Influence of Environmental Stressors on the Microbiota of Zebra Mussels (Dreissena polymorpha)

Abstract

Host-associated microbiota play a critical role in host fitness by providing nutrition, enhancing digestion capabilities, and by providing protection from pathogens. Here, we investigated the effects of two environmental stressors, temperature, and salinity, on the microbiota associated with zebra mussels (ZMs), a highly invasive bivalve in North America. To examine this in detail, lake-collected ZMs were acclimated to laboratory conditions, and subjected to temperature and salinity stress conditions. The impact of these stressors on the diversity, composition, and dynamics of ZM-associated microbiota were assessed by using amplicon- and shotgun-based sequencing, and qPCR-based approaches. Elevated temperature was found to be the primary driver of ZM mortality, although salinity alone also increased its likelihood. Stressor-induced ZM mortality, which ranged between 53 and 100%, was concomitant with significant increases in the relative abundance of several genera of putative opportunistic pathogens including Aeromonas. These genera were only present in low relative abundance in ZMs obtained from the control tank with 0% mortality. Shotgun sequencing and qPCR analyses indicated that the relative and absolute abundances of pathogenic Aeromonas species (particularly A. veronii) were significantly greater in temperature-induced dead ZMs. Taken together, our results show that environmental stress, especially elevated temperature (> 25 °C), is associated with the rapid mortality of ZMs as well as the proliferation of putative opportunistic bacterial pathogens.

Modest dispersal, low densities, and little change in water clarity characterize zebra mussel populations near the southern extent of their range

“…Zebra mussels may not be able to form large populations in Missouri because they are living in tolerable but stressful conditions. This is consistent with experimental studies that show zebra mussel mortality is higher when 2 environmental parameters are stressful but sublethal compared to just one (Mathai et al 2020).…”

Toward invasive mussel genetic biocontrol: Approaches, challenges, and perspectives

“… 121 At the same time, E. coli bacteria is an acceptable food source for many animals and has been found in the zebra mussel gut. 122 Several alternative microbial vectors have also been tested as vectors for feeding RNAi in other systems, including bacterial symbionts, 123 yeast, 124 and microalgae. 35 , 36 Due to the variation in eRNAi susceptibility between species and the fact that zebra mussels can selectively filter different particles when feeding, 87 , 125 it will be important to determine whether the feeding of RNAi trigger-expressing microorganisms is a viable delivery strategy for zebra mussels or if the amount of consumed microbe in the wild is enough to induce RNAi phenotypes.…”

Effects of Ocean Acidification, Hypoxia, and Warming on the Gut Microbiota of the Thick Shell Mussel Mytilus coruscus Through 16S rRNA Gene Sequencing

“…Both have important ecological and biological functions and regulate symbiosis, competence, virulence, secondary metabolite production, extracellular enzymes, biofilm formation, and bioluminescence in the marine environment (De Kievit, 2009;Chong et al, 2012;Mangwani et al, 2012). Changes in environmental factors such as temperature, would affect microbial community composition either directly or indirectly (Mathai et al, 2020). The increased temperature is a critical factor in regulating the bacteria virulence (Lee et al, 2001;Kimes et al, 2012) and innate immunity of bivalves (Cheng et al, 2004).…”