Dams Change Beta Diversity of Aquatic Communities in the Veredas of the Brazilian Cerrado

Abstract

The veredas are wetland ecosystems responsible for supplying most of the water for rivers and streams in the Cerrado. The veredas’ hydromorfic soils retain a large amount of rainwater, releasing it slowly during drier periods. Therefore, these habitats are often used to build dams for cattle raising. Here we assessed the environmental conditions and beta-diversity of Odonata and Heteroptera on veredas impacted by dams in the Brazilian Cerrado. We sampled biological communities and a set of environmental variables in 13 veredas, six with dams and seven without dams. One limnological variable [oxidation–reduction potential (ORP)] and one landscape metric (% of the altered area) differed among veredas with and without dams. These variables were important predictors of the beta-diversity of both Odonata (R2 = 0.650; p < 0.001) and Heteroptera (R2 = 0.740; p < 0.001). The veredas stand among the most sensitive wetland ecosystems of the Cerrado. In this study, we show, for the first time, that veredas with dams may lose environmental quality resulting in changes in biological communities, especially ecologically unique species. Because the Cerrado naturally goes through approximately 5 months of severe drought, the veredas are critical for the Cerrado’s hydric safety. Therefore, we recommend that cattle-raising activities should rely on artificial water tanks instead of using dams for water storage since it affects ecologically unique species in this poorly known ecosystem.

Use of the Zygoptera/Anisoptera Ratio (Insecta: Odonata) for Habitat Alteration Assessment in Cerrado Streams

“…This underscores the importance of this study, in that it proved that the evidence derived from the Amazon Rainforest (Oliveira-Junior & Juen, 2019) and Atlantic Forest (Ribeiro et al, 2021) could be not robust enough for this biome. Moreover, the Cerrado naturally possesses both non-forested areas (such as fields and scrub areas) (Brasil et al, 2021;Vilela et al, 2016), and gallery forests. Therefore, it is crucial to test the efficacy of Zygoptera/ Anisoptera ratios in all these landscapes, as the accuracy of this indicator may vary between them.…”

Veliidae (Hemiptera: Gerromorpha) en el piedemonte andino-pacífico en el suroeste de Colombia

“…¿A qué se debe esta alta diversidad de especies de Veliidae de rango geográfico y altitudinal restringido a este lugar del piedemonte del Pacífico? La composición de los heterópteros semiacuáticos difiere debido a alteraciones e impactos antropogénicos como el uso del suelo, la ganadería, la construcción de presas y la deforestación (Brasil et al, 2021;Giehl et al, 2020), lo que contrasta con la RNRÑ, donde se mantiene un ambiente estable y no se presentan tales impactos antropogénicos, en tanto que el ciclo del agua se garantiza con una elevada precipitación de 7.000 mm/año, lo cual favorece la permanencia de ríos, quebradas y otros cuerpos de agua en toda esta cuenca hidrográfica. Por otra parte, la vegetación de bosque pluvial premontano asegura una capa de mantillo y el depósito de hojas de palmas y otras estructuras de plantas o bromelias que permiten la permanencia temporal, el refugio o el hábitat propicio para muchas especies de Microvelia propias de las filotelmata.…”

Heterópteros aquáticos e semiaquáticos no sudoeste amazônico e o seu papel no biomonitoramento aquático

“…Um dos grandes desafios para o biomonitoramento aquático é seleção de bons bioindicadores. Em geral, as pesquisas com insetos aquáticos apresentam muitas espécies, mas nem sempre é possível identificá-las até o nível de espécie, em virtude de limitações relacionadas à descrição de formas imaturas ou mesmo pela carência de taxonomistas na Amazônia Sul-ocidental (3,8,9,14,32,35,39,(41)(42)(43).…”