Salinity decline promotes growth and harmful blooms of a toxic alga by diverting carbon flow

Global climate change intensifies the water cycle and makes freshest waters become fresher and vice‑versa. But how this change impacts phytoplankton in coastal, particularly harmful algal blooms (HABs), remains poorly understood. Here, we monitored a coastal bay for a decade and found a significant correlation between salinity decline and the increase of Karenia mikimotoi blooms. To examine the physiological linkage between salinity decreases and K. mikimotoi blooms, we compare chemical, physiological and multi-omic profiles of this species in laboratory cultures under high (33) and low (25) salinities. Under low salinity, photosynthetic efficiency and capacity as well as growth rate and cellular protein content were significantly higher than that under high salinity. More strikingly, the omics data show that low salinity activated the glyoxylate shunt to bypass the decarboxylation reaction in the tricarboxylic acid cycle, hence redirecting carbon from CO2 release to biosynthesis. Furth..., We tested physiological, biochemical and molecular biological performances of Karenia mikimotoi under high salinity (33PSU) and low salinity (25PSU)., , # Salinity decline promotes growth and harmful blooms of a toxic alga by diverting carbon flow

[https://doi.org/10.5061/dryad.7pvmcvf29](https://doi.org/10.5061/dryad.7pvmcvf29)

Description of the data and file structure

The physiological, biochemical, and molecular biological performances of Karenia mikimotoi under high salinity (33PSU) and low salinity (25PSU). We have four groups for cell concentration assay: 20 PSU, 25 PSU, 33 PSU, and 37 PSU, each in triplicate. The rest measurements have two groups: 25 PSU and 33 PSU, each in triplicate. The results file contains the measurement results of cell concentration (at days 1,5,8,10,12,14 and 16), photosynthetic efficiency (Fv/Fm) (at days 1,5,8,10,12,14 and 16)， CN ratio, cellular protein content, oxidative stress-related enzyme activity and cellular ROS content; Table S1- contains primers used in the study, Table S2-field nutrient data, Table S3-a summary of annotation of unigenes in each database, Table S4-metabolites, Table S5-dif...