“A mysterious brain disease is killing birds
in the southeastern United States and
scientists can't find the cause.” - CNN
Website
http://www.nwhc.usgs.gov/publications/fact_sheets/pdfs/avm091002.pdf
Title
ASSESSMENT OF THE POTENTIAL FOR
AN AVIAN VACUOLAR MYELINOPATHY
OCCURRENCE IN NEW HANOVER
COUNTY PONDS
Overview
1.
Introduction
1.
2.
3.
4.
Avian Vacuolar
Myelinopathy
2.
Avian Wildlife
3.
Invasive Aquatic Weeds
4.
Cyanobacteria
Methods
1.
Pond locations
2.
Pond Areas
3.
Sampling Techniques
4.
Avian Wildlife Surveys
Results
1.
Pond locations
2.
Pond Areas
3.
Aquatic Vegetation
4.
Avian Wildlife
Discussion
AVIAN
= BIRDS
VACUOLAR
= ACCENTUATION OF
CELLULAR SWELLING
MYELINOPATHY
= DISEASE OF MYELIN (A
FATTY NERVE
COATING)
1.
1.1
Introduction
1. Avian Vacuolar Myelinopathy
First discovered at DeGray Lake, Arkansas
• 1994-1995, 29 bald eagles died
• 1996-1997, 26 bald eagles died
American coots also discovered
dead during the two winters.
Affected birds appeared intoxicated,
demonstrating a lack of coordination while
flying, swimming, and walking.
THOMAS, N. J., C. U. MYETEYER, AND L. SILEO. 1998. Epizootic vacuolar myelinopathy of
the central nervous system of bald eagles (Haliaeetus leucocephalus) and American coots
(Fulica Americana). Veterinary Pathology 35: 479-487.
1.
1.1
Introduction
1. Avian Vacuolar Myelinopathy
Examination of
affected birds
revealed vacuolation
of the white matter of
the central nervous
system
Substances known to
cause similar lesions
in animals have not
been identified in
cases of AVM
THOMAS, N. J., C. U. MYETEYER, AND L. SILEO. 1998. Epizootic vacuolar myelinopathy of
the central nervous system of bald eagles (Haliaeetus leucocephalus) and American coots
(Fulica Americana). Veterinary Pathology 35: 479-487.
1.
1.1
Introduction
1. Avian Vacuolar Myelinopathy
http://www.aphis.usda.gov/vs/ceah/cei/taf/emergingdiseasenotice_files/avm_0101.htm
AVM has been documented in 11 lakes across 5 states since
its discovery
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
AVM has been documented in 8 species of
birds:
1.
Bald Eagle, Haliaeetus leucocephalus (~ 100)
2.
American coot, Fulica americana (1,000s)
3.
Ring-necked duck, Aythya collaris
4.
Mallard duck, Anas platyrhynchos
5.
Bufflehead, Bucephala albeola
6.
Canada goose, Branta canadensis
7.
Great Horned Owl, Bubo virginianus (2)
8.
Killdeer, Charadrius vociferous (1)
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
Study: Healthy coots and mallards were released on an AVM
positive lake (Lake Surf, NC)
Results:
•
the birds were diagnosed with AVM within 5 days of release
•
only the birds released during November developed AVM
Significance:
•
causative agent is site specific
•
contraction of AVM is seasonal, causative agent may only be
present at lethal levels during the winter months
•
source of disease is most likely a naturally occurring chemical
toxin
ROCKE, T. E., N. J. THOMAS, T. AUGSPURGER, AND K. MILLER. 2002. Epizootiologic studies
of avian vacuolar myelinopathy in waterbirds. Journal of Wildlife Diseases 38: 678-684.
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
Study: Tissues of American coots confirmed AVM positive fed to
red-tailed hawks, Buteo jamaicensis
Results:
•
all five hawks developed microscopic lesions associated with
AVM despite lack of neurological dysfunction
Significance:
•
AVM can be spread by ingestion of affected birds
•
confirmed method of exposure to bald eagles and suggests
susceptibility of other birds of prey
FISHER, J. R., L. A. LEWIS-WEIS, AND C. M. TATE. 2003. Experimental vacuolar myelinopathy
in red-tailed hawks. Journal of Wildlife Diseases 39: 400-406
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
Study: Attempts to transmit AVM to mallard ducks by 4 methods of
exposure
Results:
1.
direct exposure to affected birds
=
negative
2.
ingestion of water
=
negative
3.
ingestion of aquatic plants
=
negative
4.
ingestion of sediment
=
negative
Significance:
•
samples either did not contain causative agent or it was not in a
high enough concentration to induce AVM
•
affected birds may be present for some time after the agent is
no longer active
LARSON, R. S., F. B. NUTTER, T. AUGSPURGER, T. E. ROCKE, N. J. THOMAS, AND M. K.
STOSKOPF. 2003. Failure to transmit avian vacuolar myelinopathy to mallard ducks. Journal
of Wildlife Diseases 39: 707-711.
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
Study: Attempts to transmit AVM to domestic chicken and swine
by ingestion of affected birds and plant material
Results:
•
swine did not develop AVM
•
chicken developed AVM from both feeding trials
Significance:
•
mammals may not be susceptible
•
causative agent is most likely associated with the plant material
collected from the AVM positive site
LEWIS-WEIS, L. A., R. W. GERHOLD, AND J. R. FISHER. 2004. Attempts to reproduce
vacuolar myelinopathy in domestic swine and chickens. Journal of Wildlife Diseases 40: 476484.
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
Study: Establishing a link between aquatic plant material and AVM
in Mallards
Results:
•
•
two types of cyanobacteria discovered associated with the
plant material collected during an outbreak
1.
Pseudanabaena catenata
2.
an unknown species of Stigonematales
Six of Nine ducks fed the plant material developed AVM
Significance:
•
established cause-effect link between AVM and aquatic
vegetation
•
both species of bacteria are capable of producing harmful
toxins
BIRRENKOTT, A. H., S. B. WILDE, J. J. HAINS, J. R. FISHER, T. M. MURPHY, C. P. HOPE, P. G.
PARNELL, AND W. W. BOWERMAN. 2004. Establishing a food –chain link between aquatic
plant material and avian vacuolar myelinopathy in mallards (Anas platyrhynchos). Journal of
Wildlife Diseases 40: 485-492.
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
Study: Surveys of AVM positive and negative ponds for aquatic
vegetation and cyanobacteria
Results:
•
Three types of invasive aquatic plants dominated AVM positive
ponds
1.
Hydrilla (Hydrilla verticillata)
2.
Brazilian elodea (Egeria densa)
3.
Eurasian watermilfoil (Myriophyllum spicatum)
•
Unknown species of Stigonematales rare in AVM negative
ponds
•
Stig. species dominated up to 95% of invasive weeds in AVM
positive ponds
WILDE, S. B., T. M. MURPHY, C. P. HOPE, S. K. HABRUN, J. KEMPTON, A. BIRRENKOTT, F.
WILEY, W. W. BOWERMAN, AND A. J. LEWITUS. 2005. Avian vacuolar myelinopathy linked to
exotic aquatic plants and a novel cyanobacterial species. Environmental Toxicology 20: 348353.
1.
1.1
Introduction
1. Avian Vacuolar Myelinopathy
"Percentage of coverage of suspect Stigonematales species on three
invasive aquatic plants in reservoirs where AVM has not been
documented."
WILDE, S. B., T. M. MURPHY, C. P. HOPE, S. K. HABRUN, J. KEMPTON, A. BIRRENKOTT, F.
WILEY, W. W. BOWERMAN, AND A. J. LEWITUS. 2005. Avian vacuolar myelinopathy linked to
exotic aquatic plants and a novel cyanobacterial species. Environmental Toxicology 20: 348353.
1.
1.1
Introduction
1. Avian Vacuolar Myelinopathy
"Percentage of coverage of suspect Stigonematales species on three
invasive aquatic plants in confirmed AVM reservoirs."
WILDE, S. B., T. M. MURPHY, C. P. HOPE, S. K. HABRUN, J. KEMPTON, A. BIRRENKOTT, F.
WILEY, W. W. BOWERMAN, AND A. J. LEWITUS. 2005. Avian vacuolar myelinopathy linked to
exotic aquatic plants and a novel cyanobacterial species. Environmental Toxicology 20: 348353.
1.
Introduction
1. Avian Vacuolar Myelinopathy
1.1
Study: Mallard ducks released onto a small pond (1.6 ha) with a
dense infestation of hydrilla and 50% to 95% coverage of
the unknown Stigonematalan species
Results:
•
15 of the 20 ducks released on the pond developed AVM within
6 weeks
Significance:
•
AVM had only been documented on ponds greater than 450 ha
•
The unknown Stigonematales species has been documented at
ALL locations that have had cases of AVM
WILDE, S. B., T. M. MURPHY, C. P. HOPE, S. K. HABRUN, J. KEMPTON, A. BIRRENKOTT, F.
WILEY, W. W. BOWERMAN, AND A. J. LEWITUS. 2005. Avian vacuolar myelinopathy linked to
exotic aquatic plants and a novel cyanobacterial species. Environmental Toxicology 20: 348353.
1.
1.1
Introduction
1. Avian Vacuolar Myelinopathy
Conclusions provide the basis for this study:
“We hypothesize that three elements are needed to produce
AVM:
1.
an abundance of preferred aquatic vegetation (e.g. hydrilla)
2.
an abundance of the suspect Stigonematalan species
growing on available substrate
3.
and herbivores waterfowl.”
WILDE, S. B., T. M. MURPHY, C. P. HOPE, S. K. HABRUN, J. KEMPTON, A. BIRRENKOTT, F.
WILEY, W. W. BOWERMAN, AND A. J. LEWITUS. 2005. Avian vacuolar myelinopathy linked to
exotic aquatic plants and a novel cyanobacterial species. Environmental Toxicology 20: 348353.
1.
1.2
Introduction
2. Avian Wildlife, Bald Eagle
Populations declined from
hunting, use of DDT, and loss
of habitat
Endangered Species Act in
1973 helped increase nesting
sites
Growth rates of
North Carolina bald
eagle populations
as a result of the
North Carolina Bald
Eagle Project.
From (Bald eagle
fact sheet, 2005)
1.
Introduction
2. Avian Wildlife, Bald Eagle
1.2
Susceptibility to AVM:
•
Opportunistic feeders: mostly fish but also other vertebrates
including waterfowl whether alive or dead. AVM outbreaks
killing many coots can provide a significant source of food.
•
Nests located within ½ mile from water
•
Mature eagles return to site of birth to breed
Populations increase approximately 8.5% per year. However,
AVM can set back populations by decades.
•
An estimated 30% to 65% of population was killed during
DeGray Lake outbreak
•
Approximately 100 killed by AVM to date
1.
1.2
Introduction
2. Avian Wildlife, American coot
Migratory, fresh water birds
Osprey and Eagle are main
predators
Omnivorous: consume small
animals and insects. Primary
diet consists of submerged
aquatic vegetation which they
dive for in shallow water.
Demonstrate a preference for
hydrilla
Thousands killed by AVM to date
1.
Introduction
3. Invasive Aquatic Weeds
1.3
Negative Impacts:
1.
Navigation
2.
Water quality
3.
Hydropower
4.
Irrigation
5.
Fisheries
6.
Recreation
7.
Native vegetation
8.
Wildlife
9. Ability to “harbor the vector of human and animal diseases”
(Kay, 1992)
1.
1.3
Introduction
3. Invasive Aquatic Weeds
1.
1.3
Introduction
3. Invasive Aquatic Weeds, Hydrilla
Introduced to US as an aquarium plant
Found growing wild in Florida in 1960 and spread throughout US
NC hydrilla first discovered in Raleigh in 1980
2002 North Carolina hydrilla infestations
http://www.weedscience.ncsu.edu/aquaticweeds/hydrilla2002.html
1.
1.3
Introduction
3. Invasive Aquatic Weeds, Hydrilla
Extremely adaptive
Rooted to bottom by rhizomes in up to 30 ft of water
Leaves grow in whorls of 3-8 with serrated edge
1.
1.3
Introduction
3. Invasive Aquatic Weeds, Hydrilla
Reproduction
•
Fragmentation – broken
stem fragments can
survive for days before
rooting to bottom
•
Tubers and turions –
specialized structures
capable of producing
new plants when
released
•
Seeds – contributes little
due to successful
vegetative means
1.
Introduction
3. Invasive Aquatic Weeds, Hydrilla
1.3
Management
1.
Physical
•
2.
Mechanical
•
3.
tools, rakes
Biological
•
4.
drawdown
Grass carp
(Ctenopharyngodon idella)
Chemical
•
herbicides
1.
1.3
Introduction
3. Invasive Aquatic Weeds, Brazilian elodea
Introduced to US as an aquarium plant, “Anacharis” in late 1800s
Similar to Hydrilla but lacks special structures (tubers, turions)
Reproduces primarily through fragmentation
Managed primarily by grass carp
1.
1.3
Introduction
3. Invasive Aquatic Weeds, Eurasian watermilfoil
Introduced to US as an
aquarium plant, first
discovered in D.C. in 1940s
Leaves thin and feather-like
Reproduces primarily
through fragmentation,
without turions
First discovered in NC in
1965 on Currituck Sound.
Spread from 40 to 32,000 ha
in 9 years.
Less desirable food source
for grass carp
1.
Introduction
4. Cyanobacteria
1.4
“Blue-green algae”
•
Similar to Plants
•
•
contain chlorophyll and
release oxygen during
photosynthesis
Similar to Bacteria
•
lack a nucleus and
chloroplasts
•
Produce wide range of
toxins sometimes released
during blooms
1.
1.4
Introduction
4. Cyanobacteria
Suspect cyanobacteria
responsible for causing
AVM is a filamentous form
found attached to
submerged aquatic
vegetation
New species of
Stigonematales
Large colonies can be
seen on the underside of
leaves
WILDE, S. B., T. M. MURPHY, C. P. HOPE, S. K. HABRUN, J. KEMPTON, A. BIRRENKOTT, F.
WILEY, W. W. BOWERMAN, AND A. J. LEWITUS. 2005. Avian vacuolar myelinopathy linked to
exotic aquatic plants and a novel cyanobacterial species. Environmental Toxicology 20: 348353.
2.
Methods
2
Google Earth used to locate 56 ponds based on size and
accessibility
Ponds surveyed for presence of submerged aquatic vegetation
•
Hydrilla
•
Brazilian elodea
•
Eurasian watermilfoil
Ponds surveyed for presence of susceptible avian wildlife
2.
2.2
Methods
2. Pond Areas
ArcView GIS software used to calculate pond areas
2.
2.2
Methods
2. Pond Areas
ArcView GIS software used to calculate pond areas
2.
2.2
Methods
2. Pond Areas
2.3/
2.4
2.
Methods
3. Sampling Techniques/4. Avian Wildlife Surveys
Sampling Techniques
•
Visual inspection and sampling tool used from shore to
retrieve submerged vegetation
•
Suspect samples taken to UNCW for positive identification
Avian Wildlife Surveys
•
Species of waterfowl
and birds of prey
identified at each site
3.1/
3.
3.2/
3.3
Results
1. Pond Locations / 2. Pond Areas / 3. Vegetation
Pond Locations
•
56 Natural ponds, Commercial and Residential Retention
ponds surveyed throughout New Hanover County
Pond Areas
•
35.3 ha to 0.13 ha
Aquatic Vegetation
•
NO pond contained the
invasive species of interest:
hydrilla, Brazilian elodea, or
Eurasian watermilfoil
•
One site (Airlie Lake) had
infestation of coontail
(Ceratophyllum)
3.
3.4
Results
4. Avian Wildlife
17 of 56 sites contained various species of birds
1.
American coot (Fulica americana)
2.
Canada goose (Branta canadensis)
3.
Snow goose (Chen caerulescens)
4.
Mallard duck (Anas platyrhynchos)
5.
Great blue heron (Ardea herodias)
6.
White ibis (Eudocimus albus)
7.
Great egret (Ardea alba)
8.
Mute swan (Cygnus olor)
9.
Redhead (Aythya valisineria)
10. Turkey vulture (Cathartes aura)
11. Assorted diving ducks, gulls, and domestic waterfowl
3.
3.4
Results
4. Avian Wildlife
American coots on Greenfield Lake, 1/25/06
Table 1: Results of ponds surveyed greater than 1 hectare
Site
Date
Surveyed
Description
Area
(acres)
Coordinates
Area
(hectares)
Vegetation
Avian Wildlife
emergent, green algae
AC, CG, MD, BH, GE,
RH, TV, DD, Various
ducks, gulls, and
domestic waterfowl
1
11/17/2005
01/25/2006
Greenfield Lake
34°12'37.78"N 77°56'14.15"W
87.24
35.30
2
10/14/2005
Randall Pkwy
Reservoir
34°13'48.13"N 77°53'51.35"W
22.94
9.28
emergent
BH, CG, DD, Various
ducks
3
10/19/2005
NP
34° 7'3.09"N
77°55'17.03"W
14.03
5.68
no access
none
4
10/19/2005
Silver Lake
34° 8'34.50"N 77°54'56.31"W
10.68
4.32
emergent, green algae
CG
5
10/19/2005
NP?
34° 5'30.36"N 77°55'6.76"W
9.40
3.81
no access
no access
6
11/3/2005
Airlie Lake
34°12'57.56"N 77°49'40.20"W
8.21
3.32
Ceratophyllum (coontail)
CG, WI, MD, BH, GE, S
7
11/3/2005
NP
34°13'53.42"N 77°50'51.51"W
7.85
3.18
green algae
none
8
11/3/2005
RP
34°17'25.28"N 77°49'55.81"W
7.79
3.15
none
none
9
11/9/2005
NP?
34°16'48.36"N 77°45'59.53"W
7.05
2.86
none
CG, WI, MD, DD
10
10/14/2005
CP
34°11'27.22"N 77°54'40.58"W
4.65
1.88
green algae
DD
11
11/3/2005
RP
34°15'2.44"N
77°49'25.94"W
3.35
1.36
emergent, green algae
none
12
11/17/2005
RP
34°18'11.42"N 77°52'51.56"W
3.16
1.28
none
CG
13
10/19/2005
CP
34° 6'12.59"N
77°54'39.40"W
3.16
1.28
none
none
14
10/19/2005
RP
34° 9'40.77"N
77°52'46.67"W
2.91
1.18
water lily (unknown species), green algae
none
15
11/17/2005
RP
34°17'58.48"N 77°52'37.06"W
2.69
1.09
none
none
16
11/17/2005
RP
34°18'8.18"N
2.68
1.09
none
CG
77°53'2.84"W
Table 2: Results of ponds surveyed between 1 and 0.4 hectares
Site
Date
Surveyed
Description
Coordinates
Area
(acres)
Area
(hectares)
Vegetation
Avian Wildlife
17
11/3/2005
RP
34°17'16.78"N 77°50'18.58"W
2.45
0.99
none
none
18
10/14/2005
RP
34°10'38.70"N 77°53'49.29"W
2.44
0.99
none
none
19
11/9/2005
NP?
34°17'44.15"N 77°48'18.90"W
2.42
0.98
none
none
20
10/19/2005
CP
34° 6'5.30"N
77°54'57.38"W
2.40
0.97
none
none
21
11/3/2005
RP
34°11'36.70"N 77°52'43.06"W
2.35
0.95
none
MD
22
11/3/2005
CP
34°16'14.56"N 77°49'58.65"W
2.09
0.84
none
MD
23
11/17/2005
RP
34°18'9.35"N
77°52'39.90"W
2.04
0.83
none
none
24
10/19/2005
CP
34° 5'46.42"N
77°54'57.91"W
1.86
0.75
none
none
25
10/19/2005
RP
34° 7'15.10"N
77°53'9.81"W
1.73
0.70
green algae
none
26
10/14/2005
RP
34°10'16.13"N 77°54'56.41"W
1.55
0.63
green algae
none
27
10/19/2005
RP
34° 4'14.70"N
77°53'45.53"W
1.45
0.59
water lilly (unknown species)
none
28
10/14/2005
RP
34°12'0.91"N
77°55'44.29"W
1.33
0.54
emergent
MD
29
10/14/2005
RP
34°11'36.06"N 77°54'23.38"W
1.26
0.51
green algae
none
30
10/19/2005
RP
34° 7'37.52"N
77°53'11.95"W
1.23
0.50
none
CG
31
11/3/2005
RP
34°16'26.53"N 77°49'24.46"W
1.21
0.49
none
none
32
10/14/2005
CP
34°11'48.71"N 77°54'26.88"W
1.19
0.48
emergent
DD
33
11/3/2005
RP
34°16'34.20"N 77°49'35.26"W
1.16
0.47
none
none
34
10/19/2005
RP
34° 9'5.51"N
77°52'30.93"W
1.09
0.44
emergent
BH
35
11/3/2005
CP
34°16'12.09"N 77°49'33.57"W
1.01
0.41
none
none
Table 3: Results of ponds surveyed less than 0.4 hectares or unavailable
Site
Date
Surveyed
Description
Coordinates
Area
(acres)
Area
(hectares)
Vegetation
Avian Wildlife
36
10/19/2005
RP
34° 9'2.83"N
77°52'34.89"W
0.95
0.39
emergent, green algae
none
37
10/14/2005
RP
34° 9'38.06"N
77°53'57.51"W
0.95
0.39
green algae
none
38
10/14/2005
RP
34°11'58.74"N 77°55'35.60"W
0.95
0.39
emergent
none
39
10/19/2005
RP
34° 9'50.25"N
77°51'43.29"W
0.95
0.38
none
none
40
10/14/2005
RP
34° 9'40.62"N
77°54'8.01"W
0.87
0.35
water lily (unknown species), green
algae
BH, SG
41
11/3/2005
RP
34°15'6.94"N
77°49'24.65"W
0.81
0.33
none
none
42
11/3/2005
RP
34°10'39.65"N 77°52'52.82"W
0.79
0.32
green algae
none
43
11/3/2005
CP
34°11'37.46"N 77°53'5.34"W
0.72
0.29
green algae
none
44
11/3/2005
RP
34°11'50.44"N 77°50'23.89"W
0.68
0.28
none
none
45
11/9/2005
NP?
34°17'42.67"N 77°48'10.29"W
0.67
0.27
none
none
46
10/19/2005
RP
34° 5'47.89"N
77°55'15.13"W
0.65
0.26
none
none
47
11/9/2005
RP
34°17'41.62"N 77°48'14.91"W
0.31
0.13
none
none
48
10/14/2005
CP
34°14'59.41"N 77°52'53.94"W
unavailable
unavailable
no access
CG, DD
49
10/14/2005
CP
34°15'0.22"N
77°53'5.27"W
unavailable
unavailable
no access
none
50
10/14/2005
RP
34° 9'19.91"N
77°54'5.05"W
unavailable
unavailable
none
CG
51
10/14/2005
RP
34° 9'40.07"N
77°53'53.50"W
unavailable
unavailable
emergent
none
52
10/19/2005
RP
34° 6'32.55"N
77°54'49.19"W
unavailable
unavailable
emergent, green algae
MD, DD
53
10/19/2005
RP
34° 6'20.71"N
77°54'35.22"W
unavailable
unavailable
none
none
54
11/3/2005
CP
34°14'25.65"N 77°49'54.41"W
unavailable
unavailable
none
CG, S
55
11/3/2005
CP
34°14'40.09"N 77°50'3.77"W
unavailable
unavailable
none
none
56
11/9/2005
RP
34°18'13.47"N 77°46'30.53"W
unavailable
unavailable
none
none
4.
Discussion
4
NONE of the 56 ponds surveyed will currently produce an AVM
occurrence based on Dr. Wilde’s hypothesis
The Suspect bacteria has been documented on several native species:
1.
Coontail (Ceratophyllum demersum)
2.
Illinois pondweed
3.
Bladderwort
4.
Lemon bacopa (Bacopa caroliniana)
5.
Fragrant water lily (Nymphaea odorata)
6.
Watershield (Bransenia shreberi)
4.
Discussion
4
Therefore the potential exists for a future occurrence of AVM at several
sites:
1.
Airlie Lake
•
3.32 ha
•
Significant
population of
water birds
•
Infestation of
coontail
4.
Discussion
4
2.
Sites 14, 27, and 40
•
Contained various species of water lilies
•
All less than 1.18 ha
•
Lack susceptible
birds
4.
Discussion
4
3.
4.
Greenfield Lake
•
35.3
•
Highest number of susceptible birds including American coot
•
Significant infestation of preferred vegetation could harbor the
suspect Stigonematalan species in large enough numbers to
produce AVM
Sites 2, 4, and 9
•
9.28 ha to 2.86 ha
•
several species of susceptible birds including mallard ducks
and Canada geese
•
An infestation of vegetation could support the bacteria and
produce an AVM occurrence
4.
Discussion
4
Birds at Greenfield Lake
4.
Discussion
4
Green algae at Greenfield
Lake
4.
Discussion
4
The 56 ponds surveyed
represent an estimated
1/5 of the total ponds
in New Hanover
County.
Many ponds too small
for consideration or
not accessible due to
location.
A more thorough
survey should include
ALL ponds greater
than perhaps 1 ha.
4.
Discussion
4
Current research:
1.
Suspect bacteria has been cultured and fed directly to American
coots
•
Did not produce AVM lesions
•
2.
Grass carp fed hydrilla material with associated Stig. Bacteria
•
Developed lesions similar to those seen in birds
•
Carp then fed to mallard ducks
•
3.
May require environmental triggers to produce toxicity
Ducks developed AVM lesions
Methods are being developed for extracting the toxins produced
by the bacteria
4.
Discussion
4
Future research:
1.
Continue to focus on suspect Stig. species and isolation of it’s
toxic metabolites
2.
Determine the environmental factors responsible for controlling
it’s production
3.
Accurate database of sites infested with aquatic vegetation
capable of supporting bacteria
4.
Continue to focus on how AVM is spread
5.
Increase public awareness to reduce number of undiagnosed
cases of AVM.
4.
Discussion
4
Contacts:
AVM
1.
USGS National Wildlife Health Center at (608) 270-2400,
http://www.nwhc.usgs.gov/disease_information/avian_vacuolar_myelinopathy/index.jsp
2.
Southeastern Cooperative Wildlife Disease Study at (706) 542-1741,
http://www.uga.edu/scwds/index.htm
3.
U.S. Fish and Wildlife Service at (919) 856-4520, http://nc-es.fws.gov/ecotox/avm.html
4.
South Carolina Algal Ecology Lab,
http://links.baruch.sc.edu/scael/research/avm/avm.html
5.
NC Wildlife Resources Commission at (919) 707-0050, http://www.ncwildlife.org/
Invasive Weeds
1.
NC Aquatic Weed Control Program at (919) 733-4064,
http://www.ncwater.org/Education_and_Technical_Assistance/Aquatic_Weed_Control/
2.
New Hanover County Cooperative Extension at (910) 452-6393,
http://newhanover.ces.ncsu.edu/
Questions?