The Sea at Night

Often for a few weeks in summer, along the Southern California coast, there is a ‘red tide’. This happens when there is a sudden bloom of plankton called dinoflagellates (Lingulodinium polyedra, the species often found in Southern California red tides). As the plankton multiplies, the water turns rust red.

At night the presence of the dinoflagellates becomes magical due to their bioluminescence, glowing brightly when they are disturbed. Breaking waves flash a brilliant blue. And the movements of swimmers are outlined in flowing swirls of lights.

I grew up on this coast, and in my youth, would often sneak down to the beach for swims at night during red tide season.

I’ve been on many night dives – usually snorkelling, and I love them. As I write this blog, images from those nightly swims fill my mind…

I am floating above a sargassum meadow in the twilight. From the corner of my eye I notice a subtle movement – a cuttlefish among the seaweed. Stilling myself, I watch patiently. The cuttlefish is at first startled, then becomes used to my presence and resumes his hunt for shrimp among the algae fronds. His tentacles stiffen to a point when he spies a prey, he turns white as one arm  strikes as quick as lightning to snatch a tasty snack.

A shadowy wolf-eel in the moonlight slithering through turtle grass. A school of fish in ghostly grey slip past me, scarcely noticed, camouflaged perfectly in the moonlit waters.

I enter a sea pen along the edge of a mangrove forest for a night population survey of sea cucumbers we are raising. The pen seems alive with shrimp flinging themselves through the air like popcorn! I’ve never seen anything like this before. As I swim through the pen, they seem to be everywhere, bouncing off my legs and back. I see no evidence of a predator, so perhaps this is their mating dance.

Romance rises with the full moon on the reef. Many species that are ‘broadcast spawners’ who release their sperm and eggs at the height of the moon’s cycle. Sea cucumbers are among these and rise up; dancing in the moonlight for the next generation. It can be spectacular.

In another blog, I’ve written about my adventure with an octopus nicknamed Octavia, who allowed me to watch her hunt over three nights. I felt very honoured.

Then, there is the ‘pixie dust’. If I turn off my underwater flashlight in the tropics and wave my hands underwater, blue sparks fly from my fingertips. These bright flashes are comb jellies lighting up in the dark as they are disturbed.

The sea at night is a place of wonder.


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