Colony Location and Captivity Influence the Gut Microbial Community Composition of the Australian Sea Lion (Neophoca cinerea)

Abstract

Gut microbiota play an important role in maintenance of mammalian metabolism and immune system regulation, and disturbances to this community can have adverse impacts on animal health. To better understand the composition of gut microbiota in marine mammals, fecal bacterial communities of the Australian sea lion (Neophoca cinerea), an endangered pinniped with localized distribution, were examined. A comparison of samples from individuals across 11 wild colonies in South and Western Australia and three Australian captive populations showed five dominant bacterial phyla: Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Fusobacteria. The phylum Firmicutes was dominant in both wild (76.4% ؎ 4.73%) and captive animals (61.4% ؎ 10.8%), while Proteobacteria contributed more to captive (29.3% ؎ 11.5%) than to wild (10.6% ؎ 3.43%) fecal communities. Qualitative differences were observed between fecal communities from wild and captive animals based on principal-coordinate analysis. SIMPER (similarity percentage procedure) analyses indicated that operational taxonomic units (OTU) from the bacterial families Clostridiaceae and Ruminococcaceae were more abundant in wild than in captive animals and contributed most to the average dissimilarity between groups (SIMPER contributions of 19.1% and 10.9%, respectively). Differences in the biological environment, the foraging site fidelity, and anthropogenic impacts may provide various opportunities for unique microbial establishment in Australian sea lions. As anthropogenic disturbances to marine mammals are likely to increase, understanding the potential for such disturbances to impact microbial community compositions and subsequently affect animal health will be beneficial for management of these vulnerable species. IMPORTANCEThe Australian sea lion is an endangered species for which there is currently little information regarding disease and microbial ecology. In this work, we present an in-depth study of the fecal microbiota of a large number of Australian sea lions from geographically diverse wild and captive populations. Colony location and captivity were found to influence the gut microbial community compositions of these animals. Our findings significantly extend the baseline knowledge of marine mammal gut microbiome composition and variability. It is predicted that global change will have many major, but as yet unknown, impacts on aquatic ecosystems. Marine mammal species, including bottlenose dolphins, sea otters, manatees, and gray whales, have been proposed as sentinels for diverse threats to aquatic health, including disease transmission, changes in food webs, and contaminant levels (1-6). The key roles and contributions of microbes to mammalian host health are becoming increasingly recognized, yet remain largely unexplored for marine mammals (7). An understanding of the impacts of anthropogenic pressures on marine mammal microbial communities and of the potential cascade of impacts on marine health is necessary for full exploration of the roles a...

Comparison of the gut microbiota of captive common bottlenose dolphins Tursiops truncatus in three aquaria

“…; Delport et al . ). The same may, therefore, be true of other marine mammals including common bottlenose dolphin.…”

Terrestriality and bacterial transfer: a comparative study of gut microbiomes in sympatric Malagasy mammals

“…However, captivity alters microbiome composition in mammals [12,[29][30][31], and, when animals are compared across geographic regions, host phylogenetic differences may be confounded by differences in local microbial taxa [15,32]. Thus, many of these prior studies did not have sufficient data for resolving the relative influences of various heritable and environmental factors.…”

Conserving the holobiont

“…The current evidence confirms that captivity alters the community structure, and in many cases, the diversity of animal gut microbiota (e.g. Borbon‐Garcia, Reyes, Vives‐Florez, & Caballero, ; Cheng et al, ; Delport, Power, Harcourt, Webster, & Tetu, ; McKenzie et al, ; Wasimuddin et al, ), although there is little evidence to date equating these changes with harm.…”

“…(e.g Borbon-Garcia, Reyes, Vives-Florez, & Caballero, 2017;Cheng et al, 2015;Delport, Power, Harcourt, Webster, & Tetu, 2016;McKenzie et al, 2017;Wasimuddin et al, 2017),. although there is little evidence to date equating these changes with harm.…”