L. NIKOLOVA, K. DOCHIN and D. TERZIYSKI
Institute of Fisheries and Aquaculture, BG-4003 Plovdiv, Bulgaria
NIKOLOVA, L., K. DOCHIN and D. TERZIYSKI, 2013. Some parameters of the fishponds ecosystem for rearing carp in autochthonous monoculture. Bulg. J. Agric. Sci., 19: 584-589
The study was conducted at the Institute of Fisheries and Aquaculture- Plovdiv. Two groups of the ponds with different structure of fish stocking were set: I group: K1 - 500 pcs.ha-1; K0 - 15 000 pcs.ha-1; II group: K1 - 500 pcs.ha-1; K0 - 30 000 pcs. ha-1. In all ponds fish was reared in autochthonous (based only on developing in ponds natural food) mixed monoculture. To stimulate the development of natural food base in all ponds in the beginning of the vegetation period was applied cattle manure in quantity 3 000 kg.ha-1. In addition, 450 kg.ha-1 of quicklime was used. Quantities of used fertilizer and lime complied with the requirements of organic aquaculture standards. Throughout the entire vegetation period was carried out monitoring hydrochemical, hydrophysical, hydrobiological parameters of the experimental ponds. In this study the chlorophyll-a was not credible indicator for phytoplankton biomass. Macrophyte density is a factor influencing not only the different parameters of aquatic ecosystem, but affecting the nature of interactions between them and therefore should be definitely considered in aquatic ecosystems research. Considering only average macrophytes density levels is not enough, as in similar average macrophytes density levels the impact of the developed macrophytes is changing depending on different development trends over time, and reached maximum macrophyte density levels in the pond.