Tides affect coastal ecosystems in several ways. The rise and fall of tides can bring in nutrients, oxygen, and plankton to coastal areas, which can support a diverse range of marine life. Tidal currents can also help disperse seeds and larvae, aiding in the reproduction and dispersal of various species. Additionally, tides can influence the erosion and deposition of sediments along coastlines, shaping the physical environment of coastal ecosystems. Overall, tides play a crucial role in the ecology and dynamics of coastal ecosystems.