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Hydrochemical conditions of three lakes located in the West Pomeranian region in the annual cycle

Tórz Agnieszka, Bonisławska Małgorzata, Nędzarek Arkadiusz, Rybczyk Agnieszka, Tański Adam

Journal of Water and Land Development

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2023

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no. 56

262--274

EN

The objective of the study was to trace the variability of the hydrochemical conditions in three lakes of the West Pomeranian Voivodeship (Poland) - Starzyca, Maszewskie and Nowogardzkie in the annual cycle. The research was done in 2018-2019, and samples for analysis were collected 4 times a year. All analyses were performed applying standard methods. Such hydrochemical indices were determined as dissolved oxygen, chemical oxygen demand, content of orthophosphates, total phosphorus, nitrite, nitrate, ammonium, chlorophyll a and iron. The study showed that all lakes in the research cycle were characterised by a polymictic type of water mixing, and the trophic level, based on the adopted criteria, indicated advanced eutrophy, which may also be caused by anthropogenic pressure. Oxygen conditions characterised by deoxidation of the waters in the bottom layer in the spring and summer seasons, and clear oxygenation in the surface water layer (in Lake Maszewskie reaching even 188.5% in the spring) confirm the significant advancement of the eutrophication process. The supply of phosphorus and nitrogen in spring from pelagic waters in the waters of the examined lakes influences concentrations of chlorophyll a in the summer. The influence of “internal supply” (bottom waters and bottom sediments) on the amount of nutrients available for autotrophs is clearly visible in the analysed lakes - an increase in nitrogen and mineral phosphorus concentrations in relation to surface waters was observed in the bottom layer.

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A new record of the invasive blue crab (Callinectes sapidus Rathbun, 1896) and his parasite from the Baltic basin

Czerniejewski Przemysław, Kasowska Natalia, Linowska Angelika, Rybczyk Agnieszka

Oceanologia

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2020

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No. 62 (1)

111--115

EN

A specimen of the invasive Callinectes sapidus was recently found in the catchment basin of the Baltic Sea (Lake Dąbie, Poland). The discovery is significant because it indicates a widening of the crab's biogeographic range in northern Europe and confirms its expansion along European estuaries. The captured juvenile specimen from Lake Dąbie (estuary of the Oder River) had a carapace width (CW) of 125.58 mm, carapace length (CL) of 53.23 mm, and weight (w) of 100.19 g. This is the first record of this species in this part of the Baltic Sea catchment basin, following the discovery of a female caught in a plaice net northeast of Copenhagen (1951) and an adult male caught off Skagen, Northern Jutland, between the Kattegat and the Skagerrak (2007).

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First data of age, condition, growth rate and diet of invasive Neogobius melanostomus (Pallas, 1814) in the Pomeranian Bay, Poland

Rybczyk Agnieszka, Czerniejewski Przemysław, Keszka Sławomir, Janowicz Mariola, Brysiewicz Adam, Wawrzyniak Wawrzyniec

Journal of Water and Land Development

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2020

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no. 47

142--149

EN

Round goby (Neogobius melanostomus (Pallas, 1814)) is an invasive species in the Oder River. In this study, age of 147 fish was determined using scales and otoliths, and the Fraser-Lee back-calculation method was used for population structure and theoretical length growth rates with 3 mathematical models of growth: von Bertalanffy, Ford–Walford and 2nd degree polynomial. Fish condition was determined using Fulton, Le Cren and Clark equations. Average total length and weight of fish was 162.00 mm and 83.00 g, respectively. Males were more abundant than females, representing 70% of the fish caught, and achieved greater total lengths and weights. Age 2+ dominated females and 3+ males age groups. Of the three mathematical models used to estimate fish growth, the 2nd degree polynomial model had the best fit to back-calculated lengths. Males had slightly higher growth rates than females in the first two years of life but comparable in subsequent years. The diet consisted of various benthic organisms that varied with fish age. The most frequently occurring food component was Dreissena polymorpha, which accounted for approximately 70% in the diet of fish with a body length greater than 191 mm.