Woods Hole Center for Oceans and Human Health
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Students and researchers from MIT prepare for sampling of waters and sediments in Lake Ponchartrain, Louisiana. They collaborated with WHOI and other researchers to determine the effects of Hurricane Katrina on human pathogens in the lake. (Photo by Martin Polz, MIT)
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Simulation after the 2005 Alexandrium bloom in the Gulf of Maine

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In its second year of operation, the Woods Hole Center for Oceans and Human Health continued studies to improve public health through enhanced understanding of how oceanic processes affect the distribution and persistence of human pathogens and toxin producing organisms. Two projects of note this year focused on the historic harmful algal bloom of Alexandrium in the Gulf of Maine, and the distribution and persistence of human pathogens in Lake Pontchartrain following Hurricane Katrina.

The bloom of Alexandrium—the worst since 1972—began just as Center investigators departed Woods Hole on May 9, 2005 on R/V Oceanus for a long-planned research expedition to study the harmful algae. The team, under the leadership of Don Anderson and Dennis McGillicuddy, documented the distribution of the toxic algae at the critical onset of the bloom, and collected samples to characterize changes in the bloom population. The team is also running numerical model simulations of the bloom to identify the underlying causes of the 2005 bloom and assess risks in future years.

In most years, Alexandrium grows to toxic levels in Penobscot Bay and Casco Bay in Maine and in Canada’s Bay of Fundy. The potent neurotoxin from Alexandrium accumulates in the meat of filter-feeding bivalves, and while it does not harm them, it can cause Paralytic Shellfish Poisoning, characterized by paralysis and respiratory problems in humans and other animals that eat the shellfish.

In 2005, concentrations of toxic algae reached levels 40 times the norm, and the plants spread southward to regions of Cape Cod Bay, Massachusetts Bay, Nantucket Sound, and Buzzards Bay that are usually not affected by this species.
Shellfish beds in Massachusetts, Maine, and New Hampshire, as well as 15,000 square miles of federal waters, were closed to shellfishing for more than a month at the peak of the seafood harvesting season. Economists for the shellfish industry and the state of Massachusetts estimated that the bloom cost the seafood industry $2.7 million per week in lost revenues, with some estimates suggesting double that amount.

In the aftermath of Hurricane Katrina, floodwaters in New Orleans resulting from levee breaches were largely discharged into Lake Pontchartrain. These floodwaters are potentially contaminated with parasites and pathogens from human sewage, along with a mixture of organic and inorganic chemicals. Center investigators participated in a rapid-response project focused on the impact of the dewatering operation on the Lake Pontchartrain ecosystem, with an emphasis on examining the occurrence and distribution of pathogens that may have potential human health effects.

Center researchers Rebecca Gast (WHOI), Linda Amaral-Zettler (MBL), Martin Polz (MIT) and Chris Reddy (WHOI) are collaborating with other center teams at Louisiana State University, the University of Miami, and the University of Hawaii. The goals of the Woods Hole group are to quantify the dynamics of potentially pathogenic bacteria of the genus Vibrio in the floodwaters and sediments, to determine the presence and distribution of Legionella species pathogenic to humans, and to assess the general microbial diversity using clone libraries to determine the presence of sequence types related to known pathogens (which may represent unidentified human pathogens). Sampling of water and sediment from Lake Pontchartrain and nearby canals has recently been completed, and the teams have begun their intensive analyses.

The conditions resulting from the tragedy in New Orleans may represent a worst-case scenario for contamination of coastal waters. Information that we recover from this work can potentially inform future efforts concerning human health issues involving microbial populations and human pathogens in coastal areas.

—John Stegeman, Director and Dennis McGillicuddy, Deputy Director

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Mail: Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, MA 02543, USA.
E-Contact: info@whoi.edu; press relations: media@whoi.edu, tel. (508) 457-2000

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