Not the sea and not a lake: meromictic water bodies separated from - - PowerPoint PPT Presentation

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Not the sea and not a lake: meromictic water bodies separated from - - PowerPoint PPT Presentation

Dec 23, 2022 172 likes •496 views

Not the sea and not a lake: meromictic water bodies separated from the White Sea Elena Krasnova, White Sea Biological Station, Lomonosov Moscow State University, Russia White Sea Biological Station of MSU Vertical structure of meromictic lake

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Not the sea and not a lake: meromictic water bodies separated from the White Sea

Elena Krasnova, White Sea Biological Station, Lomonosov Moscow State University, Russia

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White Sea Biological Station of MSU

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Vertical structure

  • f meromictic lake

Holomictic dimictic lake Bacterial sulfate-reduction: CH4 + SO4

2− → HCO3 − + HS− + H2O

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Dead zone in the Gulf of Mexico

In 2016 – 16 000 km2

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Black Sea is the largest meromictic water body with the dead zone of natural

  • rigin
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Dead zone in the Baltic Sea

In 2012 – 70 000 km2

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How does dead zone forms

Cause 1. Eutrofication. Bacterial sulfate-reduction: CH4 + SO4

2− → HCO3 − + HS− + H2O

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How does dead zone forms

Cause 2. Stratification.

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How does dead zone forms

Cause 3. Global warming.

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H2S accumulation

Black Sea – up to 9 mg/l. Norwegian fjord Framavaren, a leader among the open marine areas – up to 200 mg/l. Lake Trekhtzvetnoe – up to 600-900 mg/l H2S in its bottom water!

Lake Trekhtzvetnoe

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Main source of organic compounds in the separated lakes

Layer of autotrophic bacteria

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Photo: V. Lyagushkin

СО2 + 2Н2S light = (CH2O) + Н2О + 2S

White underwater “smoke” is a colloid sulfur produced by sulfur bacteria in anoxygenic photosynthesis:

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Colored layers with green sulfur bacteria

In the lake Trekhtzvetnoe In the lake Nizhnee Ershovskoe In the lake Elovoe In the lake Bolshye Khruslomeny In the lake Nizhnee Ershovskoe

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Ecosystem of the separating lake

F L O w Organic matter

Biogenic elements,

  • rganic matter,

bacteria

Brackish «greenhouse roof» Photic zone: oxygenic photosynthesis,

  • heat. Aerobic life.

Rhodomonas layer provides upflow of

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Anoxygenic photosynthesis Aerobic zone, decomposition of organic matter

Decomposition – “digestive zone”

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Mixotorphic cryptophyteRhodomonas bloom in the chemocline (under fluorescent microscope)

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Dinoflagellates Oxyrrhis marina Cryptophytes Rhodomonas Green sulfur bacteria (photo: A.S. Savvichev)

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Rotifers Synchaeta sp..

N E К Т О N B Е N ТH О S

Stickleback, bivalve Macoma balthica

Trophic chain in the lake Kislo-Sladkoe based on the primary production od green sulfur bacteria

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Some physico-chemical parameters in the studied lakes in summer

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Tidal power plant in Kislaya bay

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Green sulfur bacteria were main photosynthetic organisms before the Great Oxygenation Event

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Crater Gale in the Mars was once meromictic lake? What about green sulfur bacteria?