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1

Different impact of flood dynamics on the development of culturable planktonic and biofilm bacteria in floodplain lake

100%
Palijan G.
Polish Journal of Ecology
|
2010
|
tom 58
|
nr 3
Floodplains are lateral river extensions in which lotic, semi-lotic and lentic habitats are formed resulting in high habitat heterogeniety. Consequently biota development is highely influenced by its location within the floodplain and by the hydrological cycle. In the present paper the development of planktonic and biofilm bacteria associated with artificial substrates were investigated in the floodplain lake of the Danube River (Lake Sakadaš, Croatia) during different hydrological situations. The aim of the study was to investigate if there was any difference in the bacterial development between two compartments – plankton and biofilm, and how the floods influence these communities. The samples were taken monthly (July–November 2007) from surface and bottom water layer (plankton) and exposed glass slides (biofilm) at two sampling stations. For these purposes bacterial abundance was estimated by the determination of number of colony forming units (CFUs). The development of bacterioplankton was equal between the sites and had its maximum at the time of falling water after the flood pulse. Bacterioplankton abundance correlated significantly with water properties, and it had predictable dynamics comparable with the previous results established in the same floodplain area (Kopački Rit). The development of biofilm bacteria differed between the sites, and had its maximum prior to the flood pulse, or during the flood. The abundance of attached bacteria correlated with biofilm biomass while it was not significantly correlated with the water properties. Such results describe different development of planktonic and biofilm bacteria. Biofilm bacteria are more independent, compared to bacterioplankton, from the floodplain hydrology.
2

Change in metazooplankton abundance in response to flood dynamics and trophic relations in Danubian floodplain lake (Kopacki Rit, Croatia)

63%
Galir A., Palijan G.
Polish Journal of Ecology
|
2012
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tom 60
|
nr 4
This study investigated relationships of hydrological variability and potential food resources for metazooplankton groups: rotifers, cladocerans, copepods and nauplii. Samples were collected monthly during ice-free season from March until November in 2006. Two sampling stations were chosen, the one located in Lake Sakadaš, as a segment of Kopački Rit floodplain (Croatia), and the other in the River Danube. Due to hydrological conditions we divided our samples into two hydrological groups which corresponded to: 1/ increased water level i.e. disturbed phase and 2/ decreased water level representing a more stable phase. Abundance of metazooplankton was not significantly different between hydrological groups in the River Danube. However, it was significantly different between hydrological groups in Lake Sakadaš (one-way ANOSIM R = 0.688, P = 0.024), where during a decreased water level higher abundance of metazooplankton was recorded. Rotifers were the most abundant metazooplankton group during the whole investigated period at both stations and between both hydrological groups comprising almost 99% of total metazooplankton abundance. Rotifers were significantly positively correlated with the total number of bacteria, as well as with ammonium and total phosphorous concentrations. The metazooplankton community in Lake Sakadaš was negatively influenced by flooding, but not in the River Danube. Compared to the River Danube the investigated floodplain lake showed potential as a storage zone for metazooplankton development during more stable hydrological periods. During that time abundance of rotifers was related to the heterotrophic component of microbial food web. Hence, this investigation adds to the understanding of the metazooplankton dynamics in riverfloodplain systems as well as of their relations with trophic levels under variable hydrological conditions.
3

Relationship between nematode community and biomass and composition of periphyton developing on artificial substrates in floodplain lake

51%
Vidakovic J., Palijan G., Cerba D.
Polish Journal of Ecology
|
2011
|
tom 59
|
nr 3
Periphyton colonisation on artificial substrate (microscopic glass slides) was investigated from July to November 2007, in Lake Sakadaš (Danube River floodplain Kopački rit, Croatia). Two different stations were chosen due to different post – flood conditions. The aim of the study was to follow temporal changes of nematode community composition and trophic structure in relation to periphyton biomass and bacterial abundance. In bryozoan – dominated periphyton (Plumatella emarginata Allman, 1844) nematodes were represented by 86 and 87% of total associated invertebrate fauna at S1 and S2 respectively. Total nematode abundance (up to 600 ind. 10 cm-2 at one station and up to 1130 ind. 10 cm-2 at another station) correlated significantly with the abundance (meaured as CFUs – colony forming units) of copiotrophic and oligotrophic bacteria at one station (r = 0.963, 0.998, P <0.05) and with organic and inorganic content of periphyton at another station (r = 0.891, 0.899, P <0.05). Nematode trophic groups (epistrate feeders, chewers, detritus feeders and suction feeders) were equally developed at both stations except detritus feeders whose species richness and abundance were significantly higher at the S1. Epistrate feeders were the most abundant trophic group in nematode assemblages at both stations with Chromadorina bioculata being the dominant species. Change in dominance of epistrate feeders by chewers (Brevitobrilus stefanskii) and suction feeders (Crocodorylaimus sp.) coincided with the occurrence of flood pulse. Effect of flood pulse on nematode community structure was probably indirect, alterating concentration of dissolved oxygen which chromadorids are sensitive to. The structure of nematode community developed through time differs between investigated stations indicating high sensitivity to bacterial abundance, periphyton biomass and P. emarginata mats which made the habitat more diverse and patchy.
4

The impact of inundation-isolation cycles on the culturable bacterioplankton in the Danube River floodplain

51%
Palijan G., Bogut I., Vidakovic J.
Polish Journal of Ecology
|
2008
|
tom 56
|
nr 3
391-403
The investigation was conducted in the Kopački Rit Nature Park (eastern Croatia) which is established to protect the floodplain area of the Danube River. The samples were collected monthly in four sites (channels and lakes) with increasing distance from the river. The aim of investigation was to examine trophic structure of culturable bacterioplankton in relation to inundation-isolation cycles on sampling sites with unequal degree of connection with the Danube river. A change in the ratio of copiotrophs (r-strategists) to oligotrophs (K-strategists) was expected as the different organic carbon sources emerged. The composition of variables was revealed by Principal Component Analysis of abiotic water properties (temperature, water depth, transparency, pH, electrical conductivity, dissolved oxygen, nutrient concentrations) and the chlorophyll-a concentration. Scores of significant components were used in a Multiple Regression as independent variables and the relationship between the scores and abundance of colony forming units (CFUs) was examined. Regression model was significant only for copiotrophs, and their relative dominance was noticed in couple of samples on more isolated sampling sites. In all other samples oligotrophs were a dominant group, especially during the flood pulses or drainage after it. Their elevated abundance was equally distributed in all groups revealed by Principal Component Analysis, and corresponds to the fluvial action. Also concerning the η (eta) squared and R squared values from the two-way ANOVA (sites/samplings) oligotrophs are highly influenced by the sampling period i.e. inundation-isolation cycles. They are probably driven by the allochthonous organic matter provided by floods or have allochthonous origin itself. At the same time, copiotrophs are to some extent coupled with the established water properties, i. e. bottom-up controlled and their abundance is influenced by the localisation of sampling sites in the floodplain. These results describe the development of the conditions that promote habitat specific succession of the culturable bacterioplankton. Established differences had disappeared after additional inundation-isolation cycles.
5

Effects of high water levels on bacterioplankton abundance in the Danube River floodplain [Kopacki Rit, Croatia]

51%
Palijan G., Bogut I., Vidakovic J.
Polish Journal of Environmental Studies
|
2007
|
tom 16
|
nr 1
Effects of high water levels on the abundance of colony-forming units of eutrophic and oligotrophic bacteria were investigated. Changes in their proportion were exploited as the biological indicator of organic substrate availability. It was also reconsidered, to a certain extent, which source (autochtonous or allochtonous) of organic substrate and bacteria prevails during floods. Water samples were collected from the surface and from the bottom during high water levels in the floodplain lake (Kopačko Lake) and the connecting channel (Hulovo Channel). The relative abundance of oligotrophs vs. eutrophs was considerably higher at the end of investigation, to which higher abundance of eutrophs preceded at Kopaèko Lake sampling station. Also in Kopačko Lake, a considerably higher abundance of bacteria was noticed in the bottom samples during first intensive flooding pulses. Elevated bacterial abundance was connected with the sufficiently intensive floods (eutrophs dominate) but also with the water properties established following the settling down of disturbed conditions (oligotrophs dominate). Greater abundance in the bottom samples established during the first intensive pulse suggests a sediment origin of bacteria, while considerable differentiation between oligotrophic and eutrophic bacteria suggests an establishment of lower quality of organic substrate at the end of the investigation.
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