Tides

Key Concepts:

  1. The Palo Alto Baylands Nature Preserve is a part of the San Francisco Bay Estuary.
  2. Tides are an effect of oceans resulting from the gravitational pull of the moon and the sun on the earth, and storm systems in the ocean.
  3. Tides affect how humans, plants, and wildlife exist around the SF Bay Estuary.

From here you are looking at the marshlands of the San Francisco Bay from the EcoCenter in Palo Alto. These marshes, or baylands, are a type of environment that relies on the tides of the ocean to exist.

What are tides?

Tides are the rising and falling of the waters of the ocean throughout the day.

What causes tidal action?

Tidal action is caused by the gravitational pull of the sun and the moon on the earth. Here in California, we get a “high tide” twice a day and an opposite “low tide” every twelve hours. That means that if there is a high tide at 6AM, there will likely be a low tide at 12 noon, another high tide at 6PM, and another low tide at 12 midnight.

As the earth orbits around the sun, the gravity of the sun pulls on the earth, similarly, as the moon orbits around the earth, it also pulls on the earth – each of these forces cause the tide level to change.

What does it mean?

The baylands you are viewing are part of the San Francisco Bay, which is fed by the Pacific Ocean. As the tides rise, ocean and bay water fill up these marshlands with salt water, nutrients, and aquatic organisms that feed the plants and wildlife you are looking at.

All the plants you are seeing in the baylands depend on the daily high tide for water and nutrients. When the tide goes out and the water returns to the Bay, the plants roots get a chance to breathe.

Check back with our MarshCam to see how the tides change throughout the day.

Can you tell if the tide is high or low right now?

How do you think high or low tide effects the plants and animals living here?