In the first, Marian Burros (who wrote the original article) reports that restaurants and retailers nationwide are testing the mercury level of the tuna they serve. Burros mentions some push-back from the National Fisheries Institute, but in general she doesn't seem to waver from her original article's level of concern.
The second article, by Nick Fox, reinforces this concern by detailing which seafood is likely to have the lowest (or no) mercury.
What I find interesting is that neither article takes up the accusation that the original piece was, at worst, "scaremongering," as this piece from Slate claims, or simply not detailed enough to give the complete picture, as this Time article seems to suggest.
I'm not a scientist, and I have no particular stake in this issue except that, ideally, I would like to eat tuna. (Overfishing of the species being a whole other matter, of course.) Still, I find it disheartening that, once again, instead of having a rational discourse about an important topic, we're headed toward the "X is bad for you!"-type reductive argument that has led to such great moments in culinary history as margarine being recommended over butter.
(Why, yes, I have recently read Michael Pollan's In Defense of Food.)