September 16, 2005 Update
Hurricane Katrina and the Mississippi River Plume: Potential Florida Impacts
Contact: Gil McRae, FWC 727-896-8626
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A wide array of contaminants, including oil and gas products, pesticides,
industrial chemicals and heavy metals are expected to reach the Gulf of Mexico
via the Missississippi River.
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While it is likely that many contaminants will occur at levels likely to cause harm
to marine life only in the vicinity of the MS River mouth, because of the scale of
the event and uncertainty regarding the nature and level of contamination
involved, it is important to consider potential impacts to Florida.
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The degree to which MS River water reaches Florida depends on the relationship
of the river discharge to prevailing currents and winds in the Gulf of Mexico.
Again, it is unknown which specific contaminants, if any, will persist at
potentially harmful concentrations as the MS River water mixes with water from
the Gulf.
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In general, the movement of deeper waters in the Gulf of Mexico is controlled by
offshore currents, while movement of shallower water on the continental shelf
(Figure 1) is often driven more by wind conditions.
Figure 1: 3-d Bathymetry of the Gulf of Mexico. Shallower continental shelf areas are in
lighter blues, deeper waters are darker blues.
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Following Katrina’s landfall at New Orleans on August 29, 2005 circulation
patterns in the Gulf of Mexico have directed MS River discharge offshore and a
portion of the discharge has moved clockwise off the western coast of FL along
the continental shelf break.
To confirm that MS River water is not moving onto the shelf, FWC and DEP
conducted water and sediment sampling on September 16, 2005 along a 30 mile
transect SW of Panama City. These samples will be analyzed for a wide variety
of contaminants by DEP with results available by September 21, 2005. In the
event that no unusual contaminant levels are detected in these samples, they will
still provide valuable baseline data for comparison if MS River water reaches that
area in the future.
Oceanographers from NOAA, the University of South Florida (USF) and the
University of Miami (U of M) are working together to track the MS Plume water
and construct predictive models to determine if and when it will reach Florida.
The current models predict that MS River plume water will reach the FL Keys on
or about September 20, 2005 (Figure 2). It is unknown if this initial plume of
water is pre- or post- Katrina and if it contains any contaminants of concern.
Figure 2: Forecast path of water of MS River origin in the Gulf of Mexico. Courtesy of
Dr. Robert Weisberg, University of South Florida, College of Marine Science.
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Information on contaminant content of the MS River source water will be
generated by scientists on NOAA cruises currently operating and planned in the
Gulf of Mexico. The NOAA research vessel Nancy Foster is sampling off MS,
AL and FL currently (Figure 3) for a wide variety of contaminants, including
potential pathogens (bacteria, viruses), as well as fish, shrimp and crabs.
Preliminary results are expected early in the week of September 19.
NOAA has also contracted a commercial fishing vessel out of Bon Secour, AL to
sample water, sediment and fish throughout the Mississippi sound from 9/13/ 9/19/05.
Figure 3: Cruise track for the NOAA research vessel Nancy Foster in the Gulf of Mexico
9/12-9/16 2005.
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NOAA has additional cruises planned beginning in Key West and running up
along the plume path toward western Louisiana. Several automated drifters
(devices that move with the current and transmit their location) will be deployed
in the plume to provide real-time tracking capability.
FWC is working with DEP and the Florida Keys National Marine Sanctuary to
sample inshore waters of the Florida Keys if necessary. Interpretation of
laboratory results generated from the NOAA cruises will provide more guidance
on the position of MS River source water and any issues that may be related to
contamination.
MS River source water will remain a concern for at least for the next several
weeks and collaborative partnerships among FWC, DEP, DOH, NOAA, USF, and
U of M are in place to track the river water, determine its composition, and
respond appropriately.
Acronyms Used:
NOAA = National Oceanographic and Atmospheric Administration
FWC = Florida Fish and Wildlife Conservation Commission
DEP = Florida Department of Environmental Protection
DOH = Florida Department of Health