An interval of enhanced N fixation, likely in response to N limitation, occurs in the uppermost Triassic.
This interval coincides with substantial decline in estimated primary productivity.
The onset of photic zone euxinia coincides with a recovery in apparent productivity.
The introduction of deepwater f&_user=111111111&_pii=S0012821X16303375&_rdoc=1&_issn=0012821X&md5=c43f41b051cc1e03837c562055e466fa">f" data-inlimgeid="1-s2.0-S0012821X16303375-si1.gif"> may have fueled recovering productivity in the lowermost Jurassic.