The Collaborative International Dictionary of English v.0.48:

Estuarine \Es"tu*a*rine\, a.
   Pertaining to an estuary; estuary.
   [1913 Webster]

WordNet (r) 3.0 (2006):

estuarine
    adj 1: of or relating to or found in estuaries [syn:
           estuarine, estuarial]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "estuarine":
   alluvial, aquatic, balneal, bayed, deep-sea, embayed, fluviomarine,
   grallatorial, gulfed, gulflike, gulfy, littoral, natant,
   natatorial, natatory, seashore, shore, swimming, tidal, tidewater,
   water-dwelling, water-growing, water-living, water-loving