intertidal zone vs lido

intertidal zone

noun
  • The part of a shore between high water and low water, especially the beach exposed at maximum ebb spring tides. 

lido

noun
  • Part of the sea by a beach sectioned off for swimming and other aquatic activities. 

  • An outdoor swimming pool. 

How often have the words intertidal zone and lido occurred in a corpus of books? (source: Google Ngram Viewer )