Population growth ofGyrodactylus kobayashiiin goldfish (Carassius auratus) associated with host density

Abstract

Host density is a key regulatory factor in parasite transmission. The goldfish (Carassius auratus)-Gyrodactylus kobayashii model was used to investigate effects of host density on population growth of gyrodactylids. A donor fish infected by five gravid gyrodactylids was mixed with 11 parasite-free goldfish at five host densities. There was a significant positive correlation between host density and mean abundance of G. kobayashii throughout the 58-day experiment. During early infection (days 15–24), mean abundance in medium high (0.5 fish L−1) and high host density groups (1 and 2 fish L−1) was significantly higher than that in the low host density groups (0.125 and 0.25 fish L−1). At high host density, prevalence increased more rapidly, and the peak prevalence was higher. Fitting of an exponential growth model showed that the population growth rate of the parasite increased with host density. A hypothesis was proposed that higher host density contributed to increased reinfection of detached gyrodactylids. A reinfection experiment was designed to test this hypothesis. Both mean abundance and prevalence at a host density of 1 fish L−1 were significantly higher than those at 0.25 fish L−1 on days 1 and 3, which suggested that more reinfections of G. kobyashii occurred at the higher host density. Density-dependent transmission during the early infection was an important contributor of population growth of G. kobayashii, as well as density-dependent reinfection of the detached gyrodactylids.

Effects of host competence and schooling behavior on parasite transmission in a fish-gyrodactylid system: test of the dilution effect

“…Although no dilution effect was detected in the presence of the two incompetent hosts, the higher mean abundance on goldfish in the grass carp group may result from reinfection of detached gyrodactylids in the water column due to spatial distribution of goldfish in the whole tank (Jin et al 2022).…”

“…The relative abundance of lowcompetence hosts compared to competent hosts is an important component for the dilution effect (Ostfeld & Keesing 2012). Curiously, a higher density of all potential hosts (competent plus low competence) did not enhance parasite transmission, despite the fact that density of primary host play a roles in transmission of gyrodactylids (Johnson et al 2011;Jin et al 2022).…”

Аналіз Видового Різноманіття Паразитів Окремих Видів Риб Прісноводних Водойм України. Моногенетичні Сисуни

“…Згідно з даними літератури встановлено, що велику кількість зоопаразитів у карася виявляли й інші науковці [41,42], а отже, таке явище для цього виду риб є характерним. Слід зазначити, що карась вважається інвазійною рибою і відіграє велике значення у поширенні хвороб паразитарної етіології, що знаходить підтвердження у роботах науковців багатьох країн світу [43][44][45][46].…”