WWW.WAS.ORG • WORLD AQUACULTURE • DECEMBER 2025 21 To replicate the gentle dynamics of a natural oceanic habitat, a wave maker was employed. This system promoted uniform distribution of dissolved oxygen and nutrients throughout the water column, while also preventing stagnation and sediment buildup. An independent aeration system further ensured that dissolved oxygen levels remained within optimal ranges for bivalve health. At the bottom of the tank, calcified coral stones were strategically placed to aid in the sedimentation of organic waste, such as feces and pseudofeces. This material was then funneled toward a central drainage outlet, facilitating easy removal and reducing the risk of localized pollution. In contrast, Batch 2 followed a hybrid system, divided into two phases to mimic more natural ecological conditions while still ensuring surgical recovery. Initially, during a post-operative healing phase, the oysters in Batch 2 were maintained under the same controlled conditions as Batch 1. They received the same algal feeding regimen and environmental support to ensure uniformity in early recovery. This standardized beginning allowed for a fair comparison between the two groups in later phases. Following this initial phase, Batch 2 oysters were transitioned to a semi-natural flow-through system, where fresh, unfiltered seawater from the surrounding marine environment was continuously circulated through the tank. Water entered from one side and exited from the opposite side, establishing a steady current under natural light conditions. The ambient lighting encouraged photosynthesis by naturally occurring phytoplankton, which in turn served as a supplementary feed source for the oysters. This flow-through design (CONTINUED ON PAGE 22) TABLE 2. Pearl Production Outcomes in Batch 1 and Batch 2 (Gestation Period: 247 days) Parameter Batch 1 (Controlled System) Batch 2 (Semi-Natural System) Number of Oysters Implanted 160 160 Number of Pearls Harvested 37 119 Overall Pearl Yield (%) 23.1% 74.4% High-Quality Pearls (High Luster & Thickness) ≤10% ~60% Pearl Characteristics Irregular shapes, blemishes, poor nacre Symmetrical, smooth, high-luster, thick nacre Post-Operative Mortality Rate ~45% 2% TABLE 1. Comparative Rearing Conditions and System Parameters for Batch 1 and Batch 2 Parameter Batch 1 (Controlled System) Batch 2 (Semi-Natural System) Tank Volume 2,000 liters 2,000 liters Oyster Species Pinctada margaritifera, Pteria penguin Pinctada margaritifera, Pteria penguin Water Circulation Closed-loop with partial replacements Continuous flow-through from natural sea Filtration Mechanical biological filter (1,200 L/h) No artificial filtration Aeration System Installed Installed Wave Maker Installed Installed Bottom Substrate Calcified coral stones to trap waste Calcified coral stones to trap waste Algal Feeding – Post-Surgery Cultured microalgae (Walne medium), Same as Batch 1 50,000 cells/mL via drip system Algal Feeding – Recovery Phase Continued with cultured algae Switched to ambient phytoplankton under controlled conditions via unfiltered seawatern Light Conditions Controlled ambient light Natural sunlight for photosynthesis Water Temperature Controlled (20–22°C) via chiller Ambient seawater range (19–24°C) pH Maintained between 8.2–8.5 with Maintained naturally within same range sodium bicarbonate Salinity 31–32 ppt 31–32 ppt Microbial Exposure Limited to in-tank microbial ecosystem Open microbial connectivity with native marine environment (including phages) Biological Filter Operation 18 hours/day Not applicable
RkJQdWJsaXNoZXIy MjExNDY=