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.
Chitionolytic bacteria can break down chitin which represents an enormous source of organic carbon.
Some are even symbiotic and found in the intestines of certain pelagic organisms to help them digest chitin. These bacteria play a big role in making sure the billions of tons of chitin produced in the marine environment each year get broken down and their nutrients are returned to the primary food makers.