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1

Testate amoebae in karst caves of the dinaric arc (South-Eastern Europe) with a description of Centropyxis bipilata sp. nov.

100%
Bakovic N., Siemensma F. J., Bakovic R., Rubinic J.
Acta Protozoologica
|
2019
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tom 58
|
nr 4
2

Effects of water quantity on connectivity: the case of the upper Parana River floodplain

72%
Agostinho A. A., Bonecker C. C., Gomes L. C.
International Journal of Ecohydrology and Hydrobiology
|
2009
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tom 09
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nr 1
The hydrological regime is the main force driving processes in river-floodplain systems. The flood pulse concept serves as a base from which to study the processes acting in such a system. However, when the flood pulse is regulated and there is a need to re-establish the hydrography at close to natural conditions, the best way to achieve this is via ecohydrology, a newly emerging paradigm. In this paper, we use principles of ecohydrology to evaluate the effect of water quantity on the limnology, biota and fishery of the upper Paraná River systems, where a UNESCO demonstration site on ecohydrology is located. In addition, we argue that dam operation can be crucial for restoring the hydrography of the Paraná River to near natural conditions. The data used were collected between 1986 and 2006 in several habitats of the floodplain. The limnology, biota (periphyton, phytoplankton, zooplankton, benthic invertebrates, fish, macrophytes and riparian vegetation) and fishery (ecosystems services) were all influenced by the alteration in the hydrography prompted by the functioning of the dams located upstream from the demonstration site area. Moreover, the observed deterioration of the water quality due to the presence of toxic cyanobacteria is another strong argument for adjusting the dam’s operation to reestablish the timing of the floods to match critical periods of the biota in order to restore ecosystem biodiversity and services.
3

Channel-floodplain geomorphology and connectivity of the Lower Paraguay hydrosystem

72%
Drago E. C., Paira A. R., Wantzen K. M.
International Journal of Ecohydrology and Hydrobiology
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2008
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tom 08
|
nr 1
The Paraguay River is the main tributary of the Paraná River hydrosystem. Despite several studies resulting from the proposed navigation project known as the Hidrovía Paraguay-Paraná, little is known about the physical structure of their aquatic environments and its biota. The main purpose of this work is the knowledge of the primary factors which form the structure of the physical habitats in this fluvial segment. In this way, the hydrological and hydraulic regime, channel shape, substrate, hydrological connectivity and the floodplain ontogeny and its evolution were analyzed. Synthesizing we stressed herein that the dynamics of the river-floodplain morphology dependent on the large-scale longitudinal and lateral hydrological connections, and the type and degree of these connections between lotic and lentic environments drive the changes of this seasonally inundated floodplain and its water bodies. In a second paper in this volume, is presented a classification of the Lower Paraguay physical habitats and their relationships with the main physical factors.
4

The Lower Paraguay river-floodplain habitats in the context of the Fluvial Hydrosystem Approach

58%
Drago E. C., Wantzen K. M., Paira A. R.
International Journal of Ecohydrology and Hydrobiology
|
2008
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tom 08
|
nr 1
We report herein the first description of the physical structure of the aquatic habitats of the Lower Paraguay River along 390 km from Asunción city (Paraguay) to the confluence with the Paraná River. The hierarchical ordination of the Fluvial Hydrosystem Approach (FHA) allowed us to classify the Lower Paraguay as a meandering functional sector where five functional sets were identified: (a) main channel, (b) floodplain channel, (c) floodplain lentic environment, (d) tributary, and (f) aquatic-terrestrial transition zone. These functional sets encompassed twenty one functional units and sixty one major mesohabitats. We attribute the riverine habitat diversity to the changes in the channel-floodplain morphology and in the strength, duration and frequency of their hydrological connectivity. The variable riverfloodplain- tributary complex developed several types of fluvial-lacustrine boundaries and riverine ecotones.
5

Adapting floodplain connectivity conditions - a prerequisite for sustaining aquatic macrophyte diversity in the UNESCO Biosphere Reserve Lobau (Austria)

58%
Barta V., Schmidt-Mumm U., Janauer G. A.
International Journal of Ecohydrology and Hydrobiology
|
2009
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tom 09
|
nr 1
The UNESCO Biosphere Reserve Lobau (Austria), established in 1977 within the city limits of Vienna, is part of the Danube National Park and one of the ecologically richest parts of the Danube River Corridor. Hardly noticed by diverging stakeholder interests the smaller aquatic habitats in the floodplain area are acutely threatened by wetland ageing and terrestrialisation processes. In 2007 an aquatic plant survey was carried out in the water bodies of the active floodplain on the left bank of the Danube main river channel as well as in the semi-separated water bodies of the Lobau. Results clearly show the impact of through-flow on aquatic plant species composition and abundance, as these metrics are significantly higher in the semiseparated location. Suitable water regime for all sensitive aquatic plants is an essential prerequisite for sustaining aquatic macrophyte diversity in the Lobau Biosphere Reserve, and could provide an ecohydrological basis for rehabilitation activities in other regulated river floodplains located in cultivated landscapes.
6

Flooding ecology of voles, mice and shrews: the importance of geomorphological and vegetational heterogeneity in river floodplains

58%
Wijnhoven S., Van der Velde G., Leuven R. S. E. W., Smits A. J. M.
Acta Theriologica
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2005
|
tom 50
|
nr 4
453-472
Since voles, mice and shrews are important animals in food chains of river floodplains, there is a need for data on their spatial and temporal distribution in periodically flooded areas. During a live trapping study between two successive floods in an embanked river floodplain, the ’Afferdensche en Deestsche Waarden (ADW)’, six species were frequently observed, viz,Microtus arvalis (Pallas, 1778),Clethrionomys glareolus (Schreber, 1780),Sorex araneus (Linnaeus, 1758),Crocidura russula (Hermann, 1780),Micromys minutus (Pallas, 1771) andApodemus sylvaticus (Linnaeus, 1758). Ungrazed rough herbaceous vegetation appeared to be rich in numbers and species, whereas no spoors of small mammals were observed in large parts of the ADW floodplain (eg bare substrates and maize fields). Vegetation structure seemed to be very important in guiding the recolonisation process after flood events. Throughout the year the highest numbers of small mammals were captured on and near the non-flooded elevated parts functioning as refugia during inundation. Poor habitat connectivity, sparseness of non-flooded recolonisation sources and small numbers of survivors led to slow recolonisation. The time between two successive floods (eight months) was not long enough for entire recolonisation of ADW. Small mammal densities at more than 30 m from the non-flooded areas were always lower than in non-flooded areas.
7

Modeling the effects of the Vistula River’s spatial development on semi-aquatic animals

58%
Romanowski J.
Oceanological and Hydrobiological Studies
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2008
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tom 37
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nr Suppl.1
8

Ecotones of riverine ecosystems: Role and typology, spatio-temporal dynamics, and river regulation

58%
Ward J. V., Wiens J. A.
International Journal of Ecohydrology and Hydrobiology
|
2001
|
tom 01
|
nr 1-2
Natural riverine ecosystems are characterized by a high level of heterogeneity manifest across a range of spatio-temporal scales. Ecotonal habitats are both the result of and contributors to the spatio-temporal dynamics of riverine ecosystems. Natural disturbances play an important rôle in maintaining a diversity of ecotonal habitats. A typology of riverine ecotones is developed that provides an expansive perspective scaled along four dimensions (longitudinal, lateral, vertical, and temporal) and that encompasses environmental gradients and boundaries as well as distinct transition zones between adjacent patches. From this broad perspective it is apparent that riverine ecotones play important rôles relating to speciation, evolutionary invasion of fresh waters, biodiversity, bioproduction, and ecological connectivity. River regulation disrupts the natural disturbance regime downstream, thereby reducing the diversity of ecotonal habitats and their connectivity with the main river channel. The altered rôle of ecotonal habitats induced by regulation is especially pronounced in alluvial floodplaing rivers, which are characterized by a mosaic of habitat patches that collectively occupy a wide range of successional stages. Downstream hydrologic changes, such as truncated sediment transport and reductions in the frequency and intensity of flooding, typically lead to altered successional trajectories, desiccated floodplain waterbodies, severed migration pathways, and reduced exchange rates of nutrients and organic detritus across ecotone boundaries. Effective management of regulated rivers should focus on maintaining or restoring the important rôles of ecotones by re-establishing interactive pathways and by reconstituting a disturbance regime that leads to a diversity of habitat patches and successional stages.
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