Abstracts

Presented by Kevin M. Ringelman - Email: kringelman@agcenter.lsu.edu

High intensities of helminth infection have been documented to cause direct mortality or induce morbidity during the non-breeding period in waterbird species of conservation concern. One such species, the Lesser Scaup (Aythya affinis), suffers from sub-lethal effects of parasite infection, including declines in body condition which can carry-over to affect breeding success and overall population health. While scaup parasites have received substantial attention on spring migratory staging grounds in the Midwest, only one has examined intestinal helminth infections on the wintering grounds where scaup begin building lipid reserves for migration. We enumerated helminths in the lower gastrointestinal systems of 33 scaup collected from a major scaup wintering habitat, Lake Pontchartrain, Louisiana during winter 2016. 75% of scaup were infected with a total of 465 helminths (mean abundance 14.09 4.07 SE). Helminth abundance did not vary by sex, but there was a weak trend for juveniles to have higher parasite abundance ( = 23.2 8.9 SE) than adults ( = 8.2 3.0 SE). We found no significant relationship between helminth abundance and body condition, likely because so few parasites infected the scaup in our sample. Our helminth counts from scaup wintering on Lake Pontchartrain were substantially lower than those observed in scaup elsewhere in the Mississippi Flyway. We identified three trematode species (Psilochasmus oxyurus, Zygocotyle lunata, and Echinoparyphium recurvatum) infecting the scaup. None of the known first intermediate hosts for these parasites have been found in Lake Pontchartrain, suggesting that this lake may provide a refuge from parasites for wintering scaup.