The effects of human care on the blowhole and gut microbiotas of two cohabiting dolphin species based on a year-round surveillance

Abstract

Understanding the effects of human care on the dynamics of the host-associated microbiota is critical for the health management of dolphins living in an aquarium. Yet this aspect remains relatively unexplored. Here, by utilizing 16S rRNA gene sequencing, we profiled the blowhole and gut bacterial communities of two bottlenose dolphins (Tursiops truncatus) and a Chinese white dolphin (Sousa chinensis) reared in the same indoor pool, based on year-round surveillance. In addition, we compared these dolphin microbiotas with those previously published datasets from wild dolphins. Our results showed that both the blowhole and the gut of the two dolphin species under human care shared a more similar microbiome than members of the same dolphin species across different habitats (human care vs wild). However, the effects of human care on the dolphin microbiome from the two body sites varied. In the aquarium, bacterial alpha diversities differed significantly between the two body sites, and the seasonal stability of the bacterial community was more evident in the gut than in the blowhole. Additionally, the blowhole bacterial composition and the predicted functional capacity from the two dolphin species showed differences and were less convergent than their gut microbiota over a decade-long cohabitation. Further analyses showed that heterogeneous and homogeneous selections (i.e., deterministic processes) contributed more to the blowhole than to the gut bacterial communities, while a dispersal limitation (i.e., a stochastic process) was more important for the gut microbiota. The present study provides the first comparative evidence that the gut microbiota may be more plastic in response to the human care environment than the blowhole microbiota. This improves our understanding of dolphin health management under human care and helps to predict their microbial responses to environmental changes.

Unveiling microbiome signature in inner body fluids: comparison between wild and aquarium small-spotted catshark (Scyliorhinus canicula)

“…PICRUSt and FAPROTAX have been recently used to compare the microbiota of dolphins under human care to those of wild animals (Wan et al, 2022). Our results show that, based on the PICRUSt, the blood microbiota in aquarium animals is rich in the glucose-1-phosphate degradation pathway and L-methionine III biosynthesis.…”

The intestinal microbiota of a Risso’s dolphin (Grampus griseus): possible relationships with starvation raised by macro-plastic ingestion

“…The Risso's dolphin shared common gut microbial members associated with Firmicutes with a wide range of toothed whales, including the Chinese white dolphin (Sousa chinensis) (Wan et al 2021), Yangtze finless porpoise (N. a. asiaeorientalis) (Wan et al 2016), bottlenose dolphin (Tursiops truncatus) (Wan et al 2022), melon-headed whales (Peponocephala electra) (Bai et al 2022), short-finned pilot whales (Globicephala macrorhynchus) (Bai et al 2021), pygmy (Kogia breviceps), and dwarf (K. sima) sperm whales (Erwin et al 2017), whereas at the genus level, the Risso's dolphin diverged from other toothed whales. For example, unlike Halomonas, Photobacterium, and Cetobacterium, detected as abundant taxa in the marine dolphins and porpoises (Wan et al 2018(Wan et al , 2021(Wan et al , 2022, the Risso's dolphin contained higher proportions of Vagococcus (5.94%) and Bacteroides (4.27%) (Fig. 1b).…”