Hard part over? Let’s see now: Mark swam underwater for a few minutes to take pictures of a hull covered in barnacles (so it appeared). I didn’t see anybody take pictures of the cargo ship, itself; so how will he prove what ship it is? Can he even prove where the photos were taken?
So you call that an investigation, Mark!? No interviews, no follow-up, no verification of the ship’s route or manifest? Maybe a fishing magazine just doesn’t have to meet the higher criteria of a more serious investigative organization…such as QAnon. Now, would a company really send out thugs to beat up Mark, as Cliff warns? Sure, they do it in movies and books all the time: “Nice cabin you got there, Mr. Trail. Be a shame if something were to happen to it.” On the other hand, I suppose the shipping company could try to hurt Mark professionally. They could finance an exposé of Mark’s most recent adventures, for example.
The Daily Trail 
I need to throw the penalty flag now.
Mussels do not grow well on moving ships. They grow on stationary things like piers, docks and rocks. While you see pictures of them on boats and engines, they too were most likely stationary. Barnacles grow on ships because they are shaped resist the water flow. Indeed, Jules own underwater drawings most resembled barnacles. Although large ships transport zebra mussels, they carry them in their bilge tanks as fresh-born glochidia, taking water from one port and discharging it in another.
How about sneaking on the ship and sampling its bilge water? Now that would be investigative journalism.
Consider the flag thrown, and rethrown, Daniel! Maybe that is what Rivera hints at in her text box in panel 4? That is, she is “allowing” Mark (and Diana) to go down a blind alley, only to find out they focused on the wrong thing and have to start over, with a new strategy.
If Rivera does do that, I’ll have a lot more respect for this story!
Thanks!