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1

Distribution of ephemeropteran nymphs associated with different stolon sections of Eichhornia azurea [Schwartz] in two floodplain lakes of the Upper Parana River [Brazil]

100%
De M. S. M., Takeda A. M., Grzybkowska M., Monkolski A.
Polish Journal of Ecology
|
2004
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tom 52
|
nr 3
Eichhornia azurea (Schwartz) Kunth is one of the most abundant species of aquatic macrophyte in the Upper Paraná River floodplain, and ephemeropteran nymphs frequently inhabit this plant. The objective of this study was to analyze the distribution of ephemeropteran nymphs associated with three sections (apical, intermediate, and basal) of E. azurea in two floodplain lakes of the Upper Paraná River as well as to establish the relation of this distribution to biotic and abiotic factors. The samplings of apical, intermediate and basal sections of E. azurea were carried out monthly from October 1997 to October 1998. Higher concentration of dissolved oxygen may contribute to greater density of nymphs on the apical plant segments near the water surface. Callibaetes willineri was the most abundant taxon, occurring on the apical and intermediate plant sections whereas Campsu- rus spp. were recorded on the basal and intermediate sections of the plant, near the sediment and, mainly during high water. Lower dissolved oxygen concentrations near the lake bottom during the high water phase might suggest that during this phase the nymphs of Campsurus violaceus also migrate to E. azurea roots. It was found that changes in water level influenced the variation of the abundance of nymphs. Other genera, such as Tricorythodes and Leptohyphes, were recorded during the high water phase, when river water enters the lakes and their shores are flooded.
2

Winter circadian activity pattern of free-ranging coypus in the Parana River Delta, eastern Argentina

100%
Palomares F., Bo R., Beltran J. F., Villafane G., Moreno S.
Acta Theriologica
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1994
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tom 39
|
nr 1
During August 1990, 3 male and 3 female coypus Myocastor coypus (Molina, 1782) were radiotracked for 42 24-h periods at the Delta of Paraná River, Argentina. Coypus were mainly nocturnal, with activity peaks around one hour after sunset and two hours before sunrise. Movement rate peaked between 02.00 and 04.00 o'clock. This pattern is similar to that observed in captive individuals and introduced feral popu­lations. Among 7 environmental factors (day period, temperature, wind, cloud cover, and presence or absence of moon, fog, and rain) only period of day and rainfall during daylight were found significantly related to coypu activity, but no environmental factor influenced coypu nocturnal rate of movement.
3

Two new species of Sciadicleithrum [Monogenea, Dactylogyridae] parasites of Neotropical cichlid fishes from the Parana River, Brazil

84%
Yamada F. H., Takemoto R. M., Bellay S., Pavanelli G. C.
Acta Parasitologica
|
2009
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tom 54
|
nr 1
6-11
Two new species of Sciadicleithrum are described from the gills of Neotropical cichlid fishes collected from Paraná River, Brazil. Sciadicleithrum satanopercae sp. nov. is described from the gills of Satanoperca pappaterra and differs from congeners by having a dorsal anchor with the distal portion complex and the inner margin with a “denticulum” between shaft and point. Sciadicleithrum joanae sp. nov. is described from the gills of Crenicichla niederleinii and C. britskii collected from Paraná River. Sciadicleithrum joanae sp. nov. differs from congeners by having a male copulatory organ comprising about half a clockwise loop and a vaginal pore “bulb-shaped”.
4

A new species of Aphanoblastella Kritsky, Mendoza-Franco and Scholz, 2000 (Monogenea, Dactylogyridae) parasitic on heptapterid catfish (Siluriformes) in the Neotropical region

84%
Yamada F. H., Acosta A. A., de Yamada P. O. F., Scholz T., da Silva R. J.
Acta Parasitologica
|
2018
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tom 63
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nr 4
5

Population demography of Oxymycterus rufus [Rodentia: Cricetidae] inhabiting a patchy environment of the delta of the Parana River, Argentina

84%
Cueto V. R., Piantanida M. J., Cagnoni M.
Acta Theriologica
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1995
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tom 40
|
nr 2
We employed a live-trapping grid encompassing several discrete vegetation patches to analyze spatial differences in the demographic structure of an Oxymycterus rufus (Fischer, 1814) population living on the delta of the Parana River, Argentina. Abun­dance, residence and reproduction of both females and males have been associated with microhabitats where food (measured through the availability of arthropods) was more abundant, and were not associated with the plant cover of those microhabitats. Our results emphasize the importance of food availability in the spatial distribution of resident and reproductive individuals, and hence in the survival and breeding success of their populations in the Parana delta area.
6

Banding chromosome pattern of two species of Pimelodus [Siluriformes, Pimelodidae] from the Parana River basin of Brazil

84%
De Souza L., Giuliano-Caetano L., Dias A. L.
Folia Biologica
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2004
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tom 52
|
nr 3-4
7

Use of benthic macroinvertebrates as organic pollution indicators in lotic environments of the Parana River drainage basin

84%
Marchese M., Ezcurra de Drago I.
Polskie Archiwum Hydrobiologii
|
1999
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tom 46
|
nr 3-4
8

Influence of livestock grazing on the capybara's trophic niche and forage preferences

84%
Quintana R. D.
Acta Theriologica
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2002
|
tom 47
|
nr 2
Trophic niche parameters and forage preferences of capybara Hydrochaeris hydro- chaeris Linnaeus, 1766 were studied at three areas of east-central Argentina: Lower Delta Islands (LDI), only capybara present; Puerto Constanza (PC), capybara and cattle, and Villaguay (VI), capybara, cattle and sheep. Significant correlation was found in the annual botanical composition of capybara faeces at LDI and PC, but no cor­relation was found between faecal composition at these two areas and those at VI. The narrowest trophic niche corresponded to LDI, while the widest corresponded to VI, with significant differences in the values among the three areas. Capybara consumed Carex riparia, Cynodon dactylon and Panicum grumosum in LDI, and P. milioides in VI in proportion greater than availability. Three and eight food items were consumed less than availability in VI and PC, respectively. The greater the species number and density of livestock animals, the more generalist the behavior of capybara, possibly due to direct interaction in the use of grazing resources. Changes in availability of foraging species may influence the capybara's preference patterns and the consumption of suboptimal feeding items may indicate a greater pressure on foraging resources in the areas where capybaras share their habitat with livestock.
9

Is the community of fish gill parasites structured in a Neotropical floodplain?

67%
Bellay S., Takemoto R. M., Oliveira E. F.
Acta Parasitologica
|
2012
|
tom 57
|
nr 1
Sixty-one specimens of the piranha Serrasalmus marginatus Valenciennes, 1837 were analyzed, aiming at assessing the community structure of their gill parasites. The samples were collected in lagoons of the Paraná, Ivinheima and Baia Subsystems within the Upper Paraná River Floodplain (Brazil). Host size and sex had little or no influence on the abundance and prevalence of parasites. The organization of the gill parasite infracommunities of S. marginatus was significantly non-random according to null models and ordination analyses. In general, parasite infrapopulations were not affected by interspecific associations or host characteristics (e.g. size, sex), what highlights the importance of local habitat characteristics to community organization of gill parasites of S. marginatus in the Upper Paraná River Floodplain.
10

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

67%
Drago E. C., Wantzen K. M., Paira A. R.
International Journal of Ecohydrology and Hydrobiology
|
2008
|
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.
11

Henneguya caudicula n.sp. [Myxozoa, Myxobolidae] a parasite of Leporinus lacustris [Osteichthyes, Anostomidae] from the high Parana River, Brazil, with a revision of Henneguya spp. infecting South American fish

67%
Eiras J. C., Takemoto R. M., Pavanelli G. C.
Acta Protozoologica
|
2008
|
tom 47
|
nr 2
149-154
12

Aquatic habitats of the Upper Paraquay River-Floodplain-System and parts of the Pantanal (Brazil)

67%
Wantzen K. M., Drago E., Da Silva C. J.
International Journal of Ecohydrology and Hydrobiology
|
2005
|
tom 05
|
nr 2
The Paraguay-Paraná river system forms an important ecological corridor across South America. Here, we report the first description of the fluvial geomorphology and the physical structure of aquatic habitats along the main channel a 200-km long section of the Upper Paraguay River between Cáceres city and Taiamã island (Mato Grosso, Brazil). Four functional sets were identified: (a) main channel and anabranches, (b) floodplain channel, (c) floodplain lake, and (d) aquatic-terrestrial-transition zone. The diversity of functional units was higher in the meandering and transitional sectors (Brillouin index 1.957 and 2.003) than in the straight and fluviolacustrine sectors (Brillouin index 1.562 and 1.577, respectively). In the transversal dimension, the relatively homogeneous habitats of the main channel contrasted with the heterogeneous floodplain habitats. We attribute this morphological diversity to changes in the hydrological connectivity, caused e.g. by drifting large macrophyte mats or by multi-year periods of higher and lower inundation phases.
13

A new trematode species parasitizing the catfish Hoplosternum littorale [Osteichthyes, Callichthyidae] from Parana River, Brazil, with an emendation of the diagnosis of Magnivitellinum [Trematoda, Macroderoididae]

67%
Lacerda A. C. F., Takemoto R. M., Pavanelli G. C.
Acta Parasitologica
|
2009
|
tom 54
|
nr 1
37-40
Magnivitellinum corvitellinum sp. nov. is a parasite from the intestine of tamboatá Hoplosternum littorale, a freshwater catfish from Paraná River, Brazil. This species has an elongate body, a small cirrus-sac, testes in the posterior half of the body and well-developed follicular vitellines. It differs from the only other species in the genus, M. simplex, in having tegumental spines along the body, ventral sucker distinctly bigger than oral sucker, oesophagus absent and vitellaria extending from posterior margin of ventral sucker to near posterior extremity of body. An emendation of the generic diagnosis is proposed in view of the presence of tegumental spines along the body, absence of oesophagus, relative size of ventral and oral suckers and uterus covering caeca from the level of ventral sucker to the end of caeca. This is the fourth trematode species recorded parasitizing Hoplosternum littorale.
14

The importance of floodplains for the dynamics of fish communities of the upper river Parana

67%
Agostinho A. A., Gomes L. C., Zalewski M.
International Journal of Ecohydrology and Hydrobiology
|
2001
|
tom 01
|
nr 1-2
The last free stretch of the River Paraná inside of Brazilian territory, about 230 km of the former 810 km, runs in a wide floodplain, which flood regime is controlled in part by upstream dams. Aim to evaluate the impacts of different levels of hydrological control on the regional fish diversity, nutritional condition, trophic categories proportion, reproduction and young abundance monthly sampling were carried, between 1986 and 1993, during three annual periods with different flood duration and intensity. Lagoons, secondary channels and river channel was sampled with gillnet of different mesh size and standardized effort. Diversity, evenness indexes and number of species increased with the occurrence of floods. The trophic category proportions varied among the periods considered, with a decrease in piscivores participation and an increase of iliophages, herbivores and insectivores (terrestrial) participation in big flood years. The tendencies for piscivores guild were not uniform to every pecies. The variations on the nutritional condition reveal that the absence of flooding has a negative effect on greater migratory species and positive on sedentary ones. The young abundance shows, however, that fail in the flooding has a strong negative impact on de recruitment of all the reproductive strategies. It’s stressed the operational procedures in the upstream dams and the maintenance of the floodplain integrity is essential to preserve the regional biodiversity, fisheries and particularly the greater migratory fishes population.
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