Nutrient limitation of phytoplankton in solar salt ponds in Shark Bay, Western Australia

R.D. Segal, Anya Waite, D.P. Hamilton

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    7 Citations (Scopus)


    The aim of this research was to examine nutrient limitation of phytoplankton in solar saltponds of varying salinity at Useless Inlet in WesternAustralia. These ponds use solar energy to evaporateseawater for the purpose of commercial salt production.A combination of techniques involving watercolumn nutrient ratios, comparisons of nutrientconcentrations to concentration of magnesium ionsand bioassays were used in the investigation. Comparisonsof changes in dissolved inorganic nitrogen tophosphorus ratios and concentrations of dissolvedinorganic nutrients against changes in concentrationsof the conservative cation Mg2? indicated thatphytoplankton biomass was potentially nitrogen limitedalong the entire pond salinity gradient. Nutrient addition bioassays indicated that in low salinity ponds, phytoplankton was nitrogen limited but in high salinity ponds, phosphorus limited. This may bedue to isolation of phytoplankton in bioassay bottlesfrom in situ conditions as well as to changes inphytoplankton species composition between ponds,and the variable availability of inorganic and organicnutrient sources. The differences in limiting nutrientbetween methods indicate that phytoplankton cellsmay be proximally limited by nutrients that are nottheoretically limiting at the pond scale. Dissolvedorganic nutrients constituted a large proportion oftotal nutrients, with concentrations increasingthrough the pond sequence of increasing salinity.From the change in nutrient concentrations in bioassaybottles, sufficient dissolved organic nitrogen maybe available for phytoplankton uptake in low salinity ponds, potentially alleviating the dissolved inorganic nitrogen limitation of phytoplankton biomass.
    Original languageEnglish
    Pages (from-to)97-109
    Issue number1
    Publication statusPublished - 2009


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