Single cell gel electrophoresis as a tool to assess genetic damage in Heleobia cf. australis (Mollusca: Gastropoda) as sentinel for industrial and domestic pollution in Montevideo bay (Uruguay)

O conhecimento dos danos no DNA em organismos aquáticos de áreas poluídas é uma questão importante, já que a contaminação pode vir a alterar os organismos em níveis subletais. Apesar dos moluscos terem sido amplamente utilizados para monitorar a poluição da água, não há registros de estudos in vivo de genotoxicidade. Heleobia cf. australis é um pequeno gastrópode amplamente distribuído em quase todos os ecossistemas costeiros uruguaios, inclusive em locais altamente poluídos. O ensaio do cometa é um biomarcador genético do dano baseado na migração de fragmentos de DNA com carga negativa produzidas por agentes mutagênicos. Foram coletados indivíduos vivos na Baía de Montevidéu (área impactada) e Laguna Garzón (área controle) para analisar a presença de agentes mutagênicos que ocasionassem dano genético. Células de organismos da área impactada apresentaram níveis significativamente mais elevados de danos genéticos do que os obtidos na área controle. Esse nível de dano foi medido pela porcentagem de DNA na cauda. Embora preliminar, esta abordagem apoia a noção de que H. cf. australispoderia ser usado como sentinela para avaliar a presença de agentes mutagênicos em ambientes estuarinos, alertando sobre o impacto da poluição em estágios iniciais.The knowledge of the extent of DNA damage in aquatic organisms in polluted areas is an important issue because contamination may alter their health at sublethal levels. Although molluscs have been widely used to monitor water pollution, there are no records of in vivo genotoxicity studies. Heleobia cf. australis, is distributed in almost all Uruguayan coastal ecosystems, including highly polluted sites. The comet assay is a damage genetic biomarker based on the migration of negatively charged DNA fragments produced by mutagenic agents in individual cells. Live individuals were collected in the Montevideo Bay (impacted area) and Laguna Garzón (control) to analyze the presence of mutagenic agents in the former site through comet assay. Cells from organisms of the impacted area showed significantly higher levels of genetic damage than those obtained in the control population, measured by percentage of DNA in the tail. Although preliminary, this approach supports the idea that H. cf. australis could be used as a sentinel to evaluate the presence of mutagenic agents in estuarine environments, alerting to the impact of contamination in its early stages

Response of estuarine free-living nematode assemblages to organic enrichment:an experimental approach

Organic enrichment, especially from anthropogenic sources, is one of the currentthreats to coastal marine biodiversity. Organic enrichment occurs mainly in sheltered soft bottoms,characterized by fine sediments, and results in multiple changes in the benthic habitat, includinghypoxia and an increased concentration of compounds that are toxic to marine invertebrates. Wereport on the results of a microcosm-based experiment (duration = 30 d), quantifying the effects oforganic enrichment on taxonomic and functional diversity of nematode assemblages from anopen/closed coastal lagoon of South America (Rocha Lagoon, Uruguay). In open/closed lagoons,the input of organic matter becomes a major disturbance due the limitation in water renewal. Inour experiment, enrichment led to reductions in abundance, richness and trophic diversity of thenematode assemblage. Rapid reductions in total abundance (after 4 d) were registered, while richnessdecreased only towards the end of the experiment (~30 d). Trophic changes were characterizedby loss of predators/omnivores and dominance of selective deposit-feeders and epigrowthfeeders.By contrast, we did not find any selective effect of enrichment associated with life historytraits (e.g. maturity index). Overall, these findings have 2 important implications for the conservationand monitoring of the health of coastal lagoons: first, monitoring of nematode assemblages atthe genus level is sufficient to detect enrichment effects; second, an index of trophic diversitywould be a good indicator of the effects of enrichment on natural communities.Fil: Kandratavicius, Noelia. Universidad de la República de Uruguay; UruguayFil: Pastor, Catalina Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; ArgentinaFil: Venturini, Natalia. Universidad de la República de Uruguay; UruguayFil: Giménez, Luis. Bangor University; Reino UnidoFil: Rodriguez, Marcel. Universidad de la República de Uruguay; UruguayFil: Muniz, Pablo. Universidad de la República de Uruguay; Urugua

Biogeochemistry of surface sediments in an Antarctic nearshore area affected by recent glacier retreat: Collins Harbour, King George Island

Biochemical composition of sedimentary organic matter, grain size, major and trace elements were analysed at 10 sampling stations in Collins Harbour, Maxwell Bay, to evaluate sources of particulate material in the seafloor. Surface sediment samples were taken with a grab, during the ANTAR XXV expedition in January 2018, onboard the BAP Carrasco from the Peruvian Navy. Coarse sediment fractions decreased, while mud content increased towards the centre of the bay. Positive correlation between mud and the biopolymeric carbon (BPC) indicated depositional conditions and organic material accumulation in the deepest central area. Proteins (PRT) predominated over other biochemical classes contributing to labile organic carbon, followed by lipids (LIP) and carbohydrates (CHO). PRT positive correlation with Ba, Ca and Al indicated that labile organic carbon inputs derived from marine primary production. Whereas, PRT positive correlation with K and Ti suggested also the influence of terrestrial supply through Collins Glacier meltwater runoff. Mn/Ti, Mn/Al and Fe/Al ratios decreased towards the centre of the bay, while the Ba/Al ratio showed the opposite trend. This distributional pattern suggested the diminish of glacial and terrigenous sedimentation towards the deepest central area of the bay, with the increment of marine particulate material deposition and accumulation. Igeo values between 0 and 1 showed unpolluted conditions in Collins Harbour for Cr, Ni, Cu, Zn, As and Pb, which concentrations may reflect background values for this area. Natural inputs from weathering, glacial runoff and marine primary production are main sources of particulate material in Collins Harbour, with none detected anthropogenic contributions

Biogeochemical and oceanographic conditions provide insights about current status of an Antarctic fjord affected by relatively slow glacial retreat

Comprender el origen, el transporte y el carácter de la materia orgánica que ingresa a los fiordos antárticos es esencial, ya que son componentes importantes del ciclo y presupuesto global del carbono. Se analizaron como indicadores de fuente depósitos macromoleculares de materia orgánica particulada, geoquímica orgánica a granel, elementos principales y traza en sedimentos superficiales de la Bahía de Collins. Como factores de control ambiental se consideraron las condiciones oceanográficas, la batimetría (multihaz) y el tamaño de grano. Las muestras de sedimentos fueron tomadas con una cuchara van Veen, durante la XXV expedición peruana ANTAR (febrero 2018), a bordo del B/O “ BAP Carrasco” de la Armada del Perú. La composición biopolimérica reveló el predominio de materia orgánica marina fresca rica en proteínas en el fondo marino de la Bahía de Collins, lo que denota un recurso alimentario de alta calidad para los heterótrofos bentónicos marinos. Según los valores de Igeo (entre 0 y 1), la Bahía de Collins se puede considerar no contaminada con niveles naturales de As, Cd, Cr, Cu, Fe, Mn, Ni, Pb y Zn. La distribución de la mayoría de estos elementos con un gradiente de disminución desde el fiordo interior poco profundo hacia el fiordo exterior más profundo, sugiere su asociación con la deposición de material detrítico y partículas litogénicas suministradas por la ablación frontal y la escorrentía del glaciar Collins. Esta primera información de referencia integral ayudaría a interpretar las reconstrucciones sedimentarias descendentes y los futuros cambios inducidos por el clima

Variación en pequeña escala de la estructura horizontal y vertical de comunidades macrobentónicas en una laguna costera del Atlántico Sudoccidental = Small-scale variation of the horizontal and vertical structure of macrobenthic communities in a coastal lagoon of the southwestern Atlantic

La Laguna de Rocha forma parte de la cadena de lagunas costeras que se extienden por la costa atlántica uruguaya y se continúa por el sur de Brasil. Presenta una dinámica ecológica compleja debido al gradiente marino-salobre. La macrofauna bentónica es un componente importante de estos ambientes estuariales que se ve afectada por la compleja dinámica del mismo. Analizamos cómo afectan las lenguas de arena (acumulaciones de arena perpendiculares a la barra) a la fauna macrobentónica. Se buscó establecer la relación del macrobentos con variables ambientales, a una escala vertical (estratos dentro del sedimento), y horizontal (a un lado y al otro de las lenguas), además de evaluar la influencia de la distancia a la intrusión marina. En todos los puntos de muestreo los parámetros ambientales (materia orgánica, fósforo total, oxígeno disuelto, clorofila-ay feopigmentos) presentaron una tendencia vertical (disminución hacia el fondo) y el macrobentos se relacionó con estos cambios. Se observó la dominancia de Heleobia australis, Nephtys fluviatilisy Heteromastus similisen diferentes estaciones y estratos. Existe una partición espacial de los recursos reflejada por estos cambios de dominancia, mientras quela distribución vertical de la comunidad macrobentónica responde tanto a las condiciones bióticas como a las ambientales

Variación en pequeña escala de la estructura horizontal y vertical de comunidades macrobentónicas en una laguna costera del Atlántico Sudoccidental

: Rocha Lagoon is part of the chain of coastal lagoons extended along Uruguayan Atlantic coast, which continues through southern Brazil. It presents a complex ecological dynamic due to the marine-brackish gradient. The benthic macrofauna is an important component of these estuarine environments which is affected by its complex dynamics. In the present work, we analysed how sand-tongues (sand accumulation perpendicular to the sandbar) affects the macrobenthic fauna. We stablished the relationship between macrobenthos and environmental variables on a vertical (different depths within the sediment) and horizontal (both sides of the sand-tongues) scales, as well as evaluating the influence of the distance to the marine intrusion. In all the sampling points, the environmental parameters (organic matter, total phosphorus, dissolved oxygen, chlorophyll-aand phaeopigments) showed a vertical trend (decreasing towards the bottom), and the macrobenthos responded to these changes. The dominance of Heleobia australis, Nephtys fluviatilisand Heteromastus similiswas observed in different sampling points and sediment depths. There is a spatial partition of resources reflected by these changes in dominance, while the vertical distribution of the macrobenthic community responds to both biotic and environmental conditions.La Laguna de Rocha forma parte de la cadena de lagunas costeras que se extienden por la costa atlántica uruguaya y se continúa por el sur de Brasil. Presenta una dinámica ecológica compleja debido al gradiente marino-salobre. La macrofauna bentónica es un componente importante de estos ambientes estuariales que se ve afectada por la compleja dinámica del mismo. Analizamos cómo afectan las lenguas de arena (acumulaciones de arena perpendiculares a la barra) a la fauna macrobentónica. Se buscó establecer la relación del macrobentos con variables ambientales, a una escala vertical (estratos dentro del sedimento), y horizontal (a un lado y al otro de las lenguas), además de evaluar la influencia de la distancia a la intrusión marina. En todos los puntos de muestreo los parámetros ambientales (materia orgánica, fósforo total, oxígeno disuelto, clorofila-ay feopigmentos) presentaron una tendencia vertical (disminución hacia el fondo) y el macrobentos se relacionó con estos cambios. Se observó la dominancia de Heleobia australis, Nephtys fluviatilisy Heteromastus similisen diferentes estaciones y estratos. Existe una partición espacial de los recursos reflejada por estos cambios de dominancia, mientras quela distribución vertical de la comunidad macrobentónica responde tanto a las condiciones bióticas como a las ambientales

The state of the art of Xyalidae (Nematoda, Monhysterida) with reference to the Brazilian records

In the current study we provide a reviewed list of valid genera and species of Xyalidae, a widespread family of mostly marine free-living nematodes. Comments are added about the historic background and taxonomic situation of the family, all valid genera and, when necessary, diagnostic characters are given. Additionally, information about distribution and geographical location of species recorded along the Brazilian coast is provided. Our review recognized 46 valid genera, 450 valid species and 73 descriptions without enough morphological information for identification (species inquerendae). Nearly 80 % of the species inquerendae belong to Daptonema and Theristus. To avoid homonymies, two Daptonema species were renamed, Daptonema biwaensis (Tsalolikhin, 2002) new name (former Mongolotheristus timoshkini) and Daptonema vietnamensis (Gagarin and Thu, 2008) new name (former D. curvatum sensu Gagarin and Thu, 2008). Cenolaimus sapeloensis is transferred to Xyala sapeloensis comb. nov. Along the Brazilian coast 28 genera and 41 species have been recorded. The species Elzalia floresi, Metadesmolaimus tersus, Paramonohystera stricta, Pseudosteineria scopae, Rhynchonema cemae, R. veronicae, Steineria ericia, S. marcorum, S. pavo, S. tripartita, Theristus acribus, T. flevensis, T. macroflevensis, T. pertenuis, T. stranus, Trichotheristus heterus, T. setosus and Zygonemella striata have the Brazilian coast as the type locality. Among all species, three occurred across three geographic regions, while the large majority was restricted to one. Xyalidae is typically encountered in oceanic sandy beaches, with only the species belonging to Daptonema, Theristus, Trichotheristus and Zygonemella being recorded in estuarine sediments. This observation suggests that the colonization of inland waters occurred multiple times along the evolutionary history

Ecología de la comunidad meiobentónica de estuarios uruguayos :una aproximación mediante múltiples escalas

Tribunal: Dr. Daniel Conde, Dr. Diego Lercari, Dra. Natalia Venturini.Orientador: Dr. Pablo Muniz.Co-orientador: Dr. Luis Giméne