Biotic and abiotic factors influencing channel catfish eggs and gut microbiome dynamics durning early life stages

Authors: ABDUL RAZAK, S - Michigan State University; GRIFFIN, MATT - Mississippi State University; MISCHKE, CHUCK - Mississippi State University; Bosworth, Brian; Waldbieser, Geoffrey - Geoff; WISE, DAVID - Mississippi State University; MARSH, T - Michigan State University; SCRIBNER, K - Michigan State University

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2018
Publication Date: 8/30/2019
Citation: S, A., Griffin, M.J., Mischke, C.M., Bosworth, B.G., Waldbieser, G.C., Wise, D.J., Marsh, T.L., Scribner, K.T. 2019. Biotic and abiotic factors influencing channel catfish eggs and gut microbiome dynamics durning early life stages. Aquaculture. 498:556-567.

Interpretive Summary: Problem: Catfish growth and health in earthen ponds can be influenced by genetic and environmental factors, and individual ponds can have unique ecosystems that affect catfish performance. In order to better understand microbial communities present in the early stages of the catfish life cycle, scientists at Michigan State University, Mississippi State University, and USDA, ARS, Warmwater Aquaculture Research Unit in Stoneville, MS, sampled hatchery and pond water, eggs, and gut tissue from newly hatched and 3 week old catfish fry. High-throughput DNA sequencing was used to determine the diversity and relative abundance of the microbes present in these samples. Several unclassified Proteobacteria and Firmicutes genera along with other opportunistic pathogens like Vibrio, Aeromonas, and Flavobacterium were associated with differences in gut bacterial communities during larval development before and after pond stocking. These experiments demonstrated that rearing environment influenced the transfer of microbes from water or food into the gut, and provided initial insights into the microbes inside the channel catfish gut. The findings suggested effective probiotic treatments to enhance 'good' microbes in the catfish gut may require manipulation of the pond or hatchery water.

Technical Abstract: This study quantifies the effects of rearing environments associated with pond aquaculture on microbial community composition in larval Channel Catfish (Ictalurus punctatus) gastrointestinal (GI) tract across early developmental stages. Larvae were reared under standard industry conditions exposed to hatchery water and sampled at five developmental stages (Egg, Swim-up, Day of stocking in nursery ponds, 24 hr post-stocking, and 21 d post-stocking). Massive-parallel sequencing of a segment of the 16S rRNA gene was conducted using an Illumina MiSeq platform to characterize the diversity and taxonomic composition of gut and water microbial communities. PERMANOVA analyses of differences in egg/gut community composition across stages indicated a significant interaction between nursery pond environment, and family (p < 0.05) during the last two stages. Several unclassified Proteobacteria and Firmicutes genera along with other opportunistic pathogens like Vibrio, Aeromonas, Flavobacterium were associated with differences in gut bacterial communities during larval development before and after pond stocking. Our study demonstrate rearing environment is an important factor influencing the transfer of microbes from water or food into the gut, and provides insight concerning the niche and ecological adaptability of microbes inside the channel catfish gut. Findings suggest probiotic treatments to enhance gut microbiota in channel catfish aquaculture may be inefficacious without concurrent pond or environmental microbial manipulation.