A report finds the overall health of the Chesapeake Bay did not improve last year despite increased restoration efforts. The report cited pollutants caused by agriculture and suburban runoff. The report also found that the population of the bay’s hallmark blue crabs declined last year to 120 million, a decrease of 23 million from 2007. On a positive note, there was an 18-percent increase in underwater bay grasses, important for filtering excess nutrients from the water and providing habitat and food for fish.