Sunday, April 8, 2012

Bad weather for Sailors, but good for Diatoms

Beach One was the location of a mass stranding of Velella lata, more commonly known as by-the-wind-sailors. These little blue creatures are no more than 5cm long and are related to jellyfishes and anemones. Their natural habitat is on the surface of the open ocean, where the Velella feed on plankton.

They move across the ocean with their distinctive transparent "sail" catching the wind, visible in this first picture.

Every now and again a change of wind direction (like the cold blast we are currently experiencing) blows thousands of Velella helplessly towards the shore.
This second picture shows the underside of the Velella where its feeding tentacles are visible.

The same sort of weather that was responsible for the stranding of the Velella brought waters rich in nutrients that has allowed the Diatoms to bloom along the surf of Beach One.

This picture taken this morning at Beach One showing the characteristic browny-green "stain" of a Diatom bloom.