Dead Sea Urchin in Tank - Help!

[Blue Ram]

I'm trying to maintain the best water quality I can in two tanks that are holding my livestock until the large tank is set up and running over the weekend. Nitrites are measuring .1 in both tanks. I have been doing small water changes each evening. Tonight when I got home the sea urchin was dead and most of the spines had fallen off the body. I have removed it and did a 10% water change. Will urchins release any deadly toxins? The corals are not looking that great but the lights were out all day. Anything else I should be doing immediately other than water changes?