Bacterial Communities and Mucus Loads in Two Wild Fish Species

Jenn Hoskins
31st July, 2024

Bacterial Communities and Mucus Loads in Two Wild Fish Species

In the gills of the sparid fishes Diplodus annularis (left) and Pagellus acarne (right), higher loads of Lamellodiscus ectoparasites are strongly correlated with an increase in potentially pathogenic bacteria like Flavobacteriaceae and a decrease in potentially protective bacteria like Vibrionaceae and Fusobacteriaceae.

Composite: Natural Science News / CC BY. [Sources]
Adapted from photos by:

Key Findings

  • The study focused on the external microbiota of two wild sparid fish species in the Mediterranean Sea and their relationship with Lamellodiscus monogenean ectoparasites
  • The composition of the external mucus microbiota varied between the two fish species and was related to the parasitic load of Lamellodiscus monogeneans
  • The findings suggest that the microbiota may influence the susceptibility of teleost fishes to ectoparasite infestations
Teleost fishes, which make up two-thirds of marine vertebrates, have an external microbiota whose role in their environment is not well understood, particularly in wild populations. This microbial community can act as a protective barrier against pathogens or be involved in host recognition by parasites. A recent study by researchers at Sorbonne Université[1] delves into the relationship between the external microbiota of teleost fishes and their ectoparasites, specifically focusing on the interaction between Sparidae (a family of teleost fishes) and their monogenean ectoparasites from the Lamellodiscus genus. The study aims to characterize the external mucus microbiota of two wild sparid species and investigate how these bacterial communities relate to varying parasitic loads of Lamellodiscus monogeneans. To achieve this, the researchers used 16s rRNA amplicon sequencing, a method that allows for the detailed analysis of bacterial communities by examining the genetic material of bacteria present in the samples. Previous research has highlighted the significant role of microbiota in host-parasite interactions. For instance, it has been shown that the microbiome can emit volatile organic compounds that attract or repel parasites[2]. This mechanism suggests that the microbiome may act as a beacon for parasites, influencing how they locate their hosts. Furthermore, studies have demonstrated that certain microbiota can protect hosts from infections and benefit host health, while changes in the microbial landscape can facilitate infections and worsen disease severity[3]. In amphibians, the skin microbiota has been found to play a crucial role in protecting against fungal pathogens and possibly other cutaneous infectious diseases[4]. These findings underscore the importance of the microbiota in host health and disease resistance, suggesting that similar mechanisms might be at play in teleost fishes. The study by Sorbonne Université expands on these earlier findings by investigating the specific relationship between the external microbiota of teleost fishes and their ectoparasites. By analyzing the bacterial communities present in the skin and gill mucus of Sparidae, the researchers aimed to determine whether these communities pre-exist monogenean infestation or follow it. The results could provide insights into whether the microbiota acts as a protective barrier or plays a role in host recognition by parasites. The researchers found that the composition of the external mucus microbiota varied between the two wild sparid species and was related to the parasitic load of Lamellodiscus monogeneans. This suggests that the microbiota may influence the susceptibility of teleost fishes to ectoparasite infestations. These findings support the idea that host-parasite associations should be considered as a tripartite interplay, where the microbiota shapes the host phenotype and its relationship with parasites. In conclusion, this study highlights the complex interactions between teleost fishes, their external microbiota, and ectoparasites. By characterizing the bacterial communities in the skin and gill mucus of Sparidae, the researchers have provided valuable insights into how these communities may influence parasitic infestations. These findings build on earlier research[2][3][4] and contribute to our understanding of the role of microbiota in host-parasite interactions, emphasizing the need to consider the microbiota as a key player in these relationships.

BiochemAnimal ScienceMarine Biology

References

Main Study

1) Link between bacterial communities and contrasted loads in ectoparasitic monogeneans from the external mucus of two wild sparid species (Teleostei)

Published 30th July, 2024

https://doi.org/10.1186/s42523-024-00329-0

Related Studies

2) Microbiomes mediate host-parasite interactions.

https://doi.org/10.1111/mec.16381

3) Host microbiota can facilitate pathogen infection.

https://doi.org/10.1371/journal.ppat.1009514

4) Characterization of the Skin Microbiota in Italian Stream Frogs (Rana italica) Infected and Uninfected by a Cutaneous Parasitic Disease.

https://doi.org/10.1264/jsme2.ME15041


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