Are these bed bugs shells?

None   they are   equally likely to occur on any plate boundary

The peak above is part of the  sierra madre occidentals ,  a chain of volcanic mountains that runs through the middle of central america. 

When a lake, river or other aquatic  system  becomes  eutrophic, it can have serious negative effects on other organisms like fish, birds and even people.if an algal bloom is so bad that it causes wide-spread death  in  the  water, the organisms that die will all sink to the bottom and start to decompose.

Bringing the tradition of carnival to brazil