Macroinvertebrates under stochastic hydrological disturbance in Cerrado streams of Central Brazil

Abstract

ABSTRACT. In the Cerrado vegetation, where the seasonal is well defined, rainfall has an important role in controlling the flow of streams and consequently on the structure of macroinvertebrates community. Despite the effects of rainfall associated with seasonality are well studied, little is known about the effects of stochastic rains on the community. In the present study we evaluated the structure and faunal composition of four first-order streams in Central Brazil during the dry season in two years, with and without stochastic rains. Community sampling was done by colonization of boards of high density polyethylene (HDPE), removed after one month submerged in streams. Analysis of Variance (ANOVA) performed indicated no difference in rarefied richness between the two periods, different from numeric density of organisms that was higher in the period without disturbance; moreover, the Detrended Correspondence Analysis (DCA) revealed differences in faunal composition between the two periods. Our results indicate that stochastic rainfall is an important factor in structuring the macroinvertebrates community in studied region.KEYWORDS. Rainfall, faunal structure, rarefied richness, numeric density, benthic fauna. RESUMO. Macroinvertebrados sob perturbações hidrológicas estocásticas em riachos de Cerrado do Brasil Central.No Cerrado, onde o regime pluviométrico é bem definido, as chuvas tem um importante papel no controle da vazão dos riachos e, por consequência, sobre a estruturação da fauna de macroinvertebrados. Apesar dos efeitos das chuvas associados à sazonalidade serem bem estudados, pouco se sabe a respeito dos efeitos de chuvas estocásticas sobre a comunidade. No presente estudo nós avaliamos a estrutura e a composição faunística de quatro riachos de primeira ordem no Brasil Central na estação seca em dois anos, com e sem chuvas estocásticas. A amostragem da comunidade foi feita através da colonização de placas de polietileno de alta densidade (PEAD), removidas após um mês submersas nos riachos. A Análise de Variância (ANOVA) realizada não indicou diferença da riqueza rarefeita entre os dois períodos coletados, diferente da densidade numérica de organismos que se mostrou maior no período em que não houve perturbação; além disso, a Análise de Correspondência Destendenciada (DCA) revelou diferenças na composição faunística entre os dois períodos. Nossos resultados indicam que as chuvas estocásticas são um importante fator na estruturação da fauna de macroinvertebrados na região estudada. PALAVRAS-CHAVE.Chuva, estrutura faunística, riqueza rarefeita, densidade numérica, fauna bentônica.

Taxonomic composition and feeding habits of Chironomidae in Cerrado streams (Southeast Brazil): impacts of land use changes

“…Another explanation is based on the fact that competition is weak in macroinvertebrates communities (Tokeshi, 1986; Tavares-Cromar and Williams, 1997; Heino et al, 2003;Saito and Mazão, 2012). In this case we consider that, in highlight the abundance of Stenochironomus in reference streams.…”

“…The Cerrado, which is considered the most threatened tropical savanna in the world (Silva and Bates, 2002) and the only savanna biodiversity "hotspot" (Myers et al, 2000), is another important ecosystem. Additionally, Brazilian Cerrado streams have distinct aquatic fauna with unique structuring patterns that are subject to different abiotic filters than evergreen formations (Wantzen, 2003;Bispo et al, 2006;Saito and Mazão, 2012).…”

Stochastic colonisation dynamics can be a major driver of temporal β diversity in Atlantic Forest coastal stream communities

“…However, we found that precipitation was seasonal, but unpredictable at the monthly scale. During periods marked by high precipitation, heavy rain events remove a large proportion of individuals from the stream, even those adapted to high flows (McMullen & Lytle, 2012; Saito & Mazão, 2012). Thus, heavy rain events should be a major driver of community temporal dynamics in streams that naturally have low insect abundance, such as those that we studied (Heino et al., 2018; Siqueira et al., 2020).…”

“…Thereby, seasonality in the Atlantic Forest may vary depending on the climatic variable considered and its effect on freshwater biodiversity remains poorly understood. For example, heavy rain events are known to modify species occurrence and their relative abundance in streams (McMullen & Lytle, 2012; Melo & Froehlich, 2001; Saito & Mazão, 2012) but their magnitude can be unpredictable regarding frequency and timing in the Atlantic Forest (Nobre & Shukla, 1996). While summer (i.e.…”

Benthos Macroinvertebrates as Bioindicator of Water Quality in Nimbai Stream at Manokwari, West Papua

“…Kelimpahan individu yang lebih tinggi ditemukan pada aliran sungai yang lambat dibandingkan aliran sungai yang cepat, yang didominasi oleh kelompok insekta. Kelompok insekta (larva maupun insekta dewasa) akan hanyut atau tidak dapat bertahan apabila volume air meningkat saat curah hujan lebih tinggi (Saito & Mazao 2012), termasuk pula kelompok Oligochaeta yang akan terbawa aliran air yang deras (Crisci-Bispo et al 2007;Martins et al 2008). Hasil yang sama juga ditemukan pada penelitian sebelumnya oleh Manangkalangi et al (2009) di sungai yang sama, menemukan kelimpahan makro avertebrata bentos yang lebih tinggi pada daerah tepi sungai yang beraliran lambat pada kondisi debit air yang rendah.…”