Popis in ocena velikosti populacije signalnega raka (Pacifastacus leniusculus, Astacidae, Decapoda) v reki Dravi med HE Vuhred in HE Ožbalt

magistrsko delo

Jernej Košir (Author), Franc Janžekovič (Mentor)

Abstract

V magistrskem delu smo proučili populacijo signalnega raka (Pacifastacus leniusculus) v reki Dravi na območju med hidroelektrarnama Vuhred in Ožbalt. Na tem območju smo preverili prisotnost signalnega raka ocenili relativno gostoto populacije. Uporabili smo 355 osebkov signalnega raka, ki smo jih lovili z vršami v štirih zaporednih nočeh. Za odlov smo pridobili dovoljenje Ministrstva za kmetijstvo, gozdarstvo in prehrano št. 3420-12/2018/5 in dopolnilno dovoljenje št. 3420-12/2018/7. Analizirali smo razlike med spoloma (spolni dimorfizem), poškodovanost in prisotnost (relativno gostoto) glede na substrat in hitrost vodnega toka. Morfometrične meritve smo izvedli s kljunastim merilom, statistične analize pa smo izvedli z ustreznimi statističnimi testi. Ugotovili smo, da je signalni rak prisoten na celotnem odseku reke Drave med hidroelektrarno Vuhred in hidroelektrarno Ožbalt, saj smo ga lovili na vseh mikrolokacijah. Povprečna relativna gostota, določena z ulovom na enoto ribolovnega napora, je 4,7 signalnih rakov/ribolovno noč in je močno povezana s hitrostjo vodnega toka in substratom. Relativna gostota signalnih rakov upada z manjšanjem hitrosti vodnega toka in z oddaljevanjem od hidroelektrarne Vuhred, z naraščanjem velikosti substrata se relativna gostota populacije zvišuje. Populacije dosegajo najvišje relativne gostote na substratu kamnometa, najnižje pa na substratu peska. Zaznali smo statistično značilen spolni dimorfizem v velikosti in širini glavoprsja in levih ter desnih škarij. V povprečju je poškodovanih 45,6 % vseh rakov. Največkrat poškodovani deli telesa so noge, sledijo škarje. Razlik pri vrstah poškodovanosti med spoloma nismo zaznali, prav tako ni razlik pri vrstah poškodovanosti glede na mikrolokacije, razlikuje se delež poškodovanih med mikrolokacijami. Vpliva številčnosti oziroma relativne gostote na poškodovanost rakov nismo potrdili.

Keywords

magistrska dela;pacifastacus leniusculus;invazivne tujerodne vrste;reka Drava;relativna gostota;

Data

Language:	Slovenian
Year of publishing:	2020
Typology:	2.09 - Master's Thesis
Organization:	UM FNM - Faculty of Natural Sciences and Mathematics
Publisher:	[J. Košir]
UDC:	595.384(043.2)
COBISS:	39264259
Views:	544
Downloads:	39
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Survey and population size estimation of signal crayfish (Pacifastacus leniusculus, Astacidae, Decapoda) in river Drava between Vuhred and Ožbalt hydroelectric power plants
Secondary abstract:	In the master's thesis, we studied the population of signal crayfish (Pacifastacus leniusculus) in the Drava River, between the hydroelectric power plants Vuhred and Ožbalt. In this area, we checked the occurrence of signal crayfish and estimated the relative population density. We used 355 specimens of signal crayfish, which we trapped with crayfish traps during four consecutive nights. We obtained a permit No. 3420-12/2018/5 from the Ministry of Agriculture, Forestry and Food and a supplementary permit No. 3420-12/2018/7. Gender differences (sexual dimorphism), injuries and presence (relative density) were analyzed. The presence was analyzed in terms of substrate and water flow velocity. Biometric measurements were carried out with a digital calliper, and statistical analyzes were performed with appropriate statistical tests. We found out that signal crayfish are present on the whole section of the Drava River between hydroelectric power plants Vuhred and Ožbalt, as they were trapped at all micro-sites. The average relative density, which is determined by catch per unit effort, is 4.7 signal crayfish/trapping night and depends strongly on the flow velocity of water and substrate. The relative density decreases with decreasing water flow velocity and with the distance from the hydroelectric power plant Vuhred, the relative density of population increases with increasing substrate size. The highest relative densities of populations are on the stone substrate and the lowest on the sand substrate. We found a statistically significant sexual dimorphism in the size and width of the cephalothorax and the left and right chelipeds. On an average 45.6 % of all crayfish are injured. The most frequently injured body parts are the legs, followed by the chelipeds. There were no differences in the types of injuries between the sexes, nor were there differences in the types of injuries by micro locations, but the proportion of injuries between micro locations differs. The influence of frequency or relative density on crayfish injury is not confirmed.
Secondary keywords:	master theses;pacifastacus leniusculus;invasive alien species;Drava river;relative density;
Type (COBISS):	Master's thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za naravoslovje in matematiko, Oddelek za biologijo
Pages:	X, 88 str.
ID:	11976096