Would it be mainly freshwater diatoms or marine water? Since they both have diatoms that differ in size and abundance. How will it affect an investigation (for a forensic scientist) if the body is moved to another location?
It is well known that brackish water habitat may have greater diversity than freshwater and marine water habitat. Because number of species of diatoms are most in marine water habitat than freshwater habitat therefore, there is possibility of getting more species of marine diatoms than freshwater.
Also forensically, the diatoms might indicate the depth of the water. Estuary/Sound waters don't always mix well. Fresh water tends to be above saltwater. Divers adjust their weight for the change in buoyancy when going from salt and freshwater. Fun question!