Local Extirpation of Stephanodiscus Niagarae (Bacillariophyceae) in the Recent Limnological Record of Lake Ontario

We investigated microfossil assemblages in recent sediments from nine stations across Lake Ontario. Stephanodiscus niagarae was not present in any of these sediment samples, marking the taxon’s extirpation from its type locality. This observation documents the end of a general reduction in size and alteration in valve morphology associated with habitat disturbance. Stephanodiscus niagarae may have been directly eliminated from the lake, or sexual reproduction may have been delayed beyond the species’ ability to sustain numbers through asexual reproduction.