Managing Coastal Image in La Paz

I took this photo while I was down in La Paz, Baja California Sur, earlier this summer. I was walking along the boardwalk when I saw this big tractor drive across the sand. "What the hell could they be doing with that," I wondered. Really, I did wonder. So I walked over and I saw these guys scooping up green moss from the sand and putting it into the tractor to be carted away--who knows where. It was apparently* an effort to clean up the beaches and provide the white sand that tourists, whether national or international,** expect. Ok, so I understand WHY they're doing this. This is something that is pretty common in coastal tourism areas--they're always trying to make the beaches look just like the magazine and TV ads, which all feature luxurious white sand beaches (preferably with no footprints). But I was wondering about the biological results of this practice. What does the moss do? Is it common for moss to accumulate on the beaches, or is this something that has come about because of all the harbors? How does the moss fit in with the larger ecosystem? Sounds silly to some, but these are the kinds of questions that go through my mind. Sometimes these little details matter.

*Ya, I really should have walked over and asked these guys what they were doing and why. That would have made sense. But for some reason I really didn't feel like getting in the way at that moment. Maybe there is a way to find out a little more about this.
**La Paz, unlike Cabo San Lucas, has a large percentage of domestic tourists in Mexico. I have not checked the official numbers, however.