yup, I'd always double check what plants have invasive habits locally before planting any pond that was likely to connect with other ecologies, phragmites has quite a good reputation for improving water quality and might be useful where its in a position where it can be confined.
Theres quite a lot of lakes out there which are dead as ponds go, after decades of barren neglect of aquatic species, introducing species which are known to be beneficial for example irises (extracting poisonous metals) and hardy waterlilies (providing shade and shelter for fish) are at least some effort to improve habitats which could be otherwise useless.
Somethings going to colonise them, it might as well be something that you can measure as having some redeeming features, While a 'birder' might be obsessive about one thing, a fishing afficienado swear by another thing, a bandwagon eco nut with an eye on political ratings may be whipping the usual headline species...
As a long term ponding nut I'm going to stick my oar in the water as being almost neutral on 'what works' to improve aquatic habitats
Regards, Andy
