Impact of Sea Otters on Ecosystems

The video explores an experiment comparing ecosystems with and without sea otters. Initial observations at Amchitka and Shemya Islands reveal the significant impact otters have on controlling sea urchin populations and maintaining kelp forests. This leads to a discussion on trophic cascades, where the presence of apex predators like otters regulates the ecosystem. The video also covers the decline in otter populations, examining various hypotheses for this change.

What was the primary focus of the initial experiment?

• To measure the size of sea urchins

• To compare ecosystems with and without sea otters

• To study the diet of sea otters

• To observe the behavior of kelp

What was the significant observation made at Shemya Island?

• Abundance of kelp

• Presence of many sea otters

• Large fish populations

• Green waters filled with sea urchins and no kelp

What hypothesis was demonstrated by the loss of sea otters?

• Yellow Sea Hypothesis

• Red Tide Hypothesis

• Green World Hypothesis

• Blue Ocean Hypothesis

What term did Payne use to describe the cascading effects of one species on others?

• Food Web

• Trophic Cascades

• Ecological Chain

• Predator-Prey Dynamics

What happens to kelp forests when sea otters are removed?

• They become more diverse

• They disappear

• They remain unchanged

• They flourish

Which species are impacted by the presence or absence of kelp?

• Virtually all coastal species

• Only birds

• Only fish

• Only invertebrates

What role do sea otters play in the coastal marine community?

• Migratory species

• Primary producers

• Decomposers

• Keystone species

What did Estes notice about the sea otter population 20 years later?

• It was declining

• It was stable

• It was increasing

• It was migrating

What were some of the hypotheses ruled out for the declining otter population?

• Overfishing and habitat loss

• Starvation and disease

• Pollution and climate change

• Predation and competition

What was the next step after ruling out starvation and disease?

• To increase food supply

• To study the impact of pollution

• To investigate a third hypothesis

• To relocate the otters