Relationships between pond water and tilapia skin microbiomes in aquaculture ponds in Malawi

Abstract

Intensification of fish farming practices is being driven by the demand for increased food production to support a rapidly growing global human population, particularly in lower-middle income countries. Intensification of production, however, increases the risk of disease outbreaks and thus likelihood for crop losses. The microbial communities that colonise the skin mucosal surface of fish are poorly understood, but are important in maintaining fish health and resistance against disease. This skin microbial community is susceptible to disruption through stressors associated with transport, handling and the environment of intensive practices, and this risks the propagation of disease-causing pathogens. In this study, we characterised the microbial assemblages found on tilapia skin - the most widely farmed finfish globally - and in the surrounding water of seven earthen aquaculture ponds from two pond systems in distinct geographic regions in Malawi. Metabarcoding approaches were used to sequence the prokaryotic and microeukaryotic communities. We found 92% of prokaryotic amplicon sequence variants were common to both skin and water samples. Differentially enriched and core taxa, however, differed between the skin and water samples. In tilapia skin, Cetobacterium, Paucibacter, Pseudomonas and Comamonadaceae were enriched, whereas, the cyanobacteria Cyanobium, Microcystis and/or Synechocystis, and the diatom Cyclotella, were most prevalent in pond water. Ponds that clustered together according to their water prokaryotic communities also had similar microeukaryotic communities indicating strong environmental influences on prokaryotic and microeukaryotic community structures. While strong site-specific clustering was observed in pond water, the grouping of tilapia skin prokaryotes by pond site was less distinct, suggesting fish microbiota have a greater buffering capacity against environmental influences. The characterised diversity, structure and variance of microbial communities associated with tilapia culture in Malawi provides the baseline for studies on how future intensification practices may lead to microbial dysbiosis and disease onset.

The Diversity and Ubiquity of Antibiotic Resistance Genes in Finfish Culture Ponds in Bangladesh

“…Of all environmental factors assessed in our study (fish species farmed in the ponds, pond location, and season/sampling timepoint), only Upazila correlated with microbial diversity. This supports previous work indicating that geography influences the microbiota composition of aquaculture ponds in Bangladesh (McInnes et al, 2021) and Malawi (McMurtrie et al, 2022). This is also true in freshwater lakes (Yang et al, 2019) and open oceans (Sehnal et al, 2021) where geography is correlated with aquatic microbial diversity.…”

“…Microbiomes were dominated by Proteobacteria for bacteria, Euryarchaeota for archaea and Uroviricota for viruses, with no obvious seasonal differences. Proteobacteria were also the most common bacterial phylum found in aquaculture earthen finfish ponds in Malawi (McMurtrie et al, 2022) and China (Liu et al, 2020; Qin et al, 2016). In another study characterising pond microbiomes across districts in Bangladesh (Mymensingh, Shariatpur, and Dhaka), Cyanobacteria were the most common phylum, however, Proteobacteria were the most highly abundant bacteria phyla in five of seven water samples in the Dhaka district (McInnes et al, 2021).…”

Pengaruh Ekstrak Daun Rhizophora mucronata Terhadap Hematologi Ikan Nila (Oreochromis niloticus) yang Diuji Tantang Aeromonas hydrophila

“…Apart from that, tilapia has advantages in immunity and physiological adaptability to high salinity ranges (Fuadi et al, 2021). The increase in tilapia production is also driven by food requirements to support human population growth (McMurtrie et al, 2022). So the level of market demand, both domestic and foreign, will continue to increase (Mandasari et al, 2023).…”