could have been taken to prevent its extinction?
Think about all of the ecosystem and economic services that we've been talking about that species provide for us:
human population has increased
, this has elicited an increase in the
destruction of natural habitat
to make room for societal expansion (cities, farms, houses).
It has also increased demands for the earth's
which destroys habitat through
pollution, overfishing, and climate change.
THE MAJOR CAUSES OF BIODIVERSITY DEPLETION:
- Habitat Destruction, Fragmentation
- Invasive Species
-Population and Resource Use Growth
- Climate Change
The largest impact on species diversity= HABITAT LOSS!
-forests, wetlands, and grasslands have been
urbanization or agriculture
*tropical rainforests are being subjected to slash
*coastal ecosystems, coral reefs, and mangroves
are being destroyed by fishing practices and
HABITAT FRAGMENTATION- occurs when large adjacent ecosystems are divided into smaller, more isolated areas
: housing developments, urban areas,
roadways, removal of trees, or agriculture
: since space is being reduced, population
density will increase, which increases competition and
cause organisms to be more susceptible to disease
INVASIVE SPECIES- occurs when nonnative species are introduced to new ecosystems intentionally or accidentally
soil erosion control
"hitchhike" by way of:
-ballast water of ships
If nonnative species out-compete native species for resources and do not have any known predators in their new environment=
a successful invasive species
What characteristics makes for a successful invasive species?
*Generalist- broad niche
EX: Japanese Beetle, Kudzu, Nile Perch, African Honeybee, Cane Toad
EX: Zebra Mussel, Gypsy Moth, Termites, Argentina Fire Ants
Normal extinction of various species as a result of changes in local environmental conditions
Percentage or number of species that go extinct within a certain time such as a year
Catastrophic, widespread, often global event in which major groups of species are wiped out over a short time compared with normal (background) extinctions.
There have been 5 mass extinctions that eliminated 50-95% of species on the planet.
Occurs when a species is no longer found in any ecosystem on the earth; can occur naturally or anthropogenically (human caused) EX: Golden Toad, Dodo Bird, Passenger Pigeon
population size has decreased to such a low level that they are at extreme risk for extinction
EX: Giant Panda, Grizzly Bear, African Elephant,
Whooping Crane, California Condor, Black Rhino,
populations that are declining due to human activity and could possibly become endangered in the near future
EX: Polar Bear
Characteristics that make species vulnerable to extinction:
1. Low Reproductive Rates (K-selected)
2. Need for Large Habitats
3. Tertiary Consumers (need lots of food for energy)
4. Specialized Niche (specialist)
5. Narrow Distribution
6. Commercially Valuable (tusks, fur, leather, etc)
US Endangered Species Act of 1973:
Identifies and provides protection for organisms that are at risk of extinction. It prohibits any federal agencies from projects that destroy its habitat and fines private land owners that disrupts its habitat
CITES (Convention on International Trade in Endangered Species)
1975 treaty to place bans on selling, hunting, or capturing of threatened or endangered species has now been signed by 172 countries
CH 10: SUSTAINING TERRESTRIAL BIODIVERSITY
Forest Ecosystems and Grassland Ecosystems
FORESTS are classified as:
Old Growth Forests
- have not been modified by
humans or natural disasters in 200 years or more
Secondary Growth Forests
- form from secondary
succession once land has been cleared from human
activity or natural disasters
1. Provide habitat for 2/3 of the earth's terrestrial species
2. Tropical Rainforests are home to >50% of the world's species
3. Ecological services like
-reducing soil erosion
-promote nutrient cycling
-influences local and regional climates
4. Economic services like
-jobs in lumber and paper industries
THREATS TO FOREST ECOSYSTEMS:
2. Forest Fires
- temporarily or permanently removing large tracts of forested land for fuelwood, agriculture, or urban development
South America, Africa, and Indonesia
- large tracts of being removed to provide space for cash crops, raising livestock, or harvesting timber resources
has already removed 78% of its original forest land
Logging Roads are first established
increases soil erosion
into rivers and streams
Three Main Types of Logging
1. Clear Cutting
2. Selective Cutting
3. Strip Cutting
removes all trees in one area at one time
most efficient for loggers, but
causes the most damage
heavy loss of soil nutrients and biodiversity
increased soil erosion
Tree Plantations (tree farms)
- commercially maintained areas for timber resources
-usually have 1 or 2 uniform tree species that will be
clear cut and replanted regularly
-not biologically diverse and depletes soil nutrients
mature or intermediate-age trees are selectively removed from forested areas
more sustainable than clear cutting
removing entire strips of trees along the contour of the land in a narrow corridor
allows for quick regeneration of trees
loggers will later move to the next strip
- fires that burn only leaf litter on the forest floor
stimulating germination in some trees and freeing up vital minerals
removes large amounts of flammable leaf litter which reduces the risk for more serious crown fires
burn tops of trees and spreads easily from treetop to treetop
*difficult to control
*kill trees and wildlife
In tropical regions, large tracts of land are being cleared through burning practices to make room for agricultural land.
- greatly reduces wildlife populations
-increases local air pollution
-increases atmospheric CO2
Strategies to reduce harm caused by forest fires:
- set small, controlled fires in high-risk areas to remove large areas of flammable overgrown leaf litter and underbrush
Healthy Forests Restoration Act
- passed in 2003 allowing timber companies to remove medium-sized commercially valuable trees in an attempt to thin forests at risk of fires
-critics to this say that this act just promotes
growth of smaller, more flammable trees
Insects and Climate Change:
Forest ecosystems have fallen victim to invasive species and diseases introduced into the US.
EX: Diseases like Dutch elm and chestnut blight have almost eliminated the American elm and chestnut trees. Rising temps due to climate change make it easier for diseases to do well in forest ecosystems.
Ch 11: Sustaining Aquatic Biodiversity
Used to catch bottom dwelling fish and shellfish (especially shrimp).
Involves dragging a funnel shaped net held open at the neck across ocean floor.
Destroys the habitat on the ocean floor
Some are big enough to fit 12 jumbo jets (yield is too big)
Bycatch: other fish, seals, sea turtles (sometimes is 12x weight of what was intended to be caught)
Large mesh allows small fish to escape
Overfishing leads to commercial extinction (and possible real extinction, in peril cod fisheries & blue fin tuna)
Bycatch is 25% of the annual catch – and nobody can eat it!
Loss of wetlands and estuaries due to human activities (threatens fish and shellfish)
Global Warming (coral reef loss)
Ozone loss (too much UV for fish on surface)
El Nino - ENSO events (affect populations/reproduction)
Biggest Threats to Fisheries
Sustainable Yield: the size of annual catch that would allow us to harvest fish indefinitely without a decline in populations
Hard to figure this number out because
Hard to estimate aquatic populations
Yield needs to change with climate, pollution and other factors affecting reproduction
Sustainable yield may still impact other parts of the food chain.
What can be done?
Annual catches increased from 1950 to 1982, but have stalled since then
The per capita catch has been decreasing and may continue to because of
Overfishing (populations too small to reproduce)
Habitat loss (especially from trawling)
So what's the big deal?
Fish farming: keep the fish in a controlled environment
Fish ranching: raise fish in captivity then release them and harvest when they return to spawn (reproduce)
Good because: efficient, reduces burden on wild populations, not dependent on oil (boats)
Bad because: genetically modified fish, waste, inputs of land and food (grain), vulnerable to disease
Used to catch anything that swims
A huge net (up to 34 miles long) is placed in the water, anything that tries to swim there is caught (like a giant spider web) by the gills
Worst type because
It kills everything (“Wall of Death”)
Leads to overharvest of desired fish
UN has mandated a stop to nets over 1.6 miles, but compliance is voluntary
Drift-Net Fishing (aka Gill Net)
Used to catch open ocean fish like swordfish, shark and tuna
A long line (80 miles long) is put into the water with thousands of baited hooks
They hook many air breathing animals and drowned them
Sea turtles, pilot whales, albatross, dolphins
Used to catch pelagic (surface dwelling) fish like tuna.
A school is located then surrounded by a net that is closed like a drawstring purse.
They kill a large amount of bycatch – especially dolphin! (look for the dolphin safe tuna!)
We get 55% of fish from the ocean
99% of that is from the coastal zone
The rest is from
Inland fishing (lakes, rivers, ponds)
1/3 of the world’s catch is used as animal feed or other non-edible products
Is that the only way to fish?
TEDs are used in prawn/shrimp trawling as an escape hatch for turtles. If turtles cannot escape from a trawl net they cannot reach the surface to breathe and may drown. TEDs consist of a grid across the end of the net which forces turtles and other large objects out of the net without the prawn catch escaping.
Fisheries: Concentrations of aquatic species suitable for commercial harvesting
How do you find fish?
Satellite Positioning System
Factory Ships (to freeze and process catch)
Definition: Aquatic species that are not the intended target of fishing. If caught they are tossed back (usually dead or dying)
Set catch limits for commercial fishing
Filter organisms from ship ballast water to reduce invasive species
Establish no fishing zones
Biggest Threats to Freshwater Ecosystems
-Rivers have been depleted due to building of dams along major rivers limiting water and nutrient flow.
-Lakes are being overharvested for water resources for agriculture, homes, and industries.
-Constant influx of toxins leading to issues like Cultural Eutrophication
-Destruction of Riparian Zone- protective strips of vegetation that protect water ways from excess toxins and nutrients are being depleted.