The BIOMAËRL programme is a 3-year collaborative programme between laboratories in UK, Spain, France and Malta which began in February 1996. Its main aims are described in the Workplan. A full inventory of the biological composition (biodiversity) of maerl bed assemblages in these regions therefore has yet to be completed, but progress is outlined below. Maerl beds are characterized by accumulation of unattached thalli of calcareous rhodophytes. This project has set out: a) to examine W. European maerl-bed biodiversity, b) to establish the functional roles played by key elements of the biota, c) to assess the impacts of a variety of anthropogenic assaults on representative grounds, and d) to compile an inventory of NE Atlantic and Mediterranean mearl-bed biota. In many ways maerl beds are analogous to sea-grass beds or kelp forests. Here is the BIOMAERL REPORT, from this project.