Which will freeze at a higher temperature of freshwater marsh or saltwater marsh?

Saltwater marshes will generally freeze at a higher temperature than freshwater marshes. This is due to the presence of salt in the water, which lowers the freezing point through a process known as freezing point depression. As a result, saltwater needs to reach a lower temperature to freeze compared to freshwater, which typically freezes at 0 degrees Celsius (32 degrees Fahrenheit). Thus, freshwater marshes are more likely to freeze at higher temperatures than saltwater marshes.