Impact of fish species on levels of lead accumulation in the meat of common bream (Abramis brama L.), white bream (Blicca bjoerkna L.) and common bleak (Alburnus alburnus L.) from the Vistula River (Poland)

AbstractThe egg release–mating comparison, heterospecific matings and mating success under two hybridization conditions – (i) mixing one sex per species and (ii) mixing both sexes from each species – were investigated to determine whether silver bream Blicca bjoerkna and common bream Abramis brama can hybridize in nature.The results revealed that non-matings in hybridization experiments of silver bream females × common bream males can be explained by territorial and aggressiveness activities observed in common bream. In common bream females × silver bream males, heterospecific matings were observed but their numbers were significantly lower than the spawning numbers, and in this experiment, a female mated with one to four heterospecific males. In mixing both sexes from both species, similar spawning – mating numbers were observed but heterospecific matings accounted for only 27% of the total matings, with 24% accounting for heterospecific matings between common bream females and silver bream males, directly or by opportunism. Mating success was characterized by the occurrence of fertilized eggs after matings.Natural hybridization occurred preferentially between common bream females and silver bream males.

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Shape of Zooplankton and Retention in Filter-Feeding: A Quantitative Comparison between Industrial Sieves and the Branchial Sieves of Common Bream (Abramis brama) and White Bream (Blicca bjoerkna)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f93-082 ◽

1993 ◽

Vol 50 (4) ◽

pp. 716-724 ◽

Cited By ~ 2

Author(s):

Coen van den Berg ◽

Jos G.M. van den Boogaart ◽

Ferdinand A. Sibbing ◽

Eddy H.R.R. Lammens ◽

Jan W.M. Osse

Keyword(s):

Channel Model ◽

Mesh Size ◽

Width Ratio ◽

Abramis Brama ◽

Filter Feeding ◽

Feeding Experiments ◽

Bream Abramis Brama ◽

Common Bream ◽

Common Bream Abramis Brama ◽

White Bream

Industrial sieves retained all cycloid copepods with a width larger than their mesh size, but Daphnia, with a width up to 1.4 times the mesh size, still passed through them. Daphnia have a lower depth/width ratio than copepods (0.599 and 0.882, respectively). Therefore, Daphnia could pass through the square meshes diagonally. In filter-feeding experiments with common bream (Abramis brama), the smallest retained copepods correspondingly were about 35% less wide than the smallest retained Daphnia. White bream (Blicca bjoerkna) did not retain copepods smaller than Daphnia. In the reducible-channel model of filter-feeding, particles are retained in the channels between the medial gill rakers. The mesh size can be reduced by lowering the lateral rakers into these channels. We calculated that zooplankton depth is the critical size parameter in reduced channels and zooplankton width in unreduced channels. We found that white bream was feeding with unreduced channels and common bream with reduced channels. The depth/width ratio (35% lower in Daphnia than in copepods) therefore explains the difference in retention of copepods and Daphnia by common bream whereas no such difference was expected for white bream. The shape of zooplankton thus affects the trophic segregation and the exploitation of food resources by fish.

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