Investigating Fish Larvae-Microbe Interactions in the 21st Century: Old Questions Studied with New Tools

Vestrum, Ragnhild Inderberg; Luef, Birgit; Forberg, Torunn; Bakke, Ingrid; Vadstein, Ôlav

doi:10.1007/978-3-319-73244-2_1

Cited by 9 publications

(10 citation statements)

References 111 publications

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“…Fish larvae are well suited for experimental studies of community assembly and dynamics of vertebrate-associated microbiota, because of their small size, rapid development, possibilities for good sample size and replication, and a wide range of experimental systems and host species (Vestrum et al . 2018 ). During the early colonisation of skin and intestinal system of fish the major source for bacteria entering the fish is assumed to be the surrounding water microbiota (Nayak 2010 ).…”

Section: Introductionmentioning

confidence: 99%

Bacterial community assembly in Atlantic cod larvae (Gadus morhua): contributions of ecological processes and metacommunity structure

Vestrum

Attramadal

Vadstein

et al. 2020

FEMS Microbiology Ecology

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Many studies demonstrate the importance of the commensal microbiomes to animal health and development. However, the initial community assembly process is poorly understood. It is unclear to what extent the hosts select for their commensal microbiota, whether stochastic processes contribute, and how environmental conditions affect the community assembly. We investigated community assembly in Atlantic cod larvae exposed to distinct microbial metacommunities. We aimed at quantifying ecological processes influencing community assembly in cod larvae and at elucidating the complex relationship between the bacteria of the environment and the fish. Selection within the fish was the major determinant for community assembly, but drift resulted in inter-individual variation. The environmental bacteria was highly dissimilar from the fish bacteria. Still, differences in the environmental bacteria strongly influenced the fish bacteria. The most striking difference was an excessive dominance of a single OTU (Arcobacter) for larvae reared in two of the three systems. These larvae were exposed to environments with higher fractions of opportunistic bacteria, and we hypothesise that detrimental host-microbe interactions might have made the fish susceptible for Arcobacter colonisation. Despite strong selection within the host, this points to a possibility to steer the metacommunity towards mutualistic host-microbe interactions and improved fish health and survival.

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Section: Introductionmentioning

confidence: 99%

Bacterial community assembly in Atlantic cod larvae (Gadus morhua): contributions of ecological processes and metacommunity structure

Vestrum

Attramadal

Vadstein

et al. 2020

FEMS Microbiology Ecology

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“…This has resulted in new knowledge on the functional roles of such microbes, including healthy development of the and a wide range of diseases not considered to be infection related, like diabetes and autism (e.g., Kanther and Rawls, 2010 ; Sekirov et al, 2010 ; McFall-Ngai et al, 2013 ; Lerner et al, 2017 ). The importance of microbe-fish interactions in host development and health are less studied, but this area of research is also rapidly progressing (see Kanther and Rawls, 2010 ; Vadstein et al, 2018 ; Vestrum et al, 2018b ). This rapid progress is largely due to a revolution in molecular and imaging methods ( Vestrum et al, 2018a ).…”

Section: Introductionmentioning

confidence: 99%

K-Selection as Microbial Community Management Strategy: A Method for Improved Viability of Larvae in Aquaculture

et al. 2018

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Aquaculture has the potential to become a major food supplier in a world with an increasing human population, and increased consumption of fish will likely have positive health implications. For marine aquaculture, the production of high quality juveniles is a bottleneck. Survival until the juvenile stage is typically as low as 10–15% for many species, which indicates suboptimal rearing conditions. Substantial evidence indicates that the poor performance and viability of larvae is largely due to detrimental larvae-microbiota interactions. This emphasises the need for microbial management strategies in the cultivation of marine fish larvae. Disinfection and probiotics are the most studied microbial management methods so far. However, most studies on these methods overlooked the role of mutualistic relationships between microbes and hosts, and have not proposed or examined methods steering toward such relationships. Based on ecological theory and a number of experiments, we find support for the hypothesis that current practise in aquaculture generally selects for r-strategic, opportunistic microbes, which results in detrimental host–microbiota interactions. Thus, the challenge is to develop technology and methods for microbial management at the ecosystem level that creates a K-selected microbial community, and by this mean select against r-strategic opportunists. Here we summarise experiments done during 25 years and with marine larvae of five different species showing that: (1) K-selection strategies result in different water microbiota with less opportunists, (2) this influences the microbiota of the fish larvae, and (3) the larvae cultivated in water inhabited by a K-selected microbiota perform better. Improved performance of larvae includes improved appetite, earlier onset of and faster growth, increased survival, and increased robustness to stress. K-selection as a method for management of the microbial community is a robust approach that allows steering of host–microbiota interactions in larviculture toward mutualism. It could also be applicable for young stages of other domesticated animals. Our review illustrates that a change from a “beat-them” to a “join-them” strategy for microbial management in larval rearing can lead to a more sustainable aquaculture industry.

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“…The basic questions, i.e., which microorganisms are colonizing developing larvae and which function do they have, still needs to be addressed in a proper way. The fast developing high throughput DNA sequencing technologies have come to the rescue, by generating a vast amount of data (Bakke et al, 2015 ; Vestrum et al, 2018 ). The next step will be to use these new techniques to get more knowledge on what the microbiota do.…”

Section: Introductionmentioning

confidence: 99%

Managing the Microbial Community of Marine Fish Larvae: A Holistic Perspective for Larviculture

et al. 2018

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The availability of high-quality juveniles is a bottleneck in the farming of many marine fish species. Detrimental larvae-microbe interactions are a main reason for poor viability and quality in larval rearing. In this review, we explore the microbial community of fish larvae from an ecological and eco-physiological perspective, with the aim to develop the knowledge basis for microbial management. The larvae are exposed to a huge number of microbes from external and internal sources in intensive aquaculture, but their relative importance depend on the rearing technology used (especially flow-through vs. recirculating systems) and the retention time of the water in the fish tanks. Generally, focus has been on microbes entering the system, but microbes from growth within the system is normally a substantial part of the microbes encountered by larvae. Culture independent methods have revealed an unexpected high richness of bacterial species associated with larvae, with 100–250 operational taxonomic units associated with one individual. The microbiota of larvae changes rapidly until metamorphosis, most likely due to changes in the selection pressure in the digestive tract caused by changes in host-microbe and microbe-microbe interactions. Even though the microbiota of larvae is distinctly different from the microbiota of the water and the live food, the microbiota of the water strongly affects the microbiota of the larvae. We are in the early phase of understanding larvae-microbe interactions in vivo, but some studies with other animals than fish emphasize that we so far have underestimated the complexity of these interactions. We present examples demonstrating the diversity of these interactions. A large variety of microbial management methods exist, focusing on non-selective reduction of microbes, selective enhancement of microbes, and on improvement of the resistance of larvae against microbes. However, relatively few methods have been studied extensively. We believe that there is a lot to gain by increasing the diversity of approaches for microbial management. As many microbial management methods are perturbations of the microbial community, we argue that ecological theory is needed to foresee and test for longer term consequences in microbe-microbe and microbe-larvae interactions. We finally make some recommendations for future research and development.

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Investigating Fish Larvae-Microbe Interactions in the 21st Century: Old Questions Studied with New Tools

Cited by 9 publications

References 111 publications

Bacterial community assembly in Atlantic cod larvae (Gadus morhua): contributions of ecological processes and metacommunity structure

Bacterial community assembly in Atlantic cod larvae (Gadus morhua): contributions of ecological processes and metacommunity structure

K-Selection as Microbial Community Management Strategy: A Method for Improved Viability of Larvae in Aquaculture

Managing the Microbial Community of Marine Fish Larvae: A Holistic Perspective for Larviculture

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