Gill Histopathology as a Biomarker for Discriminating Seasonal Variations in Water Quality

Histopathological alterations in various fish organs have a pronounced value in aquatic toxicology and are widely used in environmental monitoring. The aim of this study was to evaluate whether histopathological alterations in fish gills can discriminate seasonal variations in environmental conditions within the same aquatic ecosystem, and if so, which alterations contributed the most to seasonal differentiation. Microscopic examination of common bream Abramis brama gills displayed various alterations in gill structure, including epithelial hypertrophy, hyperplasia, mucous and chloride cell alterations, epithelial lifting, necrosis, hyperemia and aneurism. These alterations were subsequently quantified by a semi-quantitative analysis in order to detect differences in the intensity of the mentioned alterations. Epithelial hypertrophy, hyperplasia, epithelial lifting and necrosis varied significantly between seasons with only necrosis being significantly higher in the first season. Discriminant canonical analysis displayed that epithelial hyperplasia, mucous cell alterations, epithelial lifting and necrosis contributed the most to discrimination between seasons. Overall, this study demonstrates that histopathological biomarkers in fish gills can be used in discriminating seasonal variations in water quality within the same aquatic ecosystem.

FORMING OF SOME ORGANS OF HEMATOPOIESIS IN PRE-LARVAE, LARVAE AND FRY OF COMMON BREAM (ABRAMIS BRAMA L.)

Ability for hematopoiesis of spleen, intestinal mucosa, and liver is investigated for early ontogenesis of common bream Abramis brama L., a species of bony fish widespread in the Russian waters, including Astrakhan region. The samples (24 ind.) were collected in the fish farm in Kamyzyaksky district of the region in middle May 2018, after hatching. Histological analysis was made by conventional methods. Both spleen, liver, and intestinal mucosa were formed in the first days after hatching. In the spleen, such signs of hematopoiesis as dispersed new developing blood particles were found just in the first day. In the intestinal mucosa, the first foci of hematopoiesis appeared in the nineteenth day. These organs were formed completely by the end of larval development, and the most intense level of hematopoiesis was observed in that time, with forming of blood cells of all rows of hematopoiesis. On the contrary, no signs of hematopoiesis were found in the liver throughout the larval and juvenile periods.

Age and growth of common bream, Abramis brama (L.), caught at Hammam Debagh Reservoir (Guelma, northeast Algeria)

This study was conducted in Hammam Debagh Reservoir located in northeastern Algeria, which was first the subject of fish farming tests in 2001. The species tested included Chinese carp, royal carp, common carp, pikeperch, and common bream. The present work aimed to determine the age and growth of one of the most frequently caught species in the reservoir, common bream, Abramis brama. This information is essential to the knowledge of fish biology, and thereby to solving many of the problems of fish research and development. A sample of 100 common bream, A. brama, was caught with gillnets over a period of six months from December 2017 to May 2018. The results obtained fit well with the growth model and were similar to those published regarding other environments. Scales from a sample of 50 fish were read under an optical microscope, which permitted identifying five age groups. The value of the overall sex ratio (4.88) revealed a strong imbalance in favor of males throughout the study period. The relationship linking length-weight is of the minor allometry type with b < 3.