Metagenomic insights into zooplankton‐associated bacterial communities

Abstract

SummaryZooplankton and microbes play a key role in the ocean's biological cycles by releasing and consuming copious amounts of particulate and dissolved organic matter. Additionally, zooplankton provide a complex microhabitat rich in organic and inorganic nutrients in which bacteria thrive. In this study, we assessed the phylogenetic composition and metabolic potential of microbial communities associated with crustacean zooplankton species collected in the North Atlantic. Using Illumina sequencing of the 16S rRNA gene, we found significant differences between the microbial communities associated with zooplankton and those inhabiting the surrounding seawater. Metagenomic analysis of the zooplankton‐associated microbial community revealed a highly specialized bacterial community able to exploit zooplankton as microhabitat and thus, mediating biogeochemical processes generally underrepresented in the open ocean. The zooplankton‐associated bacterial community is able to colonize the zooplankton's internal and external surfaces using a large set of adhesion mechanisms and to metabolize complex organic compounds released or exuded by the zooplankton such as chitin, taurine and other complex molecules. Moreover, the high number of genes involved in iron and phosphorus metabolisms in the zooplankton‐associated microbiome suggests that this zooplankton‐associated bacterial community mediates specific biogeochemical processes (through the proliferation of specific taxa) that are generally underrepresented in the ambient waters.

Mercury-methylating bacteria are associated with copepods: A proof-of-principle survey in the Baltic Sea

“…However, given the differences in the limit of quantification among the clades (S4 Table), the between-clade differences in the hgcA abundance should be treated with caution. Moreover, although Archaea are commonly reported to occur in zooplankton guts [26], the contribution of this group can be low compared to bacteria [27]. Therefore, the lack of hgcA amplification in the assays with archaeal primers may-at least in part-be related to the poor representation of these microorganisms in the guts.…”

Copepods promote bacterial community changes in surrounding seawater through farming and nutrient enrichment

“…Our findings suggest that copepods likely influence bacterial communities surrounding them via different mechanisms, and these communities form a copepod zoosphere that in turn may be seeding the surrounding seawater beyond. The activities influencing biogeochemical cycles in these communities are likely different from activities in the surrounding free-living organisms (De Corte et al, 2018;Moisander et al, 2018) and merit further study. Given the high abundances and ubiquitous distribution of copepods, the microbial processes occurring within the copepod zoosphere are likely to be globally important.…”

Diurnal variability in alkaline phosphatase activity and the potential role of zooplankton

“…) is similar to that of APA and phosphate reported by Mahaffey et al (). Therefore, this reveals a potential link between APA zoo and phosphate stress of the ambient microbial community, suggesting a contribution from the bacterial epibiont to APA zoo (De Corte et al ).…”

“…Normalized APA zoo values have been corrected for blank associated activity. the ambient microbial community, suggesting a contribution from the bacterial epibiont to APA zoo (De Corte et al 2018). If zooplankton are a nocturnal source of AP in the surface ocean, then to resolve the diurnal variation in APA vol there must be a net sink of AP during the day.…”