The way stormwater treatment systems develop as ecosystems over time is a constant fascination to us (and hence a regular topic on Ideanthro!). In today's episode we visit the Wakerley bioretention system (asset ID #B00028 on The WSUD Map). It is large. It has three cells. New species are popping up in all of them; but more so in one of the cells than the others. We wondered why?