This volume aims to outline the value of algal culture collections to the user community and, at the same time, presents the proceedings of an international meeting held in 2002, which provided a forum for algal culture collections from all over the world to improve interactions among them.

Culture Collection of Algae have, in essence two key functions: They provide consistency and quality, traceable source material and information. They are, de facto, sources of biological standards and without these standards comparative taxonomic, physiological, ecotoxicological and ex situ ecological studies are impossible or, at best, problematic. The value of collections to the user community is widely recognized, not least in that they provide cultures that are often difficult or virtually impossible to re-isolate from their natural habitats, even when the original source is known and accessible. They provide a store of well characterized diversity for research and/or exploitation. The holdings of algal collections are extremely diverse and it is the collections' aim to make available and conserve ex situ as much of the great morphological and genetic biodiversity of microalgae as possible. For phylogenetic and taxonomic studies authentic strains, i.e. cultures derived from the material used for the original description and naming of the species, are particularly useful - these and the vast literature published on the algal culture collections' holdings make them irreplaceable and unique international resources.

The importance of maintaining biological resources for both scientific reasons and for possible future exploitation, or sustainable development, is receiving increasing international attention. Various initiatives highlight the unique value of culture collections as Biological Resource Centers (BRCs), the need to support and expand their holdings, and the importance of improving collaborations among collections. These initiatives served as a stimulus for the international symposium "Culture Collections of Algae: Increasing Accessibility and Exploring Algal Biodiversity", held at the Sammlung von Algenkulturen (SAG) at the University of Göttingen, Germany, September 2-6 2002. An excellent review of the meeting has been published by B. Surek in Protist 153, 343­355, 2002.

The 21 papers in this volume reflect the main topics of the meeting: the majority of the sessions were devoted to presentations by culture collections including historical aspects of culturing microalgae (the first thirteen papers in this volume, pp. 1-173) and the Cryopreservation of Microalgae (J.J. Brand & K.R. Diller, pp. 175-189; J.G. Day, pp. 191-205; K. Harding et al., pp. 207-226; H.C. Osório et al., pp. 227-235). In the first section of this volume we tried to provide a forum, particularly for smaller culture collections, which have had fewer opportunities, to date, to gain exposure in the scientific mainstream. Two further sessions of the meeting clearly showed the function of culture collections as valuable sources of research material, i.e. Taxonomy and Evolution of Microalgae and Cyanobacteria (D.G. Mann & V.A. Chepurnov, pp. 237-291; K. Comte et al., pp. 293-311) and Applications of rDNA Probes and DNA Microarray Techniques (R. Groben et al., pp. 313-320; K. Metfies & L.K. Medlin, pp. 321-327). It is hoped that these papers have highlighted some examples of the value of collections to the phycological community and further stimulate their scientific exploitation.

Thomas Friedl, John G. Day and Hans R. Preisig