It is interesting that this zoo does not feel they need to control otters' water quality, as most zoos would. Thanks for your replies.
@lintworm will correct me if I'm wrong, but I think Bern Tierpark also has permeable barriers between the otter and beaver pools and the river.
@FunkyGibbon That is indeed the case, so the water level is directly dependent on the water level of the Aare river. Water quality won't be problem in Bern though
