ABSTRACT: In this study, we analyzed the hypothesis that the combination of Nitrospirillum amazonense strain BR11145 with biological fertilizer prepared using Microgeo® and native microbiome from location of the product application results in morphological and nutritional gains for the initial development of sugarcane plants and soil chemistry. For this purpose, pre-sprouted sugarcane seedlings were grown in a greenhouse mesocosm experiment using soil amended with nitrogen/phosphorus/potassium fertilizer. The experimental treatments consisted of: 1) biological fertilizer with the addition of N. amazonense (100 mL ha-1), 2) biological fertilizer without the addition of N. amazonense, 3) inoculation with N. amazonense at a dose of 100 mL ha-1 with 2x108 viable cell mL-1, 4) inoculation with N. amazonense at a dose of 200 mL ha-1 with 2x108 viable cell mL-1, and 5) control, without the addition of biological fertilizer and N. amazonense. The biological fertilizer was applied at dose of 300 L ha-1, which was split at planting (200 L ha-1) and in the post-emergence phase (100 L ha-1). After 164 days of planting, it was detected an increase in leaf length +3, number of green leaves, leaf area and sulfur content in the leaves of sugarcane plants that received the biological fertilizer with the addition of N. amazonense. In conclusion, the combination of N. amazonense with biological fertilizer revealed positive effects through morphological and nutritional characteristics in sugarcane plants during their early stages of development when compared to plants grown only with the inoculation of N. amazonense, biological fertilizer or mineral fertilizers, with few notable positive effects on soil chemistry.

RESUMO: Neste estudo avaliou-se a hipótese de que a combinação de Nitrospirillum amazonense estirpe BR11145 com adubo biológico preparado com base em microbioma autóctone da localidade de aplicação do produto, produzido com Microgeo®, resulta em benefícios morfológicos e nutricionais para o desenvolvimento inicial de plantas de cana-de-açúcar e para a química do solo. Para tanto, mudas pré-brotadas de cana-de-açúcar foram crescidas em mesocosmos num experimento conduzido em casa-de-vegetação com solo enriquecido com fertilizante à base de nitrogênio/fósforo/potássio. Os tratamentos avaliados foram: 1) adubo biológico acrescido de N. amazonense (100 mL ha-1), 2) adubo biológico sem o acréscimo de N. amazonense, 3) inoculação de N. amazonense na dose de 100 mL ha-1 (2x108 células viáveis por mL), 4) inoculação de N. amazonense na dose de 200 mL ha-1 (2x108 células viáveis por mL), e 5) testemunha, sem a adição de fertilizante biológico e N. amazonense. O adubo biológico foi aplicado na dose de 300 L ha-1 sendo esta parcelada no plantio (200 L ha-1) e na fase de pós-emergência (100 L ha-1). Após 164 dias do plantio constatou-se aumento no comprimento da folha +3, número de folhas verdes, área foliar e no teor de enxofre nas folhas das plantas de cana-de-açúcar que receberam o adubo biológico combinado com N. amazonense. Conclui-se que a combinação de N. amazonense com o adubo biológico produzido com Microgeo® revelou efeitos positivos por meio de caraterísticas morfológicas e nutricionais em plantas de cana-de-açúcar durante os seus estádios iniciais de desenvolvimento quando comparadas com plantas crescidas apenas com a inoculação de N. amazonense, fertilizante biológico ou fertilizantes minerais, com poucos efeitos positivos notáveis na química do solo.

Resumo Objetivo A quantidade e a qualidade da água são essenciais para manutenção de muitos serviços ecossistêmicos, biodiversidade e bem-estar humano. No presente trabalho, utilizamos um experimento de campo para avaliar a percepção visual do público em relação à perda de qualidade da água associada à eutrofização e esverdeamento da água. Nós hipotetizamos que, com um aumento na eutrofização (ou seja, esverdeamento da água devido ao aumento da clorofila-a), as pessoas podem detectar uma perda de qualidade da água e ameaças aos serviços ecossistêmicos. Métodos Nós utilizamos uma área experimental composta por seis mesocosmos (caixas d'água de 500L) com gradiente de clorofila-a variando de águas claras (sem clorofila-a) até mesocosmos eutróficos (águas muito verdes). Um total de 100 pessoas visitaram a área experimental in-situ, e 83 pessoas visualizaram imagens dos mesocosmos. Resultados Nossos resultados indicaram que as pessoas foram capazes de detectar a perda de qualidade da água associada ao aumento das concentrações de clorofila-a, e reconheceram que estas eram menos adequadas para atividade recreativa e consumo. Além disso, essa percepção não variou por gênero, educação formal ou frequência de visitas aos ecossistemas aquáticos. Conclusões Os resultados evidenciam potencial da percepção visual do público como uma estratégia simples, rápida e de alerta precoce para programas de monitoramento da qualidade da água e também uma abordagem que fortalece o vínculo entre ciência e sociedade.

Abstract Aim The quantity and quality of water are essential to many ecosystem services, biodiversity and human well-being. In the present paper, we used a field experiment to evaluate the visual perception of the public regarding the loss of water quality associated with eutrophication and greening of water. We hypothesized that with an increase in eutrophication (i.e. greening of water due to increased Chlorophyll-a), people can detect a loss of water quality and threats to ecosystem services. Methods We used an experimental area composed of six mesocosms (500L water tanks) with a gradient of chlorophyll-a varying from clear water (without chlorophyll-a) up to eutrophic mesocosms (very green water). A total of 100 people visited the experimental area in-situ, and 83 people visualized pictures of the mesocosms. Results Our results indicated that people were able to detect the loss of water quality associated with increased concentrations of chlorophyll-a, and recognized that these were less suitable for recreational activity and consumption. Moreover, this perception did not vary by gender, formal education, or frequency of visits to aquatic ecosystems. Conclusions The results highlight the clear potential of visual public perception to be used as a simple, rapid, early-warning strategy for monitoring programs of water quality and also an approach that strengthens the link between science and society.

Resumo Objetivo Os efeitos da densidade de espécies vizinhas e da disponibilidade de nutrientes no sedimento são essenciais para compreender as regras de estruturação de comunidades de macrófitas emergentes. O objetivo deste trabalho foi investigar como a densidade de Polygonum ferrugineum e a disponibilidade de nutrientes no sedimento influenciam o estabelecimento de Alternanthera philoxeroides. Métodos Após a coleta, seccionamos os caules de cada espécie de modo que cada propágulo obtido fosse composto de dois nós. Esses propágulos foram plantados em bandejas com sedimento úmido para o enraizamento e desenvolvimento de novas folhas por 24 dias e, só então foram transferidos para os mesocosmos experimentais. Nosso delineamento experimental contou com um propágulo de A. philoxeroides submetido aos seguintes tratamentos: I – controle (plantado sozinho); II – associado com três propágulos de P. ferrugineum; III – associado a cinco propágulos de P. ferrugineum. Houve 36 mesocosmos dispostos dentro da casa de vegetação, com metades deles representando condições de baixa disponibilidade de nutrientes e metade representando condições de alta disponibilidade de nutrientes (com 12,5 g de NPK no sedimento). O experimento durou 60 dias, sendo medido as seguintes variáveis respostas: comprimento aéreo, comprimento da raiz e biomassa seca da parte aérea, raiz e total. As variáveis respostas relacionadas a biomassa foram obtidas após as plantas secarem em estufa a 60°C. Também calculamos o índice de interação relativa (RII) para cada tratamento, com o intuito de analisar as interações entre as espécies. Cada variável resposta foi analisada através de uma Anova two-way. Resultados Entre os principais resultados obtidos, pode-se destacar o menor acumulo de biomassa em A. philoxeroides em condições de baixa disponibilidade de nutrientes e de alta densidade de P. ferrugineum. Conclusões Esses resultados indicam os efeitos negativos da densidade de P. ferrugineum sobre o estabelecimento de A. philoxeroides, contribuindo para a compreensão da dinâmica e das regras de estruturação da comunidade de macrófitas emergentes.

Abstract Aim The effects of neighbor’s species density and nutrient availability in the sediment are essential to understand the structuring rules of emergent macrophyte communities. The objective of this paper was to investigate how the density of Polygonum ferrugineum and the availability of nutrients in the sediment influence the establishment of Alternanthera philoxeroides. Methods After collection, we sectioned the stems of each species so that each propagule obtained was composed of two nodes. These propagules were planted in trays with moist sediment for rooting and development of new leaves for 24 days, and only then were transferred to the experimental mesocosms. Our experimental design had an A. philoxeroides propagule submitted to the following treatments: I – control (planted alone); II – associated with three P. ferrugineum propagules; III – associated with five P. ferrugineum propagules. There were 36 mesocosms arranged inside the greenhouse, with half of them representing conditions of low nutrient availability and half representing conditions of high nutrient availability (with 12.5 g of NPK in the sediment). The experiment lasted 60 days, and the following response variables were measured: aerial length, root length, aerial, root and total dry biomass. The response variables related to biomass were obtained after the plants were dried in an oven at 60°C. We also calculated the relative interaction index (RII) for each treatment, in order to analyze the interactions between the species. Each response variable was analyzed using a two-way ANOVA. Results Among the main results obtained, we can highlight the lower accumulation of biomass in A. philoxeroides under conditions of low nutrient availability and high density of P. ferrugineum. Conclusions These results indicate the negative effects of P. ferrugineum density on the establishment of A. philoxeroides, contributing to the understanding of the dynamics and structuring rules of the emergent macrophyte community.

ABSTRACT The need to seek alternatives to improve crop nutrition given the low fertility of agricultural soils and the shortage of fertilizers is becoming increasingly important. One of these alternatives is the application of organic fertilizers and inoculation with arbuscular mycorrhizal fungi (AMF). The objective of the present work was to investigate the effect of vermicompost applications and the inoculation of a mycorrhizal biofertilizer on the nutrient supply of a Gley Nodular Ferruginous soil for pearl millet plants (Panicum italicum L.). Two experiments were carried out under mesocosmic conditions at the National Institute of Agricultural Sciences (INCA), four proportions of soil-vermicompost were studied, with and without mycorrhizal inoculation, in a completely randomized design with factorial structure and three repetitions. The height, the dry mass of the aerial biomass and the concentration and quantity of nutrients in plants, the frequency and intensity of colonization and the number of spores in the soil were evaluated. The application of vermicompost increased the availability of soil nutrients and it was reflected in the increase of the concentration and quantity of nutrients in the plants, which led to greater growth and development of these; in the presence of the pearl millet, the vermicompost application decreased the frequency and intensity of mycorrhization, which inhibited.

RESUMEN La necesidad de buscar alternativas para mejorar la nutrición de los cultivos ante la baja fertilidad de los suelos agrícolas y la escasez de fertilizantes, cobra cada día mayor importancia. Una de estas alternativas es la aplicación de abonos orgánicos y la inoculación con hongos micorrízicos arbusculares (HMA). El objetivo del presente trabajo fue investigar el efecto de las aplicaciones de vermicompost y la inoculación de un biofertilizante micorrízico sobre el suministro de nutrientes de un suelo Gley Nodular Ferruginoso para plantas de millo perla (Panicum italicum L.). Se ejecutaron dos experimentos en condiciones de mesocosmos en el Instituto Nacional de Ciencias Agrícolas (INCA), se estudiaron cuatro proporciones de suelo-vermicompost, con y sin la inoculación micorrízica, en un diseño completamente aleatorizado con estructura factorial y tres repeticiones. Se evaluaron la altura, la masa seca de la biomasa aérea y la concentración y cantidad de nutrientes en las plantas, la frecuencia e intensidad de la colonización y el número de esporas en el suelo. La aplicación de vermicompost incrementó la disponibilidad de nutrientes del suelo y se reflejó en el incremento de la concentración y la cantidad de nutrientes en las plantas, lo que originó mayor crecimiento y desarrollo de estas; en presencia del millo perla la aplicación de vermicompost hizo disminuir la frecuencia e intensidad de la micorrización, lo que inhibió el efecto de la inoculación con hongos micorrízicos arbusculares y no se afectó la producción de esporas en el suelo.

Abstract: The discharge of pollutants of anthropogenic origin with the presence of nutrients such as Nitrogen (N) and phosphorus (P), can trigger the eutrophication of bodies of water, due to the fact that excess nutrients cause an imbalance in aquatic ecosystems. The implementation of treatment systems based on biological processes emerge as an economically profitable alternative, with the possibility of generating value-added by-products in the process. In the present work, the applicability of the use of duckweed in the complementary treatment of effluents from Rotary Contact Biological Reactors (RBC) systems was evaluated with the aim of reducing the concentration of nutrients and generating enriched biomass. We worked with synthetic wastewater initially treated in a laboratory-scale RBC system. The effluent was subsequently used for the 96-hour growth of the Landoltia punctata species, on a mesocosm scale. The results indicate that removal percentages higher than 50% and 70% were obtained for N-NH and PO 3 4 respectively. Regarding the valuation of the biomass generated postharvest of L. punctata, the percentage of total proteins on average was 29.2% and for total lipids it was obtained on average 9.8%. The results obtained indicate the applicability of the species L. punctata for the polishing of effluents, demonstrating its effectiveness in the removal of nutrients and in the generation of biomass with high nutritional value, which can be implemented in animal nutrition.

Resumen: La descarga de contaminantes de origen antropogénico con presencia de nutrientes como Nitrógeno (N) y fósforo (P), pueden, desencadenar la eutrofización de cuerpos de agua, debido a que el exceso de nutrientes causa un desequilibrio en ecosistemas acuáticos. La implementación de sistemas de tratamiento basados en procesos biológicos surge como una alternativa económicamente rentable, con la posibilidad de generar subproductos de valor agregado en el proceso. En el presente trabajo se evaluó la aplicabilidad del uso de la lenteja de agua en el tratamiento complementario de efluentes provenientes de sistemas Reactores Biológicos Rotativos de Contacto (RBC) con el objetivo de reducir la concentración de nutrientes y generar biomasa en- riquecida. Se trabajó con agua residual sintética tratada inicialmente en un sistema RBC a escala laboratorio, el efluente de posteriormente se utilizó para el crecimiento durante 96 horas de la especie Landoltia punctata, a escala mesocosmos. Los resultados indican que se obtuvieron porcentajes de remoción superiores a 50% y 70% para el N-NH3 y PO43 respectivamente. En cuanto a la valorización de la biomasa generada poscosecha de L. punctata, el porcentaje de proteínas totales en promedio fue de 29,2% y para lípidos totales se obtuvo en promedio 9,8%. Los resultados obtenidos indican la aplicabilidad de la especie L. punctata para el pulido de efluentes, demostrando su eficacia en la remoción de nutrientes y en la generación de biomasa con alto valor nutritivo pudiendo ser implementadas en nutrición animal.

ABSTRACT Mining is one of the most important industrial activities in many countries; however, environmental damages associated with this activity are severely detrimental. These effects are a consequence, among other things, of heavy metals originated by mineral extraction methods. To reduce the environmental impact of this activity, it is important to develop remediation technologies, including the symbiotic relationships between species that allow high survival and proper development of plants. Therefore, a mesocosm assay was carried out to document the response of Fraxinus uhdei (Wenz.) Lingelsh (ash) inoculated with ectomycorrhizal fungi on two different substrates: a mine-derived substrate from the municipality of Tlalpujahua de Rayón, Michoacán, and an organic one. The study consisted in the inoculation of F. uhdei plants with two fungi strains, Laccaria laccata and Lactarius deliciosus, on two doses: 2.5 × 105 and 1 × 106 spores per plant. Ectomycorrhizal fungi favored the development and survival in both substrates; however, the performance of the plants was higher with the organic substrate. Height, cover, and fresh weight of plants inoculated with Laccaria laccata were the highest (66 cm, 1186 cm2, and 92 g, respectively). Mercury was lower in plants inoculated with Lactarius deliciosus (F(1, 28) = 12.22; P = 0.002) with respect to those inoculated with Laccaria laccata. Our results indicate that inoculation has a positive effect on ash growth both in an organic rich substrate and a substrate produced by mining activities, also the potential use of the tree species for remediation of mining dumps.

RESUMEN La minería es una actividad industrial importante en muchos países, a pesar de lo cual los daños que causa son cada día más graves por su impacto ecológico. Lo anterior se debe, entre otras cosas, a los efectos de los residuos de metales pesados originados por los diversos métodos de extracción de minerales. Para reducir el impacto ambiental de esta actividad es importante estudiar relaciones simbióticas entre especies que permitan favorecer la supervivencia y el desarrollo de plantas en sitios degradados por la minería, y, de esta manera, mejorar su estructura al incorporar materia orgánica y reiniciar ciclos biogeoquímicos. Por lo tanto, se llevó a cabo un ensayo en mesocosmos para documentar la respuesta de Fraxinus uhdei (Wenz.) Lingelsh (fresno) inoculado con hongos ectomicorrízicos en dos sustratos diferentes: uno proveniente de un jal del municipio de Tlalpujahua de Rayón, Michoacán, sitio donde se desarrolló actividad minera; y otro orgánico. El experimento consistió en someter a individuos de F. uhdei a inoculación con Laccaria laccata y Lactarius deliciosus con dos dosis: 2.5 × 105 y 1 × 106 de esporas por planta). Los hongos ectomicorrízicos favorecieron el desarrollo y supervivencia de las plantas en ambos sustratos. El desempeño de las plantas fue mayor en el sustrato orgánico, ya que la altura, cobertura y peso fresco de las plantas inoculadas con Laccaria laccata fueron mayores (66 cm, 1186 cm2 y 92 g, respectivamente) respecto a los otros tratamientos. La concentración de mercurio fue menor para las plantas inoculadas con Lactarius deliciosus (F(1, 28) = 12.22; p = 0.002) respecto a las inoculadas con Laccaria laccata. Este estudio indica que la inoculación favorece el desarrollo de plantas de fresno tanto en un sustrato orgánico como en un sustrato derivado de la actividad minera; asimismo, exhibe el potencial de la especie arbórea para la recuperación de sustratos mineros.

RESUMEN Esta investigación evaluó los cambios en la población cultivable de bacterias de vida libre fijadoras de nitrógeno (BVLFN) y de bacterias solubilizadoras de fósforo (BSP), así como en la nodulación de raíces por rizobios nativos, y en la colonización y número de esporas de hongos micorrízicos arbusculares (HMA) en la rizósfera de Clitoria ternatea y Brachiaria brizantha cultivadas en mesocosmos contaminados con petróleo crudo (0, 3000, 6000, 9000 y 12000 mg kg-1), durante 240 días. A las 24 h de la contaminación del suelo, las poblaciones más altas de BVLFN y BSP (5,5 y 4,9 LogUFC, respectivamente) se encontraron en el control, mientras que las poblaciones más bajas se obtuvieron a 12000 mg kg-1 (5,1 y 4,2 LogUFC, respectivamente). En contraste, a los 60 y 240 días, el control mostró bajas poblaciones de BVLFN y BSP (5,4 y 4,8 LogUFC, respectivamente) que los tratamientos contaminados. El mayor número de nódulos en raíz de C. ternatea se cuantificó en el control a los 60 y 240 días (25 y 27 nódulos, respectivamente) en comparación con el tratamiento con 12000 mg kg-1 (7 y 1 nódulos, respectivamente). A los 60 días, la colonización de HMA en ambas especies vegetales y el número de esporas disminuyeron significativamente al aumentar la concentración de petróleo crudo; sin embargo, a los 240 días, se registró el mayor número de esporas de HMA en los tratamientos con 6000 y 12000 mg kg-1. El peso seco vegetal disminuyó significativamente al aumentar las concentraciones de petróleo crudo. Clitoria ternatea fue más susceptible a la toxicidad del petróleo, aunque esta especie vegetal mostró mayor contenido de clorofila total que B. brizantha.

ABSTRACT This research evaluated the changes on populations of culturable N-fixing free bacteria (NFFB) and P-solubilizing bacteria (PSB), as well as on the root nodulation by native rhizobia, the root colonization and spore number of arbuscular mycorrhizal fungi (AMF), in the rhizosphere of Clitoria ternatea and Brachiaria brizantha grown in mesocosms contaminated with crude oil (0, 3000, 6000, 9000, and 12000 mg kg-1), for 240 days. After 24 h of soil contamination, the highest populations of NFFB and PSB (5.5 and 4.9 LogUFC, respectively) were found in control, and the lowest populations were obtained at 12000 mg kg-1 (5.1 and 4.2 LogUFC, respectively). In contrast, at 60 and 240 days, the control showed lower populations of NFFB and PSB (5.4 and 4.8 LogUFC, respectively) than contaminated treatments. The highest number of root nodules in C. ternatea was quantified in control at 60 and 240 days (25 and 27 nodules, respectively) in comparison to those observed at the treatment with 12000 mg kg-1 (7 and 1 nodule, respectively). At 60 days, AMF colonization in both plant species, and the number of spores significantly decreased as the crude oil concentration increased; however, at 240 days, the highest number of AMF spores was recorded at treatments with 6000 and 12000 mg kg-1. The dry weight of both plant species significantly decreased as crude oil concentrations increased. Although C. ternatea was more susceptible to the toxic effects of crude oil, this plant species showed greater content of total chlorophyll than B. brizantha.

Abstract Evaluating soil structure dynamics is a major challenge when analysing or modelling pedogenesis. Constructed Technosols are considered, by definition, to be good candidates for pedogenetic studies, insofar as their initial characteristics and implementation conditions are controlled. Thus, we developed an approach based on image analysis of soil microstructures in order to specify the structure dynamics of a constructed Technosol. We described and quantified porosity and aggregation descriptors on a microscale (1) from pictures of mesocosms performed during 14 months, using an innovative automatic high-resolution image-acquisition device (Soilinsight®), and (2) from thin sections sampled in situ in a 1 ha field experiment at t0 and t2 (17 months). Plant root system architecture of Lupinus albus and the behavior of introduced earthworms (Lumbricus castaneus) were described using the Soilinsight®device. After 14 months, the pore surface was 10 times greater in the presence of plants and macrofauna than in the control samples. Although the biological activity promoted the genesis of aggregates, their dynamics were irregular. In fact, the proportion of aggregates varied depending on both root age and worm action. In situ, the soil was progressively compacted due to a significant decrease in the number of >2000 µm pores. In the same way, three aggregate descriptors-number, area and shape-were selected as the most significant indicators of soil aggregation evolution during the early stages of pedogenesis. In conclusion, this approach, based on the quantification of microstructure parameters, did indeed allow the description and monitoring of 2D soil structure dynamics in both field and mesocosms conditions. Completed with 3D soil structure data, this micromorphological analysis could advantageously contribute to the impact of climatic and biological agents modelling on a structural evolution of Technosols during initial pedogenesis.

Resumen La evaluación de la dinámica estructural del suelo es una de las principales dificultades para analizar o modelar edafogénesis. Los Tecnosuelos construidos son considerados, por definición, como buenos candidatos para el estudio de la edafogénesis, ya que tanto sus características iniciales como las condiciones de implementación están controladas. Así, desarrollamos un enfoque basado en el análisis de imagen de las microestructuras del suelo para especificar la dinámica estructural de un Tecnosuelo construido. Describimos y cuantificamos los descriptores de porosidad y agregación a microescala en (1) imágenes captadas de un experimento en mesocosmos desarrollado durante 14 meses, mediante la utilización de un sistema innovador para la adquisición automática de imágenes de alta resolución (Soilinsight®) y en (2) láminas delgadas muestreadas in situ en una parcela experimental de 1 ha a t0 y t2 (17 meses). La arquitectura del sistema radical de Lupinus albus y el comportamiento de las lombrices (Lumbricus castaneus) introducidas en los mesocosmos fueron descritos gracias al sistema Soilinsight®. Después de 14 meses, la superficie de los poros es 10 veces mayor en presencia de plantas y macrofauna que en los controles. Si bien la actividad biológica promovió la formación de los agregados, su dinámica fue irregular. De hecho, la proporción de agregados varió en función de la edad de las raíces y de la acción de las lombrices. In situ, el suelo ha sufrido una compactación progresiva debido a una disminución significativa del número de poros > 2000 µm. De la misma forma, tres descriptores de los agregados -número, área y forma- han sido seleccionados como los indicadores más significativos de la evolución de la agregación del suelo durante las fases tempranas de la edafogénesis. En conclusión, el enfoque basado en la cuantificación de parámetros microestructurales ha permitido la descripción y monitoreo en 2D de la dinámica estructural del suelo en condiciones de campo y de mesocosmos. Este análisis micromorfológico, combinado con datos de la estructura del suelo en 3D, puede contribuir a la modelación del impacto de agentes climáticos y biológicos sobre la evolución estructural de Tecnosuelos durante las primeras fases de la edafogénesis.

Abstract Background: Wetlands are heterogeneous and dynamic ecosystems, very susceptible to invasions or local extinctions by the effects of invasive or over-dominant plant species. Resistance to invasion in wetlands that suffer disturbances such as fires has not been thoroughly studied. When Phragmites australis (common read) is present, its interaction with disturbance factors has led to local extinction of many native species. In a previous study, it was determined that harvesting is an effective control method for this species. But removal of aerial parts of this species generates many fragments that might propagate the species. Goals: Evaluate under controlled conditions the invasive potential of fragments of Phragmites australis in plant communities dominated by native plant species that are subjected to frequent human-made disturbances, such as fire, under controlled conditions. Methods: We carried out an experiment that consisted of two assays in 36 mesocosms with canopies of Schoenoplectus americanus. Results: Phragmites australis was practically not able to establish itself after the loss of the S. americanus canopy following fires, because the canopy of this last species recovered rapidly. Survival and growth were slightly higher in mesocosms with low disturbance (27.7% and 55.9 cm in the first assay, and 9.4%, and 60.6 cm in the second assay), when compared with controls (8.5% 35.3 cm, and 7.4% and 86.7 cm), because in control units the canopy of S. americanus was a permanent barrier to the development of P. australis. Height differences among burned and control mesocosms after the first fire event were significant (p =0.002) but not after two consecutive years of burning (p =0.085), because the few plants that survived in control units reached considerable height. Conclusions: The risk of establishment of the fragments of Phragmites australis that are generated during harvesting is low even after major disturbances of native vegetation cover.

Resumen Antecedentes: Los humedales son ecosistemas heterogéneos y dinámicos muy susceptibles a sufrir invasiones o extinciones locales por especies invasoras o sobredominantes. La resistencia a la invasión de los humedales ante factores de disturbio como el fuego ha sido poco estudiada. Cuando Phragmites australis (carrizo) se encuentra presente, su interacción con factores de disturbio ha llevado a la extinción local de muchas especies nativas. En un estudio anterior se determinó que la cosecha de esta especie es una estrategia efectiva de control. Sin embargo, la remoción de las partes aéreas genera múltiples fragmentos a partir de los cuales se podría propagar la especie. Objetivos: Evaluar, ante disturbios ocasionados por el fuego, en condiciones controladas, el potencial de invasión de fragmentos de Phragmites australis en comunidades dominadas por especies nativas. Métodos: El experimento se efectuó bajo dos quemas en 36 mesocosmos con doseles de Schoenoplectus americanus y P. australis. Resultados: Los resultados establecieron que las plantas de Phragmites australis no lograron desarrollarse después de las quemas del dosel de S. americanus, debido a la rápida recuperación del dosel de esta segunda especie. Se registró mayor supervivencia y crecimiento en los mesocosmos con bajo disturbio (27.7% y 55.9 cm en el primer ensayo; 9.4% y 60.6 cm en el segundo ensayo) en comparación con los controles (8.5%, 35.3 cm y 7.4% y 86.7 cm), ya que el dosel de S. americanus se mantuvo como una barrera al desarrollo de P. australis en los controles. Las diferencias en la altura fueron significativas después del primer evento de fuego entre los mesocosmos quemados y los de control (p =0.002), pero después de dos años de quema no lo fueron (p =0.085), debido a que las pocas plantas que sobrevivieron en los mesocosmos control alcanzaron alturas considerables. Conclusiones: Los fragmentos de P. australis representan bajo riesgo para sitios con dosel de S. americanus después de un año de registrar disturbios como el fuego.

El presente estudio, evaluó el efecto de la bioestimulación en la biorremediación de un suelo contaminado con alquitrán generado durante la producción de carbón vegetal artesanal. Se empleó suelo contaminado con alquitrán (∼12,000 mg TPH/kps) proveniente del área de estudio y se montaron ocho (8) mesocosmos (n=2), simulando condiciones de biolabranza bajo un entorno controlado en laboratorio por un periodo de 60 días. Se evaluaron dos tratamientos: fertilizante inorgánico compuesto (FIC) y urea más K2HPO4 (U), además de dos controles: atenuación natural y abiótico. Adicionalmente, se realizó el seguimiento del proceso de biorremediación a través de la medición de variables fisicoquímicas (Temperatura, pH, porcentaje de humedad, carbono orgánico, nutrientes e hidrocarburos totales de petróleo-TPHs) y microbiológicas (Recuento en placa de microorganismos heterótrofos y de degradadores de alquitrán). El mayor porcentaje de remoción de TPHs, se obtuvo en el tratamiento con FIC (28%), seguido del tratamiento con U (24%) y por último, el control de Atenuación Natural (6%). Se concluyó, que la adición de nutrientes estimuló la densidad de microorganismos heterótrofos y degradadores, lo cual optimizó el proceso de biodegradación de suelos contaminados con alquitrán, evidenciado por una disminución significativa en la concentración de TPHs en los tratamientos al final del estudio.

In this research, the effect of biostimulation on the bioremediation of a soil contaminated with tar generated during the production of artisanal charcoal was evaluated. Eight (8) laboratory mesocosm (n=2) containing tar-contaminated soil (12,000 mgTPH/kgps) taken from an artisanal charcoal factory were evaluated during 60 days under two land farming treatments and two control systems: addition of inorganic compound fertilizer (FIC), addition of urea plus K2HPO4 (U), abiotic control and natural attenuation. In addition, the performance of the bioremediation treatments was evaluated through monitoring of physiochemical (temperature, pH, moisture content, organic carbon, nutrients and total petroleum hydrocarbons-TPHs) and microbiological parameters (heterotrophic plate count microorganisms and degraders of tar). The highest removal percentage of TPH was obtained through FIC treatment (28%), followed by treatment with U (24%) and natural attenuation (6%). It was concluded that the addition of nutrients stimulated a growth in the density of heterotrophic microorganisms and degraders, which optimized the biodegradation process of the soil contaminated with tar, as evidenced by a significant decrease in the concentration of TPH for the treatments at the end of the study.

Abstract: Photosynthetic activity was estimated, in 2 different sets of experiments, as in vivo chlorophyll a fluorescence in 2 calcareous red macroalgae: Neogoniolithon brassica-florida, which forms vermetid reefs with Dendropoma petraeum, and the rhodolith-forming Lithophyllum margaritae. In the first set of experiments, vermetid reefs collected from the Cabo de Gata-Níjar Natural Park (Almería, Spain) were incubated for 6 months in outdoor mesocosms at 2 different temperatures: ambient temperature (T) and ambient temperature plus 2 oC (T+). Daily variations in effective quantum yields were related to the increase in solar radiation. Electron transport rate (ETR) was higher at T+ than at T. Oxygen production, estimated from ETR, was higher in N. brassica-florida growing in vermetid reefs in the coastal area than in those incubated in mesocosms or under laboratory conditions. In the second set of experiments, L. margaritae specimens with or without attached epifauna (mainly sponges) were collected at 2 sites (Pedregoso and CFE) on the Baja California Peninsula, Mexico, and at 2 depths (1 and 2 m). ETR values for rhodoliths collected at 1 m depth and with attached epifauna were higher than those for rhodoliths collected at 2 m depth, indicating the importance of greater incident radiation on photosynthetic activity. Photosynthetic activity was higher in L. margaritae collected from Pedregoso, the site with better water quality (high transparency and low pollution) and rocky substrate availability. In the CFE samples, the photosynthetic efficiency (αETR) was highest in rhodoliths with attached epifauna. The highest ETR values for N. brassica-florida at T+ and the highest αETR or ETR values for L. margaritae with attached sponges may be explained by the increase in CO2 available for photosynthesis due to the respiration of the associated fauna. The usefulness of in vivo chlorophyll a fluorescence for estimating photosynthetic production in calcareous macroalgae under multifactorial experiments is discussed.

Resumen: La actividad fotosintética fue estimada, en 2 series experimentales, mediante la fluorescencia in vivo de la clorofila a en 2 algas rojas calcáreas: Neogoniolithon brassica-florida, que forma arrecifes de vermétidos con Dendropoma petraeum, y Lithophyllum margaritae (rodolitos). En la primera serie, vermétidos recolectados en el Parque Natural Cabo de Gata-Níjar (Almería, España) fueron incubados en mesocosmos a diferentes temperaturas: temperatura ambiental (T) y temperatura ambiental más 2 oC (T+). Las variaciones diurnas en el rendimiento cuántico efectivo estuvieron relacionadas con el incremento de irradiancia solar. La tasa de transporte de electrones (ETR) fue más alta en el tratamiento T+ que en T. La producción de oxígeno, estimada a partir de la ETR, fue mayor en N. brassica-florida del medio natural que en vermétidos incubados en mesocosmos o en el laboratorio. En la segunda serie experimental, L. margaritae con o sin epifauna (dominada por esponjas) fue recolectada en 2 sitios (Pedregoso y CFE) de la península de Baja California, México, a 2 profundidades (1 y 2 m). La ETR de rodolitos recolectados a 1 m de profundidad con epifauna asociada fue más alta que la de aquellos recolectados a 2 m de profundidad, indicando la importancia del incremento de la irradiancia sobre la producción fotosintética. La actividad fotosintética fue mayor en L. margaritae de Pedregoso, el lugar con mejor calidad de agua (alta trasparencia y baja contaminación) y con disponibilidad de sustrato rocoso. En CFE, la eficiencia fotosintética (α ETR) fue más alta en los rodolitos con epifauna. Los valores más altos de ETR para N. brassica-florida a T+ y de α ETR o ETR para L. margaritae con esponjas fijadas podrían ser explicados por el incremento de CO2 disponible para la fotosíntesis procedente de la respiración de la fauna asociada. En este trabajo se discute la utilidad de la fluorescencia in vivo de la clorofila a para estimar la fotosíntesis en macroalgas calcáreas en experimentos multifactoriales.

The contribution of the introduced species Amynthas gracilis (Kinberg, 1867) and Octolasion cyaneum (Savigny, 1826) to the physical stability of the soil was evaluated in a mesocosm experiment. Pore formation and stable aggregates were measured; as well as changes in bulk density, porosity, and soil moisture. Mesocosm pots were organized into three treatments: 1- soil + Amynthas gracilis, 2- soil + Octolasion cyaneum and 3- soil (control containers). The experiment ran for 13 weeks and it was conducted in controlled conditions in a greenhouse. At the end of the experiment both treatments with earthworms had higher number of pores and stable aggregates at the two considered depths (0 - 5 cm and 5 - 10 cm). The presence of both earthworm species favors the formation of a significantly higher proportion of stable aggregates larger than 5 mm (60%), when compared to the control without worms. These structures helped maintaining bulk density and porosity and improved water circulation. The results show that when compared to the control, both treatments had a lower loss of pore space, lower bulk density, and higher soil moisture, all attributable to earthworm presence. It is concluded that, despite both being introduced species, in intensive agricultural systems, A. gracilis and O. cyaneum can contribute to the maintenance of soil physical stability thus helping to preserve the sustainability of agro-ecosystems, even if native species became rare or locally extinct.

En un experimento de mesocosmos se evaluó la contribución a la estabilidad física del suelo de las especies introducidas Amynthas gracilis (Kinberg, 1867) y Octolasion cyaneum (Savigni, 1826). Se midió la formación de poros y de agregados estables, así como cambios en la densidad aparente, porosidad y humedad del suelo. Los contenedores de los mesocosmos fueron organizados en tres tratamientos: 1- suelo + A. gracilis, 2. Soil + O. cyaneum, and 3. Soil (contenedores control). El experimento se realizó a lo largo de 13 semanas en condiciones controladas en invernáculo. Al final del experimento los tratamientos con ambas especies generaron poros y mostraron mayor proporción de agregados estables a las dos profundidades consideradas (0 - 5 cm y 5 - 10 cm). Ambas especies de lombrices facilitaron la generación de una proporción significativamente mayor de agregados mayores a 5 mm (60%), en comparación con los controles sin lombrices. Estas estructuras ayudaron a mantener la densidad aparente y la porosidad y mejoraron la circulación de agua. Los resultados muestran que, comparados con el control, ambos tratamientos tuvieron una menor pérdida de espacio de poros, menor densidad aparente y mayor humedad de suelo, todos atribuibles a la presencia de las lombrices. Se concluyó que, a pesar de ser ambas especies introducidas, en sistemas agrícolas intensivos A. gracilis y O. cyaneum pueden contribuir al mantenimiento de la estabilidad del suelo, ayudando así a preservar la sustentabilidad de los agroecosistemas, aun cuando las especies nativas puedan convertirse en raras o localmente extintas.

ResumoObjetivo: A tilápia do Nilo - Oreochromis niloticus (Linnaeus 1758) - é um peixe exótico com alimentação onívoro-filtradora que tem sido estocado por três décadas em lagos artificiais do Nordeste do Brasil. A maioria dos experimentos manipulando peixes onívoro-filtradores em lagos e reservatórios eutrofizados mostra que sua presença tende a aumentar a biomassa fitoplanctônica e a produção primária. Neste estudo, testou-se a hipótese de que a tilápia interage sinergicamente com o enriquecimento de nutrientes, de modo que os efeitos de peixes onívoros sobre o fitoplâncton tornam-se mais intensos com o aumento da concentração de nutrientes.MétodosUm experimento de campo com delineamento fatorial 2×3 foi realizado durante quatro semanas em 24 mesocosmos (0,25 m3), nos quais seis tratamentos foram aleatoriamente alocados: adição de peixes alevinos (F), adição de tilápia juvenil (J), adição de nutrientes (NP), adição de nutrientes e alevinos (NPA), nutrientes e tilápia juvenil (NPJ) e um tratamento controle, sem tilápias ou nutrientes (C). Uma ANOVA bifatorial com medidas repetidas foi realizada para testar os efeitos do tempo (t), da tilápia e dos nutrientes, além da interação entre tilápias e nutrientes sobre as concentrações de fósforo total, nitrogênio total e clorofila a.ResultadosOs resultados mostraram um efeito positivo da adição de nutrientes sobre as concentrações de fósforo total, nitrogênio total e clorofila; e um efeito positivo das tilápias sobre a concentração de clorofila a. Como esperado, verificou-se uma interação sinérgica entre o efeito positivo da tilápia do Nilo e do enriquecimento por nutrientes na biomassa fitoplanctônica.ConclusõesOs resultados sugerem que o controle da abundância de tilápias, através do manejo da pesca, é uma ferramenta potencial para melhorar a qualidade da água e mitigar os efeitos da eutrofização em lagos e reservatórios.

Aim: The Nile tilapia - Oreochromis niloticus(Linnaeus 1758) - is an exotic omnivorous filter-feeding fish that has been stocked for three decades in man-made lakes of Northeastern Brazil. Most experiments manipulating omnivorous filter-feeding fish in eutrophic lakes and reservoirs shows that their presence tends to increase phytoplankton biomass and primary production. In this study, we tested the hypothesis that tilapia interact synergistically with nutrient enrichment so that the effects of omnivorous fish on phytoplankton biomass becomes more intense with increasing nutrient concentration.MethodsA field experiment with a 2×3 factorial design was performed during four weeks in twenty-four mesocosms (0.25 m3) to which six treatments were randomly allocated: fingerling addition (F), juvenile tilapia addition (J), nutrient addition (NP), nutrient and fingerling addition (NPF), nutrient and juvenile tilapia addition (NPJ) and a control treatment with no tilapia or nutrients addition (C). A two-way repeated measures ANOVA was done to test for time (t), tilapia and nutrients effects and their interaction on total phosphorus, total nitrogen and chlorophyll-a concentrations.ResultsThe results showed a positive effect of nutrient addition on total phosphorus, total nitrogen and chlorophyll-a concentrations and a positive effect of tilapia on the concentration of chlorophyll-a. As expected, we found a synergistic interaction between the positive effect of Nile tilapia and nutrient enrichment on phytoplankton biomass.ConclusionsThe above results suggest that controlling tilapia abundance through fisheries management is a potential tool to improve water quality and mitigate the effects of lake and reservoir eutrophication.

OBJETIVOS: Este estudo visou testar experimentalmente a influência de um peixe planctófago filtrador (Tilapia rendalli) sobre a dinâmica fitoplanctônica de um reservatório tropical pequeno e raso (Lago Monte Alegre, Brasil). Adultos de T. rendalli deste lago alimentam-se preferencialmente de fitoplâncton e nossas hipóteses são: I) adultos de T. rendalli reduziriam a biomassa e composição do fitoplâncton através da herbivoria direta, e II) como este é um sistema eutrófico, o peixe poderia não ter grande influência sobre o fitoplâncton através da ciclagem de nutrientes. MÉTODOS: para avaliar esses diferentes efeitos sobre as algas, um experimento de campo foi feito no período de verão durante 15 dias em mesocosmos isolados do sedimento, usando um grupo controle (sem peixe) e um grupo tratamento (com um peixe em cada mesocosmo). As variáveis físicas e químicas e o fito- e zooplâncton foram avaliados no início, meio e fim do experimento. RESULTADOS: No final do experimento, foi observado um incremento significativo nas concentrações de íon amônio, biomassa fitoplanctônica total, de cianobactérias e zignemafíceas e de todas as classes de tamanho, exceto a classe II (20-30 µm) no grupo tratamento (com peixe). Foi observado o incremento da biomassa de uma cianobactéria potencialmente tóxica (Cylindrospermopsis raciborskii) no tratamento com peixe, no final do período experimental. CONCLUSÃO: Este estudo não deu suporte às duas hipóteses iniciais. Ele suporta a afirmação de que em corpos de água tropicais, com características semelhantes ao ambiente estudado, peixes planctófagos filtradores, como T. rendalli, não são efetivos na redução da biomassa fitoplanctônica através da herbivoria direta, mesmo sendo o fitoplâncton um dos seus principais itens alimentares. T. rendalli pode contribuir para o incremento da biomassa fitoplanctônica e pode promover ou incrementar a eutrofização de sistemas aquáticos.

AIM: This study aimed to experimentally test the influence of a planktivorous filter-feeding fish (Tilapia rendalli) on the phytoplankton dynamics of a small and shallow tropical reservoir (Lake Monte Alegre, Brazil). Adults of T. rendalli of this lake feed preferentially on phytoplankton, and we hypothesize that: I) adults of T. rendalli will decrease the phytoplankton biomass and composition through direct herbivory, and II) as it is a eutrophic system, fish would not have strong influence on phytoplankton through nutrient cycling. METHODS: To evaluate these different effects on algae, a field experiment was performed in the summer period for 15 days, in mesocosms isolated from the sediment, using a control group (no fish) and a treatment group (with one fish in each mesocosm). Physical and chemical variables and phyto- and zooplankton were evaluated at the start, middle, and end of the experiment. RESULTS: At the end of the experiment, it was observed a significant increase in ammonium concentrations and total phytoplankton biomass, Cyanobacteria and Zygnemaphyceae and all size classes except class II (20-30 µm) in the treatment group (with fish). The biomass increase of the potentially toxic cyanobacterium Cylindrospermospsis raciborskii was also observed in the fish treatment at the end of the experimental period. CONCLUSION: This study did not support both initial hypotheses. It supports the assertion that in tropical water bodies, with similar characteristics to the environment studied, planktivorous filter-feeding fish, such as T. rendalli, are not effective in reducing phytoplankton biomass through direct grazing, even when phytoplankton is one of their main food items. T. rendalli can contribute to the increase of phytoplankton biomass and can promote or increase the eutrophication of aquatic systems.

OBJETIVO: Avaliar o crescimento de Eichhornia crassipes (Mart.) Solms e Salvinia molesta Mitchell em tanques utilizados para o tratamento de efluente de aquicultura e comparar os resultados com dados da literatura a fim de estimar o ponto de saturação de nutrientes. MÉTODOS: Um experimento com seis tanques retangulares divididos em dois tratamentos, entrada e saída (maior e menor concentração de nutrientes, respectivamente), e as duas macrófitas aquáticas citadas acima foi realizado durante 50 dias. Um quadrante de 0,25 m² com amostras de E. crassipes e S. molesta da entrada e da saída dos tanques foi coletado semanalmente para estimar a massa fresca das macrófitas. No início e no final do experimento amostras das macrófitas foram secas em estufa a 60 ºC até peso constante para determinar a massa seca. A massa seca das macrófitas foi estimada por regressão linear simples entre a massa fresca e a massa seca (MS). RESULTADOS: As concentrações de N e P foram significativamente (P<0.05) maiores na entrada (em média 0,66 mg L-1 e 233,6 mg L-1, respectivamente) do que na saída dos tanques (em média 0,38 mg L-1 e 174,7 mg L-1, respectivamente). Entretanto, não foi observada diferença significativa no crescimento das macrófitas cultivadas na maior e menor concentração de nutrientes. Na maior e menor concentração, o ganho de biomassa de E. crassipes foi, respectivamente, de 428,5 e 402,7 g MS.m². Para S. molesta, o ganho de biomassa foi de 135,2 e 143,1 g de MS.m², na entrada e saída respectivamente. Estudos já demostraram elevado crescimento de E. crassipes e S. molesta em concentrações de nitrogênio (0.14 - 0.18 mg L-1) e fósforo (14.2 - 77.0 mg L-1) menores que às deste estudo. CONCLUSÃO: A comparação do crescimento de E. crassipes e S. molesta observado neste estudo com os de outros nos permite assumir que o ponto saturação de nutrientes de E. crassipes deve estar abaixo de 0.26 mg L-1 de nitrogênio e 77 mg L-1 de fósforo; e de S. molesta pode estar abaixo de 0.19 mg L-1 de nitrogênio e 15.1 mg L-1 de fósforo.

AIM: To evaluate the growth of Eichhornia crassipes (Mart.) Solms and Salvinia molesta Mitchell in tanks used for treating aquaculture effluent and compare the results with literature data in order to estimate the nutrients saturation point. METHODS: An experiment with six rectangular fiberglass tanks were separated in two treatments, inflow and outflow (higher and lower nutrient concentration), and the two macrophytes above cited was carried out during 50 days. A floating quadrat with 0.25 m² of E. crassipes and S. molesta at inflow and outflow of the tanks was collected weekly for fresh mass measurement. At the beginning and end of the experiment samples of macrophytes were oven-dried at 60 ºC until constant weight to determine the dry mass. Dry mass of plants was estimated by a simple linear regression analysis between fresh mass and dry mass (DM). RESULTS: The N and P concentrations were significantly higher (P<0.05) in the inflow (mean of 0.66 mg L-1 and 233.6 mg L-1, respectively) than in the outflow of the tanks (mean of 0.38 mg L-1 and 174.7 mg L-1, respectively). However, no significantly different plant growth was observed for either higher or lower concentration. For both higher and lower nutrient concentrations, the biomass gain for E. crassipes was, respectively, 428.5 and 402.7 g DM.m². For S. molesta, biomass gain was 135.2 and 143.1 g DM.m², in the higher and lower concentrations, respectively. Others studies reported high growth of E. crassipes and S. molesta in concentrations of nitrogen (0.14 - 0.18 mg L-1) and phosphorus (14.2 - 77.0 mg L-1) lower than this study. CONCLUSION: The comparison of E. crassipes and S. molesta growth in this study with others allow us to assume that the saturation point of E. crassipes should be 0.26 mg L-1 of nitrogen and 77 mg L-1 of phosphorus and for S. molesta below 0.19 mg L-1 of nitrogen and 15.1 mg L-1 of phosphorus.