Uticaj različitih tipova dodatne hrane u poluintenzivnoj proizvodnji mlađi šarana (Cyprinus carpio) na strukturu i dinamiku ribnjačkog ekosistema

Abstract

Dobro poznavanje kompleksnih ekoloških odnosa u toplovodnim ribnjacima vaţan je preduslov uspešne šaranske proizvodnje u poluintenzivnom sistemu uzgoja. Poslednjih godina dolazi do intenziviranja proizvodnje šarana u Jugoistoĉnoj Evropi (Srbiji, Bosni i Hercegovini, Hrvatskoj, Bugarskoj i Rumuniji) kroz sve širu upotrebu koncentrovane hrane, peletirane i ekstrudirane, umesto ţitarica. Intenziviranje proizvodnje ovih riba nosi sa sobom promene u strukturi i dinamici ribnjaĉkog ekosistema. U periodu od juna do oktobra u devet ribnjaĉkih objekata na ribnjaku ''Kapetanski rit'' na severu Srbije ispitivan je uticaj tri razliĉita tipa dodatne hrane za dvogodišnju šaransku mlaĊ na fiziĉke i hemijske osobine vode, strukturu fitoplanktonske, zooplanktonske i bentosne zajednice ribnjaka i rast šarana. U istraţivanju su korišćena tri tipa dodatne hrane: kombinacija ţitarica u zrnu (kukuruz, pšenica i jeĉam), komercijalna peletirana i komercijalna ekstrudirana hrana sa 25% proteina i 7% masti. Pored toga, analizirana je priroda i jaĉina meĊuzavisnosti razliĉitih komponenata ribnjaĉkog ekosistema primenom analize redundantnosti (RDA). Tip dodatne hrane nije statistiĉki znaĉajno uticao na pokazatelje kvaliteta vode, izuzev na tvrdoću vode, ali je znaĉajno uticao na brojnost cijanobakterija, zooplanktona, bentosnih organizama i rast šaranske mlaĊi. Tako su jezera sa razliĉitim tipom dodatne hrane bila ujednaĉena u pogledu kvalitativnog sastava fitoplanktonske i zooplanktonske zajednice, dok su se znaĉajna odstupanja javila u kvantitativnom sastavu planktona. Cijanobakterije su bile dominantna grupa fitoplanktonskih organizama u svim jezerima, ali je u proseku njihova brojnost bila najmanja u grupi jezera u kojima je riba hranjena peletiranom hranom. TakoĊe, proseĉna brojnost Cladocera i Copepoda je u jezerima sa peletiranom hranom bila znaĉajno veća u odnosu na jezera sa ţitaricama i ekstrudiranom hranom, a brojnost makrozoobentosa je bila veća u odnosu na jezera sa ţitaricama. Rast dvogodišnje šaranske mlaĊi je bio znaĉajno manji u objektima u kojima je korišćena kombinacija ţitarica u odnosu na zimovnike sa dodatkom peletirane i ekstrudirane hrane izmeĊu kojih nije bilo znaĉajnih razlika...

Good understanding of complex ecological relationship in carp ponds is an important prerequisite for successful common carp production in semi-intensive system. In recent years it has come to an intensification of carp production in South-East Europe (Serbia, Bosnia and Herzegovina, Croatia, Bulgaria and Romania) through the wider use of industrially compounded feeds, pelleted and extruded, instead cereals. Intensification of production of these fish carries with it changes in the structure and dynamics of the pond ecosystem. The study was conducted from June to October 2009 in nine earthen fishponds at the carp farm ''Kapetanski rit'' in the north of Serbia. The influence of three different supplemental feed types for the two-year carp fry on the physical and chemical properties of water, structure of phytoplankton, zooplankton and benthic pond communities and carp growth was examined. Three types of supplemental feed were used: a combination of cereal grains (corn, wheat and barley), commercial pelleted and commercial extruded feed with 25% of proteins and 7% of fat. In addition using the redundancy analysis (RDA), the nature and strength of the interdependence of various components of pond ecosystems was analysed. The type of supplemental feed did not significantly affect the quality of water, except the hardness of water, but had a significantly effect on the abundance of cyanobacteria, zooplankton, benthic organism and the growth of carp fry. Thus ponds with different type of supplemental feed seemed more uniform in terms of the qualitative composition of the phytoplankton and zooplankton communities, while significant discrepancies occurred in the quantitative composition of these communities. Cyanobacteria were the dominant group of phytoplankton organisms in all ponds, but on average their numbers were the lowest in the group of ponds in which pelleted feed was used. Also, the average number of Cladocera and Copepoda in the ponds with pelleted feed was significantly higher than in ponds in which cereals and extruded feed were used, and abundance of benthic macroinvertebrates was higher than in ponds in which cereals were used...