9.6 - Ocean Warming

Question 1

Atmospheric Warming ⬅️➡️ Ocean Warming

Answer 1

As the atmosphere warms, heat is transferred to the ocean
- Ocean absorbs heat radiated back to earth by greenhouse gases
- Oceans absorb much of earth’s heat due to high specific heat of water (est. 90% of earth’s warming from past 50 yrs. occured in oceans)
- Thermohaline circ. distributes heat absorbed at surface to depths & other areas of earth
- Heat absorbed by ocean can transfer back to atmosphere for decades

Question 2

Effects on Marine Species

Answer 2

Warmer water holds less O2; causing resp. stress or suffocation
- Migratory routes and mating seasons can be altered, especially for whales
- Reproductive timing, often tied to temp. change, can be disrupted (fish esp.)

• Habitat loss: coral bleaching with heating ocean; shallow, sunny waters ideal for algae & coral become deeper from ice melt
• Toxic algae blooms: toxic blue-green algae prefer warmer waters & warm temperature prevents mixing of water, enabling algae blooms
• Blue-green algae release toxins into the water that can kill marine species
  - Can also block sunlight & lead to hypoxia

Question 3

Climate Change and Coral Reefs

Answer 3

Warming Ocean:
- Thermal stress - Coral Bleaching and Infectious Diseases

Sea Level Rising:
- Sedimentation - Smothering of coral

Changes in storm patterns:
- Stronger, more frequent storms - Destruction of reef system

Changes in precipitation:
- increased runoff of freshwater, sediment, and land based pollutants - algae blooms and murky water reduces light

Altered ocean currents:
- change in connectivity and temperature regimes - lack of food and dispersal of larvae

Ocean Acidification (increased CO2):
- Reduction in pH levels - decreases growth rates and structural integrity

Question 4

Coral Bleaching

Answer 4

• Coral reef = mutualistic relationship between coral & photosynthetic algae called zooxanthellae; algae supply sugar & coral supply CO2 + detritus (nutrient containing org. matter.)
• Algae have narrow temp. tolerance and leave the reef when temp. rises
• Pollutants from runoff (sediment, pesticides, sunscreen) can also force algae from reef
• Coral lose color & become stressed and vulnerable to disease without algae (main food source)