Why Is the Sea Otter Considered a Keystone Species in Areas

question 16

Multiple Choice

Why is the sea otter considered a keystone species in areas of the Pacific Ocean?

• A)Sea otters eat barnacles and mussels,and if sea otter populations were to crash,barnacles and mussel populations in tide pools would expand,causing a decrease in biodiversity in those areas.
• B)Sea otters were introduced to control kelp and other invasive plants,and without them,the plants would grow too thick to support crab and lobster populations in the area.
• C)If sea otter populations were to crash,kelp forests could disappear because of overgrazing by sea urchins that would otherwise be controlled by the sea otters.
• D)If sea otter populations were to crash,sea urchins would be unable to survive because kelp forests would become too dense.

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Definitions:

Parametric T-test

A statistical test used to compare the means of two groups, assuming that the data are drawn from populations with normally distributed variables.

Nonparametric Counterpart

A statistical method or model that does not assume a predetermined form for the distribution of the data.

Test Statistic

A value calculated from sample data during a hypothesis test used to decide whether to reject the null hypothesis.

Matched Pairs Differences

A statistical technique used to compare two measurements taken under similar conditions from the same or matched subjects.