L. 29 - The Human Footprint Flashcards
LO
- Review how human activities affect the ecology of natural systems
- Understand the impacts of pollution and how it affects the ecology of natural systems
- Understand how pollutants move into natural systems
- Understand the ecological impacts of habitat fragmentation
- Understand the ecological impacts of climate change
- Appreciate the science behind this ecological knowledge and understanding
Toxic inputs
- Pesticides
- Manufactoring
- Industrial accidents
- Atmospheric pollution
- Chemical spills
- Plastics
- Nanoparticles
Contaminants
Contamination is the presence of a substance where it should not be or at concentrations above ground
- Should’nt be there or should be at lower concentration
Pollutants
Pollution is concentration that results in adverse biological effects to resident communities
Bioaccumulation
Occurs when an organism absorbs a toxic substance at a rate greater than it can be broken down/ destroyed
- Accumulates in the body faster than it can be broken down
Particularly in higher predators at the top of the food webs
Biomagnification
- Bioaccumulation leads to biomagnification
Occurs when there is an increase in concentration of the substance in tissues at higher trophic levels
- When predators get sick it will impact the whole ecosystem as there won’t be any top-down pressure on lower trophic levels
How pollutants travel into new environments
- Inuit people consuming PCB example
- There was no agricultural/ manufactoring in North Canada
- Bioaccumulation of PCB in narwhals from eating contaminated fish
- The inuit people would consume almost every part of the narwhal, leading to biomagnification and bioaccumulation of PCB.
How pollutants may spread
- Migration of snimals that are experiencing bioaccumulation or biomagnification
- Chemicals get into atmosphere in warm climates and travel, when a cool temperature is reached where the chemicals will fractionate out of atmosphere into water, then into animals
- Breakdowns of pollutants is usually slower in colder regions than warm/ tropical climates
Habitat Fragmentation
- One of the major contributors to biodiversity loss
- Fragment size and isolation are primary factors of diversity
- Shape matters alot as edge of fragment has a large impact
- Connectivity and corridors enhance landscapes
2 Classic effects of fragmentation
- Biomass collapse
- Irriversible shifts (ecological meltdowns)
Biomass collapse
Amazonial rainforest example:
- In the fragmented plots, the closer to the edge had a lower biomass compares to those closer to the centre
- The edge effect
The Edge Effect
The microclimate factors strongly impact the edge by:
- wind
- Hydrology
- Light
More light access allows more diverse plants to grow, such as woody wines which do NOT account for a loss of trees
Ecological Meltdown
- Habitat fragmentation and loss of large animals
- Leads to ecosystem breakdowns due to no top-down regulation
- Often leaving many/ only herbivors, eating all the plants leading to trophic cascades, further creating an ecological meltdown
Changes expected and now Observed
Animals and Plants:
- Range shifts
- Abundance changes
- Change length in growing season
- Earlier flowering, insect emergence, migration and egg laying
- Morphology shifts
Hydrology and Glaciers:
- Glacier shrinkage
- Permafrost thawing
- later freeze and earlier breakup of river/ lake ice
