Lecture 24 Flashcards
Anthropocene
The activity of human beings defines a new geological eras.
Toxic inputs
- Pesticides
- manufacturing
- Industrial accidents
- Chemical spills
- atmosphere pollutants
- plastics
- nanoparticles
Contaminants
Presence of a substance where it should not be at or at concentrations above background
Pollutants
Contamination causing biological effects to resident communities
Silent Spring
Negatives affects of pesticides apparent in Birds of Prey. Book by Rachel Carson
Bioaccumulation
Organisms absorb a toxic substance at a greater rate than that at which the substance is lost. Occurs in body tissues. Higher in predators (top of food chain)
e.g of bioaccumulation
Innuit people ate whales and other marine mammals and demonstrated high levels of PCBs though they were not manufactured in Canada. Occured due to global distillation and fractionation. Now banned.
People hunted with lead bullets and condors were eating the carcasses which killed them. 2008 saw ban in California
Habitat fragmentation
One of the major contributors to biodiversity loss. Fragment size and isolation are primary drivers of diversity. Edge effects are prevalent. Shape matters. Connectivity and corridors enhance landscapes. Role of the matrix-hospitable or not?
Biomass collapse
Rate of biomass loss greater near forest edge. Decline in above ground biomass after fragmentation (from subset of edge sites).
- High tree mortality
- No recruitment of new trees. Microclimate factors strongly affected on edges.
Ecological meltdown in predator-free fragments
Habitat fragmentation and loss of large animals. Remaining vertebrates are small, insect or seed predators/herbivores. Tend to be hyper-abundant. Densities of seedlings and saplings of canopy trees are severely reduced on herbivore-affected islands. Forest cannot recover. Evidence of trophic cascade unleashed in the absence of top-down regulation leads to ecological meltdown.
