27 research outputs found
INFLUENCE OF THE COOT (FULICA ATRA L. 1758.) POPULATION ON THE FISH DIET IN CARP PONDS
Istraživanje o temi Ā»Utjecaj populacije crne liske (Fulica atra L. 1758) na prehranu populacija riba u Å”aranskim ribnjacimaĀ« provedeno je na RibnjaÄarstvu Ā»KonÄanicaĀ« (srediÅ”nja Hrvatska) od 1985. do 1988. g.
Utjecaji se mogu okarakterizirati i kao pozitivni i kao negativni.
Pozitivni se utjecaj oÄituje u Äinjenici da u ribnjacima djeluje kao koristan bioloÅ”ki regulator: spreÄava masovan razvoj algi i viÅ”ega vodenog bilja, Äime posredno pridonosi poveÄanju koliÄine kisika u vodi; spreÄavanjem zasjenjivanja vodene povrÅ”ine potiÄe razvoj fitoplanktona i zooplanktona kao važne prirodne riblje hrane; konzumira kukce Å”tetne za ribnjaÄarsku proizvodnju; svojim ekskretima pridonosi poveÄanju koliÄine prirodne hrane u ribnjacima.
Negativni su utjecaji u smislu natjecanja (kompeticije) za hranu s ribljim vrstama u uzgoju (konzumira dodatnu riblju hranu za cijelo vrijeme prihranjivanja ribe, konzumira fitoplankton i vodane makrofite kao glavnu hranu herbivornim ribljim vrstama, zatim mekuÅ”ce i kukce koji su važna hrana zoofagnim ribama), te u smislu predator-stva, ali u vrlo maloj mjeri, jer konzumira riblji mlaÄ.
Napokon, dobiveni rezultati upozoravaju na Äinjenicu da je crna liska bitna karika u bioloÅ”kome lancu ribnjaÄkog eko-sustava, pa bi njezina potpuna odsutnost, sigurno, imala odreÄene Å”tetne posljedice za ribnjaÄarsku proizvodnju.Research on the influence of the coot (Fulica atra. F. 1758) population on the fish diet in carp ponds was carried out at the fish farm Ā»KonÄanicaĀ« (Central Croatia) from 1985-1988. This influence can be characterized as
positive and negative. The positive influence is expressed by the fact that in the fish ponds it has the effect of a useful biological regulator: it prevents massive development of algae and higher water plants, which indirectly contributes to an increase in the amount of oxygen in water; by preventing shading of water surfaces caused by the development of phyto- and zooplankton as an important natural fish food; it consumes insects which are harmful to the fish farms\u27 production; and finally, with its excretions it causes an increase of natural food in the fish pond. The negative influence is in the sense of competition for food with fish species in culture (consuming additional fish food for the whole time of supplement feeding the fish, consuming phytoplankton and water macrophyte as the main food of herbivorous fish species, then the molluscs and insects which are an important food of zoophage fish), also in the predatory sense, but in a very small amount, it consumes the fish young. Finally, the results obtained point to the fact that the coot is an important link in the biological chain of the fisheries ecosystems, therefore its\u27 complete absence would definitely have certain harmful effects in fisheries production
BIOLOGICAL REVIEW OF THE QUALITY OF WATER OF RIVER ILOVA IN THE REGION OF UPPER POILOVLJE
BioloÅ”ka ocjena kvalitete vode rijeke Ilove u podruÄju gornjeg Poilovlja utvrÄivana je u razdoblju od rujna 1988. do srpnja 1989. godine.
Svrha je istraživanja bilo oÄuvanje rijeke Ilove, kao važnog vodenog ekosistema za ovaj dio srediÅ”nje Hrvatske.
Kvaliteta vode utvrÄivala se kvalitativnom analizom mikrofitobentosa i makrofitobentosa. Ustanovljene su 62 vrste, od Äega 41 indikatorska vrsta (tablica 1). BrojnoÅ”Äu prevladavaju vrste iz skupine BACILLARIOPHYCEAE (82,54%). Od ukupnog broja indikatorskih vrsta najviÅ”e ih pripada prijelaznom oligo-betamezosaprobnom stupnju (10 vrsta ili 24,39%), a indikatori jaÄe oneÄiÅ”Äenosti (alfa-mezosaprobni stupanj) zastupljeni su sa sedam vrsta (17,07%).
Na lokalitetima I1, I2 i I3 nema znakova izrazitije oneÄiÅ”Äenosti: indeks je saprobnosti u granicama beta-mezosaprobnog stupnja (1,55-1,93),
Lokalitet I4 izrazito je oneÄiÅ”Äen, na Å”to upuÄuje ustanovljeni indeks saprobnosti od 2,58 (alfamezo-saprobni stupanj).Biological review of the quality of water of river Ilova in the region of upper Poilovlje was researched from September 1988 will July 1989. The aim of this research was to preserve the river Nova as an important water echosystem in this medium part of Croatia.
The quality of water was determined by qualitative analisys of microphitobenthosa and macrophitobenthosa.
There were found out 62 species, 41 of them were indicating species. The most frequent are Bacillariophyta (82,54%). 10 species or 24,39% of the total number of indicating species belong to oligo-betamesosaprophitic degree while 7 species or 17,7% belong to alfamesosaprophitic degree.
On the localities l1, I2 and I3 there are no signs of remarkable pollution: saprophitic index (1,55-1,93).
On the locality I4 saprophitic index is 2,58
DISTRIBUTION OF THE CRAY.FISH (ASTACUS ASTACUS L. 1758) IN THE CATCHMENT OF ILOVA AND ÄESMA
Istraživanje rasprostranjenosti potoÄnog raka Astacus astacus u slijevu izvoriÅ”nog dijela Äesme i Ilove u podruÄju gornjeg Poilovlja provedeno je od lipnj a do rujna godine 1990. Prisutnost ove vrste utvrÄena je u Ilovi (do utoka Å avarnice) , u Peratovici, Rastovcu, RajÄevici, Äesmi, GrÄevici, Barni i u Grbavcu. Prisutnost nije utvrÄena u Ilovi nizvodno od utoka Å avarnice, kao ni u samoj Å avarnici (sl.1 i tabl.1).Investigations of the distribution of the cray.fish Astacus astacus in the catchment of the source part of the Äesma and Ilova rivers in the region of Upper Poilovlje were carried out from June to September, 1990. The presence of these species was determined in Ilova (to the mouth of the Å avarnice), Peratovica, Rastovca, RajÄevac, Äesma, GrÄevica, Barna and Grbavac. Its presnece was not established in Ilova downstream from the mouth of Å avarnica, nor in the river Å avarnica (Figure 1 and Table 1)
Novi podaci o rasprostranjenosti Cobitis elongatoides BĆ£cescu & Maier, 1969 u srediÅ”njoj Hrvatskoj i prateÄoj ihtiofauni
Presented data brings data on ichthyofauna of four localities on Kupa, Orljava, Lonja and Glina Rivers of the Sava River basin (Danube drainage) in central Croatia. We have recorded one lamprey and 30 fish species, three of them not native for European fauna and eight threatened in Croatian fauna. We have found three species from the Cobitidae family, C. elongatoides, Misgurnus fossilis and Sabanajewia balcanica. Ecological characteristics of C. elongatoides distribution are discussed.U radu su prikazani rezultati istraživanja ihtiofaune na Äetiri lokaliteta na rijekama srediÅ”nje Hrvatske: Kupe, Orljave, Lonje i Gline (dunavski sliv). Ovim istraživanjima utvrÄena je jedna vrsta paklare te 30 vrsta riba, od kojih su tri alohtone u europskoj fauni, a osam je ugroženih u fauni riba Hrvatske. Iz porodice Cobitidae utvrÄene su tri vrste: C. elongatoides, Misgurnus fossilis i Sabanajewia balcanica. Raspravlja se o ekoloÅ”kim osobitostima vezanim za rasprostranjenje vrste Cobitis elongatoides