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The black-lip rock oyster, Saccostrea echinata (Quoy and Gaimard 1835), has considerable potential for aquaculture in tropical Australia and the Indo-Pacific region, due to its large size, rapid growth rates, and established market acceptance. Previous attempts to farm S. echinata failed due to an insufficient supply of wild spat limiting commercial potential; however, the prospect of oyster farming based on hatchery produced spat has stimulated renewed interest in hatchery development research for S. echinata, and projects are currently underway in Australia and in New Caledonia. Despite this, current hatchery production of S. echinata is inconsistent, and spat yields are low compared to other commercial oyster species. Development is hampered by a lack of knowledge, particularly regarding broodstock and larval biology, optimal larviculture conditions, and genetics. This information is required to develop species-specific hatchery protocols, and responsible genetic management guidelines, for this emerging hatchery-based aquaculture industry. The over-arching goal of the research reported in this thesis was to address key knowledge gaps and current bottlenecks towards development of S. echinata as a commercial aquaculture species; in particular, to provide new information to facilitate hatchery production of S. echinata, and to generate baseline genetic information, before the start of commercial-scale aquaculture of this species. This was addressed over five separate studies investigating: (1) seasonal fluctuations in the reproductive cycle of wild S. echinata broodstock and the influence of selected exogenous factors on gonad development; (2) embryonic, larval, and early post-larval development of S. echinata; (3) the synergistic effects of water temperature and salinity on embryonic and larval development of S. echinata across each major larval development stage; (4) the combined effects of larval stocking density and microalgae ration on survival and larval size of S. echinata at each major larval development stage; and (5) population genetic structure of S. echinata across northern Australia, to assess genetic connectivity and begin to clarify the geographical range of this species based on genetic data. |
