ABSTRACT Toxic cyanobacteria blooms are an increasingly common global problem due to eutrophication, the effects of climate change and increased surveillance efforts in aquatic ecosystems. In Cuba, several ecosystems have been analyzed in the eastern region, demonstrating that this risk occurs to surface and inland waters, due to climatic conditions, mainly in small ecosystems with great human pressures. However, other areas are still unexplored. The objective of this work was to implement a risk management protocol in the San Blas Lagoon, Camaguey, due to the presence of toxic cyanobacteria in the ecosystem, following a community report, with the death of domestic and wild animals; unpleasant odors and dermatological symptoms in humans. A management protocol and community actions were implemented to minimize the impact of toxic cyanobacteria. In this small eutrophic reservoir, the presence of a mixed bloom of toxigenic cyanobacteria was confirmed, being Spherospermopsis torques-reginae the majority, as well as other nine species associated with the production of microcystins, anatoxins and/or cylindrospermopsins were identified. Strategic actions were implemented to contain the risk situation, with the participation of the community and experts, led by the Camagüey Criminalistics Laboratory.

RESUMEN Las floraciones de cianobacterias tóxicas constituyen un problema global cada vez más frecuente, debido a la eutrofización, los efectos del cambio climático y a un mayor esfuerzo de vigilancia en los ecosistemas acuáticos. En Cuba se han muestreado varios ecosistemas en la región oriental, demostrando que este riesgo existe en aguas superficiales e interiores, debido a las condiciones climáticas, principalmente en pequeños ecosistemas con grandes presiones humanas. Sin embargo, otras zonas están aún inexploradas. El objetivo de este trabajo fue implementar un protocolo de gestión de riesgos en la Laguna San Blas, debido a la presencia de cianobacterias tóxicas en el ecosistema, a raíz de un reporte comunitario, con muerte de animales domésticos y silvestres; olor desagradable y síntomas dermatológicos en humanos. Se implementó un protocolo de gestión y acciones comunitarias para minimizar el impacto de las cianobacterias tóxicas. En este pequeño reservorio eutrófico se confirmó la presencia de una floración mixta de cianobacterias toxigénicas, siendo mayoritaria Spherospermopsis torques-reginae, identificándose otras nueve especies asociadas a la producción de microcistinas, anatoxinas y/o cilindrospermopsinas. Se implementaron acciones estratégicas para contener la situación de riesgo, con la participación de la comunidad y expertos, liderados por el Laboratorio de Criminalística de Camagüey.

Resumen: Antecedentes: Nostocales es un orden monofilético de cianobacterias, ampliamente distribuido, cuyas especies se caracterizan principalmente por la presencia de estructuras especializadas como heterocitos y acinetos. A pesar de ser el grupo más diverso en ambientes marinos, en México se conoce poco sobre las especies litorales. Particularmente en Veracruz solo se han registrado 17 especies, sin referencias fotográficas, morfológicas, ni datos ecológicos; estos registros solo se mencionan en listas florísticas. Preguntas y / o Hipótesis: El presente estudio tuvo como objetivo contribuir al conocimiento de la diversidad de especies Nostocales marinos bentónicos en Veracruz, México, así como brindar descripciones e ilustraciones detalladas de las especies encontradas, que puedan servir como referencia en estudios posteriores. Sitio y años de estudio: Se realizaron recolectas de crecimientos de cianobacterias en tres localidades de Veracruz en 2020. Métodos: A partir del material de campo se aislaron los organismos. Con el uso de claves taxonómicas especializadas se identificaron morfológicamente, describieron y fotografiaron. Resultados: Se obtuvo un total de 20 especies de Nostocales, de las cuales 17 fueron adiciones a la ficoflora de Veracruz, constituyendo un incremento del 55 %. Se agregan notas taxonómicas destacando las diferencias de estas con la literatura. Una de las especies fue identificada como cf. y siete como sp., debido a que sus características coincidían plenamente con la morfología genérica, pero no lo hacían completamente con la literatura. Conclusiones: Estos sugieren que varios registros podrían corresponder a nuevo taxón aún no descrita que deben ser confirmados con diferentes marcadores moleculares.

Abstract Background: Nostocales is a widely distributed, monophyletic order of cyanobacteria, whose species are mainly characterized by the presence of specialized structures such as heterocytes and akinetes. Despite being the most diverse group in marine environments, little is known about coastal species in Mexico. Particularly in Veracruz, only 17 species have been recorded, without photographic, morphological references, or ecological data; these records are only mentioned in floristic lists. Questions and / or Hypotheses: The present study aimed to contribute to the knowledge of the diversity of benthic marine Nostocales species in Veracruz, Mexico, as well as to provide detailed descriptions and illustrations of the species found, which can serve as a reference in subsequent studies. Study site and dates: Collect of cyanobacterial growths were made in three locations throughout Veracruz in 2020. Methods: The organisms were isolated from the field material. With the use of specialized taxonomic keys, they were morphologically identified, described and photographed. Results: A total of 20 Nostocales species were obtained, of which 17 were additions to the phycoflora of Veracruz, constituting an increase of 55 %. Taxonomic notes are added highlighting their differences with the literature. One of the species was identified as cf. and seven as sp., because their characteristics fully coincided with the generic morphology, but did not completely concur with the literature. Conclusions: These suggest that several records could correspond to new taxon not yet described that must be confirmed with different molecular markers.

Resumo Objetivo O objetivo deste estudo foi avaliar como a diversidade, dominância e raridade da comunidade fitoplanctônica são influenciadas por diferentes condições ambientais locais em lagos urbanos. Nós esperamos que a riqueza será influenciada negativamente em lagos com maiores concentrações de nutrientes e maior turbidez, enquanto a abundância será influenciada positivamente. Assim, haverá uma maior dominância de poucas espécies e menor raridade em lagos com essas condições, sendo esperado o contrário em lagos com menores concentrações de nutrientes e menor turbidez. Métodos As amostras do fitoplâncton e das variáveis abióticas foram coletadas em quatorze lagos distribuídos no município de Goiânia, Goiás, Brasil, durante um período chuvoso. Resultados Foi possível identificar uma heterogeneidade ambiental entre os lagos. Nós identificamos uma separação dos lagos em função da riqueza e densidade fitoplanctônica, especialmente devido à contribuição de algas verdes, desmídias e cianobactérias. A maioria dos lagos apresentou altos valores de diversidade e equitabilidade, com predominância de táxons raros e poucas espécies dominantes. As principais variáveis que estiveram relacionadas com o fitoplâncton, foram a temperatura da água, oxigênio dissolvido, turbidez e as concentrações de nutrientes. Conclusões Portanto, o estudo da diversidade, dominância e raridade baseada na riqueza e abundância fitoplanctônica e a sua relação com as diferentes condições ambientais locais pode ser um importante modelo na avaliação da qualidade da água em lagos urbanos. urbanos positivamente Assim Goiânia Goiás Brasil chuvoso verdes cianobactérias equitabilidade dominantes dissolvido Portanto

Abstract Aim The aim of this study was to evaluate how phytoplankton community diversity, dominance, and rarity are influenced by different local environmental conditions in urban lakes. We expect that richness will be negatively influenced in lakes with higher nutrient concentrations and high turbidity, while abundance will be positively influenced. Thus, lakes with these conditions will have greater dominance of a few species and lower rarity, and the opposite in lakes with lower nutrient concentrations and less turbidity. Methods Phytoplankton and abiotic variables samples were collected in fourteen lakes distributed in the municipality of Goiânia, Goiás, Brazil, during a rainy period. Results It was possible to identify an environmental heterogeneity among the lakes. We identified a separation of the lakes according to phytoplankton richness and density, especially due to the contribution of green algae, desmids, and cyanobacteria. Most lakes showed high diversity and evenness values, with a predominance of rare taxa and few dominant species. The main variables associated with phytoplankton were water temperature, dissolved oxygen, turbidity, and nutrient concentrations. Conclusions Therefore, the study of species diversity, dominance, and rarity based on phytoplankton richness and abundance and their relationship with different local environmental conditions can be an important model for assessing water quality in urban lakes. turbidity Thus Goiânia Goiás Brazil period density algae desmids cyanobacteria values temperature oxygen Therefore

Abstract In order to determine the structure and biomass of phytoplankton (picophytoplankton, nanodiatoms, and microdiatoms) under oligotrophic conditions, a study was carried out in the surface layer of the Guaymas Basin, Gulf of California, during the late summer of 2016. This study included the measurement of hydrographic, chemical, and biological variables in the surface layer of the study area. Our results showed a warm, strongly stratified, and nutrient-depleted water column associated with reduced phytoplankton biomass (<1 mg Chla·m-3). The average ratios of N:P (0.55 ± 1.34), N:Si (0.13 ± 0.18), and Fe:N (52.70 ± 29.70) indicate N-limiting conditions. The biomass contribution of phytoplankton groups fluctuated widely by depth level, with predominance of picophytoplankton (85.0 ± 2.7%) at the surface (5 m) and nano-microdiatoms (91.5 ± 5.9%) at the deepest level (35-40 m), adjacent to the thermocline. Diatoms dominated the integrated biomass between the surface and 50-m depth, with an average contribution ~6 times greater than that of picophytoplankton. Despite the ideal conditions for the proliferation of diazotrophs, the presence of Trichodesmium spp. and Richelia intracellularis was very irregular and in relatively low abundances (2,220 ± 1,575 cell·L-1). Our results are especially relevant as they suggest that, under N-limiting conditions, the paradigm of high biomass and large cell dominance in the Gulf of California may be challenged during the summer season.

Resumen Con el propósito de determinar la biomasa y la composición del fitoplancton (picofitoplancton, nanodiatomeas y microdiatomeas) bajo condiciones oligotróficas, se realizó un estudio en la capa superficial de la cuenca de Guaymas, golfo de California, durante el verano tardío de 2016. El estudio contempló la medición de variables hidrográficas, químicas y biológicas en la capa superficial del área de estudio. Nuestros resultados mostraron una columna de agua cálida, fuertemente estratificada, empobrecida en nutrientes y con biomasas fitoplanctónicas reducidas (<1 mg Cla·m-3). Los cocientes promedio de N:P (0.55 ± 1.34), N:Si (0.13 ± 0.18) y Fe:N (52.70 ± 29.70) indicaron condiciones de limitación por N. La contribución de los grupos fitoplanctónicos a la biomasa fluctuó ampliamente por nivel de profundidad, y se observó el predominio del picofitoplancton (85.0 ± 2.7%) en superficie (5 m) y de las nano-microdiatomeas (91.5 ± 5.9%) en el nivel más profundo (35-40 m), adyacente a la termoclina. Las diatomeas dominaron la biomasa integrada entre la superficie y 50 m de profundidad, con una contribución promedio ~6 veces mayor que la del picofitoplancton. A pesar de que se registraron condiciones ideales para la proliferación de cianobacterias diazótrofas, la presencia de Trichodesmium spp. y Richelia intracellularis fue muy irregular y en abundancias relativamente bajas (2,220 ± 1,575 célula·L-1). Nuestros resultados son especialmente relevantes, ya que sugieren que, bajo condiciones de limitación por N, el paradigma de la alta biomasa y dominancia de células grandes en el golfo de California puede verse desafiado durante la temporada de verano.

ABSTRACT Background: The increasing evidence of risk to the environment and human health by cyanotoxin exposure during cyanobacterial blooms has been reported worldwide. Despite the knowledge of cyanotoxin presence in Latin America, cyanotoxin bioaccumulation from freshwater environments have not been reviewed for the region. Goals: To review the current knowledge of cyanotoxin accumulation in tissues of freshwater organisms in field studies in Latin America. Methods: An extensive literature search was conducted to construct a database including information on accumulation of cyanotoxins in organisms inhabiting freshwater environments in Latin America (i.e., México to Argentina). Results: We found twenty-one studies from 2001 to 2020, including twenty-seven mostly eutrophic water bodies, the majority from Brazil. Microcystis was the most reported genus responsible for cyanotoxin production. Fish comprised most of the species accumulating cyanotoxins (20 species). Nile tilapia (Oreochromis niloticus) was the most studied species, and 80% of the fish species included have commercial importance, which highlights a potential route of exposure to humans by consumption of contaminated food. Some studies showed the reduction of cyanotoxins in tissues after an experimental depuration time. Also, calculations of the potential human intakes of microcystins by fish consumption exceeded the recommendations of tolerable intakes in most of the cases. Conclusions: In Latin America, the geographic extent of studies is narrow, however the summarized information indicates a risk for environment and human health by cyanotoxins bioaccumulation. There is a need for more efforts to generate scientific research on cyanotoxins bioaccumulation, but also for improvement of local level management policies to reduce eutrophication.

RESUMEN Antecedentes: La creciente evidencia de riesgo para el medio ambiente y la salud humana por la exposición a cianotoxinas durante las floraciones de cianobacterias se ha reportado en todo el mundo. A pesar del conocimiento de la presencia de cianotoxinas en América Latina, la bioacumulación de cianotoxinas en ambientes de agua dulce no ha sido revisada para la región. Objetivos: Revisar el conocimiento actual sobre la acumulación de cianotoxinas en tejidos de organismos de agua dulce en estudios de campo en América Latina. Métodos: Se realizó una extensa búsqueda bibliográfica para construir una base de datos que incluyera información sobre la acumulación de cianotoxinas en organismos que habitan ambientes de agua dulce en América Latina (de México a Argentina). Resultados: Encontramos veintiún estudios de 2001 a 2020, incluidos veintisiete cuerpos de agua en su mayoría eutróficos, la mayoría de Brasil. Microcystis fue el género productor de cianotoxinas más reportado. Los peces comprendieron la mayoría de las especies que acumulaban cianotoxinas (20 especies). Oreochromis niloticus fue la especie más estudiada, y el 80% de las especies de peces incluidas tienen importancia comercial, lo que destaca una vía potencial de exposición a los humanos. Algunos estudios demostraron la reducción de cianotoxinas en los tejidos después de un tiempo de depuración experimental. Además, los cálculos de las ingestas humanas potenciales de microcistinas por consumo de pescado excedieron las recomendaciones de ingestas tolerables en la mayoría de los casos. Conclusiones: En América Latina, los estudios se han realizado en pocos países, sin embargo, estos trabajos indican un riesgo para el medio ambiente y la salud humana por la bioacumulación de cianotoxinas. Se necesita más investigación científica sobre la bioacumulación de cianotoxinas, pero también esfuerzos para mejorar la gestión a nivel local con la finalidad de reducir la eutrofización.

RESUMEN Se estudió la remoción del fitoplancton mediante pretratamiento con ozono en una planta piloto que capta agua de un embalse subtropical del noroeste argentino. Se analizó la variación estacional de las abundancias por grupos algales a la entrada y salida de la planta en el período 2019-2020, y la eficiencia de remoción del tratamiento en función de dos categorías de tamaños (MDL máxima dimensión lineal) y biovolumen en especies seleccionadas. La abundancia de algas al ingreso mostró diferencias estacionales con predominio de diatomeas en invierno, Criptofíceas, Clorofíceas, Dinofíceas y Trebouxiofíceas en primavera y Cianobacterias en verano. El flujo de salida de algas también fue mayor en invierno, con predominio de diatomeas, y de cianobacterias en otoño y verano. El tratamiento produjo una reducción significativa de la densidad de algas (media del 26,94%), que aumentó aún más en algunos grupos particulares: Zygnematophyceae (68,21%), Euglenophyceae (59,80%), Cianobacterias (57,87%), Cryptophyceae (53,84%), Dinophyceae (38,59%) y Chlorophyceae (28,66%). En el seguimiento se registraron un total de 326 spp, aunque sólo 126 spp tuvieron una frecuencia de aparición en al menos el 10% de los muestreos, en su mayoría con bajas densidades. La eliminación de microalgas en la planta piloto no mostró correlaciones significativas con las dimensiones celulares de las especies seleccionadas. Las medias de la clase III de MDL =31,62 ±8,79 μm y biovolumen =4019,69 ±2711,49 μm3 tuvieron las mayores eliminaciones por tratamiento (72,97% y 72,74%, respectivamente), aunque no fueron estadísticamente diferentes de las clases restantes. Conclusión: la capacidad de eliminación de algas por el proceso de ozonización de la planta piloto produjo una reducción significativa de la densidad algal, especialmente de Cianobacterias, Zygnematoficeae, Euglenophyceae y Cryptophyceae, que en todos los casos superó el 50%.

ABSTRACT Phytoplankton removal by ozone pretreatment was studied in a pilot plant that collects water from a subtropical reservoir in northwestern Argentina. The seasonal variation of abundances by algal groups at the inlet and outlet of the plant in the period 20192020, and the removal efficiency of the treatment were analyzed as a function of two size categories (MDL maximum linear dimension) and biovolume in selected species. At the inflow, algal abundance showed seasonal differences with predominance of diatoms in winter, Cryptophyceae, Chlorophyceae, Dinophyceae and Trebouxiophyceae in spring and Cyanobacteria in summer. Algae outflow was also higher in winter, with a predominance of diatoms, and of cyanobacteria in au tumn and summer. The treatment produced a significant reduction in algal density (mean 26.94%), which increased even more in some particular groups: Zygnemato phyceae (68.21%), Euglenophyceae (59.80%), Cyanobacteria (57.87%), Cryptophyceae (53.84%), Dinophyceae (38.59%) and Chlorophyceae (28.66%). A total of 326 spp were recorded in the monitoring, although only 126 spp had a frequency of occurrence in at least 10% of the samplings, mostly with low densities. Microalgae removal in the pilot plant showed no significant correlations with cell dimensions for selected species. Class III averages of MLD =31.62 ±8.79 μm and biovolume =4019.69 ±2711.49 μm3 had the highest removals per treatment (72.97% and 72.74%, respec tively), although they were not statistically different from the remaining classes. Conclusion: the algae removal capacity by the ozonation process of the pilot plant produced a significant reduction in algal density, especially of Cyanobacteria, Zygnematoficeae, Euglenophyceae and Cryptophyceae, which in all cases exceeded 50%.

Resumen Introducción: La restauración de ecosistemas facilita la sucesión ecológica. Cuando un arrecife de coral experimenta una perturbación, la comunidad de organismos sésiles bentónicos puede seguir una trayectoria de sucesión que favorezca la dominancia del coral o un cambio de estado a un ecosistema dominado por algas. Objetivo: Comprender mejor el impacto de los trasplantes de coral en la sucesión de la comunidad bentónica sésil. Métodos: Para medir y monitorear la cobertura de coral (cm2) de Pocillopora spp. y la composición de la comunidad bentónica asociada se establecieron parches de arrecifes de coral experimentales y de control en el sitio de restauración de coral en Golfo Dulce, Pacífico Sur de Costa Rica. Treinta colonias de Pocillopora spp., se trasplantaron a los clavos en el sustrato en el parche experimental. El parche de coral de control contenía clavos sin colonias trasplantadas. Ambos tratamientos fueron fotografiados mensualmente durante un periodo de ocho meses. Los cambios en la cobertura de coral y otros organismos bentónicos sésiles se midieron a partir de las imágenes y se compararon a lo largo del tiempo entre los parches experimentales y de control. Resultados: Los trasplantes de coral experimentaron eventos de blanqueamiento de agosto a septiembre de 2019 y de enero a febrero de 2020. El primer evento de blanqueamiento puede haber sido el resultado de la sedimentación y el segundo puede deberse a las altas temperaturas. Al final del experimento, el 83 % de las colonias habían sobrevivido. Las colonias vivas crecieron significativamente después del trasplante; > 67 % de su área de cobertura inicial después de ocho meses. En el parche experimental, las áreas de Pocillopora spp., algas coralinas costrosas (ACC) y cianobacterias aumentaron mientras que el tapete de algas disminuyó. El aumento en la cobertura de coral y ACC, y la disminución en tapetes de algas en el parche experimental podría deberse a los herbívoros atraídos por los trasplantes. El aumento de cianobacterias en el parche experimental podría ser el resultado de temperaturas más altas y puede haber sido un factor en la muerte de las colonias. Conclusiones: El trasplante de las colonias de Pocillopora spp. en Golfo Dulce cambiaron la trayectoria de sucesión temprana de la comunidad bentónica sésil para favorecer la dominancia del coral en el parche experimental. Estos resultados pueden ser útiles para informar las expectativas de futuros esfuerzos de restauración.

Abstract Introduction: Ecosystem restoration facilitates ecological succession. When a coral reef experiences a disturbance, the community of sessile benthic organisms can follow a successional trajectory that favors the dominance of coral or a change of state to an ecosystem dominated by algae. Objective: To better understand the impact of coral transplants on succession of the sessile benthic community. Methods: To measure and monitor the coral cover (cm2) of Pocillopora spp., and the composition of the associated benthic community, experimental and control coral reef patches were established at the coral restoration site in Golfo Dulce, South Pacific Costa Rica. Thirty Pocillopora spp. colonies were attached to nails on the substrate in an experimental patch. The control coral patch contained nails with non-transplanted colonies. Both treatments were photographed monthly during a period of eight months. Changes in the coverage of coral and other sessile benthic organisms were measured from the images and compared over time between the experimental and control patches. Results: The coral transplants experienced bleaching events in August through September 2019 and January through February 2020. The first bleaching event possibly due to sedimentation, and the second to high temperatures. By the end of the experiment, 83 % of the colonies had survived. The live colonies grew significantly following transplantation; > 67 % of their initial coverage area after eight months. In the experimental patch, the areas of Pocillopora spp., coralline crustose algae (CCA), and cyanobacteria increased while the area of algal turf decreased. The increase in coral coverage and CCA, and decrease in algal turf in the experimental patch could be due to herbivores attracted to transplants. The increase in cyanobacteria in the experimental patch could be the result of higher temperatures and may have been a factor in the death of colonies. Conclusions: The transplantation of Pocillopora spp. colonies in Golfo Dulce changed the early successional trajectory of the sessile benthic community to favor the dominance of coral dominance in the experimental patch. These results may be useful in informing expectations for future restoration efforts.

Abstract: Aim This study aims to evaluate temporal patterns of extreme events related to precipitation on a global scale, identifying their main impacts and if there are climatic zones more susceptible to these phenomena using a scientometric approach. Methods A systematic review was conducted on scientific papers published between 1991 and July 2020, obtained from the Scopus and Thomson ISI Web of Science databases. Keywords related to precipitation extreme events and their effects on planktonic communities and freshwater ecosystems' water quality were used in the search. Results The analysis revealed a significant increase in publications, particularly from 2014 onwards, following the release of reports by the Intergovernmental Panel on Climate Change (IPCC) and the American Meteorological Society (AMS). These reports highlighted the increasing frequency of these climatic events and their potential for causing damage to humanity. In this review, we focused on extreme weather events related to precipitation such as droughts, rains, and floods. These events, due to their sudden volumetric changes, lead to immediate physical and chemical alterations in the water column. The main impacts of these extreme events on aquatic ecosystems include increased nutrient concentrations (mainly phosphorus and nitrogen), contamination by micropollutants, cyanobacteria blooms, and loss of biodiversity. Conclusions The scientometric analysis indicates that extreme weather events associated with precipitation have a detrimental effect on water quality and aquatic biodiversity, exacerbating the eutrophication process in freshwater systems.

Resumo: Objetivo Encontrar padrões temporais dos eventos extremos relacionados a precipitação em escala global, assim identificar os principais impactos e se há zonas climáticas suscetíveis a esses fenômenos em uma abordagem cienciométrica. Métodos Realizamos uma revisão sistemática investigando trabalhos científicos publicados entre 1991 até julho de 2020 nas bases de dados Scopus e Thomson ISI Web of Science. Buscamos por palavras-chave relacionadas a eventos extremos de precipitação e efeitos sobre a comunidade planctônica e a qualidade da água de ecossistemas aquáticos continentais. Resultados Observamos um aumento expressivo de publicações, especialmente a partir de 2014 após a publicação de relatórios do Painel Intergovernamental sobre Mudanças Climáticas (IPCC) e Sociedade Americana de Meteorologia (AMS), apontando a tendência de crescimento de frequência desses eventos climáticos e o potencial de danos a humanidade. Nesta revisão escolhemos os eventos climáticos extremos relacionados à precipitação (secas, chuvas e inundações), que promovem uma variação volumétrica abrupta que imediatamente causa alterações físicas e químicas na coluna d'água. Como principais impactos desses eventos extremos nos ecossistemas aquáticos encontramos aumento da concentração de nutrientes (principalmente fósforo e nitrogênio), contaminação por micropoluentes, florações de cianobactérias e perda de biodiversidade. Conclusões A análise cienciométrica revelou que eventos climáticos extremos relacionados à precipitação geram impactos negativos na qualidade da água e na biodiversidade aquática, intensificando o processo de eutrofização em sistemas aquáticos continentais.

Resumen: Las tecnologías “ómicas” son herramientas novedosas que facilitan el estudio de las comunidades microbianas de distintos ecosistemas, particularmente de la costra biológica del suelo, también llamada biocostra. Entre estas tecnologías se encuentran la genómica, transcriptómica, proteómica, metabolómica y metagenómica, que son utilizadas para analizar la diversidad y las funciones que llevan a cabo los microorganismos a través del estudio de sus biomoléculas y vías metabólicas. Entre los microorganismos que habitan la biocostra destacan las cianobacterias, las cuales son un grupo de bacterias fototróficas encargadas de realizar procesos importantes en el suelo, tal como la fijación de nitrógeno atmosférico, carbono orgánico, síntesis de clorofila y ficobilinas, así como la producción de exopolisacáridos para mejorar la estabilidad y fertilidad del suelo. Por lo tanto, el objetivo de la presente revisión es el de explorar la diversidad y la función que desempeñan estas comunidades microbianas en la biocostra, particularmente las cianobacterias, destacando los estudios realizados mediante el uso de las tecnologías ómicas. El conocimiento generado en los últimos años a través de las tecnologías ómicas ha demostrado la limitada cobertura que presentan las técnicas moleculares tradicionales, resultando en una subestimación de la diversidad real de las comunidades microbianas. Además, se ha mejorado la comprensión de los procesos ecológicos desarrollados por los microorganismos en beneficio de la biocostra, así como las capacidades funcionales individuales y colectivas, las cuales servirán como línea base para proponer estrategias importantes que solucionen la problemática de la degradación de los suelos.

Summary: The "omics" technologies are novel tools that facilitate the study of microbial communities in different ecosystems, particularly the biological soil crust, also called biocrust. These technologies include genomics, transcriptomics, proteomics, metabolomics, and metagenomics, which are used to analyze the diversity and functions carried out by microorganisms through the study of their biomolecules and metabolic pathways. Among the microorganisms that inhabit the biocrust are the cyanobacteria, which are a group of phototrophic bacteria responsible for important processes in the soil, such as the fixation of atmospheric nitrogen, organic carbon, chlorophyll and phycobilin synthesis, as well as the production of exopolysaccharides to improve soil stability and fertility. Therefore, the objective of this review is to explore the diversity and role that these microbial communities play in the biocrust, particularly cyanobacteria, highlighting studies conducted using omics technologies. The knowledge generated in recent years through omics technologies has demonstrated the limited coverage of traditional molecular techniques, resulting in an underestimation of the real diversity of microbial communities. In addition, there has been an improvement in the understanding of the ecological processes developed by the microorganisms for the benefit of the biocrust, as well as the individual and collective functional capacities, which will serve as a baseline to propose important strategies to solve the problem of soil degradation.

Resumen Introducción: El embalse Cerrón Grande de 135 km2 es el humedal más grande de El Salvador, reconocido como “Humedal de Importancia Internacional” por la Convención Ramsar. Además, es uno de los ecosistemas más contaminados a nivel nacional, enfrentando serios problemas, entre ellos, las proliferaciones de cianobacterias. Objetivo: Evaluar las relaciones entre los factores ambientales y la distribución espacial y temporal de las cianobacterias en el embalse a lo largo de un año hidrológico. Métodos: Extrajimos agua con cianobacterias de seis sitios fijos, desde octubre 2018 hasta septiembre 2019. Resultados: Identificamos 16 géneros, el más abundante Microcystis sp. Además, Dolichospermum sp.; Microcistis sp. alcanzaron 1.5 x 106 células/ml en junio 2019, principalmente en el sector noroeste, que es poco profundo y cercano a las zonas de confluencia de afluentes altamente contaminados que llegan al embalse. El sector sureste más profundo tenía bajas concentraciones de estos organismos. Los factores ambientales mayormente relacionados con dicho comportamiento fueron: fósforo, la conductividad eléctrica y el valor de Secchi, como se esperaba de un cuerpo eutrófico. Conclusiones: La variación en la concentración celular de cianobacterias en este embalse está altamente influenciada por la lluvia, la mezcla de agua y el contenido de nutrientes.

Abstract Introduction: The 135 km2 Cerrón Grande reservoir is the largest wetland in El Salvador, recognized as “Wetland of International Importance” by the Ramsar Convention. It is also one of the most polluted ecosystems nationwide, facing serious problems, among them, a proliferation of cyanobacteria. Objective: To assess the relationships among environmental factors and the spatial and temporary distribution of cyanobacteria in the reservoir throughout a hydrological year. Methods: We extracted water with cyanobacteria from six fixed sites, from October 2018 through September 2019. Results: We identified 16 genera, the most abundant Microcystis sp. And Dolichospermum sp.; Microcystis sp. reached 1.5 x 106 cells/ml in June 2019, mainly in the north-west sector, which is shallow and close to the confluence zones where highly polluted tributaries reach the reservoir. The deeper south-east sector had low concentrations of these organisms. The environmental factors mostly related to this behavior were: phosphorus, electrical conductivity and Secchi value, as expected from a eutrophic body. Conclusions: Variation in the cellular concentration of cyanobacteria in this reservoir is highly influenced by rain, water mixing and nutrient content.

RESUMEN El microfitobentos es una comunidad que agrupa a los microorganismos fotosintéticos bentónicos. En Venezuela y el resto de los países del mar Caribe, este grupo ha sido escasamente estudiado, por lo que se desconoce su diversidad. Así, se propuso describir las variaciones espaciales y temporales de su composición y abundancia en la zona costera central de Venezuela. Los muestreos fueron realizados mensualmente desde junio 2014 hasta marzo 2015, en estaciones aleatorias con profundidades inferiores a 20 m. Los datos de riqueza y abundancia fueron procesados mediante pruebas de hipótesis multivariadas (Anosim - SIMPER - nMDS). Se identificaron 327 especies, dominadas por diatomeas y dinoflagelados, sin variaciones espaciales y temporales notables. En términos de abundancia, el grupo más representativo fue el de las diatomeas (68 %), seguido por las cianobacterias (28 %). El microfitobentos presentó una variabilidad temporal en la que se alcanzaron densidades mayores entre julio y agosto, mientras que el resto de los meses presentaron abundancias similares. En términos generales, se obtuvo abundancia estándar de acuerdo con lo encontrado en otras áreas del mundo, con diferencias notables entre el microfitobentos de los sustratos evaluados y una riqueza específica alta que se mantiene constante durante todo el año.

ABSTRACT Microphytobenthos is a community that groups benthic photosynthetic microorganisms. In Venezuela and the other countries in the Caribbean Sea, this group has been scarcely studied, so its diversity is unknown. This study aims to describe the spatial and temporal variations of its composition and abundance in the central coastal zone of Venezuela. Samplings were conducted monthly from June 2014 to March 2015, in random stations at depths less than 20 m. Richness and abundance data were processed through multivariate hypothesis tests (Anosim - SIMPER - nMDS). A total of 327 species were identified, with a dominance of diatoms and dinoflagellates, without significant spatial and temporal variations. In terms of abundance, the most representative group was diatoms (68 %), followed by cyanobacteria (28 %). The microfitobenthos presented a temporal variability in which the highest densities were reached between July and August, while the rest of the months presented similar abundances. Thus, standard abundances were obtained in all the samples according to that found in other areas of the world, with notable differences between the microphytobenthos of the evaluated substrates, and a high and constant specific richness throughout the year.

RESUMEN La expansión de la frontera agrícola ocasiona pérdidas de biodiversidad y de recursos genéticos nativos, afectando la sustentabilidad del ecosistema. Se considera que la presencia y la diversidad de cianobacterias son bioindicadores sensibles al cambio en el uso de los suelos. El objetivo de este trabajo fue caracterizar las comunidades de cianobacterias presentes en suelos del noreste de la provincia de Córdoba, comparando suelos con pasturas implantadas y en condiciones prístinas. Se tomaron muestras de suelo en tres localidades, en ambientes con distintos niveles de salinidad: leve, moderado y salino. Las muestras se cultivaron en medio Watanabe, en condiciones controladas para favorecer el crecimiento de las cianobacterias. Se lograron identificar las especies de cianobacterias presentes en cada sitio, observando una dominancia de fijadoras de nitrógeno heterocistadas en los suelos con mayor salinidad. A su vez, en los tres montes de cada sitio se observó mayor riqueza de especies. Las más sensibles al cambio en el uso del suelo fueron Oscillatoria limosa y Phormidium constricta. Las cianobacterias constituyen una futura línea de investigación relacionada a la restauración y recuperación productiva de ambientes salinos, dentro de una propuesta que contribuya a favorecer la biodiversidad del suelo.

SUMMARY The expansion of the agricultural frontier causes losses of biodiversity and native genetic resources, affecting the sustainability of the ecosystem. The presence and diversity of cyanobacteria are considered to be bioindicators sensitive to land use change. The objective of this work was to characterize the communities of cyanobacteria present in the soils in the northeast of the province of Córdoba, comparing soils with implanted pastures and in pristine conditions. Soil samples were taken in three locations, in environments with different levels of salinity: mild, modérate and saline. The samples were cultured in Watanabe medium, under controlled conditions to promote the growth of cyanobacteria. An Olympus BX 50 optical microscope was used for taxonomic identification. It was possible to identify the species of cyanobacteria present at each site, observing a dominance of heterocyst nitrogen fixators in soils with higher salinity. In turn, in the three native forests present at each site, greater species richness was observed. The most sensitive to the change in land use being OscHlator¡a Hmosa and Phormidium constricta. Cyanobacteria constitute a future line of research related to the restoration and productive recovery of saline environments, under the focus of sustaining biodiversity.

RESUMO Um problema emergente para a segurança hídrica consiste nas consequências da eutrofização sobre a qualidade das águas. Metodologias de regressão convencionais não têm sido suficientes para explicar satisfatoriamente a complexidade da relação entre as variáveis hidrológicas e limnológicas desse processo. Nessa perspectiva, esta pesquisa buscou identificar preditores para variáveis indicadoras de eutrofização (cianobactérias, clorofila a, nitrogênio, fósforo e medição em disco de Secchi), por meio das relações destas entre si e entre 17 variáveis fisiográficas e climáticas das bacias hidrográficas de 155 reservatórios do semiárido brasileiro. Aplicou-se um método de aprendizado de máquina com o algoritmo classification and regression trees para árvores de decisão. Os resultados revelaram que os indicadores de eutrofização estão intrinsecamente relacionados entre si, de maneira especial as concentrações de clorofila a com os demais. A variabilidade da vazão afluente repercutiu no aumento da concentração de cianobactérias; a redução do volume de água armazenado gerou aumento da concentração de nitrogênio e fósforo; e a densidade de drenagem gerou aumento da concentração de nitrogênio. As concentrações de nitrogênio superiores a 5 mg.L−1 apresentaram consequências representativas sobre a clorofila a, a qual esteve fortemente associada às cianobactérias. O volume de água armazenado, a precipitação e a vazão afluente aos reservatórios também foram preditores da transparência das águas. Apesar de os índices de performance do modelo apontarem para margens de erro amplas para os conjuntos de dados com elevados coeficientes de variação, a aplicação de árvores de decisão pode auxiliar no entendimento de processos ocorridos e no planejamento de ações estratégicas para a governança hídrica.

ABSTRACT An emerging issue for water security is the consequences of eutrophication on water quality. Conventional regression methodologies have not been sufficient to satisfactorily explain the complexity of the relationship between the hydrological and limnological variables of this process. In this sense, this research aimed to identify predictors for eutrophication variables (cyanobacteria, chlorophyll-a, nitrogen, phosphorus, and Secchi disk measurement), through their relationships with each other and between 17 physiographic and climatic variables of the watersheds of 155 reservoirs in the Brazilian semiarid region. A machine learning method was applied with the classification and regression trees algorithm for decision trees. The results revealed that the eutrophication indicators are intrinsically related to each other, especially the concentrations of chlorophyll-a with the others. The variability of the inflow resulted in an increase in the concentration of cyanobacteria; the reduction in the volume of stored water generated an increase in the concentration of nitrogen and phosphorus; and, the drainage density generated an increase in the concentration of nitrogen. Nitrogen concentrations greater than 5 mg.L−1 had significant consequences on chlorophyll-a, which was strongly associated with cyanobacteria. The volume of stored water, precipitation and the inflow to the reservoirs were also predictors of water transparency. Although the model’s performance indexes indicate wide margins of error for datasets with high coefficients of variation, decision trees can help in understanding the processes that have taken place and in planning strategic actions for water governance.

El objetivo del estudio fue contribuir al conocimiento de la composición y estructura de la taxocenosis conformada por cianobacterias, clorofitas y euglenofitas de estos ambientes extremos, en relación a variables abióticas (conductividad eléctrica, salinidad y pH del agua, altura sobre el nivel del mar y superficie lacustre). En 2005, se efectuó un muestreo interdisciplinario de veintiséis puntos de colecta en tres provincias del noroeste argentino (NOA). Los datos abióticos y bióticos registrados en campo y en laboratorio se hicieron según protocolos convencionales. De acuerdo a los resultados, la mayoría de los ejemplares identificados en Catamarca (coincidente con Jujuy y Salta) fueron cosmopolitas y afines con la salinidad, destacándose, en general, las cianobacterias y Chroococcus turgidus dentro de este grupo; en segundo lugar, estuvieron las algas verdes y, en el caso de las euglenofitas, no fueron registradas en dicha provincia. La taxocenosis estuvo constituida tanto por especies propias del fitoplancton como de otros hábitats. Los valores bajos a intermedios de diversidad (0,01-2,85) estarían vinculados al predominio de especies raras y de unas pocas dominantes. La biomasa mostró sensibilidad a las condiciones ambientales, en general disminuyó con el aumento de la salinidad, varió entre 24.007-60.396.324 mg/ml de C. La aplicación del Análisis de Componentes Principales, tanto para variables abióticas como bióticas, fueron de utilidad porque aportaron datos complementarios sobre la ocasionar floraciones y potencialÂmente tóxicas, como Chroococcus turgidus, Microcystis flos-aquae y Nodularia spumigena conducen a sugerir un control periódico de estos cuerpos de agua.

The aim this study was to contribute to the knowledge of the composition and structure of taxocenosis formed by cyanobacteria, chlorophytes and euglenophytes of these extreme environments in relation to abiotic variables (water electrical conductivity, salinity, pH, height above sea level and lake surface). In 2005, an interdisciplinary sampling was carried out covering twenty-six collection sites in three provinces from Argentinean Northwest. Abiotic and biotic data were recorded in the field and in the laboratory following conventional protocols. According to the results, most of the specimens in the province of Catamarca (coinciding with Jujuy and Salta) were cosmopolitan and related to salinity, with Cyanobacteria and Chroococcus turgidus standing out in general within this group; green algae were in second place, while euglenophytes were not recorded in this province. Taxocenosis was made up of phytoplankton species and those coming from other habitats. The low to intermediate values ​​of diversity (0.01-2.85) would be linked to the dominance of rare species and presence of a few taxa with high numbers of individuals. Biomass showed sensitivity to environmental conditions, highlighting in general a decrease of this variable with the increase in salinity, whose records varied between 24,007- 60,396,324 mg/ml of C. The application of the Principal Components Analysis for abiotic and biotic variables was a useful tool because it provided complementary information on the distribution of the selected sites. Finally, the quantification of cyanobacterial species potentially toxic and capable of producing blooms, such as Chroococcus turgidus, Microcystis flos-aquae and Nodularia spumigena lead to suggest a periodic control of these water bodies.

RESUMO A proliferação de cianobactérias em águas, principalmente em rios, está associada à ação antrópica e à poluição das águas provenientes das atividades da indústria, agricultura e à falta de saneamento básico. Muitos problemas de saúde ocorrem em razão das cianotoxinas produzidas por esses microrganismos. O presente trabalho teve como objetivo avaliar as densidades de cianobactérias e suas possíveis correlações com parâmetros físico-químicos nas águas captadas nos rios para o abastecimento do município de Joinville, a fim de verificar quais os fatores envolvidos no crescimento desses organismos entre os anos de 2015 e 2019. As quantidades de células de cianobactérias por mililitro de água dos últimos cinco anos dos rios Cubatão e Piraí foram analisadas a partir dos certificados de análise disponibilizados pela atual prestadora de serviços de abastecimento de água do município de Joinville. Constatou-se que os valores das densidades de cianobactérias aumentaram significativamente em ambos os rios a partir do ano de 2018. Os parâmetros físico-químicos analisados apresentaram baixa correlação com a densidade de cianobactérias entre 2015 e 2019 para os rios Cubatão e Piraí. Na tentativa de compreender esse aumento de cianobactérias, fatores climáticos como precipitação e média de temperatura anual foram estudados. O aumento expressivo na precipitação no mês de janeiro de 2018, seguido de um período de diminuição das chuvas, além do aumento gradativo da temperatura nos últimos anos, podem estar relacionados a essa elevação da densidade de cianobactérias entre 2018 e 2019, sendo necessário um acompanhamento dessa evolução nos rios de abastecimento da cidade de Joinville.

ABSTRACT The proliferation of cyanobacteria in waters, especially in rivers, is associated with anthropic action, wastewater from industries, agriculture, and the lack of basic sanitation. Many health problems occur due to the cyanotoxins produced by these microorganisms. The present study aimed to evaluate the densities of cyanobacteria and their possible correlations with physical-chemical parameters in waters from supply rivers of the city of Joinville, in order to verify which factors are involved in the growth of these organisms between the years 2015 to 2019. The amount of cyanobacteria cells per milliliter of water were analyzed from the last 5 years of the Cubatão and Piraí rivers, based on the certificates of analysis provided by the current water supply service of Joinville. It was found that the cyanobacteria density values increased in both rivers from the year 2018. The physical-chemical parameters analyzed showed a low correlation with the cyanobacteria density from 2015 to 2019 for the Cubatão and Piraí rivers. To understand this increase in cyanobacteria, other climatic factors such as precipitation and average annual temperature were studied. The expressive increase in precipitation in January 2018, followed by a period of reduced rainfall, in addition to the gradual rising temperature in recent years, might be related to this elevation in the density of cyanobacteria between 2018 and 2019, requiring monitoring of this evolution in the supply rivers of the Joinville city.