Uptake of dissolved free amino acids by larvae of the crown-of-thorns starfish, Acanthaster planci, from the Great Barrier Reef

Early brachiolaria larvae (6 days old) were reared at the Australian Institute of Marine Science for use in dissolved organic matter uptake experiments. Three dissolved free amino acids (substrates) were chosen for the experiments: alanine (neutral); glutamic acid (acidic); and arginine (basic). Between 120 and 240 larvae were placed in individual scintillation vials containing filtered seawater and maintained at 29.5°C. Experiments were run using filtered seawater with only one substrate. Different amounts of substrates were added to vials with or with larvae, as well as vials with formalin killed larvae. Triplicate 500 µl samples were withdrawn from each vial initially and then after incubation for 20, 40 and 60 minutes. Samples were passed through a 100 µm mesh screen to remove larvae and frozen in a micro-centrifuge tube for later DFAA analysis using the pre-column derivatization method with HPLC. This research was undertaken to investigate the ability of early brachiolaria larvae of the crown-of-thorns starfish, Acanthaster planci, to take up dissolved organic matter (DOM) in the form of dissolved free amino acids (DFAA).