Biology subjects

De Schryver, P.

Publications and source records attributed to De Schryver, P..

3 recordsLinked to original sources

bioRxiv2024

Molybdate application in the early stages of shrimp growth suppresses sulphide formation in a shrimp pond bottom model

Oxygen depletion and sulphide formation, resulting from the accumulation of organic waste, are common challenges in shrimp ponds that could result in complete harvest failure. The stage at which these circumstances occur during the shrimp growth period remains elusive, yet, knowledge of the timing of oxygen depletion and sulphide formation is essential to enable remediating actions. Here, we used an experimental shrimp pond model at different stages in the shrimp growth period to determine when oxygen depletion and sulphide production occur. Microscale depth measurements of oxygen and H2S were determined using microelectrodes to visualize their profiles at different depths of the water-sediment interface and the sediment. We evaluated the potential of different molybdate concentrations at different stages to determine the optimal conditions to suppress H2S formation. Oxygen depletion and sulphide production took place in the middle of the shrimp growth cycle in the simulated model of waste accumulation. The addition of molybdate was only effective in the early stages of the onset of oxygen depletion and H2S formation, and residual molybdate was required to ensure a continuous suppression of sulphide production. However, oxygen depletion could not be prevented and reintroduction of oxygen did not occur when molybdate was added. In conclusion, molybdate appeared to be an effective strategy to suppress H2S formation at the onset of its production in a shrimp pond bottom model.

microbiology↗

bioRxiv2023

Long-term sulphide mitigation through molybdate at shrimp pond bottoms

Shrimp are commonly cultured in earthen aquaculture ponds where organic-rich uneaten feed and faeces accumulate on and in the sediment to form anaerobic zones. Since the pond water is rich in sulphate, these anaerobic conditions eventually lead to the production of sulphide. Sulphides are toxic and even lethal to the shrimp that live on the pond sediment, but physicochemical and microbial reactions that occur during the accumulation of organic waste and the subsequent formation of sulphide in shrimp pond sediments remain unclear. Molybdate treatment is a promising strategy to inhibit sulphate reduction, thus, preventing sulphide accumulation. We used an experimental shrimp pond model to simulate the organic waste accumulation and sulphide formation during the final 61 days of a full shrimp growth cycle. Sodium molybdate (5 and 25 mg/L Na2MoO4.2H2O) was applied as a preventive strategy to control sulphide production before oxygen depletion. Molybdate addition partially mitigated H2S production in the sediment, and delayed its transfer to the bulk liquid by pushing the higher sulphide concentration zone towards deeper sediment layers. Molybdate treatment at 25 mg/L significantly impacted the overall microbial community composition and treated samples (5 and 25 mg/L molybdate) had about 50% higher relative abundance of sulphate reducing bacteria than the control (no molybdate) treatment. In conclusion, molybdate has the potential to work as mitigation strategy against sulphide accumulation in the sediment during shrimp growth by directly steering the microbial community in a shrimp pond system.

bioengineering↗

bioRxiv2020

Rearing water microbiomes in white leg shrimp (Litopenaeus vannamei) larviculture assemble stochastically and are influenced by the microbiomes of live feed products

The development of effective management strategies to reduce the occurrence of diseases in aquaculture is hampered by the limited knowledge on the microbial ecology of these systems. In this study, the dynamics and dominant community assembly processes in the rearing water of Litopenaeus vannamei larviculture tanks were determined. Additionally, the contribution of peripheral microbiomes, such as those of live and dry feeds, to the rearing water microbiome were quantified. The community assembly in the hatchery rearing water over time was dominated by stochasticity, which explains the observed heterogeneity between replicate cultivations. The community undergoes two shifts that match with the dynamics of the algal abundances in the rearing water. Source tracking analysis revealed that 37% of all bacteria in the hatchery rearing water were either introduced by the live or dry feeds, or during water exchanges. The contribution of the microbiome from the algae was the largest, followed by that of the Artemia, the exchange water and the dry feeds. Our findings provide fundamental knowledge on the assembly processes and dynamics of rearing water microbiomes and illustrate the crucial role of these peripheral microbiomes in maintaining health-promoting rearing water microbiomes. Originality-Significance StatementMost studies on rearing water microbiomes are characterized by sampling resolutions of multiple days and by few replicate cultivations. Through an 18-day sampling campaign in a Litopenaeus vannamei hatchery where five replicate cultivations were studied at a sampling resolution of one day, we studied the microbiome dynamics in this system. We show that the community assembly is dominated by stochasticity, which explains the heterogeneity between replicate cultivations. The dynamics of the algal community in the rearing water induced shifts in community composition at two differerent timepoints. Finally, we quantified the contribution of live and dry feed microbiomes to the rearing water community for the first time. We found that the contribution of each source was dependent on its taxonomic composition, the bacterial load caused by the addition of this source and the timing of the introduction. These new insights will aid in the further development of effective microbiome management to reduce the frequency and magnitude of bacterial diseases.

microbiology↗