Interacciones entre el mejillón dorado y macroinvertebrados bentónicos nativos del Río Uruguay

Los efectos que Limnoperna fortunei ocasiona sobre los ecosistemas vienen siendo estudiados en los últimos años a nivel nacional. No obstante, las interacciones que este invasor establece con la fauna bentónica nativa no han sido determinadas en detalle. El objetivo de este estudio fue recopilar información sobre las interacciones entre el mejillón dorado y macroinvertebrados nativos del Río Uruguay, a través de (a) relevamiento bibliográfico, (b) registro fotográfico obtenido en campo y (c) análisis de datos de un experimento de colonización realizado previamente en litorales rocosos de este río. Las interacciones reportadas en la bibliografía refirieron mayoritariamente a interacciones directas de biofouling de L. fortunei sobre especies de bivalvos y gasterópodos nativos, con potencial efecto negativo para estos individuos. La documentación fotográfica permitió reportar, por primera vez en la región, una interacción directa de L. fortunei con la familia Spongillidae, mediante la cual estos poríferos cubren y sofocan a mejillones ya asentados. Finalmente, a través del experimento realizado in situ se encontró que el mejillón genera efectos negativos indirectos sobre algunos macroinvertebrados bentónicos nativos. Según el análisis de datos, una alta abundancia de mejillones asentados se relaciona con una reducción en las abundancias de dos de los grupos bentónicos nativos dominantes de este río, como son los gasterópodos y dípteros

Interações entre o mexilhão dourado e os macroinvertebrados bentônicos nativos do Rio Uruguai

The ecosystem effects of Limnoperna fortunei have been studied nationally in recent years. However, the interactions that this invader establishes with the native benthic fauna have not been determined in detail. The objective of this study was to collect information on the interactions between the golden mussel and macroinvertebrates native to the Uruguay River, through (a) bibliographic survey, (b) photographic record obtained in the field and (c) analysis of data from an experiment of colonization carried out previously on rocky shores of this river. The interactions reported in the bibliography mainly referred to direct interactions of L. fortunei biofouling on native bivalve and gastropod species, with a potential negative effect for these individuals. The photographic documentation specifically made it possible to report for the first time in the region, a direct interaction of L. fortunei with the Spongillidae family, through which these porifers cover and suffocate already settled mussels. Finally, through the experiment carried out in situ, it was found that the mussel generates indirect negative effects on some native benthic macroinvertebrates. According to the data analysis, a high abundance of settled mussels is related to a reduction in the abundances of two of the dominant native benthic groups of this river, such as gastropods and dipterans.Los efectos que Limnoperna fortunei ocasiona sobre los ecosistemas vienen siendo estudiados en los últimos años a nivel nacional. No obstante, las interacciones que este invasor establece con la fauna bentónica nativa no han sido determinadas en detalle. El objetivo de este estudio fue recopilar información sobre las interacciones entre el mejillón dorado y macroinvertebrados nativos del Río Uruguay, a través de (a) relevamiento bibliográfico, (b) registro fotográfico obtenido en campo y (c) análisis de datos de un experimento de colonización realizado previamente en litorales rocosos de este río. Las interacciones reportadas en la bibliografía refirieron mayoritariamente a interacciones directas de biofouling de L. fortunei sobre especies de bivalvos y gasterópodos nativos, con potencial efecto negativo para estos individuos. La documentación fotográfica permitió reportar, por primera vez en la región, una interacción directa de L. fortunei con la familia Spongillidae, mediante la cual estos poríferos cubren y sofocan a mejillones ya asentados. Finalmente, a través del experimento realizado in situ se encontró que el mejillón genera efectos negativos indirectos sobre algunos macroinvertebrados bentónicos nativos. Según el análisis de datos, una alta abundancia de mejillones asentados se relaciona con una reducción en las abundancias de dos de los grupos bentónicos nativos dominantes de este río, como son los gasterópodos y dípteros.Os efeitos que o Limnoperna fortunei causa nos ecossistemas foram estudados nos últimos anos em nível nacional. No entanto, as interações que este invasor estabelece com a fauna bentônica nativa não foram determinadas em detalhes. O objetivo deste estudo foi coletar informações sobre as interações entre o mexilhão dourado e macroinvertebrados nativos do Rio Uruguai, por meio de (a) levantamento bibliográfico, (b) registro fotográfico obtido em campo e (c) análise de dados de um experimento de colonização realizada anteriormente em costões rochosos deste rio. As interações relatadas na bibliografia referem-se principalmente às interações diretas de L. fortunei bioincrustantes em espécies nativas de bivalves e gastrópodes, com potencial efeito negativo para esses indivíduos. A documentação fotográfica especificamente possibilitou relatar, pela primeira vez na região, uma interação direta de L. fortunei com a família Spongillidae, através da qual esses poríferos cobrem e sufocam mexilhões já assentados. Por fim, por meio do experimento realizado in situ, constatou-se que o mexilhão gera efeitos negativos indiretos sobre alguns macroinvertebrados bentônicos nativos. De acordo com a análise dos dados, uma alta abundância de mexilhões assentados está relacionada a uma redução nas abundâncias de dois grupos bentônicos nativos dominantes deste rio, como gastrópodes e dípteros

A Global Assessment of the Effects of Eucalyptus Plantations on Stream Ecosystem Functioning

Forest change is a major environmental problem worldwide. Forest streams, with their large aquatic–terrestrial interface and strong dependence on terrestrially derived organic matter, are highly sensitive to forest changes. Fast-wood plantations can be particularly threatening if they markedly differ from native forests. Eucalyptus plantations, in particular, cover large areas worldwide (> 20 million ha, mostly from 35°S to 35°N), but their effects on stream functioning have been addressed mostly in the Iberian Peninsula, which limits generalization to other regions. We assessed the effect of eucalyptus plantations on total (microbial decomposers and macroinvertebrates; in coarse mesh bags) and microbial-driven (in fine mesh bags) leaf litter decomposition by comparing streams flowing through native forests and eucalyptus plantations in seven regions in the Iberian Peninsula, Central Africa and South America. We found an overall significant inhibition of total litter decomposition by 23%. The effect did not significantly differ across regions, although a significant inhibition was found for Spain (− 41%), South Brazil (− 31%) and Uruguay (− 36%) (Portugal had a marginally nonsignificant inhibition by 50%) but not for other regions, suggesting that the effects of plantations in temperate climates are mediated through effects on macroinvertebrate communities. Contrarily, the overall effect for microbial-driven litter decomposition was non-significant, but it significantly differed across regions with a significant stimulation in Central Brazil (110%) and Uruguay (32%), and nonsignificant effects for other regions (Kenya had a marginally nonsignificant inhibition by 48%), suggesting that functional redundancy among microbial communities is not general and effects can occur if plantations induce changes in nutrient availability, solar irradiation or litter characteristics

Global Patterns and Controls of Nutrient Immobilization On Decomposing Cellulose In Riverine Ecosystems

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature

Length–weight relationships of 26 fish species from the middle section of the Negro River (Tacuarembó-Durazno, Uruguay)

This study provides data on the length–weight relationship (LWR) for 26 species of neotropical fishes. Specimens were collected between 2008 and 2009 from a dam-enclosed section of the middle Negro River (Uruguay). This study represents the first reference on length–weight relationships for 17 species, and also provides new maximum sizes for eight species