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Viral spread in marine environment?

How do viruses spread in marine environments? After reading about the morbillivirus causing the increase in dolphin beachings and deaths, I was wondering how a virus like this might spread in a marine environment.
gpt
Understanding aquatic disease is in three steps:  1) you have to have an environment suitable for the pathogen, 2)you have to have a susceptible, compromised/stressed individual, 3) you need the right pathogen.  When all three are positive, then disease is highly likely.  If one is negative, then you have a very low possibility.

When it comes to pathogens in general in the aquatic environment, the water itself tends to be the transmitter: that is the media/mode by which contact with may result in the transmission of pathogen to the host.  Like the common cold be can be transmitted through the air, many pathogens can be transmitted by water.

What we worry about in the realm of viral outbreaks in oceans for stocks of fish, whale, and other resources is how that virus exactly transmits itself.  You can't treat the organism without acknowledging the pathogen's mode of transmission.  Most of the time, we think of horizontal spreading of viruses: that is direct contact between infected individuals or the media that is occupied by a pathogen.  Basically: organism-to-organism whether directly (touch) or indirectly (touching the transmitting material).  There can be also vertical spreading (from mother to daughter/son).

Many disease causing pathogens are found in the soils more so than the water column.   This is because eventually diseases in the water column have to fall because they are particles and are subject to Stokes' Law.  The only way to counteract this and remain in the water column is to be buoyant in some capacity (have a vacuole or something).  Or, it divides fast enough to infect carriers.

Carriers are disease vectors such as little fish, inverts, or other plankters that can carry the disease itself, but don't necessarily become affected by it.  When an organism eats a carrier, or comes into contact with the carrier in a way that's similar to how a remora attaches to a shark, then it can be sick.

Finally, diseases and carriers of disease in the oceans move about with the help of vector dynamics (movements of carriers) and the currents/tides themselves (physical moving of pathogenic particles).  Pathogens can be killed in bad environments by chance so this is one reason why you may see local diseases.  Other reasons are that there are no individuals to infect so there's no chance for the disease to occur.  However it can still persist there in the carriers.  And further, other areas may aggravate the occurrences of viral disease so that it may be even more devastating than the source area of the disease.

Simply put, viral dynamics in water are not too dissimilar than viruses in air media.