Biochemical composition of turbinid snails and its sensitivity to ocean climate change

Information on the biochemical composition of under-utilised species, such as turban snails, is required to establish their nutritional quality, and improve consumer acceptance as a novel food source. Turbo militaris, Lunella undulata and L. torquata are large common gastropod species with overlapping distributions in eastern Australia. The edible foot tissue from these three species was analysed for comparison of their proximate composition, fatty acids and mineral elements. All species were found to have a high protein content and low lipid levels that are rich in polyunsaturated fatty acids (PUFAs), with a favourable ratio of omega–3/omega–6 PUFAs for human consumption. Turban snails also provide a good source of essential elements. To quantify the temporal changes in nutritional properties, L. undulata was collected monthly from the same site, Evans head, NSW from December 2013 to January 2015. Sex, shell sizes and gonadosomatic index (GSI) were recorded in order to investigate if these parameters influence the condition index (CI), meat yield (MY), proximate composition and trace elements of the edible foot tissue. The flesh of L. undulata can be considered nutritious and generally safe for human consumption all year round, but for the purpose of sustainable harvest, the peak spawning should be avoided to allow for successful reproduction. A manipulative experiment to investigate the effects of 38-day exposure to near-future ocean warming and acidification revealed that temperature alone affects the percentages of PUFAs in the foot tissue. Nevertheless, the main nutritional properties of high protein and low lipids dominated by PUFAs were consistently found in the Turbinidae. Toxic heavy metal elements remained well below the maximum allowed under Australia and New Zealand Food Standards. Based on their upper thermal limit, turban snails may be resilient to near-future ocean-warming, but they prefer lower temperatures, which could result in a southward retraction of the distribution of these species in NSW, Australia. Overall, this study shows that turban snails can provide a fisheries resource of similar quality to abalone, but ocean warming may influence the range of the target populations and the quality of lipids, but the product would be otherwise little-affected.