Mussels and Local Conditions Interact to Influence Microbial Communities in Mussel Beds.

Edward Higgins,Thomas B. Parr,Caryn C. Vaughn

doi:10.3389/fmicb.2021.790554

Abstract

Microbiomes are increasingly recognized as widespread regulators of function from individual organism to ecosystem scales. However, the manner in which animals influence the structure and function of environmental microbiomes has received considerably less attention. Using a comparative field study, we investigated the relationship between freshwater mussel microbiomes and environmental microbiomes. We used two focal species of unionid mussels, Amblema plicata and Actinonaias ligamentina, with distinct behavioral and physiological characteristics. Mussel microbiomes, those of the shell and biodeposits, were less diverse than both surface and subsurface sediment microbiomes. Mussel abundance was a significant predictor of sediment microbial community composition, but mussel species richness was not. Our data suggest that local habitat conditions which change dynamically along streams, such as discharge, water turnover, and canopy cover, work in tandem to influence environmental microbial community assemblages at discreet rather than landscape scales. Further, mussel burrowing activity and mussel shells may provide habitat for microbial communities critical to nutrient cycling in these systems.

Highlights

Key ecosystem processes are carried out by both microbes and animals, but microbial communities are important to evaluate in tandem with animal influences on ecosystem function as microbiome data combined with environmental data improve our understanding of ecosystem processes (Graham et al, 2016)
While Weingarten et al (2019) found that microbial communities retained by freshwater mussels were influenced by species as well as site, our study found that microbes on the shell and in material passed through the gut, did not differ between our focal species
In our exploratory study of the microbiomes of mussels and the environment they inhabitat we found that mussel microbiomes were less diverse than those of the sediment, mussel abundance was a significant predictor of sediment microbial community composition, and local habitat influenced microbial assemblage composition more than site spatial location along the river

Summary

Introduction

Key ecosystem processes are carried out by both microbes and animals, but microbial communities are important to evaluate in tandem with animal influences on ecosystem function as microbiome data combined with environmental data improve our understanding of ecosystem processes (Graham et al, 2016). Effects of animals on microbial communities are important and underexplored (Skelton et al, 2017; Fitzpatrick et al, 2018; Thoemmes and Cove, 2020). It is important to understand baseline interactions between animals and microbes in the wake of climate and land use change. In this context, streams are a good study system because they are globally threatened by pollution and climate change (Jury and Vaux, 2005)

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Discussion

Conclusion