Original scientific paper
INFLUENCE OF STOCKING STRUCTURE ON THE DYNAMICS OF ABIOTIC PARAMETERS IN CARP PONDS I. DYNAMICS OF PHYSICO-CHEMICAL PARAMETERS IN FRY POND
S. Mišetić
Abstract
Research on the dynamics of the physico-chemical parameters was carried out in 3 ponds of "Zagreb Fisheries" — the fish farms of Pisarovina in 1980. In nursury fish pond 1 year old carp fingerlings were cultured, obtained by free spawning of carp parents, and in nursury ponds 5 and 6 two year old carp were used for culture. The amount of stocked fish in fish ponds 5 and 6 was 269.2, that is 138.6 kg/ha. A large amount of dead fish was recorded for fish pond 5. Water samples for physico-chemical analysis in fish ponds 1 and 6 were collected in the time periods of the inflow of water until catching time or the occurence of ice. Fish pond 5 was filled in the autumn of the previous year.
Results of the analysis, which included the basic abiotic parameters: temperature, depth and water transparency, oxygen concentration, free carbonic acid, pH values, total and differencial alcalinity, total carbonic and noncarbonic hardness, organic matter, ions NH4+ and PO4xexp(-3) are presented in Tables 1-3.
The greatest similarity between the investigated fry ponds was in the thermic and txemporal dynamics of the water transparency. This ctn be connected with the stocking structure of the ichthiofauna, which was not sufficient to hasten the rotation of matter between the abiotic components of the ground and free water and therefore to influence the decrease of water transparency.
In the period of high water transparency intensive development of higher water plants was established. This resulted in a large concentration of oxygen, a deficit of free and bound carbonic acids and the presence of hydroxide components of alcalinity. Hydrorides in fry pond 1 were determined when the value of total alcalinity was 80.8 mg CaC03 X dm3.
Keywords
STOCKING STRUCTURE; DYNAMICS OF ABIOTIC PARAMETERS; CARP PONDS; FRY POND
Hrčak ID:
76745
URI
Publication date:
1.3.1989.
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