Phytoplankton is a key Biological Quality Element (BQE) monitored under the Water Framework Directive (WFD).

Analyses of lake phytoplankton provide an important indication of the presence and extent of nutrient pressures. Measures of phytoplankton abundance, species composition and bloom intensity are used to report WFD status class to the European Commission.

ENSIS has been contracted by the Environment Agency to undertake annual (since 2007) enumeration and biovolume estimation of lake phytoplankton samples for approximately 70 sites per year. The samples are taken in July, August and September and tell us about the summer phytoplankton community. In combination with chlorophyll data collected monthly throughout the whole year, the phytoplankton samples are used to determine ecological status for phytoplankton as required by the WFD.

Similar contracts have been awarded by Natural Resources Wales (2013 to date) and Northern Ireland Environment Agency (2009-2011).

Counts are carried out using the Utermöhl technique according to CEN standard “Water quality – Guidance standard for the routine analysis of phytoplankton abundance and composition using inverted microscopy (Utermöhl technique)”. Sedimentation chambers (5ml, 10ml or 15ml) are used to settle and count the sub samples. Biovolumes are estimated based on measurements of individuals of each taxa.

Sedimentation Chambers
Sedimentation chambers (5ml, 10ml or 15ml) used to settle and count the sub samples
Paediastrum Colony photo
Biovolumes are measured for each object- either whole colonies (e.g. Paediastum sp. above)/ filaments or cells.