Structure of potamoplankton along a gradient of preservation of riparian vegetation in subtropical streams

Abstract

Water quality in lotic and lentic systems is greatly influenced by the land use in the adjacent areas. This study was conducted in order to assess whether different degrees of preservation of riparian forest (from well preserved with 30m wide up to degraded with < 5 m wide) influence potamoplankton community structure. The study was conducted in three streams in the upper region of the Rio dos Sinos basin, at four sampling sites, with different width of the forest. Samplings were gathered for abiotic and biological analysis in winter (August 2010) and summer (January/February 2011). The analysis of environmental and biotic variables indicated that seasonality was the main determinant of biomass patterns, regardless of the width of riparian vegetation. The potamoplankton community of the studied streams responded to environmental conditions, although lack of significant difference among the different degrees of riparian vegetation preservation has been observed. Increasing trends on biomass, richness and diversity of species, and higher concentrations of total phosphorus and nitrogen in the non-preserved areas might indicate that the different gradients of preservation of riparian vegetation are related with the water quality in subtropical streams and consequently with the potamoplankton structure.

Tema 9___gestão Ambiental E Sustentabilidade

“…Vale destacar que se observou em áreas rurais, à jusante e montante de P4, a existência de fossas sépticas indicando exacerbação da degradação antrópica de rios e mananciais freáticos. Os resultados do IQA mostraram relação com o risco potencial da erosão devido à supressão de vegetação e empobrecimento do solo após sua utilização como pasto e outros fins (PERESIN et al, 2014, ZIMMERMAN et al, 2008. A BHRP mostrou boas condições de oxigenação não sendo encontrada diferença estatística (p > 0,05) nos valores de oxigênio dissolvido entre as estações amostrais (Figura 4).…”

Drivers of seasonal dynamics of phytoplankton community in subtropical streams: a study case

“…The presence of Euglenophyceae, constituted of mixotrophic organisms, can be related to higher concentrations of organic matter (Reynolds et al 2002;Padisák et al 2009;Descy et al 2012), which, in turn, may be associated with a higher loading of TDS. This loading can occur from the riverbank to the aquatic environment in lotic systems (Vannote et al 1980), especially in shallow streams with small width; therefore, it can be strongly influenced by the input of the margins (Safonova and Shaulo 2009;Peresin et al 2014).…”

“…In streams, the phytoplankton is subjected to unidirectional flow and is influenced by the physical and geographical characteristics of the drainage basin use, in addition to the strong influence of seasonal hydrological patterns (Abonyi et al 2014). Furthermore, the riparian vegetation integrity is highly essential to environmental quality recovery considering that the vegetation in these environments acts as a retention filter for organic components, sediments and pollutants that are usually carried into the ecosystems (Dosskey et al 2011;Fernandes et al 2014) as well as prevents eutrophication and the frequency of algal and cyanobacterial blooms (Peresin et al 2014 Phytoplankton species have widely different responses to environmental filters, including the forms of acquisition of light and nutrients, tolerance to high levels of turbulence, ability to inhibit loss processes and sedimentation, and ability to avoid the continuous downstream transport (Reynolds and Descy 1996;Naselli-Flores and Padisák 2016). In addition, the phytoplankton can be more susceptible to light limitation in lotic systems due to higher turbidity from suspended material (Chételat and Pick 2006).…”