The food chain on a coral reef is not dependent on primary production. One type of deep sea community is a chemosynthetic vent community . It is characterized by a hydrogen sulfide-based chemosynthesis . They were first discovered in 1977. Black smokers were first discovered in 1979.
Bacteria are the basis of the food chain here.
They also exist as symbionts within tube worms or clams. Zonation is due to temperature and age of the vent community. Another type of deep sea community is a cold seep community . These are based on methane seeps . Natural oil and gas seeps are common in the Northern Gulf of Mexico.