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This study investigates the distribution, prevalence, and effects of the swimbladder parasite Anguillicola crassus in American eels in the Northeastern Atlantic. The study examines the life cycle, biogeography, and potential impacts of the parasite on eel populations.
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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 Ingested by Eel Intermediate/ Paratenic Host 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)
1995 Texas (TPWD; Moravec) 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)
Objectives • Determine northern extent of parasite range in USA • 2) Examine prevalence & intensity within NE • 3) Examine effects of parasite/eel interactions
Methods • Northeastern Distribution Yellow eels * • Summer 2005 • Southern Sampling Survey • CT, RI, S.-MA • Northern Sampling • N.-Ma,NH, ME n=13 n=10 n=3
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
35% N. KINGSTON 28% Prevalence of Infection: Rhode Island 69%
7% 33% 62% Prevalence of Infection: Massachusetts BOSTON 76% 16% PLYMOUTH 52% 21% NEW BEDFORD 58% 64% 33%
0% BANGOR 0% Kennebec River Estuarine eels 26% 0% 0% 0% 0% 31% 60% 35% PORTLAND Prevalence of Infection: Maine 58% 65% 53%
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