Question 27·Hard·Central Ideas and Details
In a report on coastal ecosystem management, marine biologist Naila Jordan and her team analyze the long-term effects of reintroducing sea otters to temperate kelp forests along the Pacific Northwest. The researchers compared 30 years of data from bays where otters had been absent with data from bays in which otters had been reintroduced halfway through the study period.
According to the report, in bays without otters, sea urchin populations “expanded unchecked, consuming young kelp at rates that hindered forest recovery.” By contrast, five years after otter reintroduction, urchin densities declined by roughly 80 percent, while kelp canopy cover more than doubled. The authors note that this increase in kelp biomass is associated with an estimated 1.4-fold rise in annual carbon sequestration, adding that “the magnitude of this change underscores the pivotal, if indirect, role of apex predators in mitigating coastal carbon loss.”
What does the text most strongly suggest about bays lacking sea otters during the study period?
For inference questions that ask what the text "most strongly suggests," first underline the part of the passage that describes the specific group or situation in the question (here, bays without otters), then underline the contrasting description (bays with otters). Trace the cause-and-effect chain the author describes, and ask, "If X causes Y, what does that imply about places without X?" Finally, eliminate answer choices that introduce new topics (like biodiversity here), make extreme claims (such as total collapse), or describe patterns the passage never mentions (like frequency of fluctuations), and choose the answer that is a cautious, logical extension of the stated facts.
Hints
Focus on the comparison
Reread the sentences that contrast bays without otters to bays where otters were reintroduced. What key differences in sea urchins and kelp does the author highlight?
Notice the chain of effects
In the bays with otters, what happens to sea urchin density and kelp canopy cover, and how do the authors say this change in kelp relates to carbon sequestration?
Infer the situation in bays without otters
If otter reintroduction leads to more kelp and higher annual carbon sequestration, what is reasonable to infer about the amount of carbon sequestered in bays where otters were absent during the same period?
Step-by-step Explanation
Clarify what the question is asking
The question asks what the text most strongly suggests about bays lacking sea otters during the study period. That means you should focus on details describing bays without otters and what can reasonably be inferred about them, especially compared with bays with otters.
Find what the passage says about bays without otters
The passage states that in bays without otters, sea urchin populations "expanded unchecked" and that they consumed young kelp at rates that hindered forest recovery. This tells you:
- Urchin numbers became very high.
- These urchins were eating so much young kelp that kelp forests struggled to recover. So, less kelp biomass was present or regrowing in these bays.
Connect otters, kelp, and carbon sequestration
Next, look at the contrast: in bays with otter reintroduction, urchin densities dropped by about 80 percent, kelp canopy cover more than doubled, and this increase in kelp biomass is linked to a 1.4-fold rise in annual carbon sequestration. The authors say this shows the important role of apex predators (like otters) in preventing coastal carbon loss. So:
- More otters → fewer urchins → more kelp → more carbon is sequestered each year.
- By comparison, bays without otters had the opposite pattern: more urchins and less kelp.
Match the correct inference to the answer choices
If more kelp leads to more annual carbon sequestration, and bays without otters had urchins eating the kelp and slowing forest recovery, then those bays would not have gained the extra carbon sequestration that came with otter reintroduction. Therefore, the best supported inference is that they sequestered less carbon annually than they likely would have if sea otters had been present.