Mather Field Vernal Pools

The Three Phases of the Vernal Pool Ecosystem

The Wet Phase: Winter in the Vernal Pools

As soon as the winter rains begin to puddle in the vernal pools, tiny creatures called bacteria and protozoa spring to life. Many of them feed on detritus, bits of dead plants and animals that lie on the bottom of the pool. These detritus feeders are, in turn, eaten by many other tiny animals. Microscopic (very tiny) green plants called algae are the next to appear. They are like tiny floating food factories, providing the energy that powers most of the other species in a vernal pool.

Now that the winter pools are full of water and are teeming with bacteria, algae and protozoa, many more aquatic species begin to appear. The water signals to the resting spores, eggs, and cysts of aquatic life that it is time to hatch and grow. Within a few weeks, dozens of species of invertebrates (small animals without backbones) will be living in the pools. Each aquatic species must hurry and complete its life cycle before the pool dries out in the spring.

When vernal pools are full of aquatic life, it’s like putting a meal on the table. Frogs, snakes, birds, and mammals come to the vernal pools for dinner. The food web connects all the species in the vernal pool grassland ecosystem. An ecosystem is a community of plants and animals that depend on one another and their environment for survival.


Pacific Chorus Frog

 Fact of Life: Not every individual of a species will survive long enough to reproduce. Most will become food for another creature. In an ecosystem the survival of the individual does not matter. The survival of the species is what is important. As long as some individuals reproduce, the species will continue.

We know very little about this ecosystem and the species that call it home. There is so much left to discover. However, we do know one thing for sure: vernal pool creatures need clean water. Clean water is the key to abundant life.

This baby Water Flea is surrounded by microscopic diatoms. Protozoa, bacteria, diatoms, and algae are all microscopic, meaning we need a microscope to see them at all.
An aquatic beetle larva known as a "Water Tiger" eats a Water Boatman. Like many invertebrates, they are macroscopic. Although you can see them with your naked eye, you need a magnifying lens to see their parts.

Mather Web • Lessons & Worksheets • Animal Facts • Plant Facts

 
©