Highly Diverse Synechococcus Pigment Types in the Eastern Indian Ocean

Area of Science:

• Marine microbiology
• Phycology
• Oceanography

Background:

• Marine picocyanobacteria, particularly Synechococcus, display remarkable pigment type (PT) diversity.
• This diversity enables efficient light spectrum utilization and adaptation to various light niches.

Purpose of the Study:

• To investigate the diversity and distribution patterns of Synechococcus PTs in the Eastern Indian Ocean (EIO), Strait of Malacca (SSM), and Sri Lanka coastal waters (SSL).
• To understand the ecological factors driving the niche partitioning of different PTs.

Main Methods:

• Pigment type analysis in surface waters of EIO, SSM, and SSL.
• PT-specific quantitative polymerase chain reaction (qPCR) for precise abundance determination.
• Correlation analysis with environmental factors like nutrients and stratification.

Main Results:

• All detected PTs contained phycourobilin (PUB) and belonged to PT 3.
• PT 3a and PT 3eA dominated shallow/coastal waters (SSM, SSL), while high PUB PTs (3dA, 3c/3dB) were found in the open ocean (EIO).
• The novel PT 3f was abundant across all sites, especially in the EIO's upper euphotic layer, and negatively correlated with nutrient levels, suggesting adaptation to oligotrophic conditions.

Conclusions:

• Distinct PTs exhibit clear niche partitioning within the euphotic zone, influenced by light, nutrients, and water stratification.
• High diversity within PTs at different locations provides insights into their broad ecological niches.
• Synechococcus PT diversity is a key factor in marine primary productivity and ecosystem dynamics.