INVESTIGATION OF RELATIONS BETWEEN ABIOTIC VARIABLES, THEIR INFLUENCE ON THE PLANKTON PRIMARY PRODUCTIVITY AND THE MANURING EFFECT IN FISH PONDS

TERZIYSKI, D., R. KALCHEV, H. KALCHEVA and V. ALEXANDROV, 2016. Investigation of relations between abiotic variables, their infl uence on the plankton primary productivity and the manuring effect in fi sh ponds. Bulg. J. Agric. Sci., 22: 485–491 The experiment was carried out within three consecutive years (2004, 2005 and 2006). Seven earthen fi sh ponds (area varying from 1.8 to 3.9 dа) located in the Institute for Fishery and Aquaculture, Plovdiv, Bulgaria were included in the investigation. A manure dose of 3000 kg.ha–1 was used. The aim of this study was investigation of relations between the abiotic factors, their infl uence on the plankton primary productivity (PP) and the manuring effect in fi sh ponds. The bigger part of the abiotic factor variation was defi ned by the differences between the monthly sampling compared to the changes in the ponds within investigation period (2004/05/06). Concerning the abiotic factors there was a difference between fi rst and last months. The great seasonal variability decreases the chance to fi nd differences between the manured and the control ponds. The abiotic factors as the permanganate oxidability, oxygen content and рН value in the manured ponds had a higher level compared to control ponds during 2005. An increased level of the oxidability, phosphate phosphorus and рН value was found in the manured ponds during 2006.