Recurring patterns in bacterioplankton dynamics during coastal spring algae blooms.

Area of Science:

• Marine microbial ecology
• Biogeochemical cycles
• Carbon cycling

Background:

• Heterotrophic bacteria remineralize algae biomass, a key process in marine carbon cycling.
• Massive marine algae blooms support secondary blooms of planktonic bacteria.
• Bacterial successions during blooms often involve distinct clades like Flavobacteriia, Gammaproteobacteria, and Roseobacter.

Purpose of the Study:

• To investigate recurring patterns in bacterial clade successions during spring phytoplankton blooms.
• To analyze functional gene patterns related to algal biomass degradation.
• To test the hypothesis that bacterial succession is governed by deterministic factors like substrate availability.

Main Methods:

• Four consecutive years of dense sampling during spring phytoplankton blooms.
• High-resolution taxonomic analyses of bacterial communities.
• Metagenome sequencing to assess functional gene profiles.

Main Results:

• Recurring patterns in bacterial community succession were detected, even at the genus level.
• Consistent patterns were observed in functional genes, particularly those involved in algal polysaccharide degradation.
• Substantial inter-annual variation in phytoplankton blooms did not obscure these deterministic bacterial patterns.

Conclusions:

• Bacterial succession during spring phytoplankton blooms exhibits deterministic principles.
• Substrate-induced forcing, such as the availability of algal polysaccharides, strongly influences bacterial community structure and function.
• These findings enhance our understanding of microbial roles in marine carbon cycling.