About the database

The database has been compiled and edited by Peter V York and David M John of the Department of Botany, The Natural History Museum, Cromwell Road, London SW7 5BD, UK, and is intended to be used in conjunction with The Freshwater Algal Flora of the British Isles (2002; edited by DM John, BA Whitton and AJ Brook) which is available directly from the publisher, Cambridge University Press, or from the Natural History Museum Shop (cost £80).

The colour images in the database are of live algae showing cell form, chloroplasts if present and other cytological features. About two thirds of the images are in the CD photo catalogue that accompanies the Flora (compiled and edited by Peter V York, David M John and Leslie R Johnson). Eventually the database will reference more than 1000 images and currently includes about 350 species belonging to more than 150 genera in 12 phyla. The diatoms are not included in the database.

These photomicrogaphs are intended as an aid for identification and form a 'virtual collection' when accompanied by additional information. The algae have been photographed under various light microscopy techniques, such as brightfield, differential interference contrast and phase contrast illumination. Digital image auto-montaging software, developed by Synoptics in collaboration with the Natural History Museum, has been used to produce completely in-focus photomicrographs from an electronically processed series of optical slices. Occasionally scanning electron microscope photographs are included to aid the interpretation of structures visible under the light microscope. The photomicrographs are also supplemented by habitat photographs and photomacrographs, especially where algae form conspicuous macroscopic growths or discolour water to form a plankton bloom.

Taxa are listed alphabetically within their respective phyla and are accompanied by one or more thumbnail images. Note that thumbnails are not intended for identification. Normal conventions of specimen orientation are not necessarily followed.

Accompanying each image entry is the following information: currently accepted name, authority, a unique eight-digit code (Whitton, John, Kelly, Haworth, 2003. A Coded List of Freshwater Algae of the British Isles, 2nd Edition), dimension of alga, type of photograph (brightfield, differential interference contrast, phase contrast), copyright holder, collection information (where known), additional remarks if needed, plus a reference to the page and plate number if described in the Flora.