Alternative host identity and lake morphometry drive trematode transmission in brook charr

Area of Science:

• Ecology
• Parasitology
• Aquatic Ecosystems

Background:

• Parasite prevalence and abundance in aquatic ecosystems vary greatly due to biotic and abiotic factors.
• The interplay between these factors and their combined effects on parasite dynamics remain poorly understood in natural systems.

Purpose of the Study:

• To investigate the combined effects of biotic and abiotic factors on the prevalence and abundance of two digenean trematode genera (Crepidostomum and Apophallus) in brook charr.
• To understand parasite transmission strategies in relation to environmental gradients in Canadian Shield lakes.

Main Methods:

• Studied 23 Canadian Shield lakes with varying fish species richness, biomass, morphometry, and physico-chemical conditions.
• Quantified prevalence and abundance of Crepidostomum and Apophallus in brook charr (Salvelinus fontinalis).
• Analyzed the relationship between parasite metrics and environmental variables, considering different transmission strategies.

Main Results:

• Biotic factors were identified as primary drivers of parasite abundance and prevalence.
• Apophallus showed a negative association with fish species richness and biomass gradients.
• Crepidostomum abundance was more influenced by host identity than diversity gradients.
• Lake area positively correlated with Apophallus prevalence and abundance.

Conclusions:

• Biotic factors, particularly fish community structure, play a critical role in regulating parasite dynamics in boreal lakes.
• Abiotic factors like lake size also influence parasite transmission success.
• Integrated analysis of biotic and abiotic factors is essential for a comprehensive understanding of parasite transmission in aquatic ecosystems.