The influence of geographical location, host maturity and sex on intestinal helminth communities of the double-crested cormorantPhalacrocorax auritusfrom the eastern United States

Abstract

Here the intestinal helminth infracommunities of 218 double-crested cormorants (Phalacrocorax auritus) from 11 locations in Alabama, Minnesota, Mississippi and Vermont are documented. Trematode infections were present in 98% of hosts; 65% of cormorants carried cestode infections, 4% were infected with acanthocephalans and 66% had nematode intestinal parasites. Parasite infracommunities of hosts collected on wintering grounds had higher richness and diversity than did birds collected on breeding grounds. Differences in parasite richness and diversity between male and female P. auritus were also detected, but not between immature and mature bird hosts. Parasite intensity did not differ by sex, maturity, or between breeding and wintering season. The most common parasite was Drepanocephalus auritus (spathans), which is recognized as a disease agent that negatively impacts the catfish aquaculture industry in the US. Echinochasmus sp. in double-crested cormorants is documented for the first time in the United States. We suggest that the differences observed among parasite infracommunities could be associated with the foraging distances travelled by P. auritus during breeding and wintering seasons, which is limited by allocation of parental care during the breeding season.

A morphological and molecular study of adults and metacercariae ofHysteromorpha triloba(Rudolpi, 1819), Lutz 1931 (Diplostomidae) from the Neotropical region

“…Finally, Lutz (1931) evaluated morphological characters based on its life cycle and transferred it to the new genus Hysteromorpha . Since then, H. triloba has been recorded in several countries, such as Argentina, Brazil, Venezuela, Mexico, USA and Canada in the Americas, associated with the Neotropical cormorant N. brasilianus and the double-crested cormorant N. auritus , suggesting that H. triloba can be regarded as a member of the ‘core’ helminth fauna of these two fish-eating bird species (Fedynich et al ., 1997; Drago et al ., 2011; Locke et al ., 2011; Monteiro et al ., 2011; O´Hear et al ., 2014; Sheehan et al ., 2016). In contrast, the metacercaria of H. triloba exhibits low host specificity, since it has been recorded in at least eight species of freshwater fishes from unrelated families, such as Cyprinidae, Characidae, Catostomidae, Ictaluridae, Ariidae and Pimelodidae (see Pérez-Ponce de León et al ., 2007; Locke et al ., 2011).…”

Multilocus phylogenetic analysis and morphological data reveal a new species composition of the genusDrepanocephalusDietz, 1909 (Digenea: Echinostomatidae), parasites of fish-eating birds in the Americas

“…Localities in other countries. Colombia (Rietschel & Werding, 1978), Venezuela (Lutz, 1928; Caballero Caballero & Díaz Ungria, 1958), Argentina (Ostrowski de Núñez, 1968; Drago et al ., 2011), USA (Threlfall, 1982; Fedynich et al, 1997; Flowers et al ., 2004; Griffin et al ., 2014; O'Hear et al ., 2014; Sheehan et al ., 2016), Paraguay (Kostadinova et al ., 2002) and Canada (Robinson et al ., 2010; Wagner et al ., 2012) (see table 2).…”

“…With the re-allocation of D. mexicanus and the synonymy of D. auritus with D. spathans proposed in this study, the genus Drepanocephalus now contains three nominal species: (1) D. spathans , associated with the Neotropical cormorant N. brasilianus , the double-crested cormorant N. auritus and the brown booby S. leucogaster , distributed widely across the Americas, in Argentina, Brazil, Paraguay, Venezuela, Colombia, Mexico, USA and Canada (Ramos-Ramos, 1995; Kostadinova et al ., 2002; Wagner et al ., 2012; Griffin et al ., 2014; O'Hear et al ., 2014; Pinto et al ., 2016; Sheehan et al ., 2016); (2) D. mexicanus , only found parasitizing the Neotropical cormorant N. brasilianus distributed in Mexico and Brazil; and, finally, (3) D. olivaceus from N. brasilianus in Venezuela and Brazil.…”

“…For instance, considering the current controversy and status of D. auritus , Sheehan et al . (2016) actually identified adult specimens in cormorants from 11 locations in Alabama, Minnesota, Mississippi and Vermont, USA as D. ( auritus ) spathans .…”

“…Fresh samples of these trematodes allowed us to analyse their morphology using light and scanning electron microscopy, and to obtain DNA sequences; host details and geographic distribution of Drepanocephalus species across the Americas were also retrieved from several bibliographical sources. In some cases, the literature indicates confusion about the taxonomic status of D. spathans / D. auritus (see Drago et al ., 2011; Sheehan et al ., 2016). In this study, we conducted a multilocus phylogenetic analysis of species of Drepanocephalus and Petasiger , using newly generated as well as available sequences from GenBank to assess their evolutionary relationships within the Echinostomatidae.…”