Abstract Given that diatom assemblages are a well-recognised method of characterising the water quality in freshwater streams, it seems reasonable to investigate its applicability to solar saltfields. A summer collection of benthic diatoms was undertaken in the salinas of the Dry Creek solar saltfields in South Australia for this purpose. The facility inputs seawater both from a low nutrient samphire creek and poorer quality, high nutrient samphire creek. Salinity and nutrient status of the pools and concentrating salinas have been thoroughly characterized over many years. The addition of JJ periphytometers to the sam- pling regime in the summer of 2001–2002 allowed the collection of benthic diatoms from these sites. Of the 69 species collected during the study, 16 species occurred only in oligotrophic waters with salinities less than 70 g/l TDS (total dissolved solids). Twenty species of diatoms occurred only in the eutrophic waters with salinities less than 70 g/l TDS, eight species were restricted to the hypersaline ponds and the remainder were undiscriminating in their ecological preferences. Keywords Diatoms Æ Benthic assemblages Æ Ecological preferences Æ Salinas Æ Solar saltfields Introduction Diatoms in the fossil record have been used to infer historic conditions in saline lakes by many researchers (Fritz et al., 1999). In Australia, Gell (1997) examined living diatoms from 62 lakes of varying salinity in Western Victoria, to develop a database that could be used to infer historic changes in lake salinity. He found a distinct salinity preference in many species, with 10 common species with salinity optima in excess of 26 g/l TDS. These were Navicula salincola (63.1 g/l), Navicula bulnheimii (63.1 g/l), Berke- leya rutilans (52.5 g/l), Achnanthes brevipes (51.3 g/l), Cyclotella aff. caspia (41.7 g/l), Gram- matophora oceanica (40.7 g/l), Nitzschia etohensis (36.3 g/l), Navicula incertata (34.7 g/l), Amphora coffeaeformis var. coffeaeformis (26.9 g/l) and Nitzschia pusilla (26.3 g/l). Salinity is not the only factor affecting the composition of diatom assemblages. Diatoms occurring in freshwater are known to prefer dif- fering physical and chemical conditions. Foged (1978) summarized information on pH, salinity and nutrient concentrations of the waters from which the diatoms were collected in eastern Guest Editor: John M. Melack Saline Water and their Biota F. S. Cook Æ P. S. J. Coleman (&) Delta Environmental Consulting, 12 Beach Road, St Kilda, SA 5110, Australia e-mail: peri@deltaenvironmential.com.au Hydrobiologia (2007) 576:61–68 DOI 10.1007/s10750-006-0293-y 123 SALINE WATER Benthic diatoms in the salinas of the Dry Creek saltfields, South Australia Faith S. Cook Æ Peri S. J. Coleman Ó Springer Science+Business Media B.V. 2006