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Rheophilic fish in oxbow lakes of the Warta River : the effect of environmental conditions on habitat selection

Golski J., Pińskwar P., Jezierska-Madziar M., Andrzejewski W., Mazurkiewicz J., Stanisławski D., Urbańska M.

Oceanological and Hydrobiological Studies

2017

Vol. 46, No. 1

38--49

Oxbow lakes are typical elements of meandering watercourses and are considered to be key components of floodplains of natural rivers. A permanent connection with the river promotes the use of these water bodies by ichthyofauna as spawning grounds, shelter for fry, feeding and wintering grounds. The aim of this study was to determine which rheophilic species inhabit oxbow lakes and how environmental conditions affect habitat selection and fish behavior. Analyses were conducted on six oxbow lakes of the Warta River in the Koło-Poznań section. Fish and water samples were collected for three years, in spring, summer and late autumn. Variation in environmental conditions in the analyzed water bodies results in a considerable diversity of the ichthyofauna, including rheophilic species, in individual seasons of the year. In the course of the study, nine rheophilic fish species were recorded, including four from the lithophilic reproductive guild having the highest environmental requirements. Relative abundance of rheophilic species in the dominance structure ranged from 0 to 100%, depending on the reservoir and seasons, with an average of 7% for all catches. For comparison, their relative abundance in the adjacent parts of the river was 12 and 23%.

Natural and anthropogenic transformations of water and marsh vegetation in Lake Zbęchy (Wielkopolska Region)

Gołdyn H., Arczyńska-Chudy E., Pińskwar P., Jezierska-Madziar M.

Oceanological and Hydrobiological Studies

2008

Vol. 37, No.2

77-87

Lake Zbęchy is situated in the General Chłapowski Landscape Park, which is the model of a rural area that has been subjected to agricultural pressure for many years. Over a thirty-year period (1976-2006) serious changes in the plant associations of Lake Zbęchy have occurred. The maximal depth of plant occurrence decreased from 3.6 m in 1976 to 2 m at present. The area overgrown by submerged macrophytes decreased from 13 to 0.2 ha. The community of Nitellopsidetum obtusae that dominated the belt of submerged plants during the 1970s has entirely disappeared from the lake. The decreasing phytolittoral area in the lake is the result of progressive lake eutrophication and water pollution. The transformations of reed and sedge communities are of a partially natural and partially anthropogenic character. The ecological status of the lake has deteriorated significantly. The ecological state of the lake in 1976 was good according to the Water Framework Directive. Currently, it is sufficient, but the ESMI value of 0.21 only slightly exceeds that of a bad ecological state (0.20-0.00). The level of lake development in the succession process was between mature and aged in 1976; now it is classified as definitely aged.