QUALITATIVE COMPONENTS OF PLANKTON ALGAE (Chlorophita) IN CARP POND

Istraživanje je provedeno na ribnjačarstvu•”Draganići”, u ribnjaku 1, u tijeku uzgojnih sezona godine 1980., 1981. i 1983. U ribnjaku se uzgajala konzumna riba, s nasadom jednogodišnjega ribljeg mlađa u količini 2.034 ind.ha-1, 5.450 ind.ha-1 i 2.488 ind.ha-1 u pojedinim godinama. Riba je prihranjivana žitaricama. Gnojidba ribnjaka provedena je mineralnim gnojivima NPK (17: 8: 9), a količina gnojiva u pojedinim godinama iznosila je 450 kgha-1 i 370 kgha-1 uz višekratnu aplikaciju. Kemizam vode u tijeku istraženih uzgojnih senoza varirao je u granicama koje su karakteristične i za druge šaranske ribnjake u Hrvatskoj. Variranje anorganskih soli dušika i fosfora u tijeku istraženog razdoblja bilo je unutar amplitude: za N03- od 0,01 do 0,057 mg. 1-1, za NH4+ od 0,08 do 1,15 mg. 1-1, a PO43- od 0,10 do 1,20 mg. 1-1. U kvalitativnom sastavu planktonskih Chlorophyta nađena je ukupno 81 vrsta u tijeku tri uzgojne sezone, odnosno 51 vrsta (63%) godine 1980., 61 vrsta (75%) 1981. i 42 vrste (52%) 1983. Najvećim su se brojem javljali rodovi Scenedesmus, Ankistyodesmus, Pediastrum, Crucigenia, Oöcystis, Cosmarium., Closterium i Staurastrum. Floristički sastav Chlorophyta u istraženom ribnjaku bio je sličan u tijeku svih triju godina istraživanja, uz QS=73%, 60% i 55%. Nije bila izražena povezanost kvalitativnog sastava planktonske zajednice Chlnrophyta i gustoće riba u ribnjaku koji se prihranjuje žitaricama.Investigations were carried out at the fish farm•”Draganići” in fish pond, during the 1980, 1981 and 1983 culturing seasons. Consumnction fish were cultured, with a stocking of one year old fish fry at quantities of 2034 ind/ha 5450 ind/ha and 2488 ind/ha in each year. The fish were fed with grains. Fertilization of the ponds was with mineral fertilizer NPK (17:8:9) and the amount of fertilizer in each year was 450 kg/ha and 370 kg/ha with numerous applications. The water chemistry during the investigated culturing seasons varied within the limits which are characteristic for the other carp ponds in Croatia. Variation of anorganic nitrogen salts and phosphor during the investigation period was within the amplitudes: for N03- from 0.01 to 0.057 mg.l-1, for NH4+ from 0.08 to 1.15 mg.l-1 and PO43- from 0.10 to 1.20 mg.l-1. The qualitative components of the planktonic Chlorophites was found in a total of 81 species during the tree culturing seasons, that is 51 species (63%) in 1980, 61 species (75%) in 1981 and 92 species (52%) in 1983. The greatest number of species were the families of: Scenaedesmus, Ankistyodesmus, Pediastrum, Crucigenia, Oöcystis, Cosmarium, Closterium i Staurastrum. The floral components of Chlorophita in the fish pond was similar during all three years of investigation, with QS=73%, 60% and 55%. There was no expressed relation of the qualitative components of the plankton community of chlorophytes and the density of fish in the pond where the fish were fed with grains