1) According to recent publications (see Diaz and Rosenberg, 2008 /Nature/), the Baltic remains the largest hypoxic zone on average.

2) I’m not sure what you are referring to by “deeper”. Hypoxia does form on the bottom. This year, the hypoxic zone extended closer to the surface than in normal years.

3) Yes, scientists consider the hypoxic volume, although area remains the primary measure to assess progress towards nutrient reduction goals. Efforts are underway to improve monitoring in the Gulf of Mexico that would allow for complimentary reporting of hypoxic volume in addition to area.

In response to the other questions….Unfortunately, I am not an expert on Baltic Sea hypoxia, so would not be speaking from an informed position if I were to attempt to answer your question on land-use changes in Europe. In terms of the application of science to reduce hypoxic zones, there has been the direct use of this research to attempt to reduce their impacts. For example, in the Gulf of Mexico, science has identified nutrients as the primary cause of the hypoxic zone as well as identified agriculture as the primary source of these nutrients.

Further, research indicated that to implement the 2001 Gulf Hypoxia Action Plan a 30% reduction in nitrogen would be required. Continued scientific investments have led to refinements in that approach. Thus, at the time of the release of the 2008 Gulf Hypoxia Action Plan it was recommended that a 45% reduction in nitrogen would be required as well as a 45% reduction in phosphorus. Ongoing research will likely continue to refine nutrient levels required to reduce the hypoxic zone as well as advance our understanding of the ecological and socioeconomic impacts of the hypoxic zone.

For more information on the science and management of the hypoxic zone, I would recommend the following web sites:

http://www.cop.noaa.gov/stressors/extremeevents/hab/features/hypoxiafs_report1206.html
http://www.epa.gov/msbasin/

2) What does “deeper” mean? The hypoxic zone starts from the bottom up, it seems.

3) Do scientists consider the hypoxic volume? Should they?

Thanks