The supply of nutrients, primarily nitrates, to the euphotic zone is thought to impact levels of dissolved oxygen.
12.
The biological pump is the conversion of particulate organic matter in the euphotic zone and transference to the deeper ocean.
13.
Yet during winter convective mixing, nutrients penetrate the euphotic zone, causing a short-lived phytoplankton bloom in the spring.
14.
Ammonium and nitrite show a maximum concentration at 50 80 m ( lower end of the euphotic zone ) with decreasing concentration below that depth.
15.
However, vertical mixing also causes high losses, as phytoplankton are carried below the euphotic zone ( so their respiration exceeds primary production ).
16.
As with self-shading within water-whitening coccolithophore plankton blooms, this may reduce photosynthetic productivity by altering the geometry of the euphotic zone.
17.
Plankton drive the " biological pump ", a process by which the ocean ecosystem transports carbon from the surface euphotic zone to the ocean's depths.
18.
The dysphotic zone, where light intensity is considerably less than 1 % of surface irradiance, extends from the base of the euphotic zone to about 1000 metres.
19.
The dysphotic zone, where light intensity is considerably less than 1 % of surface irradiance, extends from the base of the euphotic zone to about 1000 meters.
20.
Indeed, in their original paper, Eppley & Peterson noted that : " To relate new production to export requires that nitrification in the euphotic zone be negligible ".
