Introduction

The silica-scaled chrysophytes are unicellular flagellates, photosynthetic or colourless, solitary or colonial, assigned to the class Chrysophyceae. These organisms have species-specific silica structures, which are formed in silica deposition vesicles (SDVs) derived from the Golgi apparatus. The scales do not create a static armour but a dynamic structure that adjusts to the addition of new scales during both cell growth and division. To date, the taxonomy of the silica-scaled chrysophytes is completely based on the morphology of silica scales. The scales vary in size from around 1-10 µm. For accurate identification at the species level, using Electron Microscopy (EM) is essential. Silica-scaled chrysophytes are very special amongst the protists in that they adhere to a species concept, one of morphology, that extends beyond standard protist cell structure, the silica scales giving us an extra morphological criteria on which to base taxonomical efforts.

Members of the silica-scaled chrysophytes are an important part of the freshwater phytoplankton. They could form the majority of phytoplankton in oligotrophic freshwater lakes and ponds. Knowledge of the chrysophyte occurrence and their ecological ranges is useful for monitoring of the status and quality changes of water bodies. Paleolimnological studies have mainly been focused on monitoring eutrophication, acidification and trends in climatic changes. Due to their well-established species identification concept, wide distribution and narrow occurrence spectra, the silica-scaled chrysophytes present themselves as an excellent paleoecological indicator, giving the oportunity to estimate, with more precision, distribution patterns and ecological preferences of particular chrysophyte species. Even so, comprehensive collection of all records about the occurrences of silica-scaled chrysophytes is still needed.

We have established an on-line database where all records dealing with the European silica-scaled chrysophytes can be simply stored and catalogued for reference and use in any subsequent investigations. The database has been developed to store the data about each collection made (including the geographical coordinates, temperature, pH, and conductivity values) and to store a collection of TEM, SEM, or LM microphotographs. For each species listed in the database, the photo gallery, list of all records, and the distribution map are provided, and automatically updated with any new entry. For those species having more than 20 records, the distribution frequencies along the pH, conductivity, and temperature gradients are shown as well.

At the moment, the database holds information about the distribution and ecology of 204 species and infraspecific taxa, based on more than 7500 entries.

We actively invite everybody who is interested in Chrysophyte biogeography, ecology and taxonomy to participate in this database. We have already included published records about the occurrences of silica-scaled chrysophytes in Europe, and will continue to add newly published data to our database. Despite, we will be grateful to everybody who can include its own, even unpublished records or EM pictures.