Impacts of seawater desalination on the giant Australian cuttlefish Sepia apama in the upper Spencer Gulf, South Australia

With seawater desalination expanding rapidly, it is important that ecological studies are undertaken to determine the effects of brine discharge on the marine species in the area. The abundance of giant Australian cuttlefish (Sepia apama, Gray 1849) eggs and environmental data were recorded at nine sites near Point Lowly, Spencer Gulf, South Australia, an area where the largest desalination plant in the Southern hemisphere is proposed. In addition, the effects of different concentrations of desalination brine on the growth, survival and condition of cuttlefish embryos were investigated. The primary egg-laying sites for the cuttlefish were in the vicinity of Stony Point (sites 4 and 3) and the area with the least egg abundance was on the eastern and western areas around Point Lowly (sites 9 and 7) where no eggs were found. The survival of embryos decreased with an increase in salinity, with no embryos surviving to full term in salinities greater than 50‰. Mean weight and mantle length also decreased with increasing salinity. Besides elevated salinity, the brine also had increased concentrations of Ba, Ca, K, Sr and Mg relative to water near Point Lowly. Brine discharge from seawater desalination poses a potential threat to the unique spawning aggregation of the giant Australian cuttlefish, in the upper Spencer Gulf, South Australia.

随着海水淡化产业的快速扩张，开展生态学研究以探明浓盐水排放对区域海洋物种的影响已成为当务之急。本研究于澳大利亚南澳州斯宾塞湾洛蒂角（Point Lowly）附近的9个采样点位，记录了巨型澳大利亚乌贼（Sepia apama, Gray 1849）的卵丰度及环境数据——该区域为南半球拟建规模最大的海水淡化厂场址。此外，本研究还探究了不同浓度的海水淡化浓盐水对乌贼胚胎的生长、存活及健康状态的影响。该乌贼的主要产卵场集中于斯通角（Stony Point）周边区域（采样点3与4），而卵丰度最低的区域为洛蒂角周边的东部与西部海域（采样点7与9），此处未检出乌贼卵。胚胎存活率随盐度升高呈下降趋势，当盐度超过50‰时，无胚胎可发育至孵化足月。平均体重与外套膜长度同样随盐度升高而显著降低。除盐度升高外，相较于洛蒂角附近的天然海水，浓盐水还富集了钡（Ba）、钙（Ca）、钾（K）、锶（Sr）与镁（Mg）等元素。海水淡化厂排放的浓盐水，对南澳州斯宾塞湾北部海域独特的巨型澳大利亚乌贼产卵聚集种群构成潜在生态威胁。