Gut content analysis of Lake Michigan waterbirds in years with avian botulism type E mortality, 2010–2012

Abstract

Waterbird die-offs caused by Clostridium botulinum neurotoxin type E (BoNT/E) have occurred sporadically in the Great Lakes since the late 1960s, with a recent pulse starting in the late 1990s. In recent die-offs, round gobies (Neogobius melanostomus) have been implicated as vectors for the transfer of BoNT/E to fish-eating birds due to the round goby invasion history and their importance as prey. Dreissenid mussels (Dreissena spp.) are also potentially involved in BoNT/E transmission to birds and round gobies. We examined gut contents of waterbirds collected in Lake Michigan during die-offs in 2010 -2012, and the gut contents of culled, presumably BoNT/E-free double-crested cormorants (Phalacrocorax auritus). Round gobies were found in 86% of the BoNT/E-positive individuals, 84% of the BoNT/E-negative birds, and 94% of the BoNT/E-free cormorants examined. Double-crested cormorants, ring-billed gulls (Larus delewarensis), and common loons (Gavia immer) consumed larger-sized round gobies than horned and red-necked grebes (Podiceps auritus and P. grisegena), white-winged scoters (Melanitta deglandi), and long-tailed ducks (Clangula hymealis). Other common prey included dreissenid mussels, terrestrial insects, and alewives (Alosa pseudoharengus). Our data emphasize the importance of round gobies and mussels in diets of Lake Michigan waterbirds and suggest they may play a role in the transfer of BoNT/E to waterbirds; however, round gobies and mussels were found in BoNT/E-positive, -negative, and -free individuals, suggesting that other factors, such as alternative trophic pathways for toxin transfer, bird migratory timing and feeding locations, prey behavior, and individual physiological differences across birds, may affect the likelihood that a bird will succumb to BoNT/E intoxication.

Enigmatic decline of a common fish parasite (Diplostomum spp.) in the St. Lawrence River: Evidence for a dilution effect induced by the invasive round goby

“…Ring-billed gulls are opportunistic omnivorous birds that feed on prey according to their availability and abundance ( Cotter et al., 2012 ). A recent analysis of stomach contents of ring-billed gulls in Lake Michigan revealed that the round goby was the most frequent prey item (76%), replacing other native forage fish, notably during the gull's post-breeding season ( Essian et al., 2016 ). Assuming a comparable shift in the diet of gulls in the St. Lawrence River, it is reasonable to expect that they would have ingested fewer metacercariae of Diplostomum spp.…”

Ecological plasticity of tubenose goby, a small invader in South Moravian waters

“…Both of these parasites mentioned above were common in ponds and reservoirs in this study as such large waterbodies tend to attract their definitive bird hosts. Though piscivorous birds have been shown to include non-native gobies in their diet (Essian et al, 2016), it is the round goby that is commonly taken (Jakubas & Mioduszewska, 2005;Johnson et al, 2010), with smaller species such as the tubenose goby being largely ignored. Unfortunately, predation on tubenose goby by piscivorous birds has not been studied in the lower Morava/Dyje River region, making it difficult to predict its effect on birds' parasite dynamics.…”

Infection of Diplostomum spp. in invasive round gobies in the St Lawrence River, Canada

“…The round goby is among the most successful invasive species in the St Lawrence River, becoming one of the most abundant fish species in the littoral zone (Morissette et al, 2018). Gobies have inserted themselves into local food chains and are now prey to avian and piscine piscivores in the Great Lakes-St Lawrence River basin (Johnson et al, 2005;Reyjol et al, 2010;Essian et al, 2016). Indeed, the round goby is now one of the most important prey items for ring-billed gulls, an important definitive host for Diplostomum spp., in the Great Lakes (Essian et al, 2016).…”