Gonadal alterations in male whitefish Coregonus fatioi: no evidence for genetic damage reducing viability in early life stages

Abstract

In recent years, numerous cases of morphological gonadal alterations in fish have been recorded throughout the world and across a wide range of species. In the whitefish Coregonus fatioi from the pre-alpine Lake Thun (Switzerland), the frequency of gonadal alterations is particularly high and the variety of alteration types large. Little is known about the proximal causes and the direct consequences of these morphological features on population persistence. In particular, the potential for the observed alterations to be the phenotypic expression of reduced genetic quality has not yet been addressed. In this study, we used offspring survival during embryogenesis as a proximate indicator of male genetic quality and tested whether the presence of gonadal alterations in males is an indicator of reduced quality. Embryos resulted from in vitro fertilizations of gametes from 126 males and females. We found no significant correlation between embryo survival and gonadal alteration in adults. Our findings suggest that in C. fatioi of Lake Thun, alterations in gonad morphology are not a phenotypic expression of variation in genetic quality. KEY WORDS: Gonadal alterations · Genetic quality · Embryo survival · Whitefish · Lake Thun Resale or republication not permitted without written consent of the publisherDis Aquat Org 81: 119-125, 2008 et al. 2005) are known for occasionally hosting intersex individuals, i.e. individuals characterized by the simultaneous presence of both male and female gonadal features (Nolan et al. 2001). However, the prevalence of some types of gonadal alterations is much higher in Lake Thun than in other Swiss waters. Lake Thun therefore appears as a unique case with respect to both the large variety of deviations and their high frequency (Bernet et al. 2004). Over a 3 yr period of sampling, Bernet et al. (2004) recorded that 35% of whitefish (281 out of 808 fish) were affected, among them males and females of all age classes, from 1 to 6 yr, and individuals of different species (see Douglas et al. 1999 for a discussion of the taxonomy of Alpine whitefish). The deviations observed in these individuals included fusions to the trunk musculature, asymmetries, compartmentations, constrictions atrophy/aplasia and intersex (see Bernet et al. 2004 for a precise description of these alterations).The reasons for the observed patterns are not clear yet, but several factors may individually or jointly affect gonadal morphology and development in fish. Hybridization, i.e. the mating of individuals from different species or subspecies, appears to be one of them (Chevassus 1983). Among the known environmental factors, temperature, parasites, and chemical substances are often cited as primary determinants (reviewed in Blazer 2002). Finally, hatchery management might add to the aforementioned exogenous factors. In particular, fertilization practices, such as single male or sequential fertilizations (Wedekind 2002, Wedekind & Müller 2004), may decrease the overall genetic quality of individual fish, whic...

Testing the effects of genetic crossing distance on embryo survival within a metapopulation of brown trout (Salmo trutta)

“…This result is consistent with other salmonid studies employing various group-rearing conditions (e.g. Beacham 1988;Nagler et al 2000;Urbach et al 2008;Janhunen et al 2010). Janhunen et al (2010) and others suggested that detecting paternal effects at embryonic stages depends on the kind and amount of environmental variance allowed for in the experiment, a prediction verified in recent studies on brown trout (Jacob et al 2010) and whitefish Coregonus palaea (e.g.…”

Zooplankton Feeding Induces Macroscopical Gonad Malformations in Whitefish (Coregonus ssp.) from Lake Thun, Switzerland

“…Thus, the increased prevalence of gonad malformations in Lake Thun coregonids is unlikely to represent a genetic predisposition. This interpretation is supported by the findings of Urbach et al [41] and Bittner et al [35]). Finally, the fact that the prevalence of gonad malformations in Lake Biel whitefish reared in Lake Thun water and fed with Lake Thun zooplankton did not differ significantly from the prevalence of gonad malformations in Lake Thun whitefish reared under identical conditions argues against a contribution of "gene × environment" interaction.…”

Histotoxicity of AIEgen Based on Triphenylamine for the Simultaneous and Discriminatory Sensing of Hg2+ and Ag+ Directly in Aqueous Media for Environmental Applications

“…To assess further on a more precise level, research on histology was conducted because it is crucial in identifying the detrimental impact of pollutants on living tissues. 30,31 A primary lamella (Pl) with a robust central venous (Cv), operational erythrocytes (Ey), mucus cells (Mc), chloride cells (Cc), and basal undifferentiated cells (Bu) was seen in the histopathological examination of control fish gill tissue (Figure 1G1). Coherent capillary-lumen lacuna (Cl), pillar cells (Pc), and intact epithelial layers (El) with a normal interfilament spacing (Ifs) were also prominently evident in the secondary lamellae (Sl) of the control group gill.…”