Can reducing inputs of reactive nitrogen really reduce eutrophication?

I’ve come across an interesting debate in the literature on the benefit of nitrogen management with respect to reducing eutrophication, a widely known consequence of anthropogenic nutrient inputs to aquatic ecosystems.    

Schindler et al. (2008) carried out a 37 year experiment in a small lake designed to test the assertion that controlling nitrogen inputs could be effective in controlling eutrophication.  Over the 37 year period, the annual addition of phosphorous remained constant, whereas the amount of nitrogen added was gradually reduced each year.  For the final 16 years of the experiment only phosphorous was added to the lake.  The results showed that reducing nitrogen inputs increasingly favoured nitrogen-fixing cyanobacteria as a response by the phytoplankton community to extreme seasonal nitrogen limitation.   The additional nitrogen fixation that resulted allowed biomass to continue to be produced in proportion to phosphorus, and the lake remained highly eutrophic, despite showing indications of extreme nitrogen limitation seasonally.  These results led Schindler et al. to conclude that management of eutrophication is dependent only on the reduction of phosphorous inputs. 

The trends in nitrogen/phosphorous ratio and phytoplankton biomass occurring during the same experiment were later investigated by Scott and McCarthy (2010) and this resulted in an alternate conclusion.  Scott and McCarthy noted that after 1990 (the date when nitrogen addition to the lake ceased) the total N concentration decreased, which resulted in a decrease in the ratio of total N to total P and suggested increasing N deficiency.  There was also a significant decrease in phytoplankton biomass between 1997 and 2005.  These observations led to the conclusion that the lake had become increasingly N-limited since the input of nitrogen was stopped and that natural nitrogen fixation by cyanobacteria wasn’t enough to make up the shortfall in Nr concentration.  It was also found that phytoplankton biomass decreased in response to the decreased N availability, leading Scott and McCarthy to conclude that the degree of eutrophication can in fact be controlled by managing N inputs together with phosphorous.