Did The Mother Shark Get One Of The People On The Wooden Float??

I've always wondered about this. During the beach scene, after biting Kelly, the shark heads over to this wooden float type thing upon which a handful of people are standing. We see the float fall apart, sending its passengers plunging into the water. We can see a lot of motion and flailing limbs as the people struggle to reach the surface. To me there appears to be a dark cloud of blood forming underwater around some of the swimmers. I could be mistaken, but if there is indeed a cloud of blood....wouldn't that imply the mother shark claimed one of them as a victim. The more times I see the scene the more certain I become the shark ate someone there. However we are never given any confirmation on this, we are just told later that (I believe)seven people have been injured at the beach area.

Does anyone know about this? I'd be curious to see what others think. Thanks