Ecology: Human Impacts David Mellor, PhD Citizen Science Coordinator Virginia Master Naturalists

Overview of Ecology Definition and Scope Energy and Food Webs Nutrient Cycles Population Dynamics Ecological Interactions Community Structure Ecosystem Services Human Impacts

Human Impacts and Threats 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

Resource Overuse Overharvesting or overgrazing Any unsustainable natural resource extraction “Tragedy of the Commons”

Tragedy of the Commons

Impacts of Biodiversity Loss on Ocean Ecosystem Services (Worm et al., Science, 2006) Resource Overuse

Contamination of watershed is caused by runoff from: Construction Sites Cropland Pasture Impervious surfaces in urban areas Point Source Pollution Watershed Pollution

Effects of watershed pollution Algae grow out of control Loss of biodiversity from aquatic plant reduction Blocks light from reaching bottom of streams and lakes Die and decompose quickly Decomposition uses up O 2 Excessive nutrients run into waters

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 CO 2 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?