Optimizing stocking density and microalgae ration improves the growth potential of tropical black‐lip oyster, Saccostrea echinata, larvae

Abstract

The combined effects of stocking density and microalgae ration on survival and size of Saccostrea echinata larvae were studied in two‐factor experiments for the major developmental stages: D‐veliger (1‐day posthatch [dph], Experiment 1), umbonate (12 dph, Experiment 2), and eyed (19 dph, Experiment 3) larvae. Larvae were stocked into replicate sets of four 10‐L aquaria with ambient 1‐μm filtered sea water (28 ± 1.5°C and 36 ppt) and cultured for four days at densities of 0.5, 2, 5, 7, or 10 larvae/mL and provided with microalgae rations at each of five densities (cells larvae−1 day−1); 0, 1, 3, 5, or 8 × 103 (D‐veliger larvae, Experiment 1); 0, 5, 12, 18, or 25 × 103 (umbonate larvae, Experiment 2); and 0, 15, 30, 40, or 60 × 103 (eyed larvae, Experiment 3). Microalgae rations for each larval life stage were selected on the basis of increasing food requirement with larval size and comprised a 2:1:1 mixture of Chaetoceros calcitrans, Tisochrysis lutea, and Pavlova spp., calculated on an equal dry‐weight basis. Contour plots were generated from larval survival and larval size (dorso‐ventral measurement [DVM]) data to determine optimal culture conditions. Larvae showed high survival (54–100%) over a wide range of both treatment parameters across all life stages, confirming broad tolerance limits for this species. The interaction effects of larval stocking density and microalgae ration on larval size were significant (p < 0.001) across all life stages. Results indicate that maximum larval size (DVM) is achieved when S. echinata are cultured at: 6–8 larvae/mL and fed 5–6 × 103 cells larvae−1 day−1 for D‐veligers (mean DVM >80 μm), at 2–8 larvae/mL and fed 11–25 × 103 cells larvae−1 day−1 for umbonate larvae (mean DVM > 190 μm), and at 1–4 larvae/mL and fed 15–40 × 103 cells larvae−1 day−1 for eyed larvae (mean DVM >230 μm). Results will help refine current hatchery methods for S. echinata supporting further development toward commercial aquaculture production of this species.

Optimizing Microalgae Diet, Temperature, and Salinity for Dwarf Surf Clam, Mulinia lateralis, Spat Culture

“…Numerous studies have proven that the growth and survival of bivalves will be reduced if they take too much or too little microalgae, such as researches in P. margaritifera (Linard et al, 2011), M. edulis (Thomsen et al, 2013), and M. galloprovincialis (Weston et al, 2021). Stocking density is another important factor affecting food availability, and densitydependent growth and survival have been reported for many bivalves under culture conditions (Liu et al, 2010;Nowland et al, 2019). In P. martensii, the interaction between microalgae concentration and stocking density was evaluated, and the optimal culture conditions of 50.85 cells µl −1 and 1.6 ind ml −1 were obtained to maximize the growth and survival (Wang et al, 2021).…”

“…In Arctica islandica, the maximum growth rate (58.26 µm day −1 ) was observed at the microalgae concentration of 1.5 × 10 4 cells ml −1 , and insufficient or excessive microalgae is not conducive to the growth (Ballesta-Artero et al, 2018). In addition, stocking density is also an important factor affecting the utilization of food, and density-dependent growth and survival have been reported in many bivalves (Liu et al, 2010;Nowland et al, 2019). Hence, optimizing the conditions of microalgae concentration and stocking density is necessary to ensure the food availability for the bivalve.…”

Growth of V. parahaemolyticus in Tropical Blacklip Rock Oysters

“…In contrast, Blacklip Rock Oysters (BROs) ( Saccostrea lineage J) occur naturally in the Indo-Pacific region including across northern Australia [ 3 ] and are grown commercially on a limited scale. There is increasing interest in expanding the production of BROs in this region, particularly in remote Aboriginal communities, with current research focused on securing consistent spat supply and optimising production methods [ 4 , 5 ].…”