Figure 10. Comparison of the relative abundance of Ammonia beccarii (colored symbols; red symbols: 1996/1997 data; blue symbols; 1960s data; green symbols: 1948 data) with the absolute abundance of Clostridium perfringens spores (black symbols). C. perfringens data in numbers of spores per gram of dry sediment from BUCHHOLTZ TEN BRINK et al., this volume.