Ocean Acidification Threat (04:58)
Coral reefs are home to 25% of marine species. Mark Wiegardt and Sue Cudd run an oyster hatchery in the Pacific Northwest. In 2007, larvae began dissolving due to low seawater pH levels. They add soda ash to lower acidity, but cannot duplicate beneficial bay microorganisms.
Compromising Calcium Carbonate (03:50)
Driven by increased CO2 emissions, ocean acidity is increasing by 5% per decade. Scientists initially believed ocean absorption of carbon dioxide was beneficial. Learn about the chemical reaction devastating shellfish.
Natural Ocean Acidification Laboratory (04:11)
Scientists cannot yet predict how acidification will affect individual species within marine ecosystems. Coral reefs are especially vulnerable. Katharina Fabricius studies a Papua New Guinea (PNG) reef where volcanic activity produces CO2 bubbles.
Experimental Challenges (04:05)
Fabricius' team studies a PNG coral reef with naturally high acidity against a control site. Learn about coral polyp feeding and growth. Thick skinned porites corals dominate the reef. The team experiences weather and technical difficulties.
Changes in Coral Reef Biodiversity (05:40)
Laetitia Plaisance studies species affected by coral reef acidification. Dead coral heads from a control site have an abundance of life, while those from the CO2 rich site have fewer species forming the food chain base.
Plankton Changes (04:19)
Cold water absorbs more CO2 than warm water. Australian scientist Donna Roberts studies terapods in Antarctica; shells collected today are 35% smaller than those caught in 1997. They are crucial to marine food chains.
Mass Extinction Scenario (03:06)
Ocean acidification could devastate the food chain. When the Permian era ended, volcanic activity increased CO2 levels and killed 96% of all marine life. Organisms cannot adapt to sudden changes; millions of people rely on coral reefs.
Fish Changes (02:55)
Danielle Dixson joins Fabricius' team in PNG to study how a CO2 rich environment will affect fish species. Lab experiments have shown damage to brain chemistry and behavior. Fish use their sense of smell to detect food and predators in the water.
Ocean Acidification and Fish Behavior (03:30)
Dixson tests fish survival instincts. Fish from a CO2 rich site are attracted to a predator scent, whereas fish from a control site are repelled by it. Fish from the control site stay close to shelter, whereas fish from the CO2 site take risks.
Genetic Adaptations (05:19)
Sea grass thrives at a CO2 rich coral reef site; scientists hope fish will adapt to ocean acidification. Upwelling causes fluctuating Pacific Ocean pH levels. A California experiment shows sea urchins can be cross-bred to have stronger calcium carbonate shells.
Coral Reef Survival Mechanisms (01:59)
Near Palau, a shallow coral reef with naturally high acidity is healthy—possibly because it is sheltered from storms, or due to genetic factors. Most reefs rely on fast growing corals to rebuild foundations.
Coral Spawning Experiment (03:47)
Fabricius' team tests whether coral reefs are adapting to acidity by placing blank tiles in sites with normal and high CO2 levels. Tiles from the control site have young coral establishing, while tiles from the high CO2 site do not.
Future of Coral Reefs (02:54)
Papua New Guinea locals are concerned about how ocean acidification will impact their marine environments. There will likely be less biodiversity and fewer fish. Scientists recommend reducing or capturing CO2 emissions.
Credits: Lethal Seas (00:51)
Credits: Lethal Seas
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