These areas are the product of upwelling which transports nutrients to the photic zone . Smaller total amounts are produced along the coasts and in upwelling regions but these amounts are concentrated in smaller areas, making these areas very rich in primary production on a per unit area basis. Food Chains and Webs Primary production forms the first link in the food chains that link plants, herbivorous animals, and carnivorous animals. Together they make up the total production of the sea. Where there is high primary production there are large populations of animals.
Animals are consumers , they feed on the primary producers or on other consumers.
Whether herbivores or carnivores they are still ultimately dependent on the primary producers for their food. The most numerous and greatest biomass of herbivores are the plant-eating zooplankton . These animals are the primary consumers which convert plant tissue to animal tissue. In turn, they become the food for the other zooplankton, the carnivores or secondary consumers . There may be many or few links in the food chain that leads to the top carnivore , a predator on which no other organism preys.