Cycles - Emission shader on fluid is leaving artifacts in the render

Hey everyone, I was hoping someone could help me with an issue that I’m having. I’m rendering a fulldome animation of a volcano following this tutorial: I’m just about to start compositing, but my renders are including this terrible artifact that’s completely ruining it. By messing around with the shaders, I’ve discovered that the issue is coming from the emission shader on the fluid/lava. Does anyone know what’s happening here? I’ve included rendered stillframes and the .blend can be found here: