Thesis (Ph.D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 201-227) Also available in print.

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 201-227).

This thesis has two parts. In the first part there is described an optimal methodological process for screening tests used in subsequently. Fertilized fish eggs of Oryzias latipes were incubated in 6 tests with different numbers (from 1 to 6) with standard conditions in ISO water. In the tests, hatching performance and duration of embryonic development were investigated and the results were applied on screening tests. The other part of the thesis is aimed on the proof of potential toxic effects of water with cyanobacterial water bloom. The fertilized eggs of Oryzias latipes were embedded into the test in stage 6 to 8. Three samples of cyanobacterial biomass from free waterbodies with known species composition and microcystin {--} LR, YR and RR contents were tested. The hatching performance, duration of embryonic development, lethal and sublethal effects were monitored during the tests. The tests were performed according to the OECD 212. There were detected significant differences in hatching performance, duration of embryonic development and in some cases also in induction of deformities between the control group and the tested groups.

In this diploma thesis, I deal with the influence of the sampling site on water quality in natural bathing lakes (Hostivar reservoir, Seberak pond and Vyzlovka pond) in this. I have established that hygienically significant kinds of phytoplankton may differ in terms of water quality especially where there are cyanobacteria constituting water bloom. Surface water bloom may be moved by wind to the lee side of the water body (Microcystis sp.). Aphanizomenon flos-aquae water bloom floating in water column can be affected by wind and by water flow (which may be partly affected by wind as well). With the prevailing fibrous Planktothrix agardhii which does not connstitute water bloom the concentration of chlorophyll-a and cyanobacterial cell abundance in individual sampling sites are similar although the concentration of chlorophyll-a a is about 200 g.l-1 . Microcystis sp. and Scenedesmus sp. survive under eutrophic conditions in competition. From the microbiological perspective, water quality can differ within a single sampling site in places at a distance of less than 100 m. Microbial contamination can be caused by bathers, water birds, farm animals and probably by the removing of microorganisms from sand, mud and sediments on the beach or shore. Rain episodes probably increase the abundance of E.coli...

The aim of this study was to design and optimize new PCR primers for detection of potential cyanobacterial producers of cytotoxic lipopeptides puwainaphycins and minutissamides in environmental samples. Samples from two distinct localities were tested, as suggested based on preliminary data. The first set of samples consisted of cyanobacterial soil biofilms from sheep pastures affected by Alveld illness in Norway. The other one contained samples of planktic cyanobacaterial blooms from Protected Landscape Area Třeboň and its vicinity. Three different approaches were used for evaluation of the presence of cyanobacterial lipopeptide producers: microscopy, PCR with the designed primeres, and liquid chromatography-mass spectrometry analysis. Results of this study confirmed the specificity of the newly designed PCR primers. The presence of producers of puwainaphycins/minutissamides was proven at both tested localities.

Dumbliai – mikroskopiniai planktono organizmai – vienas iš pagrindinių hidroekosistemų komponentų, pirminiai organinės medžiagos producentai. Didėjant vandens telkinių trofiškumui, mažėja dumblių rūšių įvairovė, keičiasi vyraujančių rūšių kompleksas. Dažnai eutrofikuotuose vandens telkiniuose ima dominuoti prokariotiniai autotrofiniai mikroorganizmai – melsvabakterės, kurios sukelia intensyvius vandens „žydėjimo“ procesus ežeruose, jūrinėse lagūnose, jūrose bei vandenynuose. Dėl šios priežasties blogėja vandens kokybė. Pastaraisiais dešimtmečiais išsamių tyrimų objektu visame pasaulyje tampa toksiniai fitoplanktono dumbliai ir melsvabakterės. Tyrimais yra nustatyta, kad pusė iš visų vandens „žydėjimo“ atvejų yra toksiški (RAPALA, LAHTI, 2002). Pasaulyje atliekami monitoringiniai tyrimai, siekiant įvertinti toksinių dumblių ir melsvabakterių vystymosi tendencijas, priklausomybę nuo aplinkos sąlygų, toksinio vandens „žydėjimo“ priežastis. Pasitelkiant cheminius bei genetinius metodus, nustatoma toksinių medžiagų cheminė sudėtis, vertinamas jų poveikis gyviems organizmams. Šiaurinės Kuršių marių dalies vasariniame planktone 2004-2006 m. aptiktos 223 dumblių rūšys, priklausančios 5 klasėms. 97 rūšys (43 %), priklauso Chlorophyceae klasei, 71 rūšis (32 %) – Cyanophyceae, 40 rūšių (18 %) – Bacillariophyceae, 9 rūšys (4 %) – Euglenophyceae ir 6 rūšys (3 %) – Dinophyceae klasei, iš jų aptiktos 26 potencialiai toksinės dumblių ir melsvabakterių rūšys, priklausančios 3 klasėms, 14... [toliau žr. visą tekstą] / Curonian Lagoon is a shallow transitional water basin located in the south-eastern part of the Baltic Sea. The southern and central parts of the lagoon contain freshwater due to discharge from the Nemunas River, while the salinity in the northern part varies from 0 to 8 PSU, depending on winds activity affecting brackish water inflow from the Baltic Sea. The investigation was carried out in the fresh-brackish water mixing zone (Influence zone of Baltic Sea), in the central part and Nemunas River influence zone in July-August 2004 - 2006. Changes in physico-chemical parameters, chlorophyll a concentration, phytoplankton and toxic algae cell density were monitored. Totally 223 species and varieties mainly belonging to Chlorophyceae (43 %) and Cyanophyceae (32 %) were found. 26 algae species from 3 algae classes (Cyanophyceae, Chlorophyceae and Dinophyceae) were identified as potential toxic species in the northern part of Curonian Lagoon during 2004 and 2006 summer time. Dominated toxic species Ahpanizomenon flos-aquae, Microcystis aeruginosa, M. viridis, M. wesenbergii, Woronichinia compacta. Phytoplankton biomass in Curonian Lagoon surface ranged from 12,27 to 50,22 mg/l. The peak of phytoplankton (33,11 mg/l) and potential toxic algae (28,67 mg/l) biomass in 2004 summer time was observed near by Klaipeda Strait, were Aphanizomenon flos-aquae contain 36 % from total biomass. In 2005 summer time the highest phytoplankton (50,22 mg/l) and toxic algae (21.46 mg//l) biomass were... [to full text]

Good quality of bathing water is an increasingly important factor taken into account when we choose summer vacations, a place to stay for a weekend or a weekend trip destination. In the Czech Republic, bathing waters may be divided according to the legal status into outdoor swimming pools, surface waters used for bathing (swimming areas), other water surfaces or artificial pools. In my thesis I dealt only with outdoor swimming pools and swimming areas. The difference between them lies in the fact that outdoor swimming pools have their own operators who monitor water quality and provide other services in the waterside. Usually there is a fee charged. Swimming areas have no operators and water quality monitoring is placed under the responsibility of regional public health authorities. In the Czech Republic, at present, 188 outdoor swimming pools and swimming areas have been monitored on a regular basis each bathing season. For my research I chose four sites located in the South Bohemian region and four sites in the South Moravian region. For each of these eight sites, I collected results of laboratory analyses, including categories of water quality in bathing seasons of the past five years, it means from the year 2005. With these obtained data I assessed the water quality development both during the bathing season of 2009 and its evolution over the past five years. On the basis of particular categories of water quality I also tried to compare water quality in the South Bohemian and the South Moravian region and also to compare water quality between individual sampling points in one locality. Another aim was to evaluate some measures and interventions made in order to improve water quality. I focused particularly on the pond Olšovec in the South Moravian region and the VN (water reservoir) Orlík in the South Bohemian region. The results do not show any prominent changes in water quality both during the bathing season 2009 and over the past five years. Pronounced fluctuations in water quality were recorded only at certain locations during the 2007 bathing season. Not even between individual regions significant differences in water quality were found. The proportion of individual water quality categories in the two regions did not differ by more than 4%. We can therefore say that water quality in selected localities in the South Bohemian and South Moravian regions is comparable. As for certain measures and interventions implemented to improve water quality, it is important to focus also on the wider neighborhood of the locality, because it could also be a source of substances worsening water quality.