Final answer:
The phrases 'crucial biodiversity data' and 'flourishing underwater rocky habitat' in the excerpt help determine the meaning of biodiversity, highlighting it as the variety of life and its importance in marine ecosystems.
Step-by-step explanation:
The two phrases that help determine the meaning of the word biodiversity as it is used in the context of sea life are: “crucial biodiversity data” and “ourishing underwater rocky habitat.” The phrase “crucial biodiversity data” suggests that understanding the variety of life, including species richness and abundance, is essential for the conservation of marine ecosystems. The mention of “ourishing underwater rocky habitat” implies the diversity of life relies on, and contributes to, the health of these marine habitats. The term biodiversity within this context signifies the variety of life forms in the sea and their importance to maintaining the ecological balance of marine ecosystems.