Organic debris that drifts down from the upper, lighted regions of the oceanic province, and is the base of food chains for organisms of the deep ocean is called:

The answer to the question is the Marine snow.
In the deep ocean, marine snow is a continuous shower of mostly detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below. Marine snow particles are found throughout the world's oceans in all parts of the water column.