I'm not really sure it is the WPG
, I think it is more like what spectrum of light can pierce what depth of water. As you get deeper in water, less spectrums of light can reach it. I can't remember exactly, but I think the yellows/reds/blues/and green is the order in depth, that the different spectrums of light can pierce. That's why you see lots of color with in the first atmosphere of SW
(atmosphere is about 33feet), after that, the above mentioned colors start fading. Once you get to, maybe around 90 feet, about the only colors are green or maybe a little blue. I know this is not exactly right, as it had been a long time since I knew this stuff. Hopefully, one of our marine biologist-type folks can put it better or correct me. So to wrap it up, the 37G may have had the proper lighting to encourage the coraline growth.
PS. If I am tottaly, I will correct this post, so definitely let me know!