intertidal zone vs littoral

intertidal zone

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

littoral

noun
  • The zone of a coast between high tide and low tide levels. 

  • A shore. 

adj
  • Of or relating to the shore, especially the seashore. 

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