TY - JOUR

T1 - Cable bacteria generate a firewall against euxinia in seasonally hypoxic basins

AU - Seitaj, Dorina

AU - Schauer, Regina

AU - Sulu-Gambari, Fatimah

AU - Hidalgo-Martinez, Silvia

AU - Malkin, Sairah Y.

AU - Burdorf, Laurine D. W.

AU - Slomp, Caroline P.

AU - Meysman, Filip J. R.

PY - 2015/10/27

Y1 - 2015/10/27

N2 - Seasonal oxygen depletion (hypoxia) in coastal bottom waters can lead to the release and persistence of free sulfide (euxinia), which is highly detrimental to marine life. Although coastal hypoxia is relatively common, reports of euxinia are less frequent, which suggests that certain environmental controls can delay the onset of euxinia. However, these controls and their prevalence are poorly understood. Here we present field observations from a seasonally hypoxic marine basin (Grevelingen, The Netherlands), which suggest that the activity of cable bacteria, a recently discovered group of sulfur-oxidizing microorganisms inducing long-distance electron transport, can delay the onset of euxinia in coastal waters. Our results reveal a remarkable seasonal succession of sulfur cycling pathways, which was observed over multiple years. Cable bacteria dominate the sediment geochemistry in winter, whereas, after the summer hypoxia, Beggiatoaceae mats colonize the sediment. The specific electrogenic metabolism of cable bacteria generates a large buffer of sedimentary iron oxides before the onset of summer hypoxia, which captures free sulfide in the surface sediment, thus likely preventing the development of bottom water euxinia. As cable bacteria are present in many seasonally hypoxic systems, this euxinia-preventing firewall mechanism could be widely active, and may explain why euxinia is relatively infrequently observed in the coastal ocean.

AB - Seasonal oxygen depletion (hypoxia) in coastal bottom waters can lead to the release and persistence of free sulfide (euxinia), which is highly detrimental to marine life. Although coastal hypoxia is relatively common, reports of euxinia are less frequent, which suggests that certain environmental controls can delay the onset of euxinia. However, these controls and their prevalence are poorly understood. Here we present field observations from a seasonally hypoxic marine basin (Grevelingen, The Netherlands), which suggest that the activity of cable bacteria, a recently discovered group of sulfur-oxidizing microorganisms inducing long-distance electron transport, can delay the onset of euxinia in coastal waters. Our results reveal a remarkable seasonal succession of sulfur cycling pathways, which was observed over multiple years. Cable bacteria dominate the sediment geochemistry in winter, whereas, after the summer hypoxia, Beggiatoaceae mats colonize the sediment. The specific electrogenic metabolism of cable bacteria generates a large buffer of sedimentary iron oxides before the onset of summer hypoxia, which captures free sulfide in the surface sediment, thus likely preventing the development of bottom water euxinia. As cable bacteria are present in many seasonally hypoxic systems, this euxinia-preventing firewall mechanism could be widely active, and may explain why euxinia is relatively infrequently observed in the coastal ocean.

KW - sediment biogeochemistry

KW - cable bacteria

KW - coastal hypoxia

KW - sulfur cycling

KW - microbial competition

KW - DISTANCE ELECTRON-TRANSPORT

KW - COASTAL MARINE SEDIMENT

KW - BIOGEOCHEMICAL PROCESSES

KW - SULFIDE OXIDATION

KW - SULFATE REDUCTION

KW - SULFUR OXIDATION

KW - BEGGIATOA SPP.

KW - SEA-FLOOR

KW - IRON

KW - MANGANESE

U2 - 10.1073/pnas.1510152112

DO - 10.1073/pnas.1510152112

M3 - Journal article

C2 - 26446670

VL - 112

SP - 13278

EP - 13283

JO - Proceedings of the National Academy of Sciences

JF - Proceedings of the National Academy of Sciences

SN - 0027-8424

IS - 43

ER -