Revista de Biología Tropical / International Journal of Tropical Biology and Conservation, es una revista de acceso abierto completo de la Universidad de Costa Rica centrada en la biología tropical y la conservación. Todos los números, desde 1953 hasta la actualidad, están disponibles para su descarga gratuita. aquí. NUESTRO ENFOQUE (Objetivo) Nuestra revista publica artículos científicos que aumentan nuestra comprensión de la biología, la conservación y las ciencias biomédicas de la vida en los trópicos. Los criterios de selección son la cantidad y calidad de la nueva información y su interés potencial tanto para el público en general como para los especialistas. Los ecosistemas estudiados, o al menos los organismos, deben ser tropicales. COBERTURA TEMÁTICA Números regulares Damos preferencia a artículos de fondo que incluyen preguntas de estudio comprobables, por ejemplo, estudios con un diseño experimental que evalúe factores que influyen en variables biológicas, o estudios que explican los mecanismos subyacentes a fenómenos biológicos o biomédicos como, por ejemplo, el comportamiento o la fisiología. Los estudios de campo deben presentar patrones temporales o espaciales. También damos la bienvenida a estudios sistemáticos o filogenéticos por encima del nivel de especies, metanálisis y estudios bibliométricos que examinan críticamente lo que se conoce y lo que queda por hacer en cualquier campo de la biología tropical. Los artículos de revisión se publican en su mayoría por invitación del Consejo Editorial a autoridades reconocidas. Otros especialistas interesados en enviar una revisión primero deben enviar un esquema de manuscrito titulado al correo biologia.tropical@ucr.ac.cr. Las propuestas aceptadas reciben la misma evaluación que los manuscritos regulares. Todas las revisiones y metanálisis deben identificar y llenar los vacíos en el conocimiento, presentar avances metodológicos y proponer futuras direcciones de investigación. Nota sobre datos antiguos: Si su trabajo se basa en datos antiguos, recomendamos compararlos con datos más recientes, o usarlos como parte de meta-análisis, para darles mayor valor. Los estudios basados en datos recopilados hace más de seis años deben incluir una justificación de por qué siguen siendo de interés y, en el caso de estudios de campo, deben presentar patrones espaciales o tendencias temporales de importancia histórica. El Comité Editorial evalúa la validez de los métodos y la relevancia de los resultados antes de enviar el manuscrito a revisión. La revista ahora cuenta con un número al año (publicación continua del 1 de enero al 31 de diciembre) y publica los artículos la misma semana en la que se tiene disponible una versión editada. Hasta 2021 publico cuatro números regulares por año: número 1 (enero-marzo), número 2 (abril-junio), número 3 (julio-septiembre) y número 4 (octubre-diciembre). No publicamos notas; comunicaciones cortas; listas de especies; nueva especie única; extensiones de rango; nuevos registros y otros estudios preliminares o breves; o informes técnicos altamente especializados basados en protocolos (por ejemplo, estudios agrícolas, forestales, bioquímicos, microbiológicos, acuícolas, pesqueros o similares que solo aplican técnicas bien conocidas a casos particulares de interés local). NÚMEROS ESPECIALES Los números especiales financiados por organizaciones de investigación se aceptan después de la aprobación del Comité Editorial. Pueden contener una diversidad de tipos de informes, incluidos artículos breves, nuevos registros, nuevas descripciones de especies, listas de verificación, informes técnicos, etc. Para publicar un número especial, comuníquese con biologia.tropical@ucr.ac.cr para obtener una estimación de costos. PÚBLICO META Personas investigadoras con interés en el estudio de todos los campos de la biología tropical. PORQUÉ PUBLICAR EN LA REVISTA DE BIOLOGÍA TROPICAL? Totalmente indexada: Revista de Biología Tropical está incluida en Science Citation Index Expanded, REDIB Journals Ranking, Current Contents, Google Scholar, Biological Abstracts y alrededor de 50 otros índices internacionales. Rápida decisión y publicación (7 días para la primera decisión, 5-7 meses para aceptación definitiva, 6-8 meses desde el envío hasta la publicación). Razonable: utilizamos un sistema de doble ciego para una evaluación justa de los manuscritos. Alto impacto, no solo por su índice de citas, sino también porque es muy leído en países con la mayor biodiversidad tropical, lo que garantiza que su artículo tendrá el mayor impacto en la conservación de la biodiversidad tropical. Factor de impacto de Web of Science de 0.6. Factor de impacto en SJR de 0.28 (Q2). Un trato personalizado por parte de nuestro dedicado personal. Juntas editoriales y científicas de clase mundial. Acceso abierto: Todos los artículos, desde el primer número en 1953 hasta el presente, están disponibles gratuitamente en línea (Archivos), por lo que es más probable que sean citados que los artículos detrás de muros de pago. PUBLICACIÓN GRATUITA: Cada artículo recibe 10 páginas de espacio libre en formato PDF, que es suficiente para la mayoría de los artículos científicos. Se pueden publicar páginas adicionales diagramadas en el pdf a $50 cada una. Material complementario como textos adicionales, figuras, tablas, gráficos y bases de datos con un costo de $60. Póngase en contacto con biologia.tropical@ucr.ac.cr para obtener más información. OAI-PMH: https://revistas.ucr.ac.cr/index.php/RBT/oai
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Assessment of the relative abundance and habitat of Neotropical Otter Lontra annectens (Carnivora: Mustelidae) in Durango, Mexico
Introduction: Neotropical otter (Lontra annectens) is a widespread aquatic mammal in Mexico. Unfortunately, anthropogenic activities in Mexico have modified and polluted the habitat of this otter species, which has been listed as threatened. In Durango State, Neotropical otters thrive in preserved areas within the Sierra Madre Occidental. However, there are few scientific reports of their presence at the San Diego River. Objective: To evaluate the habitat and compare the relative otter abundance over a 10 km section of the San Diego River using two widely used methods. Methods: The habitat was characterized by measuring the river's physical structures, water physicochemical analyses, and plant species identification by strata and cover. Otter abundance was estimated by counting scats and latrines over 15 months. Data were analyzed with a stepwise regression to obtain the habitat variables significantly correlated with otter abundance. Results: Vegetation was composed of a gallery forest with low deciduous forest associations. The highest plant cover corresponded to the herbaceous stratum (50.87 %), followed by the tree stratum (30.4 %) and the shrub stratum (18.71 %) and the species Salix bomplandiana, Baccharis salicifolia, Sanvitalia ocymoides, and Muhlenbergia montana had the highest Importance Value Index (IVI). Otter abundance was 0.50 ± 0.14 otters km-1 using Method 1 ( ) and 1.12 ± 0.30 otters’ km-1 using Method 2 (E), with significant differences between them. Conclusion: A model was constructed to predict the number of scats (SC) about otter abundance; the significant habitat variables were smaller rock diameter (SRD), a greater distance to the shoreline (DSL), turbidity (TB), and pH.
Copyright (c) 2026 Revista de Biología Tropical https://creativecommons.org/licenses/by/4.0
Mangrove forest structure, water quality, and carbon storage at Palmares, northern Pacific coast of Costa Rica
Introduction: Mangroves provide many ecosystem services, yet they continue to be degraded and decline in numbers. Effective management strategies need baseline information to assess habitat condition and potential decline. In Costa Rica, mangroves on the North Pacific are the least studied. Objective: To provide the first characterization of forest structure and carbon content of the Palmares mangrove. Methods: A total of 58 square plots (5 × 5 m) were sampled between March 2022 and April 2023. In each plot, mangrove species, stem height, and circumference were quantified. Samples were collected to estimate interstitial water salinity, fine root content, and sediment grain size, bulk density, and carbon content. Mangrove biomass and organic carbon (OC) were calculated using allometric equations. Water quality was assessed at six sites in the main channel during the dry and rainy seasons of 2023. Results: Six mangrove species were identified at Palmares. Rhizophora spp. (55 % of plots) and Avicennia spp. (29 %) were the most abundant, while Laguncularia and Conocarpus were rare. Average tree height was 8 ± 7 m, width 11 ± 12 cm, and density 1 833 ± 1 757 stems ha-1. Rhizophora spp. were taller and wider than Avicennia spp. Interstitial water salinity at Palmares was 34 ± 14, which was higher during the dry season and in Avicennia spp. plots. Sediment was mainly composed of silt-clay (52 %), which was higher in Rhizophora spp. plots. Sediment bulk density was 0.8 ± 0.3 g cm-3 and fine roots < 1 %. Above-ground biomass OC averaged 224 ± 335 Mg ha-1 and was higher in Rhizophora spp. plots. Sediment OC was 8 ± 3 % and inorganic carbon 3 ± 1 %. OC was higher in sediments of Rhizophora spp., with higher silt-clay, larger mangroves, and lower densities. There was no clear pattern of variation in water parameters along the main channel. Conclusions: This first characterization of Palmares mangrove can serve as a baseline for further studies and effective management and conservation strategies.
Short-term variability of fish larvae assemblages in Malpelo island, an isolated oceanic island in the Eastern Tropical Pacific
Introduction: Oceanic islands are key biogeographic features that influence the distribution and diversity of marine organisms, particularly in tropical ecosystems. Malpelo Island, located 380 km off the Colombian Pacific coast, is the only oceanic island in the country and a strategic site for assessing ichthyoplankton dynamics in the Eastern Tropical Pacific (ETP). Objective: To characterize the taxonomic composition and spatial ecological structure of fish larvae assemblages associated with Malpelo Island in the Colombian Eastern Tropical Pacific under prevailing hydrographic conditions. Specifically, to assess differences in species richness, abundance, and diel vertical distribution between insular and adjacent offshore sites. These patterns are interpreted in the context of localized larval retention and vertical migratory behaviors, potentially shaped by insular oceanographic features. Methods: Short-term variability in larval fish assemblages was evaluated using vertical zooplankton trawls conducted in September 2012 and July 2016 across three depth strata. Fish larvae were identified to the lowest possible taxonomic level, and hydrographic profiles of temperature and salinity were obtained using CTD casts. Results: A total of 26 taxonomic units representing eight orders and twelve families were recorded. Assemblages near the island included epipelagic and reef-associated taxa such as Sardinops sagax and Anchoa spp., while offshore stations were dominated by mesopelagic species including Diogenichthys laternatus and Vinciguerria lucetia. Although larval abundance did not differ significantly between locations (MW; p = 0.38), assemblage similarity was low (45 %) and species turnover high (79 %). Larvae exhibited diel vertical migration, occupying deeper strata (50-100 m) during daylight and ascending to shallower layers (0-50 m) at night, influenced by local thermocline and halocline depth. Conclusions: These findings highlight the ecological distinctiveness of Malpelo Island and its role in supporting larval fish diversity in tropical oceanic environments. The results provide baseline data for future ecological monitoring and conservation planning in insular marine habitats of the ETP.
Diversity of aquatic Diptera (Insecta: Diptera) in a high-Andean watershed of Tolima Colombia
Introduction: Aquatic dipterans are key components of mountain lotic ecosystems due to their diversity, ecological sensitivity, and bioindicator value. The Combeima River Basin (Tolima, Colombia) is a high-Andean basin essential for water supply, but it is affected by anthropogenic pressures. Objective: To expand knowledge on the diversity and abundance of aquatic dipterans along the Combeima River Basin (Ibagué, Tolima) during contrasting hydrological periods. Methods: Three samplings were conducted over an annual hydrological cycle (September 2022, June and September 2023), covering both the dry and rainy seasons. Five samples were taken at each station using three different sampling methods: Surber net (on sediment, rock, and leaf-litter substrates), screen net, and sieves. All samples were pooled into a unique sample for data treatment. Larvae were separated, preserved, and identified using available taxonomic keys; for Chironomidae, clearing and mounting techniques were applied, considering different diagnostic characters for identification. Diversity was estimated using Hill numbers and rarefaction curves. NMDS and ANOSIM analyses were applied to explore community patterns. Results: A total of 1 586 larvae belonging to 11 families and 28 genera were collected. Chironomidae were the most abundant (74.56 %), followed by Simuliidae (15.76 %) and Blepharoceridae (6.24 %). In contrast, Dolichopodidae, Dixidae, and Stratiomyidae were scarce, with only four, two, and one individual recorded per family, respectively. Differences in richness and dominance were observed among stations and periods, related to altitude and anthropogenic disturbances. NMDS showed grouping by station, with greater heterogeneity in impacted sites. Conclusions: Aquatic dipteran communities reflected the combined influence of natural environmental factors and anthropogenic disturbance. A progressive replacement of sensitive by tolerant genera was observed, indicating a clear ecological tolerance gradient and reinforcing their value as bioindicators of environmental quality. These findings provide a robust ecological baseline for future monitoring and conservation programs in high-Andean microbasins.
Bioavailability and bioaccumulation of microplastics on marine zooplankton in a Marine Protected Area of Caribbean
Introduction: Microplastics are present throughout the global ocean and can be ingested by many species, including zooplankton. Although they fall within the size range of zooplankton prey, there are few in situ studies on microplastic ingestion. Objective: To evaluate the bioavailability and bioconcentration of microplastics in seven representative taxonomic groups of zooplankton within a Marine Protected Area (MPA) in the Caribbean. Methods: To elucidate the biodisponibility of microplastics, twelve stations were sampled with oblique towns using mini-bongo net during two contrasting hydroclimatic seasons in 2022. In the laboratory, we analyzed size, shape and polymer compositions of microplastics at each water sample using stereoscopy and FTIR-ATR with 4 cm- 1 resolution. Seven dominant zooplankton groups were selected from different trophic levels to assess the ingestion encounter rate and bioaccumulation of microplastics. Results: A median bioavailability of microplastics of 0.091 microplastics/m³ was recorded (mainly polyester and PET fibers and fragments), with significant differences between seasons (Kruskal-Wallis, p = 1.5 ×10-⁹). Zooplankton mainly ingested black fragments with an Encounter Rate of 0 to 0.22 microplastics/ind., and the observed bioconcentration in the taxonomic groups was > 1, indicating direct or indirect bioaccumulation. Conclusion: The bioavailability of microplastics in the MPA is lower than in other regions of the world, and the temporal variability is modulated by the Caribbean's oceanographic dynamics and river inputs into the coastal zone. Six of the seven analyzed zooplankton groups accumulate microplastics, with Paracalanidae showing the highest bioconcentration factor. These findings highlight the need to monitor and mitigate the effects of microplastics on marine ecosystems to protect both the affected species and the ecosystem services they provide.
Copyright (c) 2025 Revista de Biología Tropical https://creativecommons.org/licenses/by/4.0
Performance of the Weibull individual growth model for weight at age data
Introduction: Knowledge of different functions associated with a probability distribution, as well as their properties, can be translated into functions that provide information about different characteristics of the growth process under study. Objectives: To analyze the relationship between individual growth models and the cumulative distribution functions of continuous random variables. Methods: We compare the flexibility and goodness of fit of the Weibull-type model against the von Bertalanffy weight growth model. We fit these two growth models into two very different sets of age-weight data taken from the literature; the first comprises 22 pairs of Pacific halibut mean weight at age, and the second 900 pairs of striped bass weight-age-data. Results: The Weibull-type growth model had greater flexibility and neglected less information available in the data sets than the von Bertalanffy model. Conclusions: The Weibull model, derived from cumulative probability distribution, is a good choice to fit weight-at-age data as it is more flexible than the commonly used von Bertalanffy model.
Proximate composition and lipid content of muscle tissue by TLC-FID of seven freshwater fish species collected from Campoma Lake, Venezuela
Introduction: Lipids in fish play a fundamental role in growth, reproduction, and homeostasis, maintaining cellular integrity. Objective: To assess the nutritional quality of seven fish species from Lake Campoma through analysis of their proximate composition and lipid profile. Methods: A total of 10 kg of each species Cichlasoma kraussii, Pimelodus clarias, Hoplias malabaricus, Aequidens pulcher, Hypostomus plecostomus, Hoplosternum littorale, and Centropomus mexicanus were collected through direct fishing in Lake Campoma. Samples were refrigerated and transported to the laboratory, where muscle tissue was dissected for subsequent analysis. Lipid fractions were determined using thin-layer chromatography with flame ionization detection (TLC-FID). Principal component analysis (PCA) was applied to explore the relationships among the evaluated parameters. Results: Centropomus mexicanus exhibited the highest lipid (2.33% w/w) and protein content (24.07%). In all analyzed species, phospholipids were the predominant lipid class (34–85%), followed by free fatty acids (7%), triacylglycerols (4%), and cholesterol (<34%). Water was the major component in the proximate analysis, ranging from 76.5% in C. kraussii to 82.5% in P. clarias, which may increase susceptibility to microbial spoilage if not stored properly. No clear association was observed between species and ash content. Conclusions: The evaluated species demonstrated high nutritional and energy value, supporting their inclusion in human diets. Phospholipids were predominant (up to 85%), followed by free fatty acids (7%) and triacylglycerols (>4%), with cholesterol levels below 37%. C. mexicanus stood out due to its high protein and energy content, while H. littorale and H. malabaricus were identified as the most nutritionally rich. These findings underscore the importance of these freshwater species as valuable sources of macronutrients and essential bioactive compounds.
Proximate composition; freshwater fish; TLC-FID; total lipids; multivariant analysis
Spatial variability and trophic structure of aquatic macroinvertebrate communities in the semi-arid Quilca-Chili basin, Peru
Introduction: The trophic structure of macroinvertebrate communities is of particular interest for understanding the functioning of the river ecosystems. Objective: To determine the community structure and functional feeding groups of aquatic macroinvertebrates in the Quilca-Chili basin. Methods: Two sampling campaigns were conducted at 26 stations, distributed across six sectors, from June to October 2022. The community structure was analyzed based on basic ecological parameters, including taxonomic richness, dominance, evenness, and diversity. Spatial variability was assessed through a similarity percentage analysis and non-metric multidimensional scaling using the Bray-Curtis distance index. The relationship with physicochemical variables was determined through canonical correlation analysis. Results: A total of 51 families were identified and assigned to functional feeding groups: predator, shredder, collector-gatherer, scraper, and filterer. The highest and lowest diversity was observed in the Sihuas sector and the Chili and Lluta sectors, respectively. Differences in community structure indices were found between the six sectors of the basin. The most abundant functional feeding groups were scrapers, while shredders and predators were the least abundant. Conclusion: The spatial distribution reflects the complexity and variability among physicochemical parameters and functional feeding groups in this basin.
functional feeding groups; macroinvertebrates; desert; high Andean; rivers
Structural analysis and health status of the mangrove forest in the coastal sector Paraguay, Guantánamo, Cuba
Introduction: Manglares are ecosystems that provide numerous benefits and environmental services to society. However, its extension is being reduced due to various human activities such as the change in soil use and coastal development, which is why studies are needed to determine the state of these ecosystems and thus propose actions for their rehabilitation. Objective: Characterize the structure and health status of manglar in the coastal sector Paraguay, Guantánamo, Cuba. Methods: The investigation took place in a mangrove forest in the coastal sector that borders Guantánamo Bay, in the eastern region of Cuba. Plots of 100 m2 aligned, perpendicular to the coast; The structure of the mangle is determined by height, diameter, basal area, volume, density and mortality. The relationship of these variables with the composition of mangle species was carried out through a Canonical Discriminant Analysis. To determine the state of health, the quotient of the number of identified tensors over the total of identified tensors is obtained, the result is the remainder and is multiplied by 100 to express it in complete numbers. Using the value obtained, the health status was classified following this scale: very high (from 100 to 71), high (from 70 to 67), medium (from 66 to 62), low (from 61 to 42) and very low (41 or less). Results: The average height of the head was 6.50 m, with a predominance of Avicennia germinans and average regeneration. New environmental tensors were identified, the majority with anthropic character and low intensity (88% are of anthropic origin and 12% are related to natural events). Conclusion: The health of the studied ecosystem presents a variation that goes from very high to low and is characterized by a low size.
basal area; coastal zone; environmental tensors; natural regeneration; forest structure
Reproduction of the sea cucumber Holothuria (Halodeima) grisea (Holothuriida: Holothuriidae) from Santa Catarina coast, southern Brazil
Introduction: The sea cucumber, Holothuria (Halodeima) grisea, is a common species in intertidal rocky shores along the Brazilian coast. Due to its abundance, it is considered a potential resource for aquaculture development. Objective: To characterize some reproductive features of H. (H.) grisea in southern Brazil, including sex ratio, gonadosomatic and maturity indices, and macro and microscopical observations of gonad tubules. Methods: Adult individuals were randomly collected in August and October 2019; February, March, May, and October 2020 at the intertidal region during low tides on the coast of Santa Catarina, Brazil. The individuals were transferred to the laboratory, where they were subject to biometry, dissection, and preservation to further macro and microscopic examinations. Results: The sex ratio was 1 : 1 and the gonad indexes were similar in both sexes and between months. Two main cohorts (25.3 and 85.3 μm) and three cytometric intervals (CI) were established. Based on histology for males, and mainly cohorts and CI for females, the individuals were categorized into five stages of the gonadal development scale (GDS) in tubules: growing, premature, mature, spawning and post spawning. Maturation and spawning events were frequent in all months, mainly February, March, and May 2020. Seven colors of the tubules were presented (transparent, transparent-pink, white, transparent-white, creamy-white, cream, and pink) with a large overlap between sex and GDS. Conclusions: This study is the first to describe the reproductive behavior of H. (H.) grisea on the coast of Santa Catarina and this population exhibits a continuous reproductive pattern with reduction in winter season. Our results can offer a baseline for future research, providing various qualitative and quantitative description tools for greater effectiveness in understanding the maturity cycle of populations and managing the sea cucumber fishery in Brazil.
Holothuroidea; reproduction; gametogenesis; gonad index; maturity index; oocyte size.
Association between the alga Spirogyra (Zygnemataceae) and heavy metals in sediments of the Chi River Basin in Northeast Thailand
Introduction: Sediments act as major sinks of heavy metals from human activities, while algae such as Spirogyra interact with these sediments through nutrient uptake and biogeochemical cycling. In the Chi River Basin, Spirogyra (“Tao”) plays both ecological and socioeconomic roles, serving as food and a bioindicator of pollution. Objective: To evaluate heavy-metal concentrations in sediments and Spirogyra and assesses their potential human health risks. Methods: Water quality, Spirogyra, and sediment samples from the Chi River Basin were analyzed for heavy metals using ICP-OES, with human health risks assessed by THQ and HI, and sediment contamination evaluated through Igeo, EF, CF, PLI indices. Results: Heavy metals (Cd, Cu, Fe, Mn, Zn) in sediments and Spirogyra from the Chi River Basin were assessed under average water conditions (pH 7.49, EC 497 µS cm–2, NaCl 0.024 %, 24.9 ± 3.52 °C), showing concentrations in algae (Fe > Mn > Zn > Cu > Cd) with THQ and HI < 1 indicating low health risk, while sediments (Mn > Fe > Zn > Cu > Cd) exhibited Igeo < 0, EF < 2, CF < 1 except for Fe (CF = 8.31), PLI < 1, and significant correlations between Mn in algae with Cu and Mn in sediments, Cu with Fe in algae, and Cd in algae with Fe in sediments. Conclusions: The findings indicate no significant heavy-metal pollution in sediments or Spirogyra from the Chi River Basin. However, due to elevated Fe contamination in sediments, periodic monitoring is recommended to safeguard ecological and food safety.
Habitat use of the Pacific eagle ray Aetobatus laticeps (Myliobatiformes: Aetobatidae) in a marine protected area of touristic importance, Banderas Bay, Mexico
Introduction: Aetobatids have low reproductive potential, with coastal and benthopelagic habits, which makes them vulnerable to anthropogenic activities. Despite this, the Pacific eagle ray Aetobatus laticeps is a poorly studied species, which makes it difficult to assess its populations to implement or improve conservation and management measures. Objective: To determine the habitat use of the Pacific eagle ray in Los Arcos (LA), Banderas Bay, Central Mexican Pacific, a protected natural area of tourist importance. Methods: From December 2015 to July 2017, 64 marine surveys were conducted to record the activity and size of eagle rays in three transects delimited by tourist use in LA. The variability in the seasonal presence of adults and juveniles, the trend in the space-time encounter rate, and its relationship with sea surface temperature (SST) were determined. Results: The encounter rate was higher in April and May (2016 and 2017), decreasing to zero during July, August, and September of 2016 (with the warmest SST) and February 2017 (with the coldest SST). Displacement activity predominated, followed by feeding activity. Recorded sizes ranged from 50-130 cm disc width (DW) (mean = 89 ± 17 cm). The site with the highest encounter rate coincides with the area of greatest tourist activity. Conclusions: This study provides evidence of the gregarious behaviour of juveniles and adults, their seasonal movements, and their relationship with SST at a limited spatial scale. Finally, it is essential to raise awareness among local communities in LA, as tourist activity may indirectly impact A. laticeps.
Molecular determination of Helicobacter pylori and detection of beta-lactamases in clinical isolates from patients in Antioquia-Colombia
Introduction: Helicobacter pylori exhibit variations in antibiotic resistance in America and Colombia. Despite the use of various treatment regimens containing amoxicillin in the department of Antioquia, Colombia, as well as in several countries across the continent, the pattern of genotypic and phenotypic susceptibility to this antibiotic remains unknown. Objective: To determine the frequency of H. pylori infection by detecting the ureA gene and amoxicillin susceptibility through beta-lactamases in H. pylori isolates from patients with gastroduodenal diseases in Antioquia-Colombia. Methods: Cross-sectional analytical study with 179 patients attending endoscopy units of seven healthcare institutions. Sociodemographic and risk factor data were collected. Moreover, biopsies from the antrum and body were taken for microbiological isolation and molecular detection of H. pylori. The sociodemographic data were assessed through frequency analysis and bivariate statistics. DNA obtained from the biopsies was amplified by PCR for the ureA gene, and beta-lactamase production was evaluated using the nitrocefin test as well as the amplification of the TEM and SHV genes. Results: It was found that 61 % (109 / 179) of patients tested positive for H. pylori; out of 84 isolates obtained by culture, none tested positive for the nitrocefin test. Significant differences were found in socioeconomic status, healthcare system, and geographical location in patients positive for the ureA gene. Two patients tested positive for molecular detection of beta-lactamases from biopsies; however, SHV and TEM genes were not found in any isolate. Conclusions: The frequency of H. pylori for ureA-gene detection is higher than previous studies and similar to other reports in other Colombian regions; consequently, this will become a good diagnostic test in the country. Finally, none of the H. pylori isolates tested positive for beta-lactamases TEM and SHV.
Effects of environmental changes on total length of three Copepod species on Gorgona island (Colombia) between 2013-2022
Introduction: Copepods are influenced by various climatic and oceanographic changes, including global warming, which increases the frequency of the warm phase of ENSO and contributes to reductions in their mean population body size. Objectives: This study evaluates the effects of temperature, salinity, and dissolved oxygen concentration—measured at standard depths—on the mean total length of three copepod species: Ditrichocorycaeus andrewsi, Centropages furcatus and Subeucalanus pileatus, within the pelagic environment of Gorgona Island over a nine-year period. Methods: Each year, 25 healthy female and male specimens per copepod species were selected during the cold-water season from 2013 to 2022. Vertical variability in temperature, salinity, and dissolved oxygen was analyzed. A mixed linear model was used to assess the independent effects of mean total length by sex, species, and year, while Spearman correlation confirmed associations with environmental variables. ANOVA followed by Tukey's test identified significant differences in total length among years for each species. Results: A weak positive correlation was detected between temperature and the total length of the three studied species. A linear mixed model confirmed a significant species-sex-year interaction effect. D. andrewsi and S. pileatus exhibited smaller sizes during warm periods, while C. furcatus displayed considerable variation with no clear association to thermal conditions. Conclusions: This study establishes a baseline for future research on the effects of climate change on copepod body size in the Colombian Pacific and the Eastern Tropical Pacific, and offers valuable insight into how interannual climatic variability shapes copepod populations in tropical environments, contributing to a broader understanding of climate change impacts on marine ecosystems.
body size; ENSO; global warming; zooplankton
Two decades of jaguar and puma (Carnivora: Felidae) activity in lowland forest of eastern Ecuador
Introduction: Jaguars (Panthera onca) and pumas (Puma concolor) are the two largest terrestrial predators in lowland Neotropical forests and as such, are important contributors to the ecosystem. Yet, long-term studies on their temporal and spatial patterns of occurrence are not common. Objectives: To update a previous eight year (2005-2012) camera-trap study on jaguars at Tiputini Biodiversity Station, Yasuní Biosphere Reserve, with data from 2014 through 2023; and to add complementary information on pumas. Methods: We used camera traps set along trails or at mineral licks to document the occurrence of jaguars and pumas. Individual jaguars were identified by their distinctive coat patterns. Results: Capture rates from 2014 to 2023 varied from 0 to 2.94 images/100 trap days for jaguars and from 0.46 to 4.88 for pumas. These rates were similar or increased across all years for both species. We identified 28 individual jaguars during the second sample period, including 18 males and seven females. Periods between captures ranged from 1 to 84 months, with eight individuals recorded over at least 36 months. Including images from the first period (2005-2012), when 21 individuals were identified, it is likely that ~50 individual jaguars have occurred in or close to the research station over 19 years. Jaguars were primarily active during daylight hours, while pumas were more active at night. Conclusions: TBS is embedded within a large biosphere reserve but is too small (~670 ha) to cover the home range of either species. Nonetheless, given the number of records and the fact that capture rates have not declined in the past two decades, this region is important for the conservation of these two species and the many prey they depend on.
Habitat preferences and simulation of physical habitat availability of Perlidae (Plecoptera) and Corydalidae (Megaloptera) in a neotropical river
Introduction: Habitat preferences represent the distribution and abundance of species among different habitat types. These preferences are highly relevant ecological information because they relate to the feeding strategies, offspring care and predator avoidance refuges of the organisms, therefore potentially influencing their fitness. Objective: To define the habitat preference of the nymphs of Anacroneuria spp. (Plecoptera) and larvae of Corydalus spp. (Megaloptera) with respect to current velocity and depth. Methods: We evaluated the abundance of Anacroneuria and Corydalus with information gathered through 15 field campaigns in three sites of the Savegre River, Costa Rica. Also, we used habitat preferences to create simulations of the physical habitat availability for these species through hydraulic models to determine habitat gain or loss due to variations in flow. Results: Anacroneuria (Plecoptera) nymphs preferred velocities of 0.9 m/s and depths between 23-36 cm, while Corydalus (Megaloptera) larvae preferred velocities between 0.6-0.8 m/s, and depths between 17-29 cm. As a case study, these preferences were modeled to determine optimal, regular or inadequate habitat availability for Anacroneuria and Corydalus given hypothetical flow variations in the Savegre River (Costa Rica). A discharge of < 8 m3/s resulted in a decrease in optimal habitat, mainly because it decreased water velocity below the preferred ranges. Also, a discharge of > 18 m3/s resulted in a decrease in optimal habitat because of the depth increase. Conclusions: This type of information is scarce or even absent for neotropical rivers, though necessary for a description of a healthy habitat. Furthermore, this habitat preference vs. modeled habitat availability approach is highly useful, -both in tropical and temperate rivers- for understanding the potential effects of any water derivation or exploitation.
Long-term monitoring of ocelots Leopardus pardalis (Carnivora: Felidae) in Tortuguero National Park, Costa Rica
Introduction: The ocelot Leopardus pardalis, though currently listed as Least Concern on the IUCN Red List, has a declining population, and faces threats such as habitat loss and fragmentation and hunting across the entirety of its geographical range, from the Southwestern United States to Northern Argentina. Being a cryptic species and with few studies monitoring ocelots over multiple years, there is a lack of information regarding ocelot ecology. Objective: To further understand the behaviour and population dynamics of ocelots within the study area, Tortuguero National Park (45 755 ha), Costa Rica, by analysing data from a long-term camera trapping study (2011-2022). Methods: Individual ocelots were identified using their unique spot markings. Sex ratio, daily activity patterns, and behaviour were evaluated, whilst ocelot minimum age was estimated for each individual and designated as either resident or transient based on the number of consecutive years observed in the study. Results: A total of 30 individual ocelots were identified (12 females, 18 males). The daily activity pattern (nocturnal) and sex ratio (1 : 0.7) were consistent with that described for the species. The movement of one individual from Tortuguero National Park to Pacuare Nature Reserve, 41 km South, highlights the importance of wildlife corridors for the species. The study also revealed evidence of a female ocelot at least 14 years of age. There are very few published occurrences of an ocelot this old in the wild. Scent marking behaviour was also recorded. Conclusions: This is the longest monitoring effort for ocelots in the country, to our knowledge. Our results highlight the importance of and need for further long-term studies of ocelots to enhance understanding of the species and thus promote the conservation of the species and its habitat.
Diversity and vertical distribution of epiphytic orchids and bromeliads in two contrasting forests from Northeast Andes of Colombia
Introduction: Functional traits analysis allows an understanding of the mechanisms that structure plant communities epiphytes. The distribution of taxonomic and functional epiphyte diversity along vertical gradients is a key tool to track epiphytes’ response to environmental changes, especially in biodiversity hotspots, where a high number of endemic species are threatened. Objective: To relate the taxonomic and functional epiphyte diversity and their vertical distribution with forest structural variables of the Montane and Dry Forest ecosystems in the Colombian Andes. Methods: Epiphyte diversity in each study site was recorded in 35 random phorophytes. Alpha and functional diversity were compared for five vertical strata of the canopy (Z1-Z5) and related to forest structural and floristics variables such as tree richness, tree density, diameter at breast height (DBH), canopy height, crown area, and canopy openness. Results: The Montane Forest presented a greater diversity of epiphytes, mainly orchids, with Stelis angustifolia as the dominant species. In contrast, the Dry Forest presented a greater Bromeliad abundance, and Tillandsia recurvata was dominant. Montane forest epiphytes were represented by three functional groups: tank-bromeliads, shallow tank-bromeliads, and ramicauls-orchids, while in the Dry Forest shallow tank-bromeliads and nebulophyte-bromeliads. Positive correlations were found between epiphyte richness, abundance, and diversity with variables related to phorophyte size (DBH and crown area) in montane forest. There was also a different tendency on the preference for some strata between Orchids (Z2-Z3) and Bromeliads (Z3-Z4). Conclusion: Differences were found in the taxonomic and functional diversity of epiphytes between the two forests, where orchids and bromeliads often coexist in similar environments but are distributed in different habitats, resulting from adaptation to specific environmental conditions, which allows them to coexist in different niches within the ecosystem.
Epiphytic macrolichen as indicators of environmental changes in a montane forest of Panama
Introduction: Corticolous lichens are organisms that respond to habitat modifications, which is why they are considered model organisms to evaluate environmental changes in different ecosystems. Objectives: To determine the species richness and community composition of corticolous macro lichens in montane forests and forest remnants. In addition, the effect of microclimatic factors in three areas with different degrees of light intensity and density of arboreous vegetation on the species distribution of recorded diversity was evaluated. Methods: The study was conducted in the Volcan Baru National Park, Panama. Three areas with different forest densities and host tree species, Comarostaphylis arbutoides and Quercus spp., were chosen, considering a total of 60 trees, 10 of each species in each area. The canopy's opening close to the host trees and its diameter at breast height were recorded. Linear models and multivariate analysis was used to determine changes in species richness and composition of epiphytic macro lichens. Results: The characteristics of the host trees (e.g. host species and area) conditioned the species richness, while the communities were limited by microclimatic changes (e.g. light) in different areas. Conclusion: The macro lichens communities analyzed responded to changes related to the host tree species and the microclimate, so they can be considered indicators of ecological continuity in tropical montane forests.
Sporogenesis and ultrastructure of spores in the fern Anemia hirsuta (Anemiaceae)
Introduction: Research into the ontogeny of sporangia and sporogenesis of leptosporangiate ferns is scarce in the scientific literature. Objectives: To describe and analyze the ontogeny of sporangia, sporogenesis, micromorphology, and ultrastructure of mature spores of the fern Anemia hirsuta. Methods: Fertile fronds of A. hirsuta were processed according to standard protocols for sectioning and embedding samples in paraffin and resin. Sections in paraffin were stained with safranin-alcian blue, Toluidine Blue, and PAS/amidoblack. Sections in resin were stained with Toluidine Blue. The samples were prepared for observation under scanning electron microscopy (SEM) to yield detailed descriptions. Mature spores were analyzed by X-ray energy dispersion (XEDS). Ultrathin sections were obtained for transmission electron microscopy (TEM) observation. Results: The entire leptosporangium is formed from a basal and an apical cell derived from a single epidermal cell of the fertile pinna. The mature leptosporangia are globose, with a subapical ring and a short pedicel. During development, the tapetum is initially cellular, and then becomes plasmodial. The sporocytes undergo simultaneous meiotic division to form tetrads of spores in a tetrahedral arrangement. The exospore is formed first, with two layers, a very thin internal layer and a thick outer layer, followed by the endospore, and finally the perispore. The spores are trilete and muriform, with simple or branched siliceous microspines. The perispore associated with the muri and grooves appears to be highly organized with evident ultrastructural differences. Conclusions: The ontogeny of the sporangia and sporogenesis of A. hirsuta is similar to that previously described for leptosporangiate ferns and recorded in some related fossil species. The highly structured and organized perispore is observed. A high silica content in the microspines of the sporodermis is herein reported for the first time in this group.
Effects of seedlac on soil bacterial diversity: An indication of environmental safety
Introduction: Lac resin, the only natural resin of animal origin, is exclusively produced by the lac insect (Kerria spp.). It is non-toxic and considered biodegradable. However, the bacteria involved in biodegradation have not been explored. Moreover, the fate of the soil bacteria during biodegradation has not been studied so far. Objective: To explore the fate of soil bacteria due to the burial of seedlac in soil to ascertain whether seedlac is environmentally safe, and to explore the possibilities of identifying any bacterial flora involved in lac biodegradation. Methods: The study began in 2016 by burying seedlac samples (semi-refined lac resin product) in the field soil and pot soil under replicated conditions. The seedlac samples were drawn from the soil in 2019, and the soil adhering to the seedlac samples was used in further experiments. The bacterial diversity of these soils was documented by sequencing the V3-V4 region of 16S rRNA through the Illumina NGS platform. Results: No significant variations were obtained in the soil bacterial diversity between samples except for the marginal increase in the count of Actinobacteria, Myxococcales, Gemmatales, Gemmataceae, the WD2101-soil group in seedlac buried pot soil, and Proteobacteria and Acidobacteria in field soil. Most of these bacterial groups are known to degrade complex organic polymers. Conclusions: Since there are no changes in the soil bacterial diversity due to seedlac burial, it may be concluded that seedlac does not affect the soil microflora and is safe for the soil environment.
Distribution, richness, and abundance of Lycaenidae (Lepidoptera: Papilionoidea)in the Loxicha Region, Oaxaca, Mexico: A regional analysis on the Pacific slope
Introduction: The Sierra Madre del Sur in Mexico, known for its geological complexity and elevational gradient, hosts diverse ecosystems. The Loxicha region in Oaxaca, with five vegetation types and a 2 500 m elevation range, has the richest documented butterfly fauna on the Pacific slope. This study focuses on Lycaenidae butterflies, exploring their distribution, richness, and abundance along vegetation and elevational transects. Objective: To document geographic, elevational, and ecological patterns of Lycaenidae butterflies on the Pacific slope Loxicha region as part of a larger project on the distribution of diurnal butterflies in the state of Oaxaca, Mexico. Also, to compare Loxicha fauna with other regions to recognize biogeographical patterns at a larger scale. Methods: Spatial and temporal patterns of Lycaenidae diversity are based on systematic sampling conducted between 2005 and 2014 along elevational (80 to 2 500 m) and vegetational transects. Exclusive and characteristic species for each elevation and vegetation type are recognized. Results: A total of 123 species of Lycaenidae were recorded: nine species of Polyommatinae and 114 of Theclinae. The highest species richness occurs in May in tropical semi-deciduous forest. It decreases with increasing elevation. The results are compared with four other butterfly families. Lycaenid community similarity in the Sierra Madre del Sur and Pacific slope is correlated with elevation and vegetation type, though variability within each grouping is significant. Higher elevation faunal isolation also plays a role, as seen in other mountainous Papilionoidea taxa. Conclusions: Lycaenidae is one of the most diverse and least known butterfly families in Mexico. This is the fourth study on the Loxicha Region's lepidopteran fauna, confirming its high diversity among five Papilionoidea families. Systematic studies aid in understanding speciation and endemism, particularly for stenotopic species. The distribution of Lycaenidae in the Loxicha region is the most comprehensive to date for any region in Mexico.
elevational gradient; Eumaeini; phenology; Sierra Madre del Sur
Phenotypic differences in sun and shade leaves of Monstera deliciosa (Araceae)
Introduction: Leaves are among the most plastic organs in plants, and their structure, while shaped by phylogeny, can show considerable phenotypic plasticity within a species in response to environmental gradients. Monstera deliciosa, a tropical hemiepiphytic vine known for high leaf heteroblasty, adapts to diverse light conditions. This makes leaf structure a useful proxy for assessing whole-plant resource allocation strategies and adaptations to environmental changes. Objective: To measure the morphological and structural differences in sun and shade leaves using nine leaf traits (petiole length, leaf width and length, effective leaf area, fenestrated area, leaf perimeter, lobulation ratio, stomatal density, and specific leaf area -SLA-). Methods: We selected 20 widely separated M. deliciosa plants on the University of Costa Rica campus in 2022, positioned in contrasting sun and shade conditions, and measured one mature leaf per plant (ten per light environment). Results: Sun leaves had higher fenestrated area, perimeter, and stomatal density, suggesting structural adaptations to high light. These traits may enhance thermal regulation by facilitating heat dissipation. Sun leaves had lower SLA, indicating thicker, denser leaves better suited to high light and wind exposure. Lobulation ratios (leaf dissection) were not different between sun and shade conditions. A principal component analysis explained 82.88% of the variation in the leaf traits, with 39 % of the variation attributed to fenestrated area, leaf perimeter, and effective leaf area. Correlation analyses showed that fenestrated area, perimeter, and stomatal density were positively associated (and negatively related to SLA), emphasizing the functional convergence of these traits, adapting the leaf phenotype to light differences. Conclusions: M. deliciosa modulates leaf morphology and structure to adapt to distinctive light conditions, with fenestration, stomatal density, and SLA emerging as crucial traits. These findings underscore the significance of environmental differences in driving leaf shape and structure.
functional traits; leaf dissection; phenotypic plasticity; plant morphology; stomatal density.
Histomorphometry of the gastrointestinal tract of the fish Pseudoplatystoma magdaleniatum (Siluriformes: Pimelodidae)
Introduction: Pseudoplatystoma magdaleniatum, commonly known as striped catfish, is an endemic species of the Magdalena River basin, characterized by its large size and high commercial value. Given its critical endangerment due to overfishing, understanding its gastrointestinal tract morphology is crucial for conservation efforts and management in fish stocking programs. Objective: To characterize the morphology, histology, and histochemical qualities of the gastrointestinal tract of P. magdaleniatum, an endemic fish species in the Magdalena River basin, Colombia. Methods: Measurements of body height and weight of 22 captured adult individuals were taken, as well as of the organs comprising the digestive tract (esophagus, stomach, and intestine), and accessory and glandular organs (liver and gonads). Histological techniques, such as Hematoxylin and Eosin staining, were performed to characterize the organs structurally. Histochemical techniques were employed to describe the dynamics of mucins, and transmission electron microscopy was used. Results: The stomach and intestine exhibited four layers: mucosa, submucosa (absent in the esophagus), muscular, and serosa. The esophagus, with only three layers, was characterized by the presence of stratified squamous epithelium with goblet cells, club cells, and taste buds. Neutral mucins were detected along the esophagus, while acidic mucins were observed in the cranial and middle regions. The stomach featured a simple columnar epithelium with abundant gastric glands and exclusively neutral mucins. Finally, the intestine was characterized by a mucosal tunic of simple cylindrical epithelium composed of enterocytes and goblet cells, abundant folds, and the presence of sulfated and carboxylated neutral and acidic mucins. Conclusions: P. magdaleniatum exhibited a relatively short intestine for its size and weight. The histology of the gastrointestinal tract further supports adaptations for a protein-rich diet. These findings provide valuable insights for understanding the digestive physiology of this endangered species, which may inform conservation efforts and management strategies.
fish; Siluriformes; histology; histochemistry; goblet cells; mucins; digestive physiology; Magdalena River basin.
Ecomorphological and behavioral differences mediating resource partitioning among syntopic stream fish species in the Amazon Rainforest
Introduction: Generalist trophic strategies and opportunistic feeding habits of nektonic fish species inhabiting oligotrophic streams in the Amazon Rainforest suggest that minor morphological and niche differences can mediate the occurrence of closely related species in sympatry, alleviating interspecific competition for resources. Objective: To analyze the ecomorphology, diet composition, vertical and horizontal habitat use, and foraging behavior of four Characiform species in syntopy, to understand resource partitioning and species coexistence. Methods: From August to October 2011 (dry season), up to 30 specimens of each species were collected from each of eight sampled streams in the Adolpho Ducke Forest Reserve, Amazonas, Brazil, for ecomorphological analyses, with up to 10 of these used for stomach content analysis. Foraging behavior was quantified through underwater observation of vertical and horizontal space use and foraging frequency in the water column. The dietary importance of food items was determined using the Feeding Index (FIi), and ecomorphological attributes were used to characterize body shape and fin morphology. Results: Differences were detected in foraging behavior and habitat use. Hyphessobrycon. aff. melazonatus predominantly occupied the stream margins, and the other species utilized the channel. Additionally, only H. aff. melazonatus exhibited a difference in stomach content composition. Ecomorphological characteristics showed divergence among species, particularly in body shape, mouth size, and orientation. Conclusions: The combined analysis demonstrated that differences observed here may mediate syntopic coexistence by alleviating interspecific competition through resource partitioning. The system’s sensitivity to anthropogenic impacts and climate change were highlighted on food availability and trophic relations of Amazon stream fishes and underscore the need for headwater stream conservation.
Amazonian fishes; oligotrophic streams; habitat use; morphology; co-occurrence.
Human disturbance promotes an increasing abundance of shrubby plants in the páramo landscape of Southern Ecuador
Introduction: The páramo grassland ecosystem is an important center of plant diversity and endemism. However, human activities, such as burning and livestock grazing, are altering the plant composition of the páramos. These changes may be associated with an increase in the abundance of shrubby species and a corresponding decrease in native grass cover. Objective: To evaluate the effects of human disturbance on the composition of woody plant species in páramo habitats. Methods: We conducted 36 transects across the páramo landscape of the Macizo del Cajas Biosphere Reserve in Southern Ecuador between April 2017 and November 2019, recording woody plant species (e.g., bushes and shrubs) along each transect. To explore variations in woody plant composition, we employed non-metric multidimensional scaling, using the proportion of disturbed area, páramo grassland, and elevation as predictor variables. Results: We recorded a total of 13 377 woody plants. The proportion of disturbed areas has an influence on the composition of the woody plant species. Shrubby species such as Diplostephium ericoides, Hypericum quitense, Valeriana microphylla, and Valeriana hirtella are more prevalent in transects with a greater proportion of disturbed areas. Conclusion: There was a greater presence of fast-growing woody plant species in response to human-induced disturbance. This suggests that native herbaceous species are gradually being replaced by woody encroachment, particularly in human-accessible páramos. Conservation and restoration efforts should take this phenomenon into account to prevent the accelerated spread of woody encroachment and enhance the availability of páramo grassland habitats.
high Andes; woody plant encroachment; plant community composition; grasslands; biosphere reserve.
Lutjanus synagris (Acanthuriformes: Lutjanidae): reproductive biology and synchronization with lunar phases in the Gulf of Salamanca, Colombian Caribbean
Introduction: Lutjanus synagris is one of the most common demersal fishes in the Colombian Caribbean and is of interest to artisanal fisheries, although in decline. The study of its reproductive patterns provides insight into its biology relevant to the general study of tropical fishes. Objective: To assess the condition factor and gonadosomatic index, to determine the monthly incidence of mature fish, to estimate the mean length at sexual maturity (Lm), and to explore predictors affecting the condition factor and gonadosomatic index in the lane snapper L. synagris. Methods: Extirpated gonads of males and females were classified according to their maturity status and related to fish length. The condition factor and gonadosomatic index were estimated according to standard formulae. Their dependency on variables related to climate, geographic space, and behavior were assessed using linear models. Results: Condition factor was stable throughout the year, while the gonadosomatic index showed an increasing pattern from the first months of the year (dry season), reaching a peak in the second semester of the year. The incidence of mature fish was higher in about the same months as when the gonadosomatic index showed high values. An Lm of 26 cm total length was estimated for both sexes, 27 cm for males and 25 cm for females. Condition factor and gonadosomatic index were associated with several predictors, notably with moon phases. Conclusion: A spatial and temporal signal for the reproductive patterns of L. synagris was found but decoupled from climate seasonality. The reproductive rhythm of L. synagris was related to moon phases as the main environmental cue.
biorhythms; condition factor; gonadosomatic index; tropical fishes.
Diet variation Sciaenidae fish in the bay of Buenaventura, Colombian Pacific
Introduction: The fish of the Sciaenidae family are important for commercial and subsistence fishing on the Colombian Pacific coast. However, it is unknown how their trophic habits vary between climatic seasons. The objective of this research was to determine the variation of diet and the presence of microplastics (MP) in species of this family and its relationship with the environmental dynamics of the water of the Buenaventura Bay, colombian Pacific. Methods: Samples were taken in dry and rainy season of 2020 and 2021 in the internal and external areas of the bay. A total of (144) individuals of the species Larimus argenteus, Stellifer zestocarus and Stellifer melanocheir, were sampled using artisanal trawling and their stomach contents were classified into five categories of food prey corresponding to crustaceans (shrimp, crabs, isopods), fish, nematodes, detritus (organic material), and MP microplastics (fibers and fragments). The analysis of stomach contents used as trophic parameters, the frequency of occurrence (% FO) and the relative importance index (IRI %) of prey. These stomach contents were related to environmental variables salinity (PSU), temperature (° C), pH, dissolved oxygen (mg l−1) and water transparency (cm) through GAM models. Results: In general, Sciaenidae fish consumed mainly crustaceans in dry season. The fish as prey supplement their diet in both periods, but their consumption intensifies in rainy season. The detritus is consumed mostly in dry season, being able to relate to the consumption of crustaceans, while the nematodes are consumed mainly in rainy season, associated with the greater consumption of fish. L. argenteus consumed more crustaceans in dry season, associated with high salinities and low temperatures, while in rainy season the intake of fish increases. While, in low temperatures increased the intake of detritus in S. zestocarus. The highest MP content in L. argenteus was found in low salinity and pH, associated with rainy season and internal zone. Conclusions: The study suggests that the diet of Sciaenidae fish is influenced by the estuarine supply, subject to environmental variation.
trophic habits; trophic ecology; estuarine fish; gut content; artisanal fishing; environmental variation; plastic pollution.
Effects of landscape structure on bird diversity in the Upper Magdalena Valley, Colombia
Introduction: Understanding the effects of landscape structure and composition on bird diversity is essential to identify distribution drivers and evaluate potential impacts of land use changes. Landscape structure refers to the spatial arrangement and organization of elements within a landscape and can be described using metrics such as the number and size of patches, their connectivity, and the degree of landscape heterogeneity. Objectives: In this study, we investigated the effects of landscape structure on the taxonomic diversity of bird assemblages in the Upper Magdalena Valley, Colombia. Methods: The study was conducted in 15 localities between June and November 2018, 2019, and 2022. We used mist nets and visual and audio surveys to evaluate bird community structure. This data was complemented with records from the eBird platform. A total de 17 565 individuals representing 401 species were recorded. We measured alpha and beta taxonomic diversity. Landscape structure was characterized by using a variety of metrics at patch, class, and landscape level using Geographic Information Systems (GIS). Results: We found a negative effect of landscape heterogeneity on taxonomic diversity. Our results indicate that landscape transformation leads to a reduction in bird diversity. In contrast, non-fragmented landscapes may have the potential to support taxonomically diverse bird assemblages, characterized by the presence of specialist species with a more restricted distribution. Conclusions: These findings highlight the susceptibility of specialist bird species to landscape change and highlight the importance of protecting and conserving natural areas to maintain taxonomic diversity of bird communities. Bird taxonomic diversity was influenced by landscape components such as landscape heterogeneity and patch perimeter, which had a negative effect on species abundance and richness.
Alkaloid-enriched extracts from the tree Neltuma flexuosa (Fabaceae): chemical characterization, fractionation, and cytotoxic effects
Introduction: Neltuma flexuosa is a key species in arid regions, offering nutritional benefits but also containing alkaloids that can pose toxicological risks. Objective: To analyze the chemical composition and alkaloid content of N. flexuosa pods collected over four years (2019-2022) in Cafayate, Argentina, considering the influence of climatic variations, and to evaluate their potential cytotoxic effects on C6 glioma cells. Methods: Dried and ground pods were analyzed for chemical composition using standard methods. Alkaloid-enriched extracts (AEE1-AEE4) were obtained through acid/base extraction and analyzed by HPLC-HRMS for juliprosine and juliprosopine quantification. AEE4 was fractionated using flash chromatography, yielding fractions (F1-F5), which were also analyzed for alkaloid content. Cytotoxicity on C6 glioma cell lines was evaluated using crystal violet staining assay, and apoptosis induction was confirmed in C6 cells treated with AEE4 using the TUNEL assay. Results: Chemical analysis revealed interannual variations in pod composition, particularly in fiber and protein content. HPLC-HRMS identified juliprosine and juliprosopine, with the highest concentrations in AEE4. Fractionation of AEE4 by flash chromatography yielded an alkaloid-rich fraction (F4). Cytotoxicity assays demonstrated dose-dependent reductions in cell viability, with AEE4 exhibiting the lowest 50 % cytotoxic concentration (CC50) values. Furthermore, F4 displayed the highest cytotoxicity against C6 cells. TUNEL assays confirmed the induction of apoptosis by AEE4. Conclusions: These findings provide valuable insights into the chemical composition, alkaloid content, and cytotoxic effects of N. flexuosa extracts, contributing to the development of guidelines for their safe and sustainable use as a feed resource.