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| Predominant Bacteria Isolated from Moribund Fusconaia ebena Ebonyshells Experiencing Die-offs in Pickwick Reservoir, Tennessee River, AL. |
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| Photo: Moribund (Fusconaia ebena) Ebonyshells. Photo credit: Clifford E. Starliper, USGS |
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| Photo: Processing mussels for recovery of bacteria. Photo credit: Clifford E. Starliper, USGS. |
Mussel die-offs have been noted in recent years in Pickwick Reservoir, Tennessee River, AL. The primary affected species was Fusconaia ebena, but also affected to lesser degrees were Ellipsaria lineolata, Quadrula pustulosa and Q. quadrula. These events were characterized by large numbers of empty shells, fresh-dead and live individuals that were presumed to be diseased, because of weak and slow valve closure responses to external stimuli. Anecdotal evidence suggested the possible involvement of an etiological agent, such as a bacterial pathogen. The die-offs have occurred within Pickwick Reservoir (river miles 236 – 256) in sequential years over the past approximately 10 years. These timeframes have coincided with reduced basin inflows and warmer water temperatures. The majority of the moribund and freshly dead F. ebena were females possibly predisposed to infection and disease from ongoing reproductive activity. Affected and healthy-cohort mussels were collected to characterize the bacterial flora prior to, during, and following a July 2006 die-off, and during a subsequent die-off in September 2008. The numbers of total bacteria from both the 2006 and 2008 die-offs were significantly greater from the diseased specimens. For example, from the September 2008 die-off the mean count from diseased F. ebena soft tissues was 9.75 × 106 cfu/g, which was more than 100 times greater (p = 0.025) than the mean from healthy cohorts (6.74 × 104 cfu/g). The predominant bacteria from affected F. ebena from July 2006 were Hafnia alvei and Aeromonas sobria, whereas from September 2008 the predominant bacteria were Enterobacter spp., A. schubertii, A. veronii bv. veronii and A. veronii bv. sobria.
For more information contact Clifford E. Starliper, Leetown Science Center.
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| Avian Influenza Virus Found in Western Atlantic Harbor Seals |
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Photo: Map showing approximate area of recent elevated marine mammal strandings and mortality. Photo credit: USGS. |
In autumn of 2011, juvenile harbor seals (Phoca vitulina) died in unusually high numbers along the coast of Maine, New Hampshire and Massachusetts. Most of the animals showed signs of respiratory infection, and some also had skin lesions on the trunk and flippers. The USGS-National Wildlife Health Center, Columbia University and other laboratories were invited by the National Oceanic Atmospheric Administration (NOAA) to participate in the investigation into the cause of this unusual mortality event. While many animals were too decomposed for examination, tissues from five seals in good condition were collected by the staff of New England Aquarium, and were forwarded to NWHC for diagnostic evaluation. Influenza virus RNA was detected directly from tissues from each of the five animals and when sequenced, H3N8 influenza virus was identified. Tests at Columbia University further showed direct evidence of influenza replication in respiratory tissues. NWHC was able to rapidly isolate the virus from multiple tissues from four of the animals. Full-length RNA segment sequencing of the virus shows that the seal H3N8 is an avian influenza virus with no evidence of reassortment with other influenza viruses. The virus is most closely related to H3N8 viruses isolated from ducks from the Midwest but is distinct from the H3N8 lineage in dogs and horses. This is the first record of H3N8 in marine mammals associated with a mortality event. How it was introduced into the Western Atlantic harbor seal population and whether it contributed to the wider seal mortality event remain under investigation.
For more information, contact Hon Ip, USGS National Wildlife Health Center.
Collaborators:
Additional Resources:
NOAA Declares String of Seal Deaths in New England an Unusual Mortality Event
New England Aquarium Seal Strandings
Animal Rescue and Rehabilitation Program
University of New Hampshire Department of Molecular, Cellular, and Biomedical Sciences
Comprehensive Harbor Seal Survey Underway off New England Coast
University of New England Marine Animal Rehabilitation Center
Woods Hole Oceanographic Institution, Northeast PSP Background Information and Related Resources
Posted: February 1, 2012 |
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U.S. Department of the Interior |
U.S. Geological Survey
