Quantifying parasitic swimbladder nematodes and their effect on the body condition of Lake Whitefish in Great Slave Lake

• Main Author: Friesen, Caitlyn
• Language: English
• Published: 2024
• Subjects: swimbladder nematodes; Lake Whitefish; Cystidicola farionis; Effects of parasite infection; Great Slave Lake
• Online Access: http://hdl.handle.net/1993/38282

Parasites are known to impact the health of their hosts due in part to depleting available energy. Although Cystidicola farionis are common parasitic swimbladder nematodes of Lake Whitefish, it is difficult to ascertain how infection affects the host’s health. It is essential to understand parasite and host biology to assess the effects of parasitic infection on the host’s body condition. Given that of the Cystidicola species, only C. farionis has been identified in Lake Whitefish, it is predicted that the nematodes will be identified as such. Reproduction is a major driver of an individual’s health, and female Lake Whitefish invest more energy in reproductive events than males. The Fulton’s (K) condition index was used to assess somatic body condition, where the inclusion of gonad weight could potentially mask a sex-specific effect of parasite infection. The gonadosomatic index (GSI) was used to determine if C. farionis infection has a sex-specific effect on Lake Whitefish’s body condition. Swimbladder nematodes were identified based on egg morphology and genetic sequencing of the 28S and ITS-2 regions of the ribosomal DNA. For the first time in Great Slave Lake, C. farionis was identified based on morphological and genetic analysis, and prevalence was estimated at 54% in mature Lake Whitefish with a mean intensity of infection of 9.74 nematodes per infected host. T-tests indicated that body condition did not differ between Lake Whitefish infected with C. farionis and those uninfected. Although, linear regression models revealed that as the intensity of infection increased, K values of mature Lake Whitefish and GSI for current-year spawning females declined. There did not appear to be a sex-specific effect of infection, although future examination of current-year spawning males and immature Lake Whitefish could provide further insight into the impact of C. farionis infection.