The Palaeoenvironmental Implications of the Distribution of Intertidal Foraminifera in a Tropical Australian Estuary: a Reconnaissance Study S.K. HASLETT Modern intertidal foraminifera were investigated in a mangrove-lined microtidal distributary channel of the Barron River Delta (Cairns, Queensland, Australia). A monospecific assemblage of Trochammina inflata characterises saltmarsh environments (Biozone 1), whilst the more regularly inundated tidal flat is dominated (>55%) by Ammonia beccarii (Biozone 2). Within the tidal flat environment, two foraminiferal subdivisions can be recognised; a high tidal flat assemblage (Biozone 2a) characterised by >70% Ammonia beccarii and low diversity, and a low tidal flat assemblage (Biozone 2b) with 55–65% Ammonia beccarii and high diversity (due to the settling out of small allochthonous species transported into the estuary from shelf environments). Foraminiferal distributions are also compared with tide levels estimated in the field. It appears approximately that Biozone 1 occurs between High Water and Mean High Water (MHW), Biozone 2a between MHW and Mean Tide Level (MTL), and Biozone 2b between MTL and Low Water. From this preliminary study, it is concluded that foraminifera possess significant potential in palaeoenvironmental studies of tropical Australian estuaries as indicators of intertidal environments, and also tidal levels. Introduction Foraminifera are marine Sarcodine Protozoa that possess tests (shells) that are preservable in the fossil record. Their life habits embrace planktonic and benthonic modes. Planktonic forms generally inhabit the open ocean and seldom live in coastal waters in any abundance, whilst benthonic foraminifera exist on substrates from abyssal plains to high intertidal areas. Many species of foraminifera have narrowly defined niches, making them ideal for palaeoenvironmental analysis (Murray, 1991). Analysis of foraminifera in the modern intertidal zone has found that species inhabit narrowly defined niches (for example, high and low saltmarshes, tidal flats and tidal creeks), and that certain assemblages are indicative of 67 Australian Geographical Studies • March 2001 • 39(1):67-74 Simon Haslett is a Lecturer in Physical Geography in the School of Geography and Development Studies (Quaternary Research Unit), Bath Spa University College, Newton Park, Bath, BA2 9BN, United Kingdom.