What finally brings the attention of the sea elf back to the conversation when Tanis interrupts it?

The thing that brings back the sea elf to the conversation when Tanis interrupts it is when he mentions the dragons being reawakened. Tanis asks Zebulah whether or not they have dragons beneath the sea, and Apoletta, the sea elf, answers him. This concerns her, as if these dragons of the sea have awoken, even the sea elves at the bottom of the ocean are no longer safe.