Response of Lake Michigan benthic algae to in situ enrichment with Si, N, and P

Addition of Si alone had little stimulatory effect on algal biomass, while enrichment with Si + N + P led to the greatest increase in chlorophyll a, particulate Si, total biovolume, and diatom biovolume after 14 d of incubation. By day 31, communities on control and Si substrata exhibited little change in biomass and remained dominated by diatoms (98% of total biovolume), while algal biomass on both N + P and Si + N + P substrata increased more than eightfold and consisted mainly of Stigeoclonium tenue (Chlorophyta) and Schizothrix calcicola (Cyanophyta). Benthic diatoms in Lake Michigan are thus not currently limited by Si, but may become Si limited following enrichment with N + P. -from Authors