Parasitism, space constraints, and gonad asymmetry in the pollan (<i>Coregonus autumnalis</i>)

Harrod, Chris; Griffiths, David

doi:10.1139/f05-175

Cited by 4 publications

(9 citation statements)

References 20 publications

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“…Probably due to their inconspicuous nature, constrictions and asymmetries have not been subject of descriptions in scientific literature until recently. For example, Harrod & Griffiths (2005) observed asymmetrical gonads in pollan Coregonus autumnalis (Pallas) from Loch Neagh, Ireland, in 70% of the population. Also, comparable data have been reported for Lake Constance, where 14% in a sample of 1442 C. lavaretus had gonad strands being >40% different in their mass (Roesch, 2007).…”

Section: Discussionmentioning

confidence: 99%

How normal is abnormal? Discrimination between deformations and natural variation in gonad morphology of European whitefish Coregonus lavaretus

Bittner¹,

Bernet²,

Wahli³

et al. 2009

Journal of Fish Biology

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The gonad morphology of whitefish Coregonus lavaretus collected in Lake Thun, Switzerland, and two neighbouring lakes was assessed in order to differentiate between 'normal' and 'abnormal' character states of gonad morphology, which had been previously described in C. lavaretus from Lake Thun (constrictions, asymmetries, aplasia, compartmentations, fusions and hermaphroditism). In total, 4668 fish were collected and analysed using two complementary sampling schemes: (1) monthly samples of catches by the commercial fishermen and (2) samples of ripe spawners of all known 33 spawning sites of the three lakes. Considerable variation in gonad morphology in C. lavaretus populations of all lakes was found. Notably, all deviation types were observed in fish of all three lakes. Asymmetries and constrictions were frequent in all three lakes and showed systematic differences in frequency between the two sampling strategies. This indicates that asymmetries and constrictions represent to a large extent natural variation in gonad morphology of C. lavaretus and are also prone to considerable measurement error. In contrast, aplasia, fusions, compartmentations and hermaphroditism occurred predominantly in one C. lavaretus form of Lake Thun and in particular in populations spawning at great depths. This suggests that these deviation types are probably reliable indicators for gonad deformations and supports the interpretation that Lake Thun harbours a unique case of deformed gonads in C. lavaretus of yet unknown origin.

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Section: Discussionmentioning

confidence: 99%

How normal is abnormal? Discrimination between deformations and natural variation in gonad morphology of European whitefish Coregonus lavaretus

Bittner¹,

Bernet²,

Wahli³

et al. 2009

Journal of Fish Biology

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“…In male pollan somatic condition, relative liver size and gonad size (Harrod and Griffiths, 2005) all decline with increasing infection intensity. The hepatosomatic index i.e.…”

Section: Costs Of Parasitism In Pollanmentioning

confidence: 96%

“…This parasite has been noted in the lough by earlier workers but there has been no previous assessment of its intensity or impact on pollan. However, Harrod and Griffiths (2005) have shown that I. erraticus affects gonad size and symmetry in pollan.…”

Section: Introductionmentioning

confidence: 98%

Ichthyocotylurus erraticus (Digenea: Strigeidae): factors affecting infection intensity and the effects of infection on pollan ( Coregonus autumnalis ), a glacial relict fish

Harrod

Griffiths

2005

Parasitology

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Lough Neagh pollan are heavily infected with the strigeid Ichthyocotylurus erraticus , with 100% prevalence and median infection intensities of 600+ metacercariae in the pericardial cavity of mature fish. Female fish were more heavily infected than males. Infection intensity, which rose in summer, varied with pollan size, year, sampling bay within the lough and water depth within bays. Heavily infected pollan were caught further offshore than lightly infected fish. Spatial variation in pollan infection intensity corresponded to variation in the abundance of the first intermediate host, Valvata snails. The data suggest that heavily infected fish had lower food intakes. Parasitism reduced condition and liver size in male fish but condition in heavily parasitized females increased. Infection intensity was greater in larger fish of a given age. These patterns are discussed in the context of risks and rewards. The data suggest that inshore waters in summer are the preferred habitat of pollan and that the greater infection intensity of offshore fish results from their reduced competitive ability as a consequence of parasitism and the increased risk of infection there.

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“…Given the fact that fish sexual differentiation and gonad development are subject to genetic and environmental influences [7,17], alterations in gonad morphology can be induced both by endogenous and exogenous factors as well as their interaction. Accordingly, gonad abnormalities of fish have been associated, among others, with genetic quality and hybridization status of the broodstock [18,19], autoimmune disease [20], changes in physical water parameters [21,22] or parasite infection [23,24]. One environmental factor that has attracted particular attention as a cause of gonad abnormalities in fish is aquatic contamination by anthropogenic chemicals [4,15,[25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

“…Whitefish species can show considerable morphological variability, which may be related to the genetic divergence and adaptive radiation of coregonids in many lakes of the Northern hemisphere [33][34][35][36][37]. On the other hand, environmental factors such as parasites or anthropogenic contaminants are also known to cause phenotypic variations of whitefish gonads [24,38].…”

Section: Introductionmentioning

confidence: 99%

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

Bernet

Wahli

Küng³

et al. 2020

Fishes

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Alterations in gonad morphology are widespread in wild fish populations. Whitefish (Coregonus spp.) from Lake Thun, Switzerland, display a high prevalence of macroscopical gonad malformations including fusions to the musculature, segmented gonads and intersex condition. The aim of the present study was to evaluate whether the gonad morphological changes in Lake Thun whitefish are caused by genetic factors, environmental factors (water, diet) or “gene × environment” interaction. We performed two independent experiments of a three-year duration in which we reared whitefish from fertilization until adulthood and tested the possible causative factors using a matrix design: (i) genetics—comparing the prevalence of gonad malformations in whitefish of different genetic origin reared under identical environmental conditions (same diet, same water, same experimental facility); (ii) environment—comparing the prevalence of gonad malformations in whitefish of the same genetic origin reared in different water sources and/or fed with different diets; and (iii) gene-environment interaction—comparing the prevalence of gonad morphological alterations in relation to the combinations of genetics and environmental factors. Two diets were used for the rearing experiments: either zooplankton collected in Lake Thun which represents the natural diet of whitefish, or an artificial dry food which was used as control. The key finding of this study is that the inducing factor of the gonad malformations is contained in the zooplankton of Lake Thun. Fish fed with this diet developed a significantly higher prevalence of malformations than fish from any other treatment, irrespective of the genetic origin and/or the water source. This result could be repeated in the two independent experiments. Importantly, the prevalence values observed in the experimental fish fed with Lake Thun zooplankton were similar to the prevalence values recorded in free-ranging whitefish in the lake. The findings of this study advance the understanding of the causes of gonad morphological alterations in wild fish populations.

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Parasitism, space constraints, and gonad asymmetry in the pollan (Coregonus autumnalis)

Cited by 4 publications

References 20 publications

How normal is abnormal? Discrimination between deformations and natural variation in gonad morphology of European whitefish Coregonus lavaretus

How normal is abnormal? Discrimination between deformations and natural variation in gonad morphology of European whitefish Coregonus lavaretus

Ichthyocotylurus erraticus (Digenea: Strigeidae): factors affecting infection intensity and the effects of infection on pollan ( Coregonus autumnalis ), a glacial relict fish

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

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