Dissolution was high throughout the profile—in most cases, only 10–20% of the valves considered as pristine (Fig. 4). High relative percentages of A. baicalensis and of benthic Fragilaria (sensu lato) were positively correlated (r=0.29 and r=0.26, respectively) to samples with large proportions of pristine valves. There were no significant relationships between this index of dissolution and any of the other dominant taxa. Fragmentation of the valves was also high. On average only 45% of the total count was represented by whole valves (Fig. 4) and high percentages of non-fragmented valves were positively correlated with the percentages of pristine valves. The percentages of pristine valves showed high variation (20–70%) and by contrast with the dissolution index, they were significantly correlated with the variations in percentages of many dominant taxa.