Forecasting the impact of an invasive macrophyte species in the littoral zone through aquatic insect species composition

Invasive macrophytes threaten freshwater ecosystem biodiversity. We analyzed the impact of the invasive white ginger lily (Hedychium coronarium J. Kõnig, Zingiberaceae) on aquatic insect assemblages living in the littoral zone of a tropical reservoir. We took aquatic insect samples in the littoral zone on four main vegetal profile banks: white ginger monotypic bank, forest partially invaded, native macrophyte monotypic bank and riparian forest. At each vegetal bank, we measured abiotic variables such as dissolved oxygen, pH, water temperature and depth. We analyzed the aquatic insects through abundance, richness and Simpson diversity. We used the non-Metric Multidimensional Scaling (nMDS) analysis to analyze the spatial distribution of each assemblage, and Analysis of similarities (ANOSIM) to verify differences amongst dissimilarity distances. Additionally, we analyzed the main taxa associated with invasive macrophytes through indicator species analyses using IndVal index. We observed that the invasive macrophyte banks presented higher abundance of associated specimens, as well as lower dissimilarity of aquatic insect assemblages. Additionally, invasive macrophytes shifted the water pH and littoral depth of reservoir banks. The IndVal index indicated eight aquatic insects as indicator species. Labrundinia unicolor Silva, 2013, Ablabesmyia depaulai Neubern, 2013 and Diastatops Rambur, 1842 were indicator species on banks. We concluded that invasion of white ginger lily caused loss of shallow littoral habitat and altered the pH of the surrounding water probably by high decomposition rate and high production of plant biomass. We suggest the use of species of aquatic insects as indicator species to monitor white ginger lily impact in freshwater systems.(AU)

Forecasting the impact of an invasive macrophyte species in the littoral zone through aquatic insect species composition

Invasive macrophytes threaten freshwater ecosystem biodiversity. We analyzed the impact of the invasive white ginger lily (Hedychium coronarium J. Kõnig, Zingiberaceae) on aquatic insect assemblages living in the littoral zone of a tropical reservoir. We took aquatic insect samples in the littoral zone on four main vegetal profile banks: white ginger monotypic bank, forest partially invaded, native macrophyte monotypic bank and riparian forest. At each vegetal bank, we measured abiotic variables such as dissolved oxygen, pH, water temperature and depth. We analyzed the aquatic insects through abundance, richness and Simpson diversity. We used the non-Metric Multidimensional Scaling (nMDS) analysis to analyze the spatial distribution of each assemblage, and Analysis of similarities (ANOSIM) to verify differences amongst dissimilarity distances. Additionally, we analyzed the main taxa associated with invasive macrophytes through indicator species analyses using IndVal index. We observed that the invasive macrophyte banks presented higher abundance of associated specimens, as well as lower dissimilarity of aquatic insect assemblages. Additionally, invasive macrophytes shifted the water pH and littoral depth of reservoir banks. The IndVal index indicated eight aquatic insects as indicator species. Labrundinia unicolor Silva, 2013, Ablabesmyia depaulai Neubern, 2013 and Diastatops Rambur, 1842 were indicator species on banks. We concluded that invasion of white ginger lily caused loss of shallow littoral habitat and altered the pH of the surrounding water probably by high decomposition rate and high production of plant biomass. We suggest the use of species of aquatic insects as indicator species to monitor white ginger lily impact in freshwater systems.

Forecasting the impact of an invasive macrophyte species in the littoral zone through aquatic insect species composition

ABSTRACT Invasive macrophytes threaten freshwater ecosystem biodiversity. We analyzed the impact of the invasive white ginger lily (Hedychium coronarium J. König, Zingiberaceae) on aquatic insect assemblages living in the littoral zone of a tropical reservoir. We took aquatic insect samples in the littoral zone on four main vegetal profile banks: white ginger monotypic bank, forest partially invaded, native macrophyte monotypic bank and riparian forest. At each vegetal bank, we measured abiotic variables such as dissolved oxygen, pH, water temperature and depth. We analyzed the aquatic insects through abundance, richness and Simpson diversity. We used the non-Metric Multidimensional Scaling (nMDS) analysis to analyze the spatial distribution of each assemblage, and Analysis of similarities (ANOSIM) to verify differences amongst dissimilarity distances. Additionally, we analyzed the main taxa associated with invasive macrophytes through indicator species analyses using IndVal index. We observed that the invasive macrophyte banks presented higher abundance of associated specimens, as well as lower dissimilarity of aquatic insect assemblages. Additionally, invasive macrophytes shifted the water pH and littoral depth of reservoir banks. The IndVal index indicated eight aquatic insects as indicator species. Labrundinia unicolor Silva, 2013, Ablabesmyia depaulai Neubern, 2013 and Diastatops Rambur, 1842 were indicator species on banks. We concluded that invasion of white ginger lily caused loss of shallow littoral habitat and altered the pH of the surrounding water probably by high decomposition rate and high production of plant biomass. We suggest the use of species of aquatic insects as indicator species to monitor white ginger lily impact in freshwater systems.

New species of Lopesia (Diptera, Cecidomyiidae) associated with Eichhornia azurea (Pontederiaceae) from Brazil / Nova espécie de Lopesia (Cecidomyiidae, Diptera) associada a Eichhornia azurea (Pontederiaceae) do Brasil

A new species of gall midge, Lopesia eichhorniae sp. nov. (Cecidomyiidae, Diptera), associated with rhizomes of Eichhornia azurea (Sw.) Kunth (Pontederiaceae) is described. This is the first record of Lopesia galls in this species of macrophyte, quite common in natural and artificial lakes in Southeast Brazil. Illustrations of the adults (male and female), pupa, larva, and gall of the new species are presented.(AU)

Uma espécie nova de cecidomiídeo galhador, Lopesia eichhorniae sp. nov. (Cecidomyiidae, Diptera), associada a rizomas de Eichhornia azurea (Sw.) Kunth (Pontederiaceae) está sendo descrita neste trabalho. Esse é o primeiro registro de galhas de Lopesia nessa espécie de macrófita, muito comum em lagos naturais e artificiais na região Sudeste do Brasil. Ilustrações de adultos e imaturos da espécie nova e de suas galhas são apresentadas.(AU)

New species of Lopesia (Diptera, Cecidomyiidae) associated with Eichhornia azurea (Pontederiaceae) from Brazil / Nova espécie de Lopesia (Cecidomyiidae, Diptera) associada a Eichhornia azurea (Pontederiaceae) do Brasil

A new species of gall midge, Lopesia eichhorniae sp. nov. (Cecidomyiidae, Diptera), associated with rhizomes of Eichhornia azurea (Sw.) Kunth (Pontederiaceae) is described. This is the first record of Lopesia galls in this species of macrophyte, quite common in natural and artificial lakes in Southeast Brazil. Illustrations of the adults (male and female), pupa, larva, and gall of the new species are presented.

Uma espécie nova de cecidomiídeo galhador, Lopesia eichhorniae sp. nov. (Cecidomyiidae, Diptera), associada a rizomas de Eichhornia azurea (Sw.) Kunth (Pontederiaceae) está sendo descrita neste trabalho. Esse é o primeiro registro de galhas de Lopesia nessa espécie de macrófita, muito comum em lagos naturais e artificiais na região Sudeste do Brasil. Ilustrações de adultos e imaturos da espécie nova e de suas galhas são apresentadas.

Emergence of Chironomidae (Insecta: Diptera) in a floodplain lake of the upper Paraná river, Mato Grosso do Sul State, Brazil / Emergência de Chironomidae (Insecta: Diptera) em uma lagoa de inundação do alto rio Paraná, Estado do Mato Grosso do Sul, Brasil

To investigate the emergence of Chironomidae in different habitats of a floodplain lake of the upper Paraná river floodplain, four collection points were established: marginal regions (one with numerous macrophytes species, other dominated by only Polygonum sp.), central region and linking channel. Adults were captured by surface emergence traps assembled every three months, from May 2001 to March 2002. The traps remained for a period of about 48 hours, obtaining quantitative data for richness and abundance. 944 adults distributed into three subfamilies and 40 taxa were captured. The taxa identified at the species level were: Goeldichironomus neopictus, G. petiolicola, G. maculatus, Tanytarsus ligulatus, Parachironomus atroari, P. guarani and P. cayapo. Higher abundances were observed for Polypedilum (Tripodura) sp.1 and Tanytarsus ligulatus. There was a considerable variation in the richness among the collection points, mainly on the marginal area, with 38 taxa. In the central region (five taxa) and in the linking channel, were registered the predominance of Aedokritus sp. The higher diversity and abundance of Chironomidae in the littoral area may be related to the presence of aquatic macrophytes that provide shelter and food, resulting in increased recruitment of new individuals in this region.(AU)

Para investigar a emergência de Chironomidae em diferentes habitats foram estabelecidos quatro pontos em uma lagoa de inundação da planície do alto rio Paraná: dois na região litorânea (um em região com muitas espécies de macrófitas e outro dominado somente por Polygonum sp.), um na região central e um no canal de ligação. Os adultos foram capturados em armadilhas de superfície de emergência (flutuantes) instaladas trimestralmente, de maio/2001 a março/2002. As armadilhas permaneceram por um período de 48±2h, obtendose dados quantitativos para riqueza e abundância. Foram capturados 944 adultos distribuídos em três subfamílias e 40 táxons. Os táxons identificados em nível específico foram: Goeldichironomus neopictus, G. petiolicola, G. maculatus, Tanytarsus ligulatus, Parachironomus atroari, P. guarani e P. cayapo. As maiores abundâncias foram de Polypedilum (Tripodura) sp.1 e Tanytarus ligulatus. Houve considerável variação na riqueza de adultos entre os pontos de coleta, principalmente na região litorânea, com 38 táxons. Na região central (cinco táxons) e no canal de ligação, foi registrada a predominância de Aedokritus sp. As maiores abundâncias e riquezas nas regiões litorâneas podem estar relacionadas à presença de macrófitas aquáticas, que fornecem abrigo e recursos alimentares, resultando em maior recrutamento de novos indivíduos nessa região.(AU)

Kinetics of the aerobic decomposition of Talauma ovata and Saccharum officinarum - doi: 10.4025/actascibiolsci.v34i4.9396

The aim of this study is to evaluate the kinetics of aerobic decomposition of Saccharum officinarum and Talauma ovata leaves. For each species, decomposition chambers (leaves and water) were set up, which were maintained under controlled conditions. Each sampling day (1, 7, 15, 30, 39, 58, 72 and 90 days), the concentrations of total organic carbon, pH and electrical conductivity (EC) were determined in the dissolved fraction, while the mass and cell wall fractions (CWF) were determined in the particulate fraction. The pH stabilization of the chambers with T. ovata and S. officinarum leaves occurred in alkaline (ca. 8 - 8.5) and close to the neutrality (ca. 7 - 7.5) environment, respectively. The EC values were on average 1.6 times higher in incubations with T. ovata leaves. The mass loss did not differ between the species (mean = 53.85%), however the decay coefficient was higher for S. officinarum (k4 = 0.007 day-1) than for T. ovata (k4 = 0.005 day-1) leaves. The CWF mass loss (mean = 50.16%) and their coefficient (0.0090 day-1) were similar. S. officinarum decomposed faster due to its high concentrations of energetic compounds of interest to the microbiota. The slower decomposition of T. ovata may have occurred due to the presence of secondary compounds with negative effects to the microorganisms.

Kinetics of the aerobic decomposition of Talauma ovata and Saccharum officinarum / Cinéticas da decomposição aeróbia de Talauma ovata e Saccharum officinarum

The aim of this study is to evaluate the kinetics of aerobic decomposition of Saccharum officinarum and Talauma ovata leaves. For each species, decomposition chambers (leaves and water) were set up, which were maintained under controlled conditions. Each sampling day (1, 7, 15, 30, 39, 58, 72 and 90 days), the concentrations of total organic carbon, pH and electrical conductivity (EC) were determined in the dissolved fraction, while the mass and cell wall fractions (CWF) were determined in the particulate fraction. The pH stabilization of the chambers with T. ovata and S. officinarum leaves occurred in alkaline (ca. 8 - 8.5) and close to the neutrality (ca. 7 - 7.5) environment, respectively. The EC values were on average 1.6 times higher in incubations with T. ovata leaves. The mass loss did not differ between the species (mean = 53.85%), however the decay coefficient was higher for S. officinarum (k4 = 0.007 day-1) than for T. ovata (k4 = 0.005 day-1) leaves. The CWF mass loss (mean = 50.16%) and their coefficient (0.0090 day-1) were similar. S. officinarum decomposed faster due to its high concentrations of energetic compounds of interest to the microbiota. The slower decomposition of T. ovata may have occurred due to the presence of secondary compounds with negative effects to the microorganisms.

O objetivo deste estudo foi avaliar as cinéticas da decomposição aeróbia de folhas de Talauma ovata e Saccharum officinarum. Para cada espécie foram montadas câmaras de decomposição (folhas e água) que foram mantidas sob condições controladas. A cada dia amostral (1, 7, 15, 30, 39, 58, 72 e 90 dias), as concentrações de carbono orgânico total, pH e condutividade elétrica (CE) foram determinadas na fração dissolvida, enquanto a massa e as frações de parede celular (FPC) foram determinadas na fração particulada. A estabilização do pH das câmaras com folhas de T. ovata e S. officinarum ocorreram em meio básico (ca. 8 - 8,5) e próximo à neutralidade (ca. 7 - 7,5), respectivamente. Os valores de CE foram em média 1,6 vezes maiores nas incubações com folhas de T. ovata. A perda de massa não diferiu entre as espécies (média = 53,85%). No entanto, o coeficiente de decaimento foi maior para as folhas de S. officinarum (k4 = 0,007 dia-1) que para T. ovata (k4 = 0,005 dia-1). As perdas de massa da FPC (média = 50,16%) e seus respectivos coeficientes (0,0090 dia-1) foram similares. S. officinarum decompôs mais rapidamente devido às elevadas concentrações de compostos energéticos de interesse para a microbiota. A decomposição mais lenta de T. ovata pode ter ocorrido pela presença de compostos secundários com efeitos negativos sobre os micro-organismos.

Kinetics of the aerobic decomposition of Talauma ovata and Saccharum officinarum - doi: 10.4025/actascibiolsci.v34i4.9396

The aim of this study is to evaluate the kinetics of aerobic decomposition of Saccharum officinarum and Talauma ovata leaves. For each species, decomposition chambers (leaves and water) were set up, which were maintained under controlled conditions. Each sampling day (1, 7, 15, 30, 39, 58, 72 and 90 days), the concentrations of total organic carbon, pH and electrical conductivity (EC) were determined in the dissolved fraction, while the mass and cell wall fractions (CWF) were determined in the particulate fraction. The pH stabilization of the chambers with T. ovata and S. officinarum leaves occurred in alkaline (ca. 8 - 8.5) and close to the neutrality (ca. 7 - 7.5) environment, respectively. The EC values were on average 1.6 times higher in incubations with T. ovata leaves. The mass loss did not differ between the species (mean = 53.85%), however the decay coefficient was higher for S. officinarum (k4 = 0.007 day-1) than for T. ovata (k4 = 0.005 day-1) leaves. The CWF mass loss (mean = 50.16%) and their coefficient (0.0090 day-1) were similar. S. officinarum decomposed faster due to its high concentrations of energetic compounds of interest to the microbiota. The slower decomposition of T. ovata may have occurred due to the presence of secondary compounds with negative effects to the microorganisms.