Algal recruitment from lake sediments in relation to grazing, sinking, and dominance patterns in the phytoplankton community

I assessed the importance of algal recruitment from the sediment surface to the water relative to other population variables such as grazing, growth, and sinking. In four low‐productivity lake basins, which were stratified throughout the study, 32% of the identified algal taxonomic groups exhibited recruitment, whereas the other 68% spent their entire lives in the pelagic habitat. For most species, recruitment from sediment to water occurred primarily at shallow depths (<8 m) and often increased total phytoplankton abundance by 10–50% per day. Grazing was the main loss process, reducing algal abundance by usually between 10 and 50% per day; sinking rates were usually one order of magnitude lower. Recruitment was highest in shallow water (<10 m deep); when maximum recruitment occurred below the thermocline, no relation was found between recruitment and abundance in the euphotic zone, suggesting that the thermocline functioned as a physical barrier for algal vertical migration. In three of the lakebasins, recruiting algae dominated more often than expected by chance (P < 0.05), suggesting a competitive advantage with the adaptation to perform recruitment. Successful recruitment may have a considerable impact on dominance patterns in the phytoplankton community.