Keystone Arctic paleoceanographic proxy association with putative methanotrophic bacteria.

Area of Science:

• Marine biology
• Geochemistry
• Paleoceanography

Background:

• Foraminifera are typically not expected in chemosynthesis-based ecosystems due to a lack of known endemic species.
• Gas hydrate dissociation creates unique environments with potential for specialized microbial communities.

Purpose of the Study:

• To investigate the presence and cellular adaptations of foraminifera in sediments affected by gas hydrate dissociation.
• To determine if Melonis barleeanus can inhabit these extreme environments and its microbial associations.

Main Methods:

• Examined the cellular ultrastructure of Melonis barleeanus specimens from the Vestnesa gas hydrate province.
• Utilized microscopy to identify cellular features and associated microorganisms.

Main Results:

• Living Melonis barleeanus were found in sediments with gas hydrate indicators.
• Unusual pore plugs and peripheral mitochondria were observed in M. barleeanus.
• Most specimens were associated with putative Type I methanotrophic bacteria, with one showing a large concentration near the aperture.

Conclusions:

• This study provides the first evidence of living Melonis barleeanus in gas hydrate-rich sediments.
• The association with methanotrophic bacteria suggests potential adaptations to chemosynthetic environments.
• Findings impact paleoclimate records that rely on this foraminiferal species.