text: Ocean gyres typically contain 5–6 trophic levels. The limiting factor for the number of trophic levels is the size of the phytoplankton, which are generally small in nutrient limited gyres. In low oxygen zones, oligotrophs are a large percentage of the phytoplankton.
  At the intermediate level, small fishes and squid (especially ommastrephidae) dominate the nektonic biomass. They are important for the transport of energy from low trophic levels to high trophic levels. In some gyres, ommastrephidae are a major part of many animals' diets and can support the existence of large marine life.