Di Posting Oleh : Bayu Pratt
Kategori : A2 Biodiversity Threats to Biodiversity
Biodiversity is under threat in many aquatic and terrestrial ecosystems as human population continues to increase and we take more resources from the environment and produce more waste.Threats to biodiversity:
- habitat loss and degradation of the environment
- climate change
- excessive use of fertilisers --> pollution
- overexploitation and unsustainable use of resources
- alien species invasion on native species
1. Habitat loss
- destruction of natural environment: land clearing for agriculture, housing, transport,...
- e.g.: deforestation --> soil erosion --> sever land degradation
=> habitat fragmentation (habitats become divided)
- most at risk of extinction: endemic species on small islands
2. Climate change
Air pollution: combustion of fuel with high sulfur content leads to high concentrations of atmospheric SO2
SO2 in atmosphere + H2O = acid rain
- destroys vegetation
- acidification of aquatic ecosystems: animals can't breed/survive in waters of low pH
Industrialisation, extraction and combustion of fossil fuels
increases concentration of CO2 and CH4 in the atmosphere = greenhouse gas --> climate change
---> global warming
- change in distribution of terrestrial ecosystems: organisms will migrate north or south to cooler and higher latitudes. There will also be competition between migrating organisms
- acidification of the oceans: destroy CaCO3 mollusc shells
- rise in sea levels
- increase in the frequency of natural catastrophies (hurrican, flooding,...)
e.g.: flooding: increases the concentration of nutrients in coastal waters --> increases growth of phytoplanktons which provides food for starfish larvae --> adult starfish eats the coral
- coral bleaching: corals provide protection for many coastlines. Corals are very sensitive to temperature increases --> die
3. Fertilisers and pollution
*pollutant: substances that animal bodies are unable to metabolise or excrete
- factory wastes flow into rivers without any treatment --> substance persists --> enters food chains --> weakening of immune systems and reduction in fertility in birds and mammals
- marine pollutant: non-biodegrable plastic
e.g.: - animals (dolphins) get caught in discarded fishing nets and die
- turtles eat plastic bags, mistaken then for jellyfish --> chokes
- excess fertilisers (not absorbed by crop plants) drain into river --> extra nutrients cause growth of producers, such as algae:
- produce toxic substances
- algae growth unbalances food web
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