The Madeira Archipelago is located in a region that is considered oligotrophic (typically oceanic waters with low primary productivity). In part, this is due to the fact that the archipelago's islands do not have a continental platform, so its eutrophic zone (nutritious waters) is restricted to a narrow littoral fringe immediately followed by profound depths.

As we move away from the coast, it is possible to find differences in plankton formation (small living beings that float passively on the currents). The differences allow one to distinguish between the coastal water, rich with fish eggs and Noctilica sp. and the oceanic waters where the phytoplankton (vegetable beings) and the zooplankton (animals that feed on phytoplankton) density is very low.