sea sparkle!

If you ever find yourself in Leiden in the summertime, hope for warm, sunny days because there is one thing you MUST see.

During my first few weeks in Leiden, I got numerous tips and advice about things I should do and see while I’m here. One of the more unique (and magical) things I was told about was “sparkling algae” (or more technically, bioluminescence) at the beach.

[Photo credit: National Geographic]

Bioluminescence is the “production and emission of light by a living organism” (Wikipedia ;]). Phytoplankton, specifically dinoflagellates, are known to bioluminesce. Sometimes waves crashing along the shore will appear to glow a brilliant bright blue, as shown in the image above, which is a product of the bioluminescent phytoplankton. I was told that the best time to see the bioluminescence was in the middle of the night, after days of warm, sunny weather.

Earlier in July, I got to see the bioluminescence! After a couple days of warm, sunny weather, three of my fellow summer students and I biked to Katwijk around midnight to (hopefully) see the glow. As per a colleague’s advice, we went to Katwijk-North, where the River-Rijn exits into the sea. It was very, very dark in this area, and as we walked towards the river, we were sad to see no sparkling along the waves. Knowing that we may have to disturb the phytoplankton in order to see them bioluminesce, my friend picked up some sand and threw it into the river. To our surprise, the water glowed a bright blue where the sand fell. We shrieked with excitement! All of us then threw sand into the river and ripples of a glowing bright blue materialized from the black water. It was quite unbelievable!

We spent the next hour walking along the shore, getting the water to glow. As we walked along the river, towards the ocean, we quickly realized that stepping on the wet sand also created pinpoints of glowing blue. Thus, we drummed on the ground, slid our hands across the sand, and dragged our feet across the sand, to instigate the sparkling. It was spectacular and unlike anything I had ever seen before. It was like looking at stars but in the sand… sweeping our hands and feet across the wet sand created a random distribution of bright blue pinpoints. The sparkles in the sand looked as if we had sprinkled the insides of a glow stick on the sand. But perhaps even better was when we swept our feet in the water or tossed sand into the water. Ripples of glowing bright blue materialize from the interaction. It was really beautiful.

We had a lot of fun. The whole experience reminded me of the beautiful forest scene in the film Avatar, which included many bioluminescent plants and animals. To end our experience, we each took a handful of sand, made a wish, and threw the sand into the river to make the phytoplankton glow one last time.

Since that night in July, we have had many days of very warm and sunny weather in Leiden. It’s often been well into the upper 20s, which is great, not only for us, but for the phytoplankton too! Over the last few weeks, my fellow summer students have made three midnight trips to Katwijk and they’ve said the bioluminescence is more apparent each time. One of my friends even swam in the ocean with the algae glowing around her. She said it was absolutely spectacular!

So remember, if you notice it’s been warm and sunny for a couple days in a row, grab a few friends and head to Katwijk after dark! It is a phenomenon everyone needs to experience! 🙂