Example: while working in the Szczecin Lagoon on the Polish coast, we observed a specific phenomenon called the phytoplankton bloom. It involves intensive growth of phytoplankton (that is unicellular algae in the water column) at certain times of the year (Photo 1). In the Lagoon, phytoplankton blooms are persistent every year. As the remains of the phytoplankton biomass (the so-called phytodetritus) sink and are deposited on the Lagoon’s bottom, the sediment received a supply of organic material of plant origin.