Plymouth Marine Laboratory scientists detect two large algal blooms; one off Ireland and the other covering an area from the Lizard, in Cornwall, to Salcombe, in Devon

March 18th, 2011 by Plymouth Marine Laboratory

Plymouth Marine Laboratory scientists have detected two large algal blooms; one off the coast of Ireland and the other closer to home covering an area from the Lizard, in Cornwall, to Salcombe, in Devon.

When such blooms occur scientists from a range of disciplines are brought together to identify the plankton responsible and establish whether there is any threat to people or other marine life.

In this case the bloom, which is likely to discolour the sea, consists of vast numbers of a harmless microscopic plant called Skeletonema costatum and poses no threat.

The marine diatom, Skeletonema costatum (click image to expand - image courtesy of Plymouth Marine Laboratory)

Skeletonema is a beautiful microscopic plant that given the right conditions reproduces rapidly to cover large areas of coastal seas”, says PML’s Earth Observation scientist, Dr Peter Miller. “Over the winter nutrients have built up in the sea and the windy weather we have experienced recently has stirred them up to the surface.  Combined with the now calmer conditions and bright sunny days everything slotted into place to enable this plant to reproduce and form a large bloom.”

Claire Widdicombe, a plankton ecologist also at PML, identified the plant from samples collected out near the Eddystone off Plymouth, so confirming the suspicions that the bloom was not harmful. “What is interesting is the timing of the bloom”, said Widdicombe, “we would normally expect the spring bloom to be a few weeks later than this, although there is some variation and it all depends on being in the right place at the right time. A further point of interest is that this species all but disappeared from Plymouth Sound for many years and its early appearance this year is all the more unusual.”

Plymouth Marine Laboratory remote sensing images showing the Skeletonema costatum bloom off Ireland and Cornwall and Devon (click image to expand)

Long term monitoring of natural events like plankton blooms is a key part of nationwide programmes to understand and predict how our seas may be changing. Using satellites to detect the timing of such blooms is one way of trying to discover how the oceans are being affected by climate change and other environmental factors, for example.

Peter Miller and his team are continuing to watch the bloom grow after analysing data beamed down from the satellite as part of an EU funded research programme involving partners across Europe.

The AquaMar project aims to use satellites to detect algal blooms that might pose a risk to humans, fisheries and shellfisheries. By combining satellite data with a variety of techniques such as realtime sampling at sea using automated buoys and analysis using high power microscopy and flow cytometry to identify and count plankton cells, the Plymouth team and their European colleagues are refining methods of identifying the tiny plants that cause the bloom. The idea is to ensure that any analysis from space is reliable and as precise as possible, so acting as an early warning system in the case of a Harmful Algal Bloom (HAB), or to put minds at rest if the bloom is harmless, or indeed beneficial.


An image taken on 13 March 2011 showing the Skeletonema blooms in the visible spectrum (click image to expand)

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