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Factors affecting assemblage attributes of freshwater Oligochaeta in Neotropical shallow floodplain lakes. Aim: Identify the effects of sediment composition and water conditions on diversity, richness, evenness, density and composition of freshwater Oligochaeta in shallow floodplain lakes. In each lake, four sediment samples were taken from the shore and central regions, three of them were used for biological analysis, and one for granulometric analysis.

Concomitantly, temperature, dissolved oxygen, pH, conductivity, alkalinity, turbidity and chlorophyll-a were also measured. Initially, the biological samples were analyzed by a stereoscopic microscope. Oligochaeta individuals were identified under optical microscope at the lowest possible taxonomic level. For data analysis, we quantified density, richness, evenness and diversity index of freshwater Oligochaeta. In order to show differences between the months and the analyzed lakes, in relation to the percentages of coarse and fine organic material, the nonparametric Kruskal Wallis test was used.

We also calculated the sediment granulometric diversity using the Shannon-Wienner index, using a simple regression analysis. We correlated assemblage attributes of Oligochaeta with sediment diversity and the assemblage species with the limnological variables using the Spearman correlation. A total of 2, individuals were found distributed among 27 species. Assemblage attributes were not significantly correlated with sediment diversity, and 7 of the 27 species recorded showed significant correlations with at least some of the abiotic variables.

We verified that the abiotic variables of the water present greater influence on the attributes of the assemblage of freshwater Oligochaeta, when compared with sediment influences. Although we found low local diversity of this group, the wide range of water conditions offered by lakes culminates with a great species richness considering the whole landscape.

Foram encontrados 2. Floodplains are widely recognized by their high environmental heterogeneity Thomaz et al. The well-defined aquatic and terrestrial phases produce several adaptations in organisms inhabiting those areas Junk et al. Lakes are very common environments in floodplain areas, which are characterized by high accumulation of mud and organic matter Knoppers, ; Bilia et al. The organic matter is important for its great contribution in the diet of most aquatic organisms Darnell, ; Alongi, , which acts as a determinant factor on the species composition and allows the occurrence of different communities among the floodplain lakes Barreto, ; Assis et al.

Among the benthic invertebrates, Oligochaeta plays an important role representing one of the most abundant group Takeda, ; Ezcurra de Drago et al. Here, we evaluated whether sediment composition and water conditions affect assemblage attributes of Oligochaeta.

Lakes differ in relation to surface area, depth, lake levee height, main river channel distance, composition of macrophytes, riparian vegetation coverage, as well as variations in the water physical and chemical characteristics Thomaz et al. Samplings were carried out quarterly encompassing months of March, June, September and November of the year , in order to consider the different seasons of the year.

In each floodplain lake, three regions were determined, in an imaginary line from one margin to another i. At each region, four samples were performed with the modified Petersen bottom sampler 0. Three samples were used for biological analysis and one for granulometric analysis. The sediment retained in the last sieve was fixed with The granulometric composition of each lake sediment was determined using the Wentworth scale Wentworth, The difference between the initial and final weights indicates the amount of organic matter that was present in the substrate.

The screening and counting of Oligochaeta individuals were realized under a stereoscopic microscope. To analyze the assemblage attributes we calculated the density of Oligochaeta ind. Shannon index was also used to calculate the sediment diversity.

In order to evaluate differences between months and analyzed lakes, in relation to the percentages of coarse and fine organic material COM and FOM , the nonparametric Kruskal Wallis test was used. These classes of organic material size were selected due to their predominance in the sampled environments. In order to verify the relationship between sediment diversity and the species richness, evenness, density and diversity of Oligochaeta, a simple regression analysis was performed.

Sediment diversity was calculated using Shannon index, and represents a surrogate of sediment heterogeneity of organic matter composition.

The regression was performed in the software Statistica 7. Genipapo, Clara and Pousada lakes showed the highest density and species richness Figure 2. The most common species were D. We observed that in relation to the coarse organic matter the month of March differed from the months of June and September, whereas for the fine organic matter there were no differences between the months.

In relation to the coarse and fine organic matter, it was possible to observe some significant relations between the lakes Table 1. The simple linear regression analysis performed between the Oligochaeta assembly attributes and the sediment diversity showed no significant relationship Table 2 , indicating that the habitat structural components are not the main predictors of the attributes of this assembly in those shallow floodplain lakes.

However, Oligochaeta community attributes correlated significantly with some limnological variables Table 3. It was observed that Dero Aulophorus borellii Michaelsen, , and Bratislavia unidentata Harman, , had positive correlations with conductivity and alkalinity, whereas the species Nais pardalis Piguet, , and Stephensoniana trivandrana Aiyer, , had a positive correlation only with chlorophyll.

It was observed that the temperature has negative correlation with some of the Oligochaeta species found. We found no correlation between Oligochaeta community attributes and habitat heterogeneity, indicating that habitat structural components are not the main predictor of Oligochaeta assemblage in these shallow floodplain lakes.

Through the nonparametric Kruskal Wallis test, it was possible to observe that the concentration of coarse organic matter in the lakes was higher in the flood months March and December. In the flood months, the sediment present in the unconnected lakes may suffer great influence from the main rivers Bilia et al.

The lakes presented significant differences in relation to the size class of coarse and fine organic matter, due to the dense arboreal vegetation verified in the surroundings of these lakes, in which it allows the increase in the entrance of branches and leaves that become part of the sediment of these bodies of water and mainly with the distance between this lake and the main river Bilia et al.

We found many correlations between abundance of Oligochaeta species and limnological variables, indicating a stronger influence of limnogical factors than habitat components in structuring Oligochaeta assemblage. Some species were negatively correlated with temperature, as also found in studies conducted by Iliopoulou-Georgudaki et al.

According to Bechara , many species of Oligochaeta are sensitive to chemical changes in the environment such as conductivity, alkalinity, pH and turbidity, and these changes are seasonally present in floodplain due to flooding pulse, which promotes relevant limnological changes Thomaz et al.

In relation to the Oligochaeta assemblage, Pristininae, considered a cosmopolitan subfamily Martin et al. Genipapo, Clara and Pousada lakes presented a high density of species, sharing the occurrence of P. Tubificinae subfamily had A.

Although the occurrence of A. In recent years, A. The ability of this species to occur in habitats with very different conditions may be an indication of high environmental tolerance, and these characteristics may have favored the increase of its occurrence throughout the floodplain in the last decades.

However, A. There was no positive correlation between species with temperature, although this extrinsic variable being considered the most important for these organisms, mainly for controlling the asexual growth rates of many Oligochaeta species Judet et al.

Oligochaeta species reflect the conditions necessary for their occurrence in certain habitats. When some species found their set of ideal conditions in a same place, it tends to favor co-occurrence of species, which increases the diversity, richness and evenness of the assemblage.

From this, it was expected that the availability of various sizes of sediment particles and organic particles would favor the diversity of the Oligochaeta assemblage, similar to found by Fomenko , but this idea was not corroborated by our simple linear regression analysis.

Through the contradiction between our data and the literature findings, it can be inferred that the limitations imposed by the limnological variables could mask the effects of sediment heterogeneity. In this study, an ideal set of variables was not identified for the development of a very diverse local assemblage of Oligochaeta, but it can be considered that the wide range of habitats can increase the diversity of these organisms at the landscape level Williams et al.

Thus, limnological factors were more determinant for the occurrence of Oligochaeta species than the sediment particle size and organic matter composition of the sediment. Cite as: Amo, V. Acta Limnologica Brasiliensia , , vol. Coastal ecosystem processes.

Revista Brasileira de Entomologia , , 48 2 , Oecologia Brasiliensis , , 7 01 , Hydrobiologia , , 2 , Eight years of monitoring aquatic Oligochaeta from the Baia and Ivinhema Rivers.

The benthos of lakes. London: The Macmillan Press, Aquatic Oligochaeta of the World. Edinburgh: Oliver and Boyd, Verhandlungen des Internationalen Verein Limnologie , , 27, Organic detritus in relation to secondary production in aquatic communities.

Limnologie , , 15, Acta Scientiarum. Biological Sciences , , 28 4 , Benthos of a large neotropical river: spacial patterns and species assemblages in the Lower Paraguay and its floodplains. Hydrobiologia , , 3 , The effect of dissolved oxygen on the burrowing behavior of Limnodrilus hoffmeisteri Oligocheta. Hydrobiologia , , 47 2 , Abundance and first record of benthic macroinvertebrates in Lake Metztitlan, Hidalgo, Mexico. On ecological groups of Oligochaeta in the Dnieper.

In: G. Aquatic Oligochaetes. Moscow: Nauka, , pp. The Odonata Insecta assemblage on Eichhornia azurea Sw. Acta Limnologica Brasiliensia , , 18 4 , Revista Colombiana de Ciencia Animal , , 7 2 , An application of different bioindicators for assessing water quality: a case study in the rivers Alfeios and Pineios Peloponnisos, Greece. Ecological Indicators , , 2 4 , Ecology and production of the profundal benthos in relation to phytoplankton in Lake Esrom.

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Fundamentos de limnología neotropical / Gabriel Roldán Pérez, John Jairo Ramírez Restrepo

Colonization process of diatoms on artificial substrates in the River Danube near Budapest Hungary. Hydrobiologia, v. Effects of the discharge on periphyton abundance and diversity in a large river River Danube, Hungary. ALOI, J. A critical review of recent freshwater periphyton field methods. A comparison of the attached algal communities of a natural and an artificial substrate.


Fundamentos de Limnología Neotropical

Influence of environmental parameters on fish assemblage of a neotropical river with a flood pulse regime, Central Brazil. This study aims to determine which of twelve environmental parameters five physicochemical and seven hydromorphological influence on the fish assemblage structure of the lower Mortes River basin located in the Bananal floodplain of the Araguaia River basin, Central Brazil. Sampling was conducted in six stretches of m each during the high and low waters. Fish were captured using gill nets and environmental parameters were measured by portable equipment or determined visually. The co-inertia analysis indicated that two physicochemical dissolved oxygen and water transparency , and four hydromorphological channel width and depth, riparian vegetation cover and type of the riverside substrate parameters structure the fish assemblages, both driven by the regional hydrological patterns flood pulse. These results are explained by fish-environmental parameters relationship characteristic of the aquatic Neotropical systems.

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