Transcript Distribution of the swimbladder Anguillicola crassus American eels in the Northeastern Atlantic

Distribution of the swimbladder
parasite Anguillicola crassus in
American eels in the Northeastern
Atlantic
University of Massachusetts Dartmouth
Department of Biology
Amy Aieta
&
Kenneth Oliveira
Life History of Anguilla rostrata
Silver phase
Yellow phase
Glass eel/Elver
Leptocephalus
larvae
Egg
The life cycle of Anguillicola crassus
L3-L4 swimbladder wall
L4-L5 swimbladder lumen
Intermediate/
Paratenic Host
Ingested by Eel
L2 Released
L2 molts to L3
Intermediate Host
Biogeography of Anguillicola crassus
•Identified in Southeast Asia 1974
•(Anguilla japonica)
•Early 1980s introduced to Europe
•(Anguilla anguilla)
•1995 found in North America
• (Anguilla rostrata)
Occurrence of A. crassus in North America
2003 N. Dartmouth, MA
Hudson River (Barse and Secor 1999)
Chesapeake Bay (Barse and Secor 1999;
Barse et al. 2001)
South Carolina (Fries et al. 1996)
1995 Texas (TPWD; Moravec)
Objectives
1) Determine northern extent of parasite range in
USA
2) Examine prevalence & intensity within NE
3) Examine effects of parasite/eel interactions
Methods
n=13
Northeastern Distribution
Yellow eels *
•Summer 2005
Southern Sampling Survey
•CT, RI, S.-MA
n=10
n=3
Northern Sampling
•N.-Ma, NH, ME
Collection of Yellow Eels in Freshwater
Collection of Silver Eels
Preliminary Analysis
•
•
•
•
Eels euthanized w/Clove oil
Weighed/length measured
Parasites counted
Parasite length measured
Analysis
Prevalence
Example 30%
infected
Mean Intensity
1.67 parasites
Results
35%
N. KINGSTON
28%
69%
Prevalence of Infection:
Rhode Island
7%
33%
62%
Prevalence of Infection:
Massachusetts
BOSTON
76%
16%
PLYMOUTH
52%
21%
NEW BEDFORD
64%
33%
58%
0%
BANGOR
Kennebec River
Estuarine eels
31%
60%
PORTLAND
58%
65%
53%
26%
0%
0%
0%
0%
0%
35%
Prevalence of Infection:
Maine
0
15 5.1
.2
-2
0.
20
2
.3
-2
25 5.3
.4
-3
0.
30
4
.5
-3
5.
35
5
.6
-4
0.
6
>4
0.
6
-1
10
.1
<1
Mean Parasite Intensity
8
n = 315
6
4
2
0
Eel Size Class (cm)
Log 10 Eel Weight
4
Nonparasitized r2 = 0.99 (n = 523)
Parasitized r2 = 0.98 (n = 315)
3
2
1
0
-1
-2
1.6
1.8
2.0
2.2
2.4
2.6
Log 10 Eel Length
2.8
3.0
Silver Eel Data: Paskamansett River
Year
Prevalence
Mean Intensity
2003
28%
2.9
2004*
52%
5.8
2005
?
?
Significance
Prevalence: Fischer's Exact Test p = .008
Intensity: T-test p = .007
Conclusions
Current Northern Limit
• Sedgeunkedunk Stream, ME
• 44°45.306N, tributary of the Penobscot River
• No latitudinal trend
• Possible ballast water introduction
• Temperature: not an apparent limiting factor
Influences of Parasite
• All size classes infected
• No apparent detrimental effects on eel weight/length
• Suspected negative impact on migrating silver eels
Questions/Discussion