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The primary producers of deep sea hydrothermal vent ecosystem are:
a. Coral reefs
b. Green algae
c. Chemosynthetic bacteria
d. Blue-green algae

Answer Verified Verified
Hint: The primary producer is an organism which converts the abiotic source of energy in form of stored energy that can be utilized later by it or by other organisms. Primary producers lie at the lowest trophic level in the ecosystem and are the foundation of unidirectional energy flow.

Complete answer:
> The hydrothermal vents are the fissures on the seabed which geothermally heated the water. These are commonly found near active volcanoes, where the tectonic plates have moved apart in ocean basins. The ecosystem which is found in deep sea hydrothermal vents is somehow different from the ecosystem that is usually found on earth’s surface. Almost all the organisms under deep sea occur independently of the sun, out of which some depend on oxygen which is produced by chemosynthetic bacteria present there. The chemosynthetic bacteria forms a thick layer on the sea bed and attracts many other organisms to feed on them. These chemosynthetic bacteria form the base of the food chain as they are the primary producers of the deep sea hydrothermal vent ecosystem.

> Coral reefs are the underwater ecosystem formed by the deposition of corals. Corals are the members of phylum Cnidaria and the deposits which are found under sea are the polyps attached to their substrates. These include jellyfish and sea anemones. The corals secrete hard carbonate exoskeletons which hold and provide support to the corals. Corals are mainly found in shallow tropical waters and sometimes in cold and deep waters also.

> Green algae or chlorophyceae are the organisms belonging to the group of algae which are capable of producing their own food. They contain the photosynthetic pigment chlorophyll which helps them to synthesize their own food. These are mainly found in freshwater or saline water and sometimes also on land but not in deep seas. These may be unicellular, multicellular or maybe colonial.

> Blue green algae, also called cyanobacteria contain the bacteria that are photosynthetic in nature. These bacteria have their own photosynthetic pigment called chlorophyll which they use to synthesize their own food. These are found in fresh water sources or in terrestrial environments. These are known to cause algal blooms in some of the water bodies.

Hence, The correct answer is option (B).

Note: The green algae and the cyanobacteria, these both are photosynthetic in nature which means they have to be near the surface of water so that they can easily obtain sunlight to complete their process of photosynthesis. Thus, the green algae and cyanobacteria cannot be found in deep seas as the availability of sunlight is very low in that area.