Besides the Gnome being attacked by an alligator gar or horseshoe crab.....
I think the most likely thing would be a water spider. When I was paddling the cypress swamp in southern Illinois, the thing that I had to contend with most of the time was trying to keep all of the spiders that would walk on top of the water from climbing into my kayak. Lucky for me most of them were very small. At one point I saw a large sized spider heading quickly for my kayak and I quickly paddled away as fast as I could! Eeek!
So I think most likely he will be fighting off lots of spiders!