{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T05:38:39Z","timestamp":1777009119329,"version":"3.51.4"},"reference-count":48,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,4,11]],"date-time":"2026-04-11T00:00:00Z","timestamp":1775865600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Special Survey on River- and Lake-Migratory Fish Resources in Yueqing City","award":["25FW044"],"award-info":[{"award-number":["25FW044"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biology"],"abstract":"<jats:p>Ayu (Plecoglossus altivelis) is an East Asian amphidromous river fish, yet seasonal microbiota dynamics remain unclear. We investigated ayu in the Dajing Stream (Zhejiang Province, China) by synchronously sampling water microbiota (H), gut content microbiota (N), and gut tissue-associated microbiota (C) across four seasons. Each season, four fish were collected, and an overlapping pooling strategy (abc\/abd\/bcd) generated three composite replicates for C and N (n = 3 composites\/season); water was collected as three field replicates (n = 3\/season), yielding 36 samples (12 per niche). Using 16S rRNA amplicon sequencing and COI barcoding of stomach contents, we observed the clearest seasonal differentiation in H and seasonal variation in N consistent with diet shifts, whereas C was comparatively stable. COI signals indicated a diet dominated by aquatic insects in spring\/summer, which shifted toward smaller prey (e.g., rotifers) in winter. Together, these results highlight strong niche partitioning and season-linked shifts in water and gut content communities relative to the more stable tissue-associated microbiota. These findings should be interpreted as exploratory and require validation in larger individual-level studies.<\/jats:p>","DOI":"10.3390\/biology15080605","type":"journal-article","created":{"date-parts":[[2026,4,13]],"date-time":"2026-04-13T11:38:26Z","timestamp":1776080306000},"page":"605","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Seasonal Dynamics of the Gut Microbiota of Ayu (Plecoglossus altivelis) Revealed by a Cross-Sectional Seasonal Survey in the Dajing Stream, Zhejiang Province, China"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-4143-8538","authenticated-orcid":false,"given":"Yuqian","family":"Wu","sequence":"first","affiliation":[{"name":"Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai 200092, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Heng","family":"Xu","sequence":"additional","affiliation":[{"name":"Yueqing Municipal Agricultural and Rural Development Center, Yueqing, Wenzhou 325600, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haichuan","family":"Li","sequence":"additional","affiliation":[{"name":"Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai 200092, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hufeng","family":"Chen","sequence":"additional","affiliation":[{"name":"Yueqing Municipal Agricultural and Rural Development Center, Yueqing, Wenzhou 325600, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Libing","family":"Zhang","sequence":"additional","affiliation":[{"name":"Yueqing Municipal Agricultural and Rural Development Center, Yueqing, Wenzhou 325600, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shahid","family":"Ali","sequence":"additional","affiliation":[{"name":"Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, IL 60637, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jinyuan","family":"Che","sequence":"additional","affiliation":[{"name":"Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai 200092, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Baolong","family":"Bao","sequence":"additional","affiliation":[{"name":"Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai 200092, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/j.eng.2022.12.011","article-title":"The Fish Microbiota: Research Progress and Potential Applications","volume":"29","author":"Luan","year":"2023","journal-title":"Engineering"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Egerton, S., Culloty, S., Whooley, J., Stanton, C., and Ross, R.P. 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