Hypoxia is one of the most important stressors affecting the health conditions of coastal ecosystems. In highly productive ecosystems such as the Humboldt Current ecosystem, the oxygen minimum zone ...is an important abiotic factor modulating the structure of benthic communities over the continental shelf. Herein, we study soft-bottom macrobenthic communities along a depth gradient-at 10, 20, 30 and 50 m-for two years to understand how hypoxia affects the structure of shallow communities at two sites in Mejillones Bay (23°S) in northern Chile. We test the hypothesis that, during months with shallow hypoxic zones, community structure will be much more dissimilar, thereby depicting a clear structural gradient with depth and correlated abiotic variables (e.g. organic matter, temperature and salinity). Likewise, during conditions of deeper hypoxic zones, communities will be similar among habitats as they could develop structure via succession in conditions with less stress. Throughout the sampling period (October 2015 to October 2017), the water column was hypoxic (from 2 to 0.5ml/l O2) most of the time, reaching shallow depths of 20 to 10 m. Only one episode of oxygenation was detected in June 2016, where normoxia (>2ml/l O2) reached down to 50 m. The structure of the communities depicted a clear pattern of increasing dissimilarity from shallow normoxic and deep hypoxic habitat. This pattern was persistent throughout time despite the occurrence of an oxygenation episode. Contrasting species abundance and biomass distribution explained the gradient in structure, arguably reflecting variable levels of hypoxia adaptation, i.e. few polychaetes such as Magelona physilia and Paraprionospio pinnata were only located in low oxygen habitats. The multivariable dispersion of community composition as a proxy of beta diversity decreased significantly with depth, suggesting loss of community structure and variability when transitioning from normoxic to hypoxic conditions. Our results show the presence of semi-permanent shallow hypoxia at Mejillones Bay, constraining diverse and more variable communities at a very shallow depth (10-20 m). These results must be considered in the context of the current decline of dissolved oxygen in most oceans and coastal regions and their impact on seabed biota.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The decapod fauna in the intertidal zone of the rocky shores of Chile is highly diverse, especially along the northern and central mainland coasts, where the influence of the cold Humboldt Current ...results in high productivity. One of the most abundant species in these ecosystems is the decapod Cyclograpsus cinereus Dana, 1851. The aim of the present study, carried out in the spring and summer seasons between 2018 and 2020, was to determine the spatial distribution patterns of the decapod C. cinereus in different sites along the rocky shores of Antofagasta bay, northern Chile, in order to establish probabilistic models that explain its distribution at each site. Individuals were counted in random quadrants in the intertidal zone. The data thus obtained were processed by application of the variance/mean ratio to determine whether the distribution of individuals was random, aggregated or uniform, associated with Poisson, negative binomial or positive binomial distributions, respectively. The data revealed aggregated (negative binomial) distribution in 15 sampling events, and uniform (positive binomial) distribution in 4 events. The sampling sites were located on rocky shores in four sectors of an urban zone, and two in a protected zone; no significant differences were found between the densities of the sites in the two zones. The results of the interpretative probabilistic models indicated aggregated distribution patterns, agreeing with previously reported interpretative probabilistic models for the distribution of decapods on the rocky shores of central and southern Chile.
RESUMEN La inserción laboral de las personas con ceguera ha sido investigada, pero no existen trabajos que indaguen sobre lo que piensan y conocen los docentes que forman a estas personas y sobre las ...dificultades de sus estudiantes para insertarse laboralmente después de su educación. El objetivo de esta investigación cualitativa fue comprender las teorías subjetivas de seis docentes de un establecimiento educacional de La Serena, Chile. El método de recolección de datos utilizado fue la entrevista en profundidad y el estudio de los datos se realizó a través de los procedimientos de codificación de la grounded theory y el análisis del contenido de las teorías subjetivas. Se encontró, como principal resultado que, para los participantes la educación inadecuada del ciego es la principal causa de la dificultad para la inserción laboral. Esta investigación puede aportar información valiosa para aquellos encargados de las políticas públicas entorno a la discapacidad visual.
ABSTRACT Even though research has been conducted on the employment integration at blind people, studies have failed to consider what teachers think and know about their blind students’ difficulties entering the workforce after completing their education. The aim of this qualitative study was to understand the subjective theories of six teachers from a school in La Serena, Chile. In-depth interviews were used to collect data, which were subsequently studied using grounded theory coding procedures and subjective theory content analysis. The main finding of this study was that participants regarded the inadequate education of blind people as the key reason for their employment difficulties. This study can provide valuable information for policymakers focusing on visual impairment.
RESUMO A inserção laboral das pessoas com cegueira foi pesquisada, mas não existem estudos que perguntem sobre o que pensam e conhecem os docentes que formam estas pessoas e sobre as dificuldades de seus estudantes para inserir-se no mercado laboral depois de sua educação. O objetivo desta pesquisa qualitativa foi compreender as teorias subjetivas de seis docentes de um estabelecimento educacional de La Serena, Chile. O método da coleta de dados utilizado foi a entrevista em profundidade e o estudo dos dados realizou-se por intermédio dos procedimentos de codificação da grounded theory e a análise do conteúdo das teorias subjetivas. Encontrou-se, como principal resultado, que para os participantes a educação inadequada do cego é a principal causa da dificuldade para a inserção laboral. Esta pesquisa pode aportar informação valiosa para aqueles encarregados das políticas públicas entorno à incapacidade visual.
BROMELIACEAE EN ALGUNOS MUNICIPIOS DE BOYACÁ Y CASANARE, COLOMBIA Alvarado-Fajardo, Viviana Maritza; Morales-Puentes, María Eugenia; Larrota-Estupiñán, Edgar Fabián
Revista de la Academia colombiana de ciencias exactas, físicas y naturales,
12/2023, Letnik:
37, Številka:
142
Journal Article
Recenzirano
Odprti dostop
Se realizó un estudio de la familia Bromeliaceae en algunas regiones de municipios en departamentos de Boyacá y Casanare, a partir de revisión de herbario y trabajo de campo. Se registraron en total ...66 especies distribuidas en diez géneros, de los cuales, Tillandsia tiene 25 especies/38%, Guzmania con 11/17%, seguida de Racinaea con 9/14%, los restantes con menos de tres especies cada uno. Se registra a Guzmania goudotiana como una especie casi amenazada.
Increasing global concern has been raised about the expansion of hypoxia in coastal waters and its potential to impact benthic ecosystems. Upwelling areas offer opportunities to study the effects of ...hypoxia on benthic communities under natural conditions. We used a biological trait-based approach and estimated functional diversity indices to assess macrobenthic community functioning along a depth gradient associated with naturally increasing hypoxia and concentrations of organic matter in the upwelling zone of northern Chile (South-East Pacific) over two years. Our results highlighted the increasing dominance of opportunistic biological traits associated with hypoxia and high organic matter content. Habitat filtering was the main process affecting the studied communities. Functional diversity patterns were persistent overtime despite the occurrence of a pulse of oxygenation. This study contributes to our understanding of how natural hypoxia impacts macrobenthic communities, providing useful information in the context of increasing eutrophication due to human influence on coastal areas.
•Three types of functional communities were found along a natural gradient of hypoxia.•Habitat filtering was the main process affecting benthic community diversity.•Hypoxia threshold of 2 mL/L dissolved oxygen for taxonomic and functional richness.•Opportunistic traits related to organic matter and hypoxia tolerance were identified.•Functional diversity in hypoxic habitats was not impacted by an oxygenation pulse.
Abstract
The decapod fauna on intertidal shores in northern Chile is characterized by its relatively high diversity and abundance due to the presence of continuous upwelling by the Humboldt Current, ...which results in a high productivity. The decapod fauna on intertidal rocky shores is characterized by coexisting species that inhabits in natural shelters such as cracks and eroded rocks, as well as among macroalgae. We aimed to monitor the brachyuran and anomuran (porcellanid) crabs in three intertidal sites during two periods of time in September-December 2019 in the Antofagasta region, one site without human intervention and two sites in the city of Antofagasta, for which we applied null models in ecology. We assumed that the communities are random, a viewpoint that is more robust because it reduces the risk of error type I. The results of the application of null models on the co-occurrence species revealed that species associations are mainly structured for all sites, whereas the niche-sharing null model revealed that the reported species did not share ecological niches and in consequence there is not interspecific competition. The results would probably indicate that the species of intertidal decapods have a micro-specific ecological-niche differentiation, which would explain the existence of structured pattern in species associations. The results were compared with information for other sites along the continental Chilean coast.
Even though research has been conducted on the employment integration at blind people, studies have failed to consider what teachers think and know about their blind students’ difficulties entering ...the workforce after completing their education. The aim of this qualitative study was to understand the subjective theories of six teachers from a school in La Serena, Chile. In-depth interviews were used to collect data, which were subsequently studied using grounded theory coding procedures and subjective theory content analysis. The main finding of this study was that participants regarded the inadequate education of blind people as the key reason for their employment difficulties. This study can provide valuable information for policymakers focusing on visual impairment.
In Chile, the species Choromytilus chorus stands out for its ecological and economic importance. This mussel has a very particular condition in the colour of the gonad, being cream‐yellow colour the ...male gonad and dark brown the female which is hardly desired by the consumers. In this context, the aim of this research is to determine the role that sex steroids have in gonadal differentiation of the mussel C. chorus. For this, juveniles with sizes 15–22 mm were selected, which were subjected to acute exposure in the form of bath for 60 days to four treatments: T1: dihydrotestosterone (DHT); T2: 17β‐estradiol (E2), T3: fadrozole (F) and T4: DHT‐F (DF), plus a control without chemicals. Each treatment as well as control included three replicates with 90 individuals each. The mussels undergoing treatment with E2 had a sex ratio (male:female) of 0.47 compared to 1:1 in the control group. In contrast, in the groups treated with DHT, F and DF the sex ratio changed to 2.0, 1.60 and 1.70 respectively. In the fertilization trials, all the mussels produced functional gametes, as they were able to generate gametes that were developed to morula, and veliger larva. Nevertheless, it should be noted that the size of oocytes from the group exposed to estradiol (61.12 ± 2.40 μm) was significantly higher than in other groups. These results support the hypothesis that sex steroids would be involved in sexual differentiation of marine bivalves.
El presente artículo es la construcción de un proceso de reflexión y resignificación del saber concerniente a la Enseñanza de la Biología, surge de la práctica pedagógica realizada por dos ...licenciadas en Biología de la Universidad Pedagógica Nacional (UPN) en el Instituto Técnico Industrial Francisco José de Caldas (ITIFJC). Durante esta experiencia se abordan reflexiones en torno a la enseñanza de la Biología suscitadas desde el contexto, las relaciones que emergen a partir de cada uno de los actores participantes (comunidad académica del ITIFJC y grupo de investigación enseñanza de la Biología de la UPN), la singularidad de cada sujeto participante y el saber, que goza de la especificidad de la Pedagogía y la Biología. De este modo, la reflexión es un elemento fundamental que todo maestro debe realizar durante su práctica pedagógica, debido a que es el punto intermedio entre lo teórico y lo práctico, es decir, es el punto donde se comienza a relacionar lo visto en la academia y a contrastar con la realidad. De acuerdo a esto, hay un antes y después de la práctica pedagógica; en el antes se da un imaginario de lo que posiblemente se irá configurando como maestro, y un después que se construye cuando se ha pasado por la práctica pedagógica, la cual empodera al maestro y lo concientiza de que los procesos en la enseñanza siempre van a ser dinámicos y flexibles.
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