Microbial Interactions in Marine Copepod Ecosystems

Marine copepods represent a pivotal interface between primary producers and higher trophic levels, hosting complex microbial assemblages on their exoskeletons, in their guts and within sinking carcasses. These associations encompass both stable symbionts and transient opportunists, notably members of Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria, which exploit nutrient‐rich microhabitats generated by copepod metabolism, excretion and sloppy feeding. Microbial communities contribute to the remineralisation of organic matter, cycling of nitrogen, phosphorus and trace elements, and the production of labile dissolved organic compounds that fuel planktonic heterotrophs. Host identity, life history traits and environmental factors such as food quality and ambient pH shape community composition, giving rise to core taxa shared across seasons as well as genus‐specific assemblages. Advances in high‐throughput sequencing and predictive functional profiling have revealed that copepod‐associated bacteria possess specialised gene repertoires for processes including methanogenesis, sulphate reduction and cobalamin synthesis. These interactions influence global biogeochemical cycles, underpin carbon sequestration and present opportunities for aquaculture enhancement and environmental remediation.

Research from Nature Portfolio

A meta‐analytical study combining machine‐learning classifiers with predictive functional profiling dissected bacteriobiomes of five copepod genera. It identified 50 key sequence variants differentiating genera and uncovered that Pleuromamma spp. communities are enriched in genes for methanogenesis and nitrogen fixation, while Temora spp. harbour pathways for assimilatory sulphate reduction and vitamin B12 synthesis. This work demonstrates host‐driven selection of microbial consortia with distinct biogeochemical roles, highlighting that copepod–microbe associations contribute specialised metabolic functions not observed in ambient seawater.

Microbial Interactions in Marine Copepod Ecosystems publication trend

The graph below shows the total number of articles in microbial interactions in marine copepod ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Microbiome: The full complement of microorganisms (bacteria, archaea, fungi and viruses) inhabiting a defined environment, such as the surfaces or internal tissues of copepods.

16S rRNA gene sequencing: A molecular method targeting the ribosomal RNA gene to characterise bacterial community composition based on conserved and variable regions.

Amplicon Sequence Variant (ASV): A unique DNA sequence obtained directly from amplicon data, representing a precise microbial taxon without clustering by similarity thresholds.

Metagenomics: The study of genetic material recovered directly from environmental samples to infer the taxonomic diversity and functional potential of entire microbial communities.

PICRUSt2: A computational tool that predicts the functional gene content of microbial communities from marker gene sequences by referencing known genomic databases.

References

1. Dynamics of Gut Bacteria Across Different Zooplankton Genera in the Baltic Sea. Microbial Ecology (2024).
2. Marine Copepods as a Microbiome Hotspot: Revealing Their Interactions and Biotechnological Applications. Water (2023).
3. Stable Associations Masked by Temporal Variability in the Marine Copepod Microbiome. PLOS ONE (2015).
4. Host-Specific and pH-Dependent Microbiomes of Copepods in an Extensive Rearing System. PLOS ONE (2015).
5. Dissolved Compounds Excreted by Copepods Reshape the Active Marine Bacterioplankton Community Composition. Frontiers in Marine Science (2017).
6. Fixed-Nitrogen Loss Associated with Sinking Zooplankton Carcasses in a Coastal Oxygen Minimum Zone (Golfo Dulce, Costa Rica). Frontiers in Marine Science (2017).
7. Meta-analysis cum machine learning approaches address the structure and biogeochemical potential of marine copepod associated bacteriobiomes. Scientific Reports (2021).
8. Nitrogen and phosphorus recycling mediated by copepods and response of bacterioplankton community from three contrasting areas in the western tropical South Pacific (20∘ S). Biogeosciences (2018).