Transcript Biodiversity & Human Health

Environmental Health
Chapter 3
Lesson 3.3
Biodiversity and Environmental
Health
PA Academic Standards for
Environment & Ecology
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Standard 4.3.10.C
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Explain biological diversity as an indicator of
a healthy environment.
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Explain species diversity.
Analyze the effects of species extinction on the
health of an ecosystem.
Learning Objectives
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Students will define and explain biological
diversity.
Students will hypothesize the effects of species
extinction on health of an ecosystem
Biodiversity and
Environmental Health
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How can we use a measure of biodiversity to
determine the health of an ecosystem?
Let’s see what Bill Nye, the Science Guy, has to say …
Biodiversity
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Definition: variety of living organisms on earth
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Biodiversity varies by habitat
The overall health of an ecosystem is directly related to its
biodiversity
When in equilibrium, the number of species is balanced by
the resources in a system
When ecosystems are stressed, the organisms and
resources in a system are no longer in equilibrium
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Biodiversity
Biomonitoring
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Definition: biological approach to monitoring an ecosystem’s
health. Using living organisms to gauge environmental health.
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Ecosystem monitoring incorporates sampling & analyzing
biological factors
Certain types of organisms occur within a limited range of
conditions
Example: ability to tolerate fluctuations in precipitation and
temperature in seasonal climates
When conditions change, the distribution and number of
organisms in an affected site will also change
These changes are the premise of biomonitoring
Biomonitoring
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How can we use biomonitoring in aquatic
systems?
• Aquatic systems generally contain populations of
bottom-dwelling invertebrate species
• If most systems have bottom-dwelling invertebrate
communities, then biomonitoring always works for a
comparison of data within systems, as well as between
unrelated systems
Benthic Macroinvertebrates
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Why use bottom-dwelling invertebrates?
 They are present in nearly all aquatic
ecosystems
 Easy to collect and identify
 Limited mobility
Inability to avoid poor water quality conditions
 Sensitive to a wide range of environmental
conditions
Invertebrate Sampling Chart
Bottom-dwelling Invertebrates:
Field Studies
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Invertebrates are collected by nets and screening devices
using a variety of sampling techniques
Identification of specimens
Data collection
• The number and type of organisms is recorded
Data Analysis
• Charts have been developed to use a scoring table that
assigns a value to the level of tolerance an organism
exhibits
• The data is “scored” using these tables
Conclusion
• Data is reviewed, compared, repeated, and an overall tally
of indicators determines the overall health of the system
Humans and Species Extinction
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Biomonitoring studies have shown that the health
of ecosystems statewide and nationally, have
improved since monitoring programs began
Despite this accomplishment, ecologists estimate
that the current rate of extinction of species is
10,000 times faster than normal extinction rates
Habitat loss is the most common reason for this
increased rate
Habitat Alternations
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Main causes of habitat destruction include
 Sprawl
 Pollution
 Logging and mining
 Fire suppression
Sprawl
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Problem: urban sprawl is the result of unplanned
development around urban areas
Problem: major cause of habitat loss from the removal of
trees to clear properties, drainage and filling of wetlands,
and increased amounts of impervious surfaces
Realistic Solution:
Smart Design
Smart Design Basics
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Aims to reduce the amount of sprawl and associated pollution
Aims to increase the amount and affordability of mass transit
systems
Aims to provide alternatives to nonrenewable fuel
consumption
Aims to provide ecological ways of incorporated the needs of a
growing population with the need for access to urban areas
Pollution
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Problem: results in the contamination of all forms
of medium: air, water, and soils
Problem: results in habitat degradation and
habitat loss
Case Study: DDT in Pennsylvania
DDT
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What is DDT?
How is DDT linked to habitat loss and decreases in
overall habitat quality in Pennsylvania?
What has been done to address the concerns
associated with the use of DDT in Pennsylvania?
DDT: Dichlorodiphenyltrichloroethane
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What is it?
• Chlorinated organic pesticide.
• Problem: Accumulates in fat.
• Problem: Attacks nervous system.
• Problem: Affects non-targeted species.
Uses of DDT
Historical
• Agricultural production
• Limits crop losses
• Forestry
• Limits insect damage
• Public health
• Malaria and Mosquito control
Current
• Malaria control in “hot spots”
Widespread Use of DDT
USDA 1947
Current Status of DDT
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Banned in US in 1972
Most other nations have banned DDT
• ~19 countries still have exemption for its use
Primarily used to control the spread of diseases by mosquitoes
Migration of DDT particle
Bioaccumulation
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(Biological Magnification)
Definition: the accumulation of potentially
harmful chemicals in organism higher in a food
chain
DDT and Food webs
Concept of Half-life
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Half-life is the amount of time it takes for half of
the chemical substance to degrade
The half life of DDT is 12-15 years. Let’s assume
that the half-life is a constant 15 years.
If we apply 100 pounds of DDT today, how much
DDT will be left after 5 half-life's?
Half-life of DDT
One Half-Life
(15 years)
Two Half-Lives
(30 years)
Three Half-Lives
(45 years)
Four Half-Lives
(60 years)
Five Half-Lives
(75 years)
50% degraded
50 lbs.
75% degraded
25 lbs.
88% degraded
12 lbs.
94% degraded
6 lbs.
97% degraded
3 lbs.
Weighing in on DDT use…
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Pro
• Toxic to wide range of
insect pests
• Appeared to have low
toxicity to mammals
and birds
• Persistent - does not
have to be reapplied
• Insoluble - doesn’t get
washed off by rains
• Inexpensive and easy to
apply
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Con
• Toxic to a wide range
of insect pests
• Toxic to mammals and
birds even in very low
concentrations
• Persistent – does not
have to be reapplied
• Insoluble – doesn’t get
washed off by
precipitation
Silent Spring
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When?
• 1962
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Who?
• Rachel Carson
• Biologist and
naturalist
• Noticed a “silent
spring”
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What?
• Silent Spring; response
to massive use of
pesticides and
subsequent wildlife
mortality
DDT Affects Non-Target Species
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Reproductive failure in birds
• Thinning of eggshells.
• Modification of parental behavior.
• High mortality of embryos and fledglings.
Pennsylvania Example:
Peregrine Falcon Populations
Value of Raptors
Rosalie Edge – Hawk Mountain
What do we know about
Latin America?
Latin America:
The DDT Connection
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Falcons and other migratory birds can travel as
far as Latin America during period of migration
Latin America still uses DDT as a means of
mosquito and pest control
Falcons traveling to these regions are coming in
contact with DDT; exposure to DDT occurs while
falcons are in Latin America
Logging and Mining: Problems
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Logging and mining have destroyed many habitats
statewide
Timber extraction increases erosion and sediments
in waterways
Acid mine drainage acidifies waterways
Logging and Mining:
Realistic Solutions
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Minimize and prevent further destruction
Create and enforce regulations that oversee land
use for these practices
Restore and replace destroyed habitats for wildlife
and recreational use
RECLAMATION
Fire Suppression: Problems
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Interrupts natural processes of ecological succession
Disturbs the cycles of organisms which depend on periodic
fires
Native plants vulnerable to competitors better adapted to
survive fires
What we want...
What we have.
Fire Suppression: Realistic Solution
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Allow controlled fires to prepare land for ecological succession to occur