Having a blooming good time in Cornwall
14th August 2009
Algal blooms are a regular occurance in UK waters and
across the world, however, they often go un-noticed by casual
sea-gazers as they are caused by microscopic plant-like organisms.
If the environmental conditions are correct these blooms can become
extremely concentrated and some species can cause what is often
referred to as a “Red Tide”.
The residents of St Austell Bay, Cornwall experienced such
an event first-hand during the early part of August 2009.
Reports of reddy-brown water and suffocating or dead marine
life on beaches and across the low tide mark were passed to PML by
local photographic agency, Apex News & Pictures. The following
day PML PhD student, Naomi Downes-Tettmar, headed for the area to
investigate and take samples, which were bought back to the lab for
analysis.
Upon arrival it was evident that the murky sea was not
detering the beach-goers as adults and children alike played in the
calm shoreline waters. Many of the children were collecting dead
marine life, ranging from starfish and rag worms to Dover
sole, from the beach and rockpools.
Speaking to some of the local fishermen, it appeared that algal
blooms are an annual event in the area but this year’s
concentration far surpassed what had previously been experienced.
At low tide the previous day locals had looked on in amazement as
the harbour bed was littered with fated marine life.
Back at the lab, Naomi and Plankton Ecologist, Claire
Widdicombe, identified the algae as the red tide dinoflagellates
species, Karenia mikimotoi, and confirmed the high
concentration. This species has been reported to cause mortalities
in organisms such as flatfish, crabs, lobsters, lugworms, cockles,
mussels, urchins, starfish and scallops, when in sufficient
density. The St Austell bloom was sampled at 5,400,000 cells per
litre compared to the 2006 K.mikimotoi bloom, off the
coast of Scotland, whick peaked at 3,700,000 cells per litre.
These data will feed into the AlgaRisk pilot
study, working towards developing an early warning alarm service
for such blooms. This is a collaborative project between PML,
the Environment Agency and
the UK Met Office, which
was initiated through the National Centre for Ocean Forcasting
(NCOF). In the future it is hoped that this service will
help fisheries and aquaculture sites in protecting their stocks by
providing early notification of approaching blooms.
The Environment Agency has advised against beach-goers bathing
in discoloured waters and to avoid contact with coastline foam and
scum. Shellfish concentrate any potential toxins so should not be
harvested during the bloom period. Once the bloom has dispersed the
shellfish will naturally filter out any toxins and will be fine to
eat again. The EA also remind the public that it is never
sensible to gather your own shellfish. Anyone experiencing skin
irritation or similar is advised to call NHS Direct on 0845
4647.