Connectivity as the control key to intensity of flood pulse in Taquari River oxbow lakes

Adriana Maria Güntzel,Eliana Aparecida Panarelli,William Marcos Da Silva

doi:10.4136/ambi-agua.2534

Abstract

The Taquari River is one of the most important tributaries of the Paraguay River, whose sediments are carried and deposited on the plain forming the largest alluvial fan in the world, known as Pantanal. In the floodplain, the course of the river has been modified by the sedimentation process, resulting in lakes with different degrees of connectivity with the river. This study assessed the influence of connectivity on the physical and chemical characteristics of water along a hydrological cycle in oxbow lakes of the Taquari River floodplain, in Mato Grosso do Sul, Brazil. Sampling was carried out monthly, from May 2005 to June 2006.The physical and chemical data of the water and the variables of river level and rainfall intensity were correlated by Principal Component Analysis (PCA). Limnological differences resulted from distinct degrees of connectivity between the oxbow lakes and the Taquari River. Variations in the dry and rainy seasons established a gradient that extends over a space-time continuum and generates greater environmental heterogeneity and, consequently, greater biodiversity. Thus we conclude that this mosaic of lakes and the surrounding landscape requires protection and preservation because of its importance for biodiversity conservation.

Highlights

Floodplains are important regulators of water-level fluctuations and biogeochemical cycles
The monthly average of precipitation and the variation in the Taquari River level are shown in Figure 3, highlighting the months when the river enters the L2, which is the lake that receives water from the Taquari River only during the flood pulse in the rainy season (Panarelli et al, 2013)
Environmental changes caused by variations in the dry and rainy seasons influenced the limnological conditions of the studied lakes

Summary

Introduction

Floodplains are important regulators of water-level fluctuations and biogeochemical cycles. Lateral systems have high residence time when compared to the river channel and are refuges for aquatic animals, providing important habitats for biological production and contributing to river biomass, as the floodplain communities increase the base of the river system food chain (Tockner and Stanford, 2002; Güntzel et al, 2010) In these systems, oxbow lakes are a functional unit formed when the river channel is isolated by a cutoff of the meander loops (Wantzen et al, 2005) and isolation increase along the time, resulting in lakes with distinct degrees of connectivity to the river (Lesack and Marsh, 2010; Panarelli et al, 2013)

Methods

Results

Conclusion