After following the great advice on this site, I've started feeding my newts earthworms. Today one 'got away' and went down into the gravel on the island in their tank. There's no chance of me finding it. I assume it's going to drown or be caught by a newt. My question is, if it does die beneath the gravel, will it be very bad for the water quality? I monitor nitrates, etc, so I can keep an eye, but I'm still a little concerned.