Study reveals unexpected cooperation between ocean viruses and grazers in controlling phytoplankton
Researchers found that when viruses and protistan grazers attack the marine cyanobacterium Prochlorococcus together, they produce more viruses and particles than expected, despite reducing overall phytoplankton mortality. The study used controlled laboratory experiments with simplified ecosystems to examine interactions typically studied in isolation. This finding suggests that virus-grazer cooperation may significantly influence how carbon cycles through ocean food webs and is exported from surface waters.
A new preprint study published on bioRxiv examined how viruses and grazers—two major causes of phytoplankton death in oceans—interact when present together. Researchers exposed the cyanobacterium Prochlorococcus to either the T7-like virus P-SSP7, the protistan grazer Paraphysomonas bandaiensis, or both simultaneously. While viruses and grazers individually caused substantial Prochlorococcus mortality, their combined effect was less than the sum of their individual impacts. Surprisingly, this did not reduce virus or grazer populations; instead, the interaction enhanced virus production, sustained grazer growth, and dramatically increased particle aggregation. The researchers propose that grazers may have shifted to consuming bacteria and damaged cells released by viral lysis, creating a cooperative dynamic rather than competition. These findings highlight how food web interactions between viruses, grazers, and phytoplankton may be critical for understanding carbon cycling and export in marine ecosystems.
What's missing
The study's own limitations and caveats are not detailed in the provided abstract. Typical considerations for such work might include: the simplified nature of the laboratory ecosystem compared to natural ocean conditions; whether findings generalize to other virus-phytoplankton-grazer combinations; the mechanisms underlying the shift to alternative food sources; and whether particle aggregation effects persist over longer timescales or in more complex communities.
What different sources said
- bioRxivCenter
Virus-grazer interplay enhances virus production, particle aggregation, and trophic efficiency during infection of Prochlorococcus
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