8.2

• Pollutants cause physiological stress such as:

  • limited growth
  • limited reproductive function
  • difficulty breathing, potential asphyxiation
  • hormonal distruption
  • death (if pollutant concentration is high enough)
• Dead zones are caused by decrease in dissolved oxygen

  • All aquatic life requires dissolved oxygen in water for respiration
  • As dissolved oxygen decreases, fewer species can be supported
  • Most fish require 3 ppm to survive and 6 ppm to reproduce
• Oxygen sag: reduction in dissolved oxygen plotted over a distance along a water body from a point at which pollutants have entered

  • Oxygen sag is a key indicator of water quality and the effects of pollution
• Biological oxygen demand (BOD): generally represents how much oxygen is needed to break down organic matter in water (by bacteria)

  • relationship between dissolved oxygen and BOD is inverse
• What type of relationship do coral reefs have with photosynthetic algae?

  Mutualistic relationship
• What happens to algae when ocean temperatures rise?

  They leave the reef due to stress
• What are the consequences for coral when algae leave due to temperature rise?

  Coral loses color and becomes vulnerable
• How do humans disrupt coral reef ecosystems?

  Through greenhouse gas emissions
• What effect do greenhouse gas emissions have on ocean temperatures?

  They cause warming of ocean temperatures
• What is the impact of overfishing on coral reef ecosystems?

  It decreases fish populations
• How does bottom trawling affect coral reefs?

  It can break reef structure and sediment
• What causes sediment pollution in oceans?

  Runoff carrying sediment into the ocean
• What is turbidity in the context of ocean ecosystems?

  Cloudiness caused by sediment pollution
• What are some toxicants that can pollute oceans?

  Sunscreen, motor oil, and pesticides
• Oil spill effects on ecosystems:

  • Hydrocarbons in crude oil are toxic to many marine animals and can kill them, especially if they ingest the oil/absorb it through their gills
  • Can cause decreased visibility and photosynthesis due to less sunlight penetrating water surface
  • oil sticking to bird's feathers
  • oil sinking to the bottom and killing bottom-dwellers due to toxicity and suffocation
• Oil spills effects on tourism:

  • Oil can wash ashore and decrease tourism revenue and kill fish, decreasing fishing industry revenue and restaurant revenue
  • Oil can settle deep in root structure of estuary habitats like mangroves/salt marshes
  • Can be toxic to salt marsh grasses, loosening their root structure --> coastline erosion, habitat removal
• What can cause oil spills?

  Underwater oil well explosions or tanker accidents
• What happens when a tanker runs into a rock or iceberg?

  It can be punctured, causing an oil spill
• What is one method used to contain oil spills on the surface?

  Using booms
• How do ships assist in oil spill clean-up?

  They use vacuum tubes to siphon oil
• What is a method for physically removing oil from beaches?

  Using towels, soap, and shovels
• What are chemical dispersants used for in oil spills?

  To break up oil and sink it
• What is a consequence of using chemical dispersants?

  They can smother bottom-dwellers
• What is one method of oil removal that involves burning?

  Burning oil off the surface
• What is a negative environmental impact of burning oil during clean-up?

  Increased CO2 in the atmosphere