Great diving beetle larvae

We went away to north Wales for 7 days and returned to find far fewer tadpoles in our garden pond than when we left and some very ferocious looking great diving beetle larvae tucking into the tadpoles. The remaining tadpoles are very twitchy and generally hide in the sediment now. I'm not sure I like this new member of the pond community even though I know it's all part of the rich web of pond life. It's survival of the fittest tadpoles I guess...