Browsing by Subject "parasite"

The aim of this study was to investigate the intestinal parasite prevalence in the animals living in the Cat valley of Helsinki Zoo. The initiative for the study came from the Zoo, as the knowledge on intestinal parasite prevalence of zoo animals is fairly limited. A study on soil contamination with parasite eggs and oocyst of selected enclosures was added, as suspicions arose that the flooring might be a possible source of reinfection. Some possible parasite control methods are discussed, and how they could be used in a zoo environment. The hypothesis of this prevalence study was that the faecal samples might contain Toxocara cati and Toxascaris leonina eggs. The hypothesis was based on the previous findings in Helsinki zoo as well as findings in other zoos and wild animals abroad. Clinical signs had not been detected from the animals that were studied in Helsinki zoo, and intestinal parasites of big cats have not been a major problem for this particular zoo. For the study, faecal samples from the animals in Cat valley were collected and studied monthly from late May until October 2016, for a period of approximately half a year. Faecal samples from eight different animal species from 13 different enclosures were studied. The species studied included amur tiger (Panthera tigris altaica), red panda (Ailurus fulgens), snow leopard (Panthera uncia), amur leopard (Panthera pardus orientalis), pallas cat (Otocolobus manul), Asian lions (Panthera leo persica), European lynx (Lynx lynx) and European Wild Cats (Felis silvestris silvestris). A total of 78 faecal samples was collected, of which 18 were found to be positive for parasite eggs. The faecal samples were studied with a modified MacMaster method. Additionally, soil samples from five different enclosures were studied by using modified centrifugation-flotation method. Most common finding were those of Toxascaris leonina (6 samples), followed by Toxocara cati (4 samples). Other findings included for example oocysts of coccidia and Strongyle type eggs, which were quite possibly from the herbivores that were used as food for the cats. The soil samples were found to contain Toxascaris leonina eggs with a larva inside, oocysts of coccidia, as well as one developing Toxocara cati egg. Based on the findings on both the faecal samples as well as soil samples, Helsinki zoo did not have major problem with intestinal parasites at the time of the study, but the soil flooring of the enclosures might act as a source of reinfection and maintain the parasites transmission cycle. (The thesis was written in English, as the student completed her matriculation examination in English (International Baccalaureate Diploma programme). The subject of the study might also be of interest in zoos abroad.)

Lepidurus arcticus (Pallas, 1793) is a keystone species in High Arctic ponds, which are exposed to a wide range of environmental stressors. This thesis provides information on the ecology of this little studied species by paying particular focus on the sensitivity of L. arcticus to acidification and climate change. Respiration, reproduction, olfaction, morphology, salinity and pH tolerance of the species were studied in the laboratory and several environmental parameters were measured in its natural habitats in Arctic ponds. Current global circulation models predict 2–2.4 °C increase in summer temperatures on Spitsbergen, Svalbard, Norway. The L. arcticus respiration activity was tested at different temperatures (3.5, 10, 16.5, 20, 25 and 30 °C). The results show that L. arcticus is clearly adapted to live in cold water and have a temperature optimum at +10 °C. This species should be considered as stenothermal, because it seems to be able to live only within a narrow temperature range. L. arcticus populations seem to have the capacity to respond to the ongoing climate change on Spitsbergen. Changes can be seen in the species' reproductive capacity and in the individuals' body size when comparing results with previous studies on Spitsbergen and in other Arctic areas. Effective reproduction capacity was a unique feature of the L. arcticus populations on Spitsbergen. L. arcticus females reached sexual maturity at a smaller body size and sexual dimorphism appeared in smaller animals on Spitsbergen than anywhere else in the subarctic or Arctic regions. L. arcticus females were able to carry more eggs (up to 12 eggs per female) than has been observed in previous studies. Another interesting feature of L. arcticus on Spitsbergen was their potential to grow large, up to 39.4 mm in total length. Also cannibalistic behaviour seemed to be common on Spitsbergen L. arcticus populations. The existence of different colour morphs and the population-level differences in morphology of L. arcticus were unknown, but fascinating characteristic of this species. Spitsbergen populations consisted of two major (i.e. monochrome and marbled) and several combined colour morphs. Third interesting finding was a new disease for science which activated when the water temperature rose. I named this disease to Red Carapace Disease (RCD). This High Arctic crustacean lives in ponds between the Arctic Ocean and glaciers, where the marine environment has a strong impact on the terrestrial and freshwater ecosystems. The tolerance of L. arcticius to increased water salinity was determined by a LC50 -test. No mortality occurred during the 23 day exposure at low 1–2 ‰ water salinity. A slight increase in water salinity (to 1 ‰) speeded up the L. arcticus shell replacement. The observations from natural populations supported the hypothesis that the size of the animals increases considerably in low 1.5 ‰ salt concentrations. Thus, a small increase in water salinity seems to have a positive impact on the growth of this short-lived species. Acidification has been a big problem for many crustaceans, invertebrates and fishes for several decades. L. arcricus does not make an exception. Strong acid stress in pH 4 caused a high mortality of mature L. arcticus females. The critical lower limit of pH was 6.1 for the survival of this acid sensitive species. Thus, L. arcticus populations are probably in danger of extinction due to acidification of three ponds on Spitsbergen. A slight drop (0.1–1.0) in pH values can wipe out these L. arcticus populations. The survival of L. arcticus was strongly related to: (1) the water pH, (2) total organic carbon (TOC) and pH interaction, (3) the water temperature and (4) the water salinity. Water pH and TOC values should be monitored in these ponds and the input of acidifying substances in ponds should be prevented.