Assessing myxozoan diversity in fish: microscopy-based detection versus high-throughput amplicon sequencing.

Area of Science:

• Parasitology
• Aquatic Ecology
• Molecular Biology

Background:

• Accurate assessment of myxozoan (Cnidaria) diversity is crucial but taxonomically challenging.
• Traditional microscopy methods often underestimate parasite diversity in wild populations.

Purpose of the Study:

• To compare the efficacy of microscopy versus high-throughput amplicon sequencing for detecting myxozoan diversity in wild fish.
• To establish a quantitative framework for future myxozoan ecological and pathological investigations.

Main Methods:

• Screened 942 organ samples from 108 wild fish from Lake Weishan, China.
• Utilized both macroscopic/microscopic examination and high-throughput amplicon sequencing.
• Analyzed amplicon sequence variants (ASVs) to identify myxozoan species and lineages.

Main Results:

• Microscopy detected only 3 species in 20.4% of fish.
• Amplicon sequencing achieved 100% host-level detection, identifying at least 102 distinct myxozoan species (12,672 ASVs).
• Identified 45 putative undescribed species; species richness varied significantly across hosts and organs, with gills showing highest diversity.

Conclusions:

• Microscopy substantially underestimates myxozoan diversity in fish.
• High-throughput sequencing provides a more comprehensive understanding of myxozoan communities.
• This study offers a quantitative framework for future myxozoan research.