1. Ch. 21.2 Life in the Oceans

2. Ocean Chemistry and Marine Life Ocean plants and animals remove and return many types of nutrients and gases to the water. Ocean plants and animals remove and return many types of nutrients and gases to the water. Some critical elements, such as nitrogen, phosphorus, and silicon, are in short supply, and can be depleted by plant growth. Some critical elements, such as nitrogen, phosphorus, and silicon, are in short supply, and can be depleted by plant growth. If this happens, ocean plant growth is slowed or stopped. If this happens, ocean plant growth is slowed or stopped.

3. When ocean plants and animals die, they sink to the bottom, along with the nutrients they have stored in their bodies. When ocean plants and animals die, they sink to the bottom, along with the nutrients they have stored in their bodies. Elements vital to ocean plant and animal life are usually consumed at the surface, but released at great depths. Elements vital to ocean plant and animal life are usually consumed at the surface, but released at great depths. The nutrients must be returned to the surface to be used by most ocean organisms. The nutrients must be returned to the surface to be used by most ocean organisms.

4. When surface water is moved offshore by winds, nutrient-rich deep water is brought to the surface in a process called upwelling. When surface water is moved offshore by winds, nutrient-rich deep water is brought to the surface in a process called upwelling.

6. Sunlight and Marine Life Sufficient sunlight for photosynthesis only penetrates to a depth of about 100 m. Sufficient sunlight for photosynthesis only penetrates to a depth of about 100 m. Plant phytoplankton supports animal zooplankton. Plant phytoplankton supports animal zooplankton. Nekton—ocean life that swims. Nekton—ocean life that swims. Benthos—organisms that live on the ocean floor. Benthos—organisms that live on the ocean floor.