Publication details

Morphological Abnormalities of Paradiplozoon homoion (Diplozoidae; Monogenea) as Indicators of Environmental Stress



Year of publication 2005
Type Article in Proceedings
Conference Ecological and Environmental Parasitology: The Impact of Global Change
MU Faculty or unit

Faculty of Science

Field Zoology
Keywords Paradiplozoon; fish; fluctuating asymmetry; environment
Description Fish ectoparasites are in direct contact with both its fish host and the surrounding environment, and both the host quality and the water quality may influence the development of the parasite. The developmental stability of individuals is assumed to be influenced by environmental stress. Here, we study various indicators of developmental stability that may be useful indicators of habitat quality. We study the occurrence of morphological abnormalities in an ectoparasite and correlate that with the fluctuating asymmetry (FA) or the deviation from the morphological mean for its fish host. Fluctuating asymmetry is defined as the random deviation from the perfect bilateral symmetry and the presence of environmental or genetic stress during ontogeny reduces the efficiency of normal developmental processes, thus increasing the level of FA. A total of 100 gudgeon (Gobio gobio) individuals were collected in monthly samples of 20 individuals from Vlara stream (CR). Fish were surveyed for all eco- and endoparasites. The monogenean ectoparasites Dactylogyrus cryptomeres and Paradiplozoon homoion reached the highest values of abundance. About 25% of the collected individuals of P. homoion showed abnormalities of the attachment sclerites (e.g. size reduction of adult parasite clamps without changes in their sclerite structure, clamps with abnormal sclerites, rudimentary clamps). Abnormalities were not observed on other monogenean parasites. The proportion of abnormal P. homoion is high, indicating a stressful environment. To assess an estimate of developmental instability of the fish host we measured eight metric and nine meristic bilateral characters on the right and the left side of the fish. In general, there was no correlation between fish FA or individual departure from the morphological mean and the number of P. homoion or the proportion of P. homoion with abnormalities. There was, however, a significant relationship between number of abnormal P. homoion and the number of asymmetric meristic traits per individual fish. This study thus indicates that the presence of morphological abnormalities in P. homoion is not dependent on the fish quality as measured by FA and morphological variability.
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