| dc.description.abstract | King prawn (Penaeus vannamei) production is one of the most valuable and fastest growing sectors in aquaculture. The industry is expanding globally, with a major shift toward indoor closed-system production where culture conditions can be carefully controlled and optimised to improve productivity, health, welfare, and quality of the product. The crustacean exoskeleton is a vital adaptation which provides mechanical support and physical protection from predation and diseases, therefore maintaining a healthy exoskeleton is important for successful culture. To grow this exoskeleton must be shed and replaced, through a process known as ecdysis. Immediately after ecdysis, the new exoskeleton must be calcified to complete the hardening process by taking up calcium and bicarbonate ions from the external water via the gills. The aims of this thesis were four-fold. Chapter Two aims to provide a comprehensive assessment of the impacts of light on aquaculture species and to identify a model system to investigate moulting in Penaeus vannamei using light manipulation. Chapter Three and Four aimed to identify the relationship between alkalinity and the net base uptake in the first 24 h post-moult and to investigate the subsequent effect of this relationship on exoskeleton composition. Significant knowledge gaps are identified for light impacts on aquaculture species, especially non-fish taxa. P. vannamei prefers moulting in the dark phase and moulting events can be constrained by reducing the dark period, generating an ideal model for investigating post-moult calcification in this species. This thesis revealed a Michaelis-Menten style saturation kinetics relationship between titratable alkalinity in the water and base uptake after moulting. It is postulated that this relationship explains why P. vannamei exposed acutely to low alkalinities post-moult have thinner, less-mineralised exoskeletons. This thesis recommends total alkalinity conditions of king prawns remain above >1,800 µmol L-1 to ensure bicarbonate uptake is not perturbed and therefore calcification is not affected. Alkalinity is a largely overlooked parameter in the industry and so this thesis highlights it’s importance for healthy king prawn husbandry. | en_GB |
