I know there's a couple on here from tpwd but I think they are game wardens. A few pond management guys as well but not that kind of biologists. Might look up pondboss, Bob Lusk, and ask him this question. I know for sure he knows who you are searching for.
Also might try Dr. Ruth Francis Floyd from The University of Florida's fisheries dpt if she's still there. Spent a decade working with her with necropsies and such. With the vegetation there she would know. Please let me know what you find.
Acute-exposure studies found that -16C for 48 hours could destroy giant salvinia, with ice formation as an important factor in below-freezing temperature events.