Desperate for online advertising, newspapers have learned to aggressively optimize their content for Google. The result: more traffic. Junky traffic.

Readers tend to spend gobs and gobs of time on newspaper sites. Indeed, their level of engagement has been print journalism's strongest asset online, but that's changing: According to data from Nielsen Online, readers are spending less time on top newspaper websites, including six minutes less per month at Washingtonpost.com, one minute less per month at USAToday.com and a minute and a half less per month at NYTimes.com.

That's a natural consequence of deriving new traffic growth from a Search Engine Optimization staff, as we've heard anecdotally is happening at many papers. The count of unique users goes up, while the value of each reader for advertisers goes down.

And when the likes of Huffington Post comes to town with a local section — HuffPo launched in New York Monday — it becomes that much harder to convince advertisers you have a special relationship with the locals.

The ideal strategy for newspapers would be to hold the local audience while cultivating new niches likely to be a lucrative as the online ad market grows more sophisticated. Unfortunately, there's hardly a newspaper in the country that can afford to take its sweet time.