Efeito de fatores abióticos sobre Brachymetra albinervis albinervis (Heteroptera: Gerridae)

Abstract

ABSTRACT. Effect of the abiotic factors on Brachymetra albinervis albinervis (Heteroptera: Gerridae). We analyzed the influence of abiotic factors, longitudinal and temporal distribution on the abundance of Brachymetra albinervis albinervis Amyot & Serville, 1843. Three sites of Cerrado stream were assessed: headwater, intermediary and river mouth, monthly for a year (June 2011 to May 2012). At each site, the following abiotic variables were monthly measured in a linear 100 meters transect: dissolved oxygen, water temperature, pH, electrical conductivity, width and depth of the stream. Were collected 111 specimens. The river mouth presented lower abundance when compared with others sites (F (2,9) = 13.721, p = 0.001). The periods of the year (rain, ebb, dry or early rains), there was no differences in the abundance. Thus, the abundance of B. a. albinervis analyzed for one year showed variation only in the streams longitudinal distribution, which was attributed to the effect of environmental changes in the river mouth, where presented lower abundance and less environmental integrity. These results contribute to the ecological knowledge of this species and discusses the change in the occurrence and abundance this species due to alteration in aquatic environments. KEYWORDS.Gerromorpha, Cerrado, aquatic insects, monitoring. RESUMO.Analisou-se a influência de fatores abióticos, distribuição longitudinal e temporal sobre a abundância de Brachymetra albinervis albinervis Amyot & Serville, 1843. Foram avaliados três sítios de um riacho de Cerrado: nascente, intermediário e foz, mensalmente durante um ano (junho de 2011 a maio de 2012). As variáveis abióticas aferidas foram: oxigênio dissolvido, temperatura da água, pH, condutividade elétrica, largura e profundidade do riacho. Em cada sítio, mensalmente coletou-se em transecção de 100 m lineares. Foram coletados 111 espécimes. A foz apresentou menor abundância quando comparada aos outros locais (F (2, 9) 13,721, p = 0,001). A abundância não variou entre os períodos do ano (chuva, vazante, seca ou início da chuva). Assim, a alteração na abundância de B. a. albinervis analisada ao longo de um ano foi influenciada pelos trechos do córrego, e essa variação foi atribuída a alterações ambientais no sítio foz que apresentou menor abundância e consequentemente é o que apresenta menor integridade ambiental. Esses resultados contribuem para o conhecimento ecológico dessa espécie e discute sobre a mudança da ocorrência da espécie em função da alteração dos ambientes aquáticos. PALAVRAS-CHAVE.Gerromorpha, Cerrado, insetos aquáticos, monitoramento.

Spatiotemporal dynamics in caddisfly (Insecta: Trichoptera) of a Cerrado stream, Brazil

“…This corroborates our hypothesis that there is an important interaction between spatial and temporal factors in determining community composition in these environments. Other studies carried out in the same stream but with other taxonomic groups have found similar results of the longitudinal distribution on the distribution of a Heteroptera population (Giehl et al, 2015), and of the temporal variation on rare and common Ephemeroptera communities (Brasil et al, 2017). In addition to a temporal evaluation of zooplankton of reservoirs in the Cerrado (Lodi et al, 2014), these previous evidences along with our results indicate a certain level of synchrony in the spatiotemporal distribution of aquatic species in the Cerrado.…”

“…The longitudinal variation occurs due to changes in environmental conditions along the stream. Site 3 (downstream) is environmentally more dissimilar than sites 1 and 2 (headwater and intermediate regions), where light input and depth are greater (Giehl et al, 2015). The river continuum concept theory (Vannote et al, 1980) posits that environments near the source and with great light input are trophically more heterogeneous and combine allochthonous energy derived from the stream banks, with autochthonous energy related to light input (algae and periphyton).…”

“…The central region of Brazil has well-defined dry and rainy seasons (Ratter et al, 1997). This climatic seasonality changes the water flow, dissolved oxygen rates, water temperature, and the litter contribution to the stream channel throughout the year (Giehl et al, 2015), and it leads to a greater habitat heterogeneity in the dry season. Therefore, the greatest diversity of aquatic insects occurs in the dry period (Bispo et al, 2006;Yokoyama et al, 2012).…”

Aquatic insects in organic and inorganic habitats in the streams on the Central Brazilian savanna

“…Other than that, specimens of the order Ephemeroptera, Plecoptera and Trichoptera (EPT) are widely used as biological indicators in ecological studies that evaluate the effect of biotic and abiotic processes in streams (Heino et al 2007;Heino 2011;Couceiro et al 2012;Heino and Peckarsky 2014;Nogueira et al 2016). Other than EPT, orders Odonata (O) (Mendes et al 2015;De Marco et al 2015;Juen et al 2016) and Heteroptera (H) (Dias-Silva et al 2010;Giehl et al 2014;Giehl et al 2015;Cunha et al 2015) were also indicated as relevant for understanding the ecological processes of aquatic insect communities in tropical streams, what reinforces the need to consider the whole EPTOH in order to understand ecological patterns of the Cerrado's aquatic insect communities.…”

Emergence Trap for the Collection of Exuviae and Adult of Odonata

“…However, we identified only 51 specieslevel individuals because some specimens were female or/and newly emerged, therefore, their structures were not in adequate condition for identification. Considering the categorization in periods of the year according to regional climate variation: rainy (January, February and March), ebb (period after the rainy season in which the water level declines) (April, May and June), dry (July, August and September), and early rainy (October, November and December) seasons (Giehl et al 2015), we recorded more emergencies in the early rain season and fewer records during the rainy and ebb season, which was also found in other studies (Salvarina et al 2017, Trapero-Quintana & Reyes-Tur 2017. This result can be explained by two phenomena Figure 2.…”