Water temperature regulates picoplankton growth and mortality during the cold season in a subtropical coastal ecosystem
Journal
Aquatic Microbial Ecology
Journal Volume
92
Start Page
1
End Page
13
ISSN
0948-3055
1616-1564
Date Issued
2026-04-09
Author(s)
Olivia, Madeline
Annabel, Clara Natalie
Chen, Patrichka Wei-Yi
Chen, Tzong-Yueh
Chang, Feng-Hsun
Shiah, Fuh-Kwo
Mukhanov, Vladimir
Tsai, An-Yi
Abstract
Marine picoplankton populations are influenced by bottom-up control (resource availability, temperature) and top-down processes (e.g. grazing, viral lysis); however, seasonal variability in the bottom-up and top-down controls of picoplankton remains unclear, especially in cold-season studies, which remain scarce due to sampling challenges. To gain insight into the role of bottom-up and top-down control as determinants of picoplankton population abundance in the cold season, we examined bacterial, Synechococcus spp., and picoeukaryotic phytoplankton growth and mortality in a subtropical coastal region during the cold season (< 25°C) using modified dilution experiments. Results showed bacterial and Synechococcus spp. production rates were positively correlated with temperature, with growth rates ranging from 0.02 to 4.91 d–1 (bacteria) and 0.29 to 6.28 d–1 (Synechococcus spp.). Nanoflagellate grazing accounted for 43–80 % of bacterial and 64–448 % of Synechococcus spp. production, with carbon losses ranging from 2.07 to 18.82 mg C m–3 d–1 (bacteria) and from 1.94 to 92.93 mg C m–3 d–1 (Synechococcus spp.), while viral lysis was minimal for both but more significant for picoeukaryotic phytoplankton. Moreover, the 3 microbial groups exhibited distinct patterns: (1) Bacterial production was nearly balanced by total mortality (grazing and viral lysis) across all temperatures; (2) Synechococcus spp. contributed significantly to picophytoplankton production but declined sharply below 20°C as grazing exceeded production; (3) Picoeukaryotic phytoplankton production surpassed Synechococcus spp. below 20°C. These findings underscore temperature-driven microbial production and grazing-dominated mortality, suggesting reduced viral lysis due to increased lysogeny.
Subjects
Microbial food web
Grazing
Viral lysis
Synechococcus spp.
Temperature-driven dynamics
Coastal ecosystem
Lysogeny
Publisher
Inter-Research Science Center
Type
journal article