8.2 - Human Impacts On Ecosystems

Question 1

Range of Tolerance

Answer 1

• Organisms have range of tolerance for abiotic conditions in their habitat (pH, temp, salinity, sunlight, nutrient levels)
• Organisms also have range of tolerance for pollutants that human activities release into the air
• Pollutants can cause physiological stress such as:
  - Limited growth
  - limited reproductive function
  - Difficulty respiring, potential asphyxiation
  - Hormonal disruption
  - Death

Question 2

Environmental Effects of Acid Rain

Answer 2

PH tolerance
- As pH decreases (more acidic) outside optimal range for a species, population declines
- when the pH leaves range of tolerance they cannot survive at all due to:
- aluminum toxicity
- disrupted blood osmolarity
- Indicator species can be surveyed and used to determine conditions of an ecosystem
- Ex: high white moss algae population indicated pH less than 6

Question 3

Temperature Tolerance of Reef Algae

Answer 3

• Coral reef = mutualistic relationship between coral and photosynthetic algae called zooxanthellae; algae supplies sugar and coral supplied CO2
• algae have narrow temperature tolerance and leave the reef hen temperature rises
  - pollutants from runoff (sediment, pesiticdes, sunscreen) can also force algae from reef
• Coral lose color and become stressed and vulnerable to diseases without algae

Question 4

Human Impacts on Coral Reefs

Answer 4

• Humans Disrupt coral reef ecosystems win greenhouse gas emissions
• overfishing decreases fish population in coral reef ecosystem and bottom trawling can break reef structue and stir up sediment
• urban and agricultural runoff also damages coral reef ecosystems
• sediment pollution: sediment carried away into the ocean by runoff makes coral reef waters more turbid, reducing sunlight
• Toxicants: chemicals in s unscreen, oil from roadways, pesticides from ag runoff
• Nutrient’s: ammonia from animal wasted, nitrates phosphates from ag or lawn fertilizers

Question 5

Oil Spill Effects

Answer 5

• Hydrocarbons in crude oil are toxic to many marine organisms and can kill them, especially if they ingest the oil or absorb through their gills/skin
• Decreased visibility and decreased photosynthesis due to less sunlight penetrating water surface
• oil sticking to bird feathers
• oil sinking to bottom and killing bottom-dwellers due to: direct toxicity or suffocation

Question 6

Oil Spill Cleanup

Answer 6

• Oil spills can occur when an underwater oil well explodes or when a tanker runs into a rock/iceberg and is punctured
• Cleanup can invoices booms on surface too contain spread and ships with vacuum tubes to siphon oil off of the surface or devices to skim it off
• physical removal of oil from beach and and rocks with towels, soaps, shovels
• Chemical dispersants sprayed on oil slicks to break up and sink to the bottom
  - Clears up surface, it can smother bottom-dwellers
  Dispersant chemicals may be harmful
• Burning oil off surface