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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