[ skip to content ]


Scientific assessments of the microbial fallout from Hurricanes Katrina and Rita in New Orleans are the subject of a commentary by Old Dominion University oceanographer Fred Dobbs in the May 29 issue of Proceedings of the National Academy of Sciences (PNAS).

Dobbs, who is a marine microbial ecologist, comments in the article on a research paper, "Impacts of Hurricanes Katrina and Rita on the microbial landscape of the New Orleans area," which appeared in PNAS earlier in May.

The lead author of the paper is Chris Sinigalliano of the University of Miami's Cooperative Institute for Marine and Atmospheric Science. More than a dozen other researchers are co-authors, representing Woods Hole Oceanographic Institution, University of Hawaii, Louisiana State University and other institutions well known for marine and environmental studies.

Dobbs' article, "Apres le deluge: Microbial landscape of New Orleans after the hurricanes," elaborates on several findings of Sinigalliano and his colleagues. These findings relate to the rapid return of Lake Pontchartrain to normal conditions and to fecal contamination found after the storms that may be attributable to long-standing problems with the New Orleans sewage system.

The lake's microbial environment "returned to pre-storm (but not pristine) conditions two months after the hurricanes," Dobbs writes.

Researchers also found no statistical difference in the level of fecal contamination when comparing sediments from areas of the city that had been flooded and those that had not been flooded. "They conclude that the source of microbial pollution was the discharge of fouled water from the city's interior, a health hazard well known before the passage of these hurricanes, and an unfortunate, if predictable, result of a defective municipal sewage system," according to Dobbs.

The ODU professor contributes an explanation as to why Lake Pontchartrain did not have an algal bloom, as might have been expected, soon after nutrient-rich floodwaters were pumped back into the lake. He suggests, among other things, that the suspended sediment in the lake may have blocked the sunlight necessary for abundant algal production, or that nitrogen-to-phosphorus ratios precluded a bloom.

Dobbs comments on mold, a type of microorganism not studied by the Sinigalliano team, but which is a post-flood public health concern in New Orleans. He also endorses the research team's recommendation that more studies be done about possible hazards from dried sediments that can be inhaled or ingested.

A "Hot Items" story on the Web site of NOAA's Office of Oceanic and Atmospheric Research notes that Dobbs' review "gives recognition for the researchers' use of multiple techniques to address the issues of microbial environmental quality."

In the commentary, Dobbs compliments the quick and thorough response of the team under difficult circumstances. The researchers' work "has generated the post-hurricane data necessary for public health (and other) decisions to be made by government officials, clean-up and repair crews, and, of course, those Crescent City citizens who simply want to return to their homes," he writes.

Dobbs, professor of ocean, earth and atmospheric sciences, had reviewed the Sinigalliano article for PNAS prior to publication, and later was invited to write the commentary that would accompany it. PNAS assigns commentaries to highlight the most interesting research papers that it publishes. Commentary authors are asked to write for a broad scientific audience.

This article was posted on: June 13, 2007

Old Dominion University
Office of University Relations

Room 100 Koch Hall Norfolk, Virginia 23529-0018
Telephone: 757-683-3114

Old Dominion University is an equal opportunity, affirmative action institution.