When we hike into the mountains in late spring, we often come across pink snowdrifts, called watermelon snow. This is really a green algae which has a secondary red caratenoid pigment. It survives in freezing water. The reddish color absorbs heat and helps to provides water from snow melt.

The algae is dormant in winter, but the spores germinate as the snows melt and the cells migrate (with a flagellate) towards the surface where they bond into cellular bands. A single teaspoon is melted snow can have about one million cells.

As we walk across the snow cups, our boots can become stained with pink watermelon snow.

Tod watermelon snow in July