An illustration of validation activities for cholorphyll concentrations map (an indicator of algae bloom) from space. The background image represents a cholorphyll concentration map derived from SeaWiFS satellite data. Areas of low concentration are coloured in blue, medium concentrations have a yellow colour and high concentrations have a dark red colour. The dots show were in-situ measurements were collected at a depth of four metres from a dedicated research cruise by the Centre for Coastal and Marine Sciences (CCMS) and Plymouth Marine Laboratory (PML) in Britain