Effect of Light and Oxygen on Freshwater Microbial Population

Effect of Light and Oxygen on Freshwater Microbial Population

Effect of Light and Oxygen on Freshwater Microbial Population

Freshwater bodies are divided into tree zones based on oxygen availability and light penetration :

a.Litoral zone  - light penetrates through it and oxygen is available.

b. Limnetic zone - open water away from the shore, has effective light penetration and oxygen is available.

c. Profundal zone - Deeper water has low oxygen and less light.

Litoral zone

Litoral zone is submerged with higher plants.

Limnetic zone

Limnetic zone contains pseudomonads and species of Caulobacter, Cytophaga  and Hyphomicrobium.

Photosynthetic algae are located inthis zone. Light is an important source of energy for them. They are primary producers of a lake and supports a population of bacteria, protozoa and other aquatic lives.

Profundal zone

Purple and green sulfur bacteria are found in this zone. They are anaerobic photosynthetic organisms that metabolize hydrogen sulfide to sulfur and sulfate in the bottom sediments of the benthic zone.

Algal growth near the surface often filters the light and use different wavelength of light from those used by the surface layer photosynthesizers.

The sediment in the benthic zone includes bacteria such as Desulfovibrio that use sulfate as an electron acceptor and reduce it to hydrogen sulfide. Methane producing bacteria are also part of these anaerobic populations.

Clostridium species are common in benthic zone and cause botulism in water flow.

Effect of Light and Oxygen on Freshwater Microbial Population

Written By

Sadia Akhtar
Student of Department of Microbiology
Jagannath University.
Email- sadiabd810@yahoo.com