Originally Posted by erp
Whoever the artist is keeps fishing line on them, so there's a clue to any would-be mystery solvers.
Most likely the bottles are being used by people fishing illegally, either out of season or without a fishing license. It's a crude but somewhat effective way of fishing that allows someone to dispose of the evidence at a moments notice should they be approached. If this is the case it should be pretty easy to find the culprits, they would be the ones sitting on the bank of the river with no fishing rod.
Are there more of these "chandeliers" in areas closer to the river or are they spread throughout the course?