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Does fish stocking rate affect the photosynthesis of Lactuca sativa grown in an aquaponic system?

Jaszczuk Zuzanna Malwina, Brysiewicz Adam, Kozioł Agnieszka, Auriga Alicja, Brestic Marian, Kalaji Hazem M.

Journal of Water and Land Development

2023

no. 58

243--252

The depletion of natural resources such as freshwater and cropland makes it necessary to find a new solution for sustainable food production. Aquaponic systems seem to be a great alternative to traditional agriculture, however, there are still many unknowns that need to be explored. It is already known how fish stocking affects water quality in aquaponic systems, but not how it affects the plants’ growth, and especially on chlorophyll fluorescence. In this study, we examined how the density of 0, 2, 4, 8, and 16 stocking fish in five aquaria affects lettuce growth. The first tank was only a hydroponic system with plants but without fish (control). In the remaining four aquaria - 2, 4, 8 and 12 specimens of common carp fry with an average weight of 20 grams (average 8.5-33.2 g) were placed in the aquaponic growing system. Physicochemical analysis of water was conducted to determine the levels of pH, electrical conductivity (EC), N-NO3, N-NO2, N-NH4, P-PO4, O2 and physiological parameters of plants (nitrogen balance index - NBI, chlorophyll content index - CCI, quantum yield - QY, flavonoid content - Flv) were analysed. The results showed that fish stocking density has different effects on plant physiological parameters, but in most cases, was insignificant. It seems that the greater number of fishes and higher density indirectly causes growth inhibition (lower photosynthetic efficiency) due to the increase of N-NO3 and a decrease of O2 in the water.

Water quality and ichthyofauna habitat conditions in Lake Czolnowskie (N-W Poland)

Brysiewicz Adam, Czerniejewski Przemysław, Kozioł Agnieszka, Rogacki Michał, Dąbrowski Jarosław

Chemistry-Didactics-Ecology-Metrology

2020

R. 25, NR 1-2

113--123

Increasing anthropopressure affects natural ecosystems and may express itself in regional or spot contamination of water and soil environment. The quality of ground and surface waters depends to a large extent on drainage area management, where biogenic substances (i.e. nitrogen, phosphorus and potassium) are transported with surface run-offs to the environment. The article discusses results of studies on the drainage area of Lake Czolnowskie (Zachodniopomorskie Province). Studies covered physical and chemical assessment of soil conditions and water quality; additionally, fish was caught using two independent methods - gillnets and power generator (pursuant to CEN EN 14011 2003 and PN-EN 14011 2006). Results obtained confirm regular run-off of biogenic materials from the surface of farmed drainage area to Lake Czolnowskie. During the period of studies, the reservoir was exposed to i.e. reduction of water oxygen (3.56 mg/dm3) and permanently elevated level of general phosphorus (0.15-0.27 mg/dm3) and ammonium acid (0.16-0.27 mg/dm3), which degraded the quality of life for ichthyofauna inhabiting the lake.