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Acta Limnologica Brasiliensia

On-line version ISSN 2179-975X

Abstract

BATISTA-SILVA, Valéria Flávia et al. Invertebrates associated to Eichhornea azurea Kunth in a lagoon of the Upper Paraná River: composition, community attributes and influence of abiotic factors. Acta Limnol. Bras. [online]. 2011, vol.23, n.4, pp. 376-385.  Epub June 14, 2012. ISSN 2179-975X.  http://dx.doi.org/10.1590/S2179-975X2012005000016.

AIM: We evaluated the composition and community attributes of invertebrates associated to Eichhornia azurea at Cascalho Lagoon, Upper Paraná River, Mato Grosso do Sul State, Brazil, over a hydrological cycle, as well the possible influence of abiotic factors upon these attributes. METHODS: The samplings were conducted during 2010 in the rainy and dry periods at stands of E. azurea. The attributes evaluated were abundance, richness, diversity, evenness and dominance. The abiotic factors, temperature, dissolved oxygen, pH and turbidity were summarized by a Principal Component Analysis (PCA). In order to verify possible differences between the mean values of the community attributes and the scores of the PCA axis in different periods, we employed null models analysis of variance. The influence of abiotic factors on each attribute was evaluated through Pearson correlations. RESULTS: We captured 3,052 individuals, distributed into 32 taxa, belonging to the phyllum Mollusca, Annelida, Nematoda and Arthropoda. Among the assessed attributes, only abundance and richness varied significantly between periods, with higher values during the rainy period. Chironomidade was dominant in both periods, whereas Notonectidae and Cyclopoida were rare in the rainy, and Bivalve, Decapoda, Haliplidae, Trichoptera and Pyralidae, in the dry period. A temporal distinction was evident only for the PCA axis 1, which represented gradients in temperature, dissolved oxygen and pH. Among the community attributes, only abundance was significant and negatively correlated with this axis. CONCLUSION: We attested that: i) the rainy period should add favorable conditions for invertebrates' higher richness and abundance in this macrophyte; ii) only the later attribute was influenced by limnological gradients.

Keywords : aquatic macrophytes; Chironomidae; limnological gradients; hydrological cycle; lentic environment.

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