 The basis of red tides are dinoflagellates. Dinoflagellates are incredible organisms that have the ability to reproduce extremely rapidly, producing large amounts of toxin that compose red tides. The original stage of the dinoflagellate is the cyst. The cyst is the stage that resides in the sediment and it can stay in this location for many years. When there's a trigger in the overlying water column, often increasing nutrients or increasing temperature, the dinoflagellate will excess into the vegetative stage. The vegetative stage is a stage that reproduces asexually and this reproduction can occur extremely rapidly, producing many millions of cells in the overlying water column in a short period of time. When conditions change, often decreasing amounts of nutrients or lower light levels, cooling temperatures, the dinoflagellate will reproduce sexually, producing gametes and these gametes will form the zygote stage that will then, in turn, form the cyst stage, which will fall to the bottom of the ocean and reside in the sediment once again for years until conditions change again.