Does water level affect benthic macro-invertebrates of a marginal lake in a tropical river-reservoir transition zone?

Abstract

Benthic macro-invertebrates are important components of freshwater ecosystems which are involved in ecological processes such as energy transfer between detritus and consumers and organic matter recycling. The aim of this work was to investigate the variation in organism richness, diversity and density of benthic fauna during the annual cycle in Camargo Lake, a lake marginal to Paranapanema River, southeast Brazil. The correlation of environmental factors with community attributes of the macro-benthic fauna was assessed. Since Camargo Lake is connected to the river, we tested the hypothesis that water level variation is the main regulating factor of environmental variables and of the composition and abundance of benthic macro-invertebrates. The results indicated that lake depth varied with rainfall, being the highest at the end of the rising water period and the lowest at the beginning of this period. The sediment granulometry was more heterogeneous at the bottom of the lake by the end of the high water period. The benthic macro-invertebrate fauna was composed by 15 taxa. The Diptera order was represented by seven taxa and had greater richness in relation to other taxa. This group was responsible for 60% of the total abundance of organisms, followed by Ephemeroptera (22%) and Anellida (16%). Significant differences were observed over time in total richness and, in density of Narapa bonettoi, Chaoborus, Ablabesmyia gr. annulata, Chironomus gigas, Larsia fittkau, and Procladius sp. 2. Total taxa richness correlated negatively with water pH, transparency, conductivity, and bottom water oxygen. Higher positive correlations were found between the densities of some taxa and bottom water oxygen, conductivity and very fine sand, silt + clay of sediment, while negative correlations were recorded with organic matter, and fine, medium and coarse sand, bottom water temperature, mean temperature and rainfall. The significant temporal difference in water level was associated with changes in abiotic factors and macro-invertebrate community attributes.Keywords: marginal lake, connectivity, water level, benthic fauna.O nível de água afeta os macro-invertebrados bentônicos de uma lagoa marginal na região de transição rio -represa de zona tropical? ResumoOs macro-invertebrados são componentes importantes de ecossistemas aquáticas continentais, envolvidos em processos ecológicos como transferência de energia entre detritos e consumidores e, reciclagem de matéria orgânica. O objetivo deste trabalho foi investigar a variação na riqueza de organismos, diversidade e densidade da fauna bentônica durante um ciclo anual na Lagoa do Camargo, marginal ao Rio Paranapanema, sudeste do Brasil. Eventuais relações de fatores ambientais com atributos da comunidade macro-bentônica foram verificadas. Visto que a Lagoa do Camargo é conectada com o rio, nós testamos a hipótese de que a variação do nível de água é o principal fator regulador das variáveis ambientais e da composição e abundância dos macro-invertebrados bênticos. Os resultados i...

Assessment of the Benthic Macroinvertebrate Communities in the Evaluation of the Water Quality of Portuguese Reservoirs: An Experimental Approach

“…The variability in loads of dissolved or particulate solids, for example, typically reflects geological variations, use of the adjacent land and precipitation [10]. These interferences change the system morphometry, its physical and chemical characteristics and the functioning and structure of biological communities, namely loss of biodiversity and the loss of ecosystem functions (e.g., less nutrient recycling) [8,11,12], affecting bacterioplankton [13,14], phytoplankton [15,16], zooplankton [17,18], benthic macroinvertebrates [19][20][21][22], fish and macrophytes [10].…”

Effects of an atypical drought on the benthic macroinvertebrate community in a tropical reservoir

“…Granulometric composition has been considered to be the factor with the highest influence on the distribution of benthic macroinvertebrates at a local scale in tropical reservoirs (Molozzi et al 2013b). Hence, the more diversified the sediment, the higher the availability of shelters and protection for these organisms (Molozzi et al 2011, Zerlin & Henry 2014.…”

“…Chaoboridae are represented by cosmopolitan and voracious organisms which predate other invertebrates, especially zooplankton. They might be found in the sediment during the day and in the water column at night, and are common in reservoirs (Zerlin & Henry 2014). Many Chironomidae larvae inhabit harsh habitats, such as fine sediments, hot waters, and low oxygen contents (Ledger et al 2012).…”

Horizontal distribution of Cladocera in a subtropical lake marginal to a river

“…Linear regression of the means crowding and mean population densities of Cladocera at two periods in Camargo Lake and patterns of species distribution. ling factor of cladoceran distribution due to the low occurrence of predators, such as Chaoborus (Zerlin and Henry, 2014), and a low density of fish larvae (Suiberto, 2005). A restrictive condition for predation on cladocerans by fish larvae and Chaoborus is water transparency (Arcifa et al, 1992;Arcifa, 1999).…”