Answer:The continental shelf.
Step-by-step explanation:
Continental shelf is the surbmarged part of a Continient in swallow ocean.
The richness in biodervasity is due to
1.shallowness of this region This characteristics permit easy penetration of sunlight for phytoplanktons and other primary producers t o supply enough food materials in thr food chains.
2.it is also the site for abundant oxygen from photolysis of water