Lethal and sublethal effects of simultaneous exposure to hypoxia and aluminium on juvenile eastern school prawn

Abstract

Estuarine waters are heavily influenced by catchment land use and run-off, and acid sulfate soils directly affect both dissolved oxygen (DO) and aluminium concentrations. This can affect harvested species (including benthic crustaceans) and can have concomitant effects on their productivity. In this study we evaluated the effects of hypoxia (DO concentrations <2mgL–1) on eastern school prawn (Metapenaeus macleayi) under enhanced and ambient aluminium concentrations (mean±s.d., 0.112±0.009 and 0.015±0.002mgL–1 respectively). There was a significant increase in survival with increasing DO and LC50 was ~0.9mgL–1, although survival decreased at higher DO concentrations in the presence of enhanced aluminium concentrations. Total fatty acid and amino acid concentrations were significantly greater in prawns subjected to hypoxia, regardless of aluminium exposure. Docosahexaenoic acid, stearic acid, palmitic acid and behenic acid (fatty acids) and leucine, isoleucine, phenylalanine and asparagine (amino acids) contributed to differences in fatty and amino acid profiles among treatments. Hypoxia and aluminium concentrations in nursery habitats of south-eastern Australian estuaries can exceed the conditions evaluated, and could thus affect survival of M. macleayi. More generally, these results have implications for other crustacean species in estuaries that drain coastal flood plains, and the fisheries that rely on them.