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THE INFLUENCE OF WATER MACROPHYTES ON THE QUANTITY OF OXYGEN IN CARP PONDS' WATER
Ljubica Debeljak
; znan. savj. Agronomski fakultet, Zagreb, Svetošimunska 25
Željko Bebek
; dipl. ing. agr. direktor ribnjačarstva »D. Miholjac«, D. Miholjac
Krešimir Fašaić
; inž. kemije, Centar za ribarstvo, Zagreb, Kneza Mislava 2/V
Milorad Mrakovčić
; zn. asistent, Centar za ribarstvo Zagreb, Kneza Mislava 2/V
Sažetak
Research on the influence of emersed macrophytes in carp ponds in fish-farm D. Miholjac was carried on during the summer months of 1988 and 1989. Six carp ponds were under research: in ponds number 1, 2, 3 and 4, the fingerlings were cultured and in the ponds number 5 and 6, marketable fish. Some ponds had 40 - 70% of their area covered by emerged macrophytes, Nymphoides peltata being the dominant species.
The results are presented in tables 3 and 4 and on figure 1. The quantity of oxygen in the water of pond areas without emersed macrophytes varied between 2.72 mgl-1 and 11,20 mgl-1 indicating temporary insufficiency as far as requirements for normal growth were concerned.
In extremely overgrown areas of the ponds, the quantity of oxygen decreased significantly varying within an amplitude from 1.28 mgl-1 to 7,84 mgl-1. As opposed to pond areas free of weeds, the quantity of oxygen was 9 - 54% lower (from 0.32 mgl-1 to 3.84 mgl-1) in overgrown parts of pond areas. The fact was even significant statistically (p < 0.05).
The results indicate significantly negative influence of emersed macrophytes on the carp ponds. The oxygen level in water becomes lower as the overgrowth of the pond area becomes more extensive. That makes the possibility of otherwise normal fish feeding by additional food less convenient. Without the additional food, total fish mass increments are lower, and the food coefficient becomes higher. All of this shows the importance of reducing the overdevelopment of emersed macrophytes in the carp ponds. Therefore, the uprooting of emersed macrophytes from carp pond areas in of utmost importance.
Ključne riječi
water macrophytes; oxygen; carp ponds
Hrčak ID:
77083
URI
Datum izdavanja:
28.5.1992.
Posjeta: 1.043 *