Sponsor
Funding was provided by Simons Foundation award LS-ECIAMEE-00001481 and NSF-OCE 1851412 to AWT, and NSF-OCE 1851537 to K.R.S. K.B. was funded through National Institutes of Health (NIH) awards UL1GM118964, RL5GM118963, and TL4GM118965.
Published In
PNAS nexus
Document Type
Article
Publication Date
2-2024
Subjects
Filter feeders -- microorganisms, Microorganisms -- Identification
Abstract
The mechanism of mortality plays a large role in how microorganisms in the open ocean contribute to global energy and nutrient cycling. Salps are ubiquitous pelagic tunicates that are a well-known mortality source for large phototrophic microorganisms in coastal and high-latitude systems, but their impact on the immense populations of smaller prokaryotes in the tropical and subtropical open ocean gyres is not well quantified. We used robustly quantitative techniques to measure salp clearance and enrichment of specific microbial functional groups in the North Pacific Subtropical Gyre, one of the largest ecosystems on Earth. We discovered that salps are a previously unknown predator of the globally abundant nitrogen fixer Crocosphaera; thus, salps restrain new nitrogen delivery to the marine ecosystem. We show that the ocean’s two numerically dominant cells, Prochlorococcus and SAR11, are not consumed by salps, which offers a new explanation for the dominance of small cells in open ocean systems. We also identified a double bonus for Prochlorococcus, wherein it not only escapes salp predation but the salps also remove one of its major mixotrophic predators, the prymnesiophyte Chrysochromulina. When we modeled the interaction between salp mesh and particles, we found that cell size alone could not account for these prey selection patterns. Instead, the results suggest that alternative mechanisms, such as surface property, shape, nutritional quality, or even prey behavior, determine which microbial cells are consumed by salps. Together, these results identify salps as a major factor in shaping the structure, function, and ecology of open ocean microbial communities.
Rights
© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Locate the Document
DOI
10.1093/pnasnexus/pgae091
Persistent Identifier
https://archives.pdx.edu/ds/psu/41616
Citation Details
Thompson, A. W., Nyerges, G., Brevick, K., & Sutherland, K. R. (2024). Ubiquitous filter feeders shape open ocean microbial community structure and function. PNAS nexus, 3(3), pgae091.