Download the Human Impacts Powerpoint

Ecology:
Human Impacts
David Mellor, PhD
Citizen Science Coordinator
Virginia Master Naturalists
Overview of Ecology
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Definition and Scope
Energy and Food Webs
Nutrient Cycles
Population Dynamics
Ecological Interactions
Community Structure
Ecosystem Services
Human Impacts
Human Impacts and Threats
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Invasive Species
Habitat Loss and Fragmentation
Resource Overuse
Watershed Pollution
Loss of Biodiversity
Climate Change
Invasive Species
• An organism that spreads aggressively outside
of its natural habitat
• Ecosystem has not evolved with it.
– Predators or grazers are not adapted to eat it
– Prey have no adaptations to defend themselves
from it
• Excludes many other species native to the
ecosystem.
Invasive Species
• An organism that spreads aggressively outside
of its natural habitat
• Ecosystem has not evolved with it.
– Predators or grazers are not adapted to eat it
– Prey have no adaptations to defend themselves
from it
• Excludes many other species native to the
ecosystem.
Invasive Species
• An organism that spreads aggressively outside
of its natural habitat
• Ecosystem has not evolved with it.
– Predators or grazers are not adapted to eat it
– Prey have no adaptations to defend themselves
from it
• Excludes many other species native to the
ecosystem.
Photo: Craig Czarnecki, MI Sea Grant
Habitat Loss and Fragmentation
• Urbanization
• Agriculture
– Crop land for human and animal feed
– Grazing
• Water development
– Dams, water use for agriculture and urbanization
• Climate change
– Especially affecting coastal areas.
Habitat Loss and Fragmentation
Habitat Loss and Fragmentation
Resource Overuse
• Overharvesting or overgrazing
• Any unsustainable natural resource extraction
• “Tragedy of the Commons”
Tragedy of the Commons
Resource Overuse
Impacts of Biodiversity
Loss on Ocean Ecosystem
Services
(Worm et al., Science, 2006)
Watershed Pollution
Contamination of watershed is
caused by runoff from:
• Construction Sites
• Cropland
• Pasture
• Impervious surfaces in
urban areas
• Point Source Pollution
Effects of watershed
pollution
Excessive nutrients run into waters
Algae grow out of control
Die and
decompose
quickly
Blocks light from
reaching bottom
of streams and
lakes
Decomposition
uses up O2
Loss of
biodiversity
from aquatic
plant reduction
Loss of Biodiversity
Genetic Biodiversity
• Variety of genes in a population
• Increases resilience to change
and disease
Ecological Biodiversity
• Variety of organisms in an
ecosystem
• Increases resilience to change
and disturbance
• Loss of ecosystem services
What is a Greenhouse Gas?
Any molecule that can exist as a gas in our atmosphere
with three or more atoms can absorb infrared
radiation.
-Water vapor
-Carbon dioxide
-Methane
-Nitrous oxide
-Ozone
*(occasionally just 2)
Greenhouse Gasses
John Tyndall, 1863
Climate Change
• Concentration of CO2
increasing in atmosphere
– Fossil fuel combustion
– Deforestation
– Agriculture
• Ecosystem Impacts
– Increased temperatures
from global warming
– Shifts in species
distribution or extinction
Questions
• Besides loss of predators, what other “missing
factors” could account for a species becoming
invasive.
• What factors are blocking our ability to easily
fix environmental problems?