I think this may be a Heisenbug. I've linked to the wiki, but basically this is a problem that appears only when looked at too closely. I just came across this in my programming studies, and like many, I fall in love with new words and want to use them.
In this instance, you may have bugged the perception by highlighting "meanwhile." In the normal flow of reading quickly, this may have been inconsequential.
Somewhere (sorry for the completely unscholarly reference) I read an essay by Orson Scott Card explaining why he became, er, less than enamoured by writing workshops. It was this tendency to look too closely at things. If you have won the reader's attention, and he or she is engaged in the material, things like "his eyes rolled down the front of her blouse" are perfectly grasped. The literal meaning of the words, though hilarious, are not perceived at all. [I got that from Stephen King, er somewhere].
Now, to do something I learned from Japanese stylists, an essay should always be concluded with "What's wrong with what I said."
Here's one thing that might be wrong with the foregoing thesis. The excerpt does not read like a chunk of story. It reads like a precis, a synopsis, and abstract, or a blurb.
Now, if that's the case, then it should be polished to critical perfection--if such a thing exists.
For a blurb, I don't like the "meanwhile" either. I would favor a harsh, contrasty jump. This way we have the jarring effect of going from the protagonist's to the antagonist's viewpoint. Since this is a story with a definite "good guy" and a definite "bad guy." It's appropriate to put in a shock bang! First, we have a detective who gets clues by listening to seashells? OK. I'm in the story. That's a great opener. Now, give me something about the killer, oh, stung to death by jellyfish? Hah. Lead with that. That's the counter to the seashell listening. It's equally weird, and... enticing. The object of the blurb is to make you want to read the story.
"....in his ear, but/however/suddenly! the seashells are silent/strange/frightened about what appear to be jellyfish marks on the first body."
[Edit] What's really wrong with this thesis.
As Standback points out in the comment below, I have misused the term "Heisenbug."
I reproduce his comment here because I do not wish to misinform people.
A Heisenbug isn't a problem that wouldn't exist if you weren't looking for it; it's a problem that clearly exists, but which changes its behavior in reponse to seemingly-trivial attempts to investigate it, making it infuriatingly difficult to track down to a root cause.
Evidently, there's a looser definition that rolls around physics departments at the colleges I've been associated with; that is, "a problem that is actually caused by looking at it." That was what I meant. Calling that a "Heisenbug" was a new twist.