For much of the twentieth century, ecologists maintained that seagrass meadows were low-productivity habitats that contributed little to global carbon cycling. Beginning in the 1990s, however, researchers showed that, per square meter, seagrasses can sequester carbon at rates rivaling or exceeding those of tropical rainforests because organic material becomes buried in the sediments beneath the grass beds. This insight has led coastal management agencies to reassess the ecological importance of seagrass meadows and to launch programs aimed at protecting and restoring them.
Which choice best expresses the main idea of the text?
For a main-idea question, identify the passage’s full progression and then test the precise claims in each option. Closely distinguish related concepts, such as productivity and carbon sequestration, and reject choices that add rankings, universal rules, or policy conclusions not stated in the text.
Hints
Separate two ecological concepts
Consider whether the passage says that seagrass meadows are highly productive or that they can store substantial carbon despite having previously been labeled low-productivity habitats.
Check the management claim
Identify exactly what agencies did after the research. Be wary of choices that turn their response into a ranking or a broader policy rule not stated in the passage.
Preserve the complete causal sequence
Look for a choice that connects the earlier assumption, the new research, and the resulting agency action without overstating any part of that sequence.
Step-by-step Explanation
Trace the passage’s development
The passage moves through three stages: ecologists once considered seagrass meadows relatively unimportant to carbon cycling, later research revealed their substantial carbon-sequestration capacity, and agencies responded by pursuing protection and restoration.
Distinguish productivity from carbon sequestration
The passage does not say that researchers proved seagrass meadows are highly productive. Instead, it explains that the meadows can sequester substantial carbon because organic material becomes buried in the sediments beneath them.
Check the scope of the management response
The text states that agencies reassessed seagrass meadows and launched protection and restoration programs. It does not say that agencies ranked seagrass restoration above forest protection or adopted sediment carbon as the primary measure of all ecological importance.
Choose the fully supported summary
The best choice accurately connects the research on carbon burial with both the reversal of the earlier assumption and the resulting protection and restoration efforts, without adding an unsupported comparison or policy claim.