In advance of the National Fireworks competition, Plymouth’s sea is putting on a stunning natural sparkling display.

Have you noticed Plymouth’s sea sparkling at night over the last few weeks? The water has been lit up by a glow of blue bioluminescence, caused by a microscopic organism known as ‘sea sparkle’.

Sea sparkle is a type of phytoplankton known as Noctiluca scintillans, a free floating algae-like species that can both photosynthesise like a plant, but also ingest particles of food like an animal. When disturbed they emit a blue glow. N. scintillans is commonly found around UK shores; however, in order to see the blue glow, they must be in high abundance.

It is a rare but stunning sight, and this year has been particularly good for this species to thrive. The prolonged period of settled weather we have been enjoying has helped create a stable warm layer of water on the sea surface. No wind means little wave action to stir up more nutrients from below so you end up with a layer of warm water with not much in it to keep many plant plankton going. However, some types of plankton known as dinoflagellates, which includes N. scintillans, can thrive in these conditions, resulting in high concentrations or ‘blooms’ of them. These blooms will likely hang around until the water gets mixed up again, bringing more nutrients back to the surface so other species can thrive.

The Continuous Plankton Recorder Survey, based in Plymouth and operated by the Marine Biological Association has been recording the spread and distribution of plankton since 1931. CPR Survey Analyst Gemma Brice said "After seeing N. scintillans on a CPR sample I was excited to see the sea sparkle from the shore in Plymouth Sound."

Head of the CPR Survey David Johns said, "We’ve been running the CPR survey for over 7 decades, and whilst N. scintillans is not rare in CPR samples, we don’t usually have the pleasure of seeing them flashing – plankton are truly fascinating!"

Noctiluca scintillans, the organism behind the phenomenon of 'sea sparkle'.

This particular algae is non-toxic and regularly blooms during the summer months. However, it is advisable not to swim when the bloom breaks down – often signalled by discoloured water or foam on the surface.

The Continuous Plankton Recorder (CPR) Survey is the world’s largest marine monitoring programme. The Survey uses a simple sampling device, towed behind ships of opportunity to record information on the spread, distribution and abundance of plankton in the world’s oceans.

Aug 7, 2018 By guba