Monitoring programme for the presence of toxin producing plankton in shellfish production areas in Scotland 2005/6. Reporting period: 01 September 2005 – 31 March 2006

This report presents the results from the monitoring carried out to detect the
presence of toxin-producing phytoplankton in shellfish production areas in
Scotland over the period Sept-05 to Mar-06. A total of 257 seawater samples
collected from 34 coastal sites were analysed, by light microscopy, for the
presence of eight potentially toxic genera or species of phytoplankton.
Pseudo-nitzschia was identified as being present above the trigger level in
some locations during September 2005, but concentrations were below
threshold between October 2005 and February 2006. A spring bloom of
diatoms was evident in all areas in March 2006, although Pseudo-nitzschia
was generally more abundant in samples from around the Shetland Islands
and mainland NW Scotland during this time, and was mostly either absent or
present in low numbers further south.
Alexandrium appeared sporadically in low concentrations throughout the
reporting period, although the data collected during March 2006 suggest an
increase in the abundance of Alexandrium around mainland NW Scotland and
Scapa Flow, Orkney. All other monitored species were observed infrequently
and at low concentrations throughout the reporting period, although
Dinophysis was reported above the trigger level on one occasion (September
2005).
A study is currently in progress to determine the suitability of ASP EnzymeLinked Immunosorbent Assay (ELISA) to detect and quantify domoic acid in
seawater (rather than shellfish tissue) samples