Microbiota of the Rearing Water ofPenaeus stylirostrisLarvae Influenced by Lagoon Seawater and Specific Key Microbial Lineages of Larval Stage and Survival

Abstract

In New Caledonia, rearing of P. stylirostris is one of the main economic activities; unfortunately, mass larval mortalities cause important production decreases, involving major economic losses for the farmers and the Territory. This phenomenon, which has occurred at any larval stage over the past decade, is poorly understood.

Active Microbiota of Penaeus stylirostris Larvae: Partially Shaped via Vertical and Horizontal Transmissions and Larval Ontogeny

“…In the hatchery, the breeding of mature Penaeus stylirostris broodstock was performed by artificially inseminating females, as described previously by Pham et al (2012) [ 26 ]. The water used to fill the hatching and rearing tanks was collected from Saint Vincent Bay after undergoing various treatments, as explained in Callac et al, 2022 and 2023 [ 27 , 28 ]. Briefly, lagoon seawater was pumped using a pumping device located in the Bay, which was a 1 cm-pore-size device, into a first reservoir (ResI).…”

“…Throughout the 10 days of larval rearing, no water exchange was applied. Several times per day, larvae were fed using the following protocol, as described in Callac et al, 2022 and 2023 [ 27 , 28 ]: microparticles were added five times per day, and frozen Tetraselmis sp. were given once a day to feed the larvae at the zoea 1 and 2 stages; then, from zoea 3 to post-larvae, microparticles as well as living Artemia sp.…”

“…Larval stages were established by observing 30 larvae per tank using a binocular magnifying glass, as described previously in Callac et al, 2022 and 2023 [ 27 , 28 ]. Each day, using the modified equation of Maddox and Manzi, the calculation of the Larval Stage Index (LSI) was determined as follows: LSI = (0 × Nii + 1 × Z1 + 2 × Z2 + 3 × Z3 + 4 × M1 + 5 × M2 + 6 × M3 + 7 × PL)/N, where Nii, Z1, Z2, Z3, M1, M2, M3 and PL correspond, respectively, to the number of larvae observed in the nauplius, zoea 1, zoea 2, zoea 3, mysis 1, mysis 2, mysis 3 and post larvae 1 stages, and N represents the total number of observed larvae.…”

“…Since the 1990s, Pacific blue shrimps have been reared in a semi-intensive way, leading to a current annual production of almost 1500 tons, while the production had reached 2000 tons at the beginning of the 2000s (FAO “Fisheries and Aquaculture”). This decrease is mainly due to two seasonal epizooties involving two Vibrio species that cause dramatic mortalities affecting juveniles and adult shrimps grown in earthen ponds [ 4 , 25 ] and to larval mortality occurring at all larval stages in hatcheries for which no causes have been found yet [ 26 , 27 , 28 ]. So far, no evidence of larval septicemia has been revealed.…”

“…Thus, multifactorial causes, as well as dysbiosis of the microbiota of the rearing water and/or of the larvae, have been hypothesized as factors inducing larval death. In previous studies dealing with the microbiota of the rearing water-hosting larvae with contrasted survival rates (from very low survival rates of 15% to 70%), we identified biomarkers specific to good or poor larval survival rates [ 27 , 28 ]. However, we lack data about the microbial diversity and structure associated with healthy Penaeus stylirsotris larvae.…”