Questions and more questions

As I scratched my thoughts about H2S and Hypoxia, several new things have emerged.
First a paper published on Lake Erie (so definitely not by me) gave phosphorus and phosphate a new role as the limiting factor in algae growth in marine waters (this has always been true of Fresh water, but the thinking has always been that it was different for salt water).
This apparently has gotten many from the EPA to question their direction in the Sound (about time).
Two questions were posed to me by Art Glowka.
The first was concerning cyano-bacteria, which are now known as blue-green algae. They fix Nitrogen, meaning that they take available nitrogen and turn it to ammonia, which in turn is changed to Nitrite (2 oxygens) and then Nitrate (3 oxygens). Could this be a pathway causing Hypoxia?
The second has to do with a graph, long published in the New York water quality report and now omitted, showing the beginning of significant Hypoxia in the Long Island Sound occurring around 1977.
This coincides with two events, me moving up to Connecticut and the beginning of sewage treatment plant "clean up".
Is it all coincidental? For one part of that, I certainly hope so, the other is a question that we may try to answer when I try to get back to the Long Island Sound.