Thank you Michael for your interesting news. The winter here (Just west of London UK) is very mild too, never known it so. My adult salamanders, which are kept outside all year to benefit from the seasonal changes, have been active every night.
I've never used brine shrimp at all however I've seen them reared from eggs. I tend to use tuberfix although in moderation as they seem to pollute the water very quickly. In the past some of my smaller larvae never seemed to grow at all and eventually wasted away despite providing not only tiny daphnia but also paramecium cultures too. Good luck with yours.