Marine avifauna, colloquially known as “seabirds,” play variable and important roles in coastal and offshore ecosystems. Parasite communities in seabirds can provide insight on these processes, through variation associated with the feeding ecology, distribution, environmental effects, and phylogeny of hosts. However, surprisingly few studies have examined these questions in seabirds, and little is known about how parasite community structure varies among trophic guilds and migratory habits. For example, parasite communities should differ in seabirds that feed in estuaries, mangroves, and other shoreline habitats. In this study, parasite communities were examined in the eight main South Florida seabird species – brown pelican Pelecanus occidentalis (n=32), northern gannet Morus bassanus (n=18), double-crested cormorant Phalacrocorax auritus (n=28), laughing gull Leucophaeus atricilla (n=40), herring gull Larus argentatus (n=10), royal tern Thalasseus maximus (n=28), least tern Sternula antillarum (n=1), and osprey Pandion haliaetus (n=8). Since 2012, seabird carcasses salvaged from local wildlife rescue agencies have been necropsied (trachea, esophagus, stomach, liver, kidneys, and intestines). Endoparasites were enumerated and partially identified.
Results/Conclusions
Preliminary endoparasite analyses have found high abundances within stomachs and intestines, but not muscle tissue or other organs. Endoparasite taxa include nematodes (e.g., Contracaecum sp.), cestodes, monogeneans, and digeneans. Species that forage further offshore (e.g., brown pelicans and northern gannets) harbor greater abundance and diversity of endoparasites (ranging in thousands and up to several species). In contrast, species that forage inshore (e.g, gulls, terns, cormorants, and osprey) display low to moderate abundance and diversity of endoparasites (hundreds and up to five species). Preliminary results indicate structural differences among communities as well. For example, bird species differed in the relative dominance of intestinal trematodes, nematodes, and blood parasites. Insight on the endoparasite faunal community within these targeted seabird species can indicate preferred prey items and variation in foraging habits (i.e., lack of targeted prey items with a shift to less preferred species).