Carnivorous Nekton are the dominant carnivorous animals of the pelagic environment and generally these animals migrate great distances in search of food. Production Food production occurs mainly through Photosynthesis. It is measured and called Primary food production which will occur in the photic zone as phytoplankton manufacture organic matter during photo. The primary productivity varies seasonally and geographically. It seems that the more vertical mixing that occurs in an area, the higher the primary production is because in the tropics where there is little vertical mixing, their Primary Productivity is low because of the depletion of nutrients in the surface waters.
Primary productivity decreases as depth increases as there is less light and less photo.
Accessory pigments in algae enable them to make the most of the little light that does get to them. Copepods metabolize droplets of diatom oil to liquid waxes and fats which can be used as long-term energy reserves. Detritus food chains are also secondary when decaying material enter the detritus chain as decaying materials, wastes, pieces of animal tissue. The swarms of Copepods feeding on diatoms excrete packets of partially digested matter called fecal pellets. While there is a loss of energy to the grazers, many consumers are adapted to feed on detritus thereby returning energy to the food chains.