Colonisation of leaf litter by aquatic invertebrates in an Atlantic Forest stream

Abstract

Riparian vegetation along streams in the Atlantic Forest in Brazil contributes to the formation of a highly heterogeneous leaf litter in streambeds. To investigate the structure and composition of the aquatic invertebrate community during the process of leaf decomposition of two plant species present along the banks of the stream studied, 21 plastic mesh bags containing 2.5g (dry weight) of leaf matter from each species (Alchornea glandulosa (Vell) and Cabralea canjerana End. and Poeppig), for a total of 5.0g, were placed in the streambed. Three bags were removed after 3, 6, 9, 12, 24, 48 and 96 days. The taxonomic density was negatively correlated with the remaining weight. The high density of collector organisms, such as Chironomidae, Oligochaeta and Amphipoda, on the last day of incubation, probably occurred due to the increased amount of fine organic matter in the more advanced decomposition stages. The highest a diversity (Shannon-Wiener) values were observed for the 3rd and 96th days of the experiment, while the b diversity values showed that these days presented the highest variation in the taxonomic composition, thus presenting a different faunistic composition. This study showed that the trophic structure and composition of aquatic invertebrates changes during the decomposition of leaf litter. The faunistic abundance and diversity observed in this study indicate that the entrance of material from plants growing along streams provides favorable conditions for the colonisation and establishment of invertebrates in lower-order streams, and thus points to the need to preserve riparian vegetation.Keywords: riparian vegetation, allochthonous materials, decomposition. Colonização de folhiço por invertebrados aquáticos em um córrego de Mata Atlântica ResumoA vegetação ripária presente ao longo de córregos em áreas de Mata Atlântica contribui para a formação de serapilheira bastante heterogênea no leito de córregos. Com o objetivo de investigar a estrutura e composição da comunidade de invertebrados aquáticos durante o processo de degradação de detritos foliares de duas espécies vegetais presentes nas margens do córrego, 21 sacos de tela plástica contendo 2.5g de peso seco de cada espécie vegetal (Alchornea glandulosa (Vell) e Cabralea canjerana End. & Poeppig), totalizando 5.0g, foram colocados no leito do córrego. Três réplicas foram retiradas após 3, 6, 9, 12, 24, 48 e 96 dias. A densidade taxonômica esteve negativamente correlacionada com o peso remanescente. A elevada densidade de organismos coletores, como Chironomidae, Oligochaeta e Amphipoda, no último dia de incubação ocorreu provavelmente devido ao aumento de matéria orgânica particulada fina nas etapas mais avançadas da decomposição. Os maiores valores de diversidade a foram observados para o 3º e 96º dias de experimento, enquanto a diversidade b mostrou que esses dois dias apresentaram a maior variação na composição taxonômica, apresentando, portanto uma composição faunística diferente. Este estudo mostrou que ocorreu modificação na estrutura...

Invertebrates, Fungal Biomass, and Leaf Breakdown in Pools and Riffles of Neotropical Streams

“…In this study, the k values (pools: k  = 0.013 d; riffles: k  = 0.021 d) were low in comparison to recorded k values for leaf breakdown of high nutritional quality from the Atlantic Rain Forest: Piper divaricatum (Piperaceae; k  = 0.182 d), Campomanesia xanthocarpa (Myrtaceae; k  = 0.052 d), Myrcia rostrata (Myrtaceae; k  = 0.042 d), and Cupania vernalis (Sapindaceae; k  = 0.037 d; see Moulton and Magalhães 2003, Tonin et al 2014). Moreover, in this same Brazilian biome, our k values was similar to those of Erythrina verna (Fabaceae; k  = 0.0202 d), M. rostrata (Myrtaceae; k  = 0.019 d) and leaf mixtures from Alchornea glandulosa and Cabralea canjerana (Euphorbiaceae and Meliaceae; k  = 0.028 d; see Moulton et al 2010, Gonçalves et al 2012b, Oliveira et al 2014). These species have low hardness and high values of N and P compared to plants of other biomes, such as the Brazilian cerrado.…”

First record of Nais schubarti Marcus, 1944 (Oligochaeta: Naididae) in the State of São Paulo

“…According to Alves et al (2008), Petsch et al (2015), Maroneze et al (2011) and Ragonha et al (2014), these organisms can be found living on sandy substrates or in organic matter enriched environments (Behrend et al, 2012). In addition, these organisms are also recorded associated with aquatic macrophytes and leaf litter (Trivinho-Strixino et al, 2000;Alves and Gorni, 2007;Gorni and Alves, 2007;Oliveira et al, 2014) with sponges (Gorni and Alves, 2008) gastropods (Gorni and Alves, 2006), insect larvae (Corbi et al, 2004) and amphibians (Oda et al, 2015). Recent studies (Gorni et al, 2015) recorded 75 species of aquatic oligochaetes in the State of São Paulo, in which 64 species (85%) belong to the Naididae family.…”

Habitat-specific benthic metabolism in a Mediterranean-type intermittent stream

“…We buried a metal chamber base y 180 mm diameter in the stream sediments (two per habitat -randomly placed). A sample of intact substrate was removed from the river bottom and gently placed on the base, where it was left submerged in the stream for 3-5 days to allow macroinvertebrates recolonization (assuming that previous studies at perennial streams of O 'Connor, 1991;Boyero, 2003;Oliveira et al, 2014 will be similarly applicable to our system). In most benthic community studies, the bases were left for longer periods (Bott et al, 1978).…”