Data from Bob Diaz, a professor at the Virginia Institute of Marine Science, Gloucester Point, are being used on a new global map created by the National Aeronautics and Space Administration to highlight the connection between human population density, nutrient pollution, and low-oxygen marine dead zones.
The map was featured as the "Image of the Day" for July 17 on NASA’s Earth Observatory website, said David Malmquist, VIMS’s director of communications. That site is produced at NASA’s Goddard Space Flight Center in Maryland.
The map, created by Goddard scientists Robert Simmon and Jesse Allen, combines Diaz’s dead-zone data with measurements of human population density and particulate organic carbon in marine waters, a VIMS report said. The population data was supplied by Columbia University’s Socioeconomic Data and Applications Center, Malmquist said, with data on particulate organic carbon from Goddard’s Ocean Color team. Particulate organic carbon is an indicator of ocean fertility, he said.
Diaz said he began studying "dead zones," which are areas of seafloor with too little oxygen for most marine life, in the mid-1980s. Diaz said he and collaborator Rutger Rosenberg of the University of Gothenburg in Sweden recorded 405 dead zones in coastal waters worldwide in a recent effort.
Diaz said he counted 304 dead zones worldwide in 1995, up from 162 in the 1980s and 87 in the 1970s. There were only 49 such zones recorded in the 1960s, he said.
Dead zones are now a key stressor of marine ecosystems, Malmquist said, and rank with over-fishing, habitat loss and harmful algal blooms as global environmental problems.
The map is available online at http://earthobservatory.nasa.gov/IOTD/view.php?id=44677. Diaz’s dead-zone data is located under the "Layers" panel and then navigate to Ocean/State of the Ocean/Dead Zones.