I'm seeing a cracked seat frame (which could happen for variety of reasons) but I'm not seeing any obvious rot, dry or otherwise. Is there an area where the wood is crumbling, powdery or getting soft? Rot requires food (the wood itself) air (which is pretty much everywhere) and pretty serious exposure to moisture to form. Since it is basically suspended mid-air with good ventilation around it, I would think a seat frame would be one of the less prone areas for rot on a canoe.