16th May, 2011

What a difference a few days make

This time last year I posted a blog entitled, “What a difference a week makes”, about changes in Phaeocystis sp. changes at station L4.

This year it’s coccolithophores. They are from the same class of phytoplankton as Phaeocystis but instead of being able to form blobby colonies that you can see with the naked eye, coccolithophores are only found as single cells and they cover themselves in chalky plates. They can form huge blooms  in the ocean, up to 6 times the size of Britain that can be seen using satellites because the coccoliths show up white against the blue of the sea. There has been evidence of a coccolithophore bloom moving into the Channel over the last couple of weeks and at L4 last Wedesday I counted about 11,ooo per teaspoon of seawater. It’s the highest number I’ve recorded in over 4 years. But it was obviously not meant to last. 5 days later and there are 10 times fewer, only about 1000 per teaspoon of seawater. It’s a much more changeable world out in the Channel than you’d think by  just looking at the surface of the sea. Not only do different species of phytoplankton bloom at the same time in different years but the blooms can be very short-lived.

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