Notes 6 – Threats to Sustainability

SCI 10 Ecosystems

Alien Species

• Alien species: aka introduced species, non-native species, exotic species

• Species introduced to new parts of the world• Can be invasive species: take over habitat of

native species– Outcompetes native species for food or other resources

• Native species: species that naturally inhabits an area

• Alien species often introduced accidentally i.e. in ballasts of ships

• Zebra mussels

• Alien species sometimes introduced by humans to control another organism

• Mosquito fish

Research 1 invasive species in Nova Scotia

• http://www.invasivespeciesns.ca/– Look under “Invasive species” then choose

“aquatic” or “terrestrial”• Where did it come from originally?• How did it get introduced into Nova Scotia• What are its effects on the Nova Scotia ecosystem

in which it now lives?• Find a picture of it• 1-2 power point slides• Due

Eutrophication

• Caused by run off of nitrogen and phosphorus into waterways (usually from fertilizer use)

• Commonly found close to golf courses and farmlands

The process

• Eutrophication: deposits of excess nutrients in bodies of water that result in large increases in plant growth

• Phosphates and nitrogen from fertilizers, or sewage, run off into bodies of water

• These nutrients stimulate excessive algae growth = ALGAL BLOOM

• The algae die off and sink to the bottom where they are decomposed by bacteria

– Bacteria use CELLULAR RESPIRATION to decompose the algal remains which uses up most of the OXYGEN at the bottom

– Other fish who live near the bottom die due to lack of oxygen• The algae bloom blocks sunlight and prevents plants from

deeper down from PHOTOSYNTHESIZING