Seasonal changes of immunocompetence and parasitism in chub (Leuciscus cephalus), a freshwater cyprinid fish

Abstract

Seasonal variation of water characteristics, predominantly temperature, is considered to strongly affect fish physiology and immunology. In nature, this variation directly influences the life cycle especially in fish parasites, but the infection of parasites is also altered by the host immune response. This study is aimed to analyze the seasonal changes in selected physiological and immunological parameters, the latter a potential measure of fish immunocompetence. Moreover, the seasonal changes in metazoan parasite infection were investigated, and the potential associations between fish physiology, immunocompetence, and parasitism were estimated. No differences in gender were recognized for immunological parameters. The significant differences in the spleen-somatic index were found among fish samples of different seasons indicating higher investment in spleen size in April (after winterizing) and August (post-breeding with low gonado-somatic index [GSI]). The significant seasonal differences in erythrocyte and leukocyte cell counts, as well as in phagocyte count affecting respiratory burst, were recorded. The general trend of leukocyte composition was similar in all seasons investigated; however, the changes in proportion of different neutrophilic cells were reported. The parasite diversity and the infection parameters in parasite communities were highest in spring and early summer. When comparing parasite abundance in infracommunities among seasons, the statistically highest values were observed in April and June for Monogenea, in April and November for Acanthocephala, and in April for Cestoda. The positive correlations between GSI and the parasite abundance of groups with higher infection parameters were found in males. Moreover, the positive association between Monogenea as the dominant parasite group and respiratory burst was observed. The higher investment in condition and the seasonal variation in GSI were associated with a decrease immune function measured by spleen size or leukocyte cell count especially for males suggesting the seasonal energy allocation between immune function and somatic or reproductive investment.

The effects of estrogenic and androgenic endocrine disruptors on the immune system of fish: a review

“…Indeed, the investigation of reproductive-immune interactions in fish has demonstrated that sexual maturation is often related to both innate and adaptive immune responses. These interactions affect innate immune proteins (Kumari et al 2006;Bowden et al 2007;Morgan et al 2008), acquired antibodies (Browser and Munson 1986;Steine et al 2001), and the number and proportion of leukocytes (Lamková et al 2007). Temperature and, to a lesser extent, other factors such as photoperiod appear to be the major cues driving these seasonal changes in immune markers (Bowden et al 2007).…”

Monogenean parasites from fishes of the Vaal Dam, Gauteng Province, South Africa. I. Winter survey versus summer survey comparison from Labeo capensis (Smith, 1841) and Labeo umbratus (Smith, 1841) hosts

“…The interaction between parasitism, water contamination and condition factor is complex, being influenced by various biotic and abiotic factors (Escher et al 1999, Thomas et al 2000, Lamková et al 2007, Pervin and Mortuza 2008, Tavares-Dias et al 2008, Arafa et al 2009). None the less water quality (with particular reference to pollutants such as heavy metals) has been shown to negatively affect monogenean parasite numbers and distribution (Dušek et al 1998, Galli et al 2001, Marcogliese 2004, Blanar et al 2009).…”

Seasonal variation in thermal tolerance, oxygen consumption, antioxidative enzymes and non-specific immune indices of Indian hill trout, Barilius bendelisis (Hamilton, 1807) from central Himalaya, India

“…temperature, photoperiod, environmental pollution, etc. (Nikoskelainen et al, 2004;Magnadóttir, 2006;Lamkova et al, 2007;Morgan et al, 2008;Valenzuela et al, 2007;Tolarova et al, 2014) as well as biotic factors i.e. pathogens or parasites (Zapata et al, 1992;Bowden et al, 2007).…”