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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13156

Nutrient storage and utilisation in relation to reproductive condition of the New Zealand scallop Pecten novaezelandiae

Ka Lai Clara Wong, Andrea C. Alfaro*

*Corresponding author:

ABSTRACT: The New Zealand native scallop Pecten novaezelandiae has high economic value from wild catch and has aquaculture potential. We investigated scallop nutrient (carbohydrates, proteins, lipids) storage and utilization in relation to a reproductive cycle at 2 sites (Hauraki Gulf, Auckland, New Zealand) over 1 year. Water samples were collected for seston and chlorophyll a analyses, and sediment samples were taken to evaluate the potential for re-suspended nutrients as food sources for scallops. Isotope (carbon and nitrogen) and proximate analyses were conducted for gonad, adductor muscle and digestive gland, seston (1.2−5 µm, >5 µm) and sediment samples. Isotope analyses revealed different signatures in suspended sediment and scallop tissues, indicating that re-suspended nutrients are unlikely to contribute to their diet. However, seston (particularly small fractions) signatures were closely related to scallop tissues, suggesting a main food source. Scallops from both sites exhibited similar reproductive cycles and utilization of nutrients. Gametogenesis started in winter (increased gonad index and energy content) and used carbohydrates stored in adductor muscles. Spawning events in spring (October−November) and summer (January−March) were associated with a sharp drop in visual gonad index (VGI), gonad index, lipid and energy contents. The energy demand required during spawning was supported by digestive gland protein. Gonad re-maturation was indicated by increases in VGI, gonad index, lipid and energy contents post-spring spawning, and gonad recovery was supported by lipids from digestive glands. Results show that P. novaezelandiae utilizes energy reserves from both adductor muscle and digestive gland to cover the full gametogenesis costs.