Functional and Compositional Changes in the Fecal Microbiome of a Shorebird during Migratory Stopover

mSystems · 3 authors, 4 centres

AI SUMMARY

FIDELITY 100%

POPULATIONRuddy Turnstones (Arenaria interpres) during spring migratory stopover at Delaware Bay, USA

INTERVENTIONNatural weight gain during stopover (birds classified as light <100g, medium 100-150g, heavy >150g)

COMPARISONBetween weight classes (light vs medium vs heavy) and between sexes

This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.

AGENT 01 · STRUCTURED SUMMARY

TRACE TO SOURCE

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TL;DR

This study of Ruddy Turnstones during migratory stopover found that both the taxonomic composition and functional gene expression of the fecal microbiome shift significantly as birds rapidly gain weight. Using 16S rRNA sequencing and metatranscriptomics, the authors identified 10 genes associated with weight class and showed that polyunsaturated fatty acid biosynthesis in the microbiota increases significantly with weight gain. These findings suggest the microbiome may play a role in the extreme weight gain that shorebirds require for long-distance migration, with implications for conservation of stopover habitats.

Full summary

3,549 CHARS

**Background:** Many migratory shorebirds undergo extreme physiological changes during stopover, including rapid weight gain (up to 7% body mass per day) to fuel long-distance flights. The role of the gut microbiome in this process is unknown, though mammalian literature shows strong links between microbiota and weight regulation. Ruddy Turnstones stop at Delaware Bay for approximately 2 weeks in May, feeding almost exclusively on horseshoe crab eggs (80-90% of gut contents), which are rich in saturated and polyunsaturated fatty acids.

**Methods:** Fecal samples were collected from 100 Ruddy Turnstones at three beaches in Delaware Bay from 7-31 May 2018. Birds were classified into three weight classes: light (<100g, n=34), medium (100-150g, n=28), and heavy (>150g, n=28). 16S rRNA gene sequencing (V4 region) was performed on 90 samples, and metatranscriptomic sequencing on 22 samples (7 light, 9 medium, 5 heavy; 14 males, 8 females). Alpha diversity (Shannon index, observed ASVs) and beta diversity (Bray-Curtis, PERMANOVA) were assessed. Differential abundance of taxa was tested using DESeq2 (α=0.001), and differential gene expression using NOISeq (α=0.001).

**Key Results:** Birds consistently gained weight over the stopover period (Linear Regression: F₁,₈₉=182.8, adj. R²=0.67, p<0.001). Alpha diversity (Shannon) differed significantly among weight classes (ANOVA: F₂,₈₈=5.648, p=0.005), with light and medium birds differing from heavy birds but not from each other. Beta diversity showed significant clustering by weight class (PERMANOVA: R²=12%, p<0.001) and sampling site (R²=3.6%, p<0.001), but not by sex. Five phyla comprised 97.3% of sequences: Fusobacteria (40.7%), Proteobacteria (26.7%), Firmicutes (18.9%), Bacteroidetes (5.8%), and Tenericutes (5.2%). Thirteen genera were differentially abundant across weight classes; notably, Vibrio, Shewanella, and Photobacterium were overexpressed in heavy birds. Functional gene communities (based on KEGG Orthology) differed significantly among weight classes (PERMANOVA: F₂,₁₉=2.78, R²=0.227, p=0.02), but not between sexes. Ten KOs were differentially expressed between weight classes (p<0.001). Expression of three polyunsaturated fatty acid pathways significantly increased with weight: linoleic acid metabolism (R²=0.19, p=0.024), alpha-linoleic acid metabolism (R²=0.23, p=0.014), and arachidonic acid metabolism (R²=0.39, p=0.001). Biosynthesis of unsaturated fatty acids was not significantly associated with weight (R²=0.03, p=0.216).

**Clinical Implications:** This study provides the first evidence that both taxonomic composition and functional gene expression of the fecal microbiome shift during rapid weight gain in a wild migratory bird. The finding that polyunsaturated fatty acid biosynthesis pathways increase with weight suggests the microbiome may contribute to fat deposition, potentially by producing essential fatty acids the host cannot synthesize. The identification of marine bacteria (Vibrio, Shewanella, Photobacterium) increasing in heavier birds, which are known PUFA producers, suggests a potential microbial contribution to the bird's energy storage. These results highlight the importance of high-quality stopover habitats where birds can obtain the dietary resources needed to support both their own physiology and their microbiome during this critical life stage. The study also demonstrates that 16S rRNA and metatranscriptomic approaches provide complementary insights, as taxonomic and functional patterns were partially decoupled.

PICO

PPOPULATION

Ruddy Turnstones (Arenaria interpres) during spring migratory stopover at Delaware Bay, USA

IINTERVENTION

Natural weight gain during stopover (birds classified as light <100g, medium 100-150g, heavy >150g)

OOUTCOME

Taxonomic composition (16S rRNA), functional gene expression (metatranscriptomics), differentially expressed genes, polyunsaturated fatty acid pathway expression

STUDY TYPE

cohort

SPECIALTY

microbiology

SUMMARISED BY

AI pipeline

FIDELITY CHECK

100% · A

ORIGINAL PAPER

PMC10134852

Functional and Compositional Changes in the Fecal Microbiome of a Shorebird during Migratory Stopover

mSystems

READ THE FULL PAPER

ABSTRACT

ABSTRACT Shorebirds migrate long distances twice annually, which requires intense physiological and morphological adaptations, including the ability to rapidly gain weight via fat deposition at stopover locations. The role of the microbiome in weight gain in avian hosts is unresolved, but there is substantial evidence to support the hypothesis that the microbiome is involved with host weight from mammalian microbiome literature. Here, we collected 100 fecal samples of Ruddy Turnstones to investigate microbiome composition and function during stopover weight gain in Delaware Bay, USA. Using 16S rRNA sequencing on 90 of these samples and metatranscriptomic sequencing on 22, we show that taxonomic composition of the microbiome shifts during weight gain, as do functional aspects of the metatranscriptome. We identified 10 genes that are associated with weight class, and polyunsaturated fatty acid biosynthesis in the microbiota is significantly increasing as birds gain weight. Our results support that the microbiome is a dynamic feature of host biology that interacts with both the host and the environment and may be involved in the rapid weight gain of shorebirds. IMPORTANCE Many animals migrate long distances annually, and these journeys require intense physiological and morphological adaptations. One such adaptation in shorebirds is the ability to rapidly gain weight at stopover locations in the middle of their migrations. The role of the microbiome in weight gain in birds is unresolved but is likely to play a role. Here, we collected 100 fecal samples from Ruddy Turnstones to investigate microbiome composition (who is there) and function (what they are doing) during stopover weight gain in Delaware Bay, USA. Using multiple molecular methods, we show that both taxonomic composition and function of the microbiome shifts during weight gain. We identified 10 genes that are associated with weight class, and polyunsaturated fatty acid biosynthesis in the microbiota is significantly increasing as birds gain weight. Our results support that the microbiome is a dynamic feature of host biology that interacts with both the host and the environment and may be involved in the rapid weight gain of shorebirds.

CITATION EXPORT

Kirsten Grond, Artemis S. Louyakis, Sarah M. Hird. Functional and Compositional Changes in the Fecal Microbiome of a Shorebird during Migratory Stopover. mSystems. (2023). https://doi.org/10.1128/msystems.01128-22

AUTHORS

3 · 4 CENTRES

Kirsten Grond, Artemis S. Louyakis, Sarah M. Hird

a Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
b Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, USA
The University of Maine
University of Pittsburgh

EDITOR / REVIEWER

Suzanne Lynn Ishaq, Brian Trevelline