Pond Boss Forums POND CONSTRUCTION Creating habitat Life span of poly rope???

I have a new pond that is just starting to fill. I have made some small PVC pipe trees and other plastic structures for fish habitat. So far I have used stainless steel wire that I already had on hand but now that it's all gone I'm wondering if polypropylene rope will last underwater to hold my structures together. I know that poly deteriorates quickly in the sunlight but it may be a good choice for underwater structures.

Any ideas would be welcome. Stainless steel wire is too expensive to continue to use.

Thanks,
LCH