Some of the bacteria involved in recycling and regeneration are autotrophic. They function as primary producers of organic compounds by reduction of carbon

Chemosynthesis Cycle

Figure 5.3 Phosphorus cycle in seawater.

Nitrogen Cycle Seawater

Figure 5.3 Phosphorus cycle in seawater.

Chemosynthesis Reaction
Figure 5.4 Nitrogen cycle in seawater. DON is dissolved organic nitrogen.

dioxide in chemosynthetic reactions which parallel the photosynthetic processes of plants, but derive energy from inorganic chemical sources rather than from light. For instance, the bacteria Nitrosomonas and Nitrobacter, which oxidize ammonia to nitrite and thence to nitrate, utilize the energy released by these reactions for synthesizing organic materials within their protoplasm. Beggiatoa and Thiobacillus are chemosynthetic autotrophs obtaining energy from oxidation of sulphide and sulphur. Beggiatoa can be seen as a white mat covering the sea-bed where conditions are anoxic, such as under floating fish farm cages. Oxidation of iron to the ferrous and thence the ferric form is another energy source for chemosynthesis. It is now known that primary production by bacterial chemosynthesis contributes a significant fraction of the food available at depths remote from the euphotic zone. Deep-sea hydrothermal vent communities (see Section 6.4.4) are entirely dependent for their energy requirements on dissolved hydrogen sulphide and particles of sulphur in the hot vent water. If the vents become inactive, the communities die. Dense clouds of chemosynthetic bacteria form the base of the food pyramid. The vent communities are thus self-contained and do not rely either directly or indirectly on sunlight. Measurements have also indicated that these communities are among the most productive in the world.

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  • Mustafa Awet
    What is the chemical formula for the phosphorus cycle?
    8 years ago

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