Literatuurstudie naar de biologie, impact en mogelijke bestrijding van twee invasieve soorten: de rode Amerikaanse rivierkreeft (Procambarus clarkii) en de geknobbelde Amerikaanse rivierkreeft (Orconectes virilis)

Dit literatuuronderzoek is een onderdeel van een breed opgezet onderzoek in het veenweidegebied naar de invloed van rivierkreeften op het ecosysteem. Specifiek wordt ingegaan op de verschillende eigenschappen van twee soorten die voor mogelijke problemen zorgen in het beheergebied van de waterschappen in het westelijk veenweidegebied, te weten de rode- (Procambarus clarkii) en de geknobbelde Amerikaanse rivierkreeft (Orconectes virilis). Het is van belang om de gevonden resultaten steeds weer in hun oorspronkelijke context te bezien. Zo is het overgrote deel van de hier gepresenteerde studies naar P. clarkii uitgevoerd in Zuid-Europa (Portugal, Spanje, Italië) en de daar geobserveerde mechanismen en kenmerken kunnen zeker van toepassing zijn op populaties in Nederland. Echter, ze kunnen ook zeker afwijken omdat hier nu eenmaal andere klimatologische of hydrologische omstandigheden heersen. De resultaten uit Zuidelijke streken geven derhalve mogelijkheden weer die van toepassing kunnen zijn op noordelijke populaties, geen absolute zekerheden

Askaridoza - stalno prisutan problem intenzivne svinjarske proizvodnje

Ascaridosis presence mast frequent, and most important, with global distribution with prevalence, dependent of bruding condition, were 5-95%. Chronical development of diseases induce permanent lasses at swine production through by low growth, weakly product results and by condemned of organs when presence larvar migration. At our parers we give outline on most important moment connected with swine askaridosis spread of parasites in our countries, pathogenesis and pathology changes and measure to prevention and eradication of diseases.Askaridoza predstavlja najčešću i najrasprostranjeniju parazitsku infekciju svinja, globalne distribucije, čija se prevalenca zavisno od uslova držanja kreće 5- 95%. Protičući u hroničnom obliku uzrokuje gubitke u svinjarskoj proizvodnji koji se manifestuju u vidu umanjenog prirasta, slabije konverzije hrane i odbacivanja organa kroz koje se odvija migratorna faza parazita. U našem radu dajemo kratak osvrt na najvažnije momente vezane za askaridozu svinja - raširenost ove parazitoze kod nas, patogenezu i patološke promene kao i mere preventive i suzbijanja oboljenja

Šuga - stalno prisutan problem intenzivne svinjarske proizvodnje

Scabies caused by Sarcoptes scabei var. suis presence most frequent, and most important health problem in farm breeding swine with global distribution with prevalence, dependent of bruding condition, were 5-95%. Chronical development of diseases induce permanent lasses at swine production through by low growth, weakly product results and by condemned of organs when presence larvar migration. At our papers we give outline on most important moment connected with swine scabies spread of parasites in our countries pathogenesis and pathology changes and measure to prevention and eradication of diseases.Šuga uzrokovana sa Sarcoptes scabei var. suis predstavlja jednu od najčešćih i najrasprostranjenijih parazitsku infekciju svinja, globalne distribucije čija se prevalenca zavisno od uslova držanja kreće 5-95%. Protičući u akutnom a potom hroničnom obliku uzrokuje rapidne gubitke svinjarskoj proizvodnji kroz umanjen prirast i slabije proizvodne rezultate. U našem radu dajemo kratak osvrt na najvažnije momente vezane za šugu svinja raširenost ove parazitoze kod nas, patogenezu i patološke promene kao i mere preventive i suzbijanja obolenja

The prevalence of Aphanomyces astaci in invasive signal crayfish from the UK and implications for native crayfish conservation

The crayfish plague agent, Aphanomyces astaci, has spread throughout Europe, causing a significant decline in native European crayfish. The introduction and dissemination of this pathogen is attributed to the spread of invasive North American crayfish, which can act as carriers for A. astaci. As native European crayfish often succumb to infection with A. astaci, determining the prevalence of this pathogen in non-native crayfish is vital to prioritize native crayfish populations for managed translocation. In the current study, 23 populations of invasive signal crayfish (Pacifastacus leniusculus) from the UK were tested for A. astaci presence using quantitative PCR. Altogether, 13 out of 23 (56·5%) populations were found to be infected, and pathogen prevalence within infected sites varied from 3 to 80%. Microsatellite pathogen genotyping revealed that at least one UK signal crayfish population was infected with the A. astaci genotype group B, known to include virulent strains. Based on recent crayfish distribution records and the average rate of signal crayfish population dispersal, we identified one native white-clawed crayfish (Austropotamobius pallipes) population predicted to come into contact with infected signal crayfish within 5 years. This population should be considered as a priority for translocation

Early life differences in behavioral predispositions in two Alligatoridae species

Behavioral predispositions are innate tendencies of animals to behave in a given way without the input of learning. They increase survival chances and, due to environmental and ecological challenges, may vary substantially even between closely related taxa. These diferences are likely to be especially pronounced in long-lived species like crocodilians. This order is particularly relevant for comparative cognition due to its phylogenetic proximity to birds. Here we compared early life behavioral predispositions in two Alligatoridae species. We exposed American alligator and spectacled caiman hatchlings to three different novel situations: a novel object, a novel environment that was open and a novel environment with a shelter. This was then repeated a week later. During exposure to the novel environments, alligators moved around more and explored a larger range of the arena than the caimans. When exposed to the novel object, the alligators reduced the mean distance to the novel object in the second phase, while the caimans further increased it, indicating diametrically opposite ontogenetic development in behavioral predispositions. Although all crocodilian hatchlings face comparable challenges, e.g., high predation pressure, the effectiveness of parental protection might explain the observed pattern. American alligators are apex predators capable of protecting their offspring against most dangers, whereas adult spectacled caimans are frequently predated themselves. Their distancing behavior might be related to increased predator avoidance and also explain the success of invasive spectacled caimans in the natural habitats of other crocodilians

Spatial dynamics of the noble crayfish (Astacus astacus, L.) in the Paklenica National Park

The aim of this work was to analyse the spatial dynamics of a noble crayfish population inhabiting the Velika Paklenica Stream (Paklenica National Park, Croatia). The study was conducted in July 2000, and between March and September 2002. Crayfish were trapped by baited LiNi traps and hand-made traps at two localities over 25 nights. We recorded the precise position of the captured crayfish, their sex, and total length. Crayfish were individually marked and then released back into the stream at the same spot where they were caught. Spatial analyses included determination of movement direction, distribution type, home range, total distance travelled, and mean daily movement. A mean home range of approximately 19 m was calculated. No difference in home range between the sexes was found. There was a large individual variation in the extent of movement without any effect of sex or size

ESTIMATION OF NOBLE CRAYFISH (ASTACUS ASTACUS L.) POPULATION SIZE IN THE VELIKA PAKLENICA STREAM (CROATIA)

Astacus astacus is one of four native European crayfish species living in Croatian freshwaters. It is naturally distributed in rivers belonging to the Black Sea Basin. To some rivers of the Adriatic Sea Basin, however, it had been introduced by man. According to the information from local people it is most likely that A. astacus has been introduced into the Velika Paklenica Stream during the first half of the 20th century. Our study stream, draining the Velebit Mountain, is situated in Paklenica National Park, Middle Adriatic. The fieldwork of our study was performed during July 2000 and 2002, respectively. To estimate the population size we used mark-recapture techniques (Jolly-Seber Method, Schnabel Method and Schumacher and Eschmeyer Method). Crayfish were trapped with baited LiNi traps that were set along the stream banks at 10 m intervals and left there overnight. Caught animals were individually marked by piercing holes into the uropods and telson and then released. In July 2000 we caught 233 crayfish in total, from which 70 specimens were trapped more than once. In July 2002 we caught 296 crayfish, from which 86 were trapped more than once. Differences in the population size between the two years are discussed