Alaska Sea Grant

The Producers in the Ecosystem

Kelp, photo courtesy of Heloise Chenelot

The Producers in the Ecosystem

Only two types of living things in the ocean make food using sunlight. These are called producers. One type is phytoplankton. Huge numbers of phytoplankton, most of them only visible under a microscope, drift with the currents and are food for the zooplankton such as copepods and young urchins.

The second type are the seaweeds, which are large algae. The largest seaweeds grow low in the intertidal zone and extend out into the subtidal zone. These are the kelps, large brown seaweeds that are glued to the rocks with their holdfast. Their long blades float at or near the surface of the water where they get sunlight to make food, which allows them to grow very fast. Their holdfast glue is very strong, and it can keep the huge kelp in one place even when strong currents and waves occur during storms.

Snails and sea urchins eat kelp, and fish, crabs, and many other animals find shelter within the dense kelp stands—called a kelp forest. Like a forest on land, the kelp forest provides food, places to hide, and a calm place away from the force of waves and winds. Many kelps die back in the winter and grow again the following spring. Large amounts of dead kelp are recycled by scavengers, including sea urchins, and decomposers.

Ribbon Kelp 

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