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Abstract Microbial mortality impacts the structure of food webs, carbon flow, and the interactions that create dynamic patterns of abundance across gradients in space and time in diverse ecosystems. In the oceans, estimates of microbial mortality by viruses, protists, and small zooplankton do not account fully for observations of loss, suggesting the existence of underappreciated mortality sources. We examined how ubiquitous mucous mesh feeders (i.e. gelatinous zooplankton) could contribute to microbial mortality in the open ocean. We coupled capture of live animals by blue‐water diving to sequence‐based approaches to measure the enrichment and selectivity of feeding by two coexisting mucous grazer taxa (pteropods and salps) on numerically dominant marine prokaryotes. We show that mucous mesh grazers consume a variety of marine prokaryotes and select between coexisting lineages and similar cell sizes. We show thatProchlorococcusmay evade filtration more than other cells and that planktonic archaea are consumed by macrozooplanktonic grazers. Discovery of these feeding relationships identifies a new source of mortality for Earth's dominant marine microbes and alters our understanding of how top‐down processes shape microbial community and function.
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This content will become publicly available on April 1, 2026
Prey particle surface property mediates differential selection by the ubiquitous appendicularian Oikopleura dioica
Abstract Cell surface properties can strongly mediate microbial interactions with predators in soil and host‐pathogen systems. Yet, the role of microbial surface properties in avoiding or enhancing predation in the ocean is less well known. Appendicularians are globally abundant marine suspension feeders that capture marine microorganisms in a complex mucous filtration system. We used artificial microspheres to test whether the surface properties of prey particles influenced selection by the appendicularian,Oikopleura dioica. We used a range of microsphere sizes (0.5, 1, 2, and 3 μm), concentrations (~ 103–106particles mL−1), and two charges (amine‐modified, more positive vs. carboxylate‐modified, more negative) to represent open‐ocean microbial communities. We found that appendicularians selected between the particles of different charge. More negatively charged particles were enriched in the gut by up to 3.8‐fold, while more positive particles were enriched in the mucous filters by up to 4.7‐fold, leading to different particle fates. These results expand understanding of the mechanisms by which filter‐feeders select between prey and reveal a mechanism by which marine bacteria could rapidly alter their susceptibility to predation, either through adaption or acclimation.
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- PAR ID:
- 10621827
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Limnology and Oceanography
- Volume:
- 70
- Issue:
- 4
- ISSN:
- 0024-3590
- Page Range / eLocation ID:
- 977 to 988
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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