ENSO‐Influenced Drought Drives Methane Flux Dynamics in a Tropical Wet Forest Soil

Global atmospheric methane growth rates have wildly fluctuated over the past three decades, which may be driven by the proportion of tropical land surface saturated by water. The El Niño/Southern Oscillation Event (ENSO) cycle drives large‐scale climatic trends globally, with El Niño events typically bringing drier weather than La Niña. In a lowland tropical wet forest in Costa Rica, we measured methane flux bimonthly from March 2016 to June 2017 and using an automated chamber system. We observed a strong drying trend for several weeks during the El Niño in 2016, reducing soil moisture below normal levels. In contrast, soil conditions had high water content prior to the drought and during the moderate La Niña that followed. Soil moisture varied across the period studied and significantly impacted methane flux. Methane consumption was greater during the driest part of the El Niño period, while during La Niña and other time periods, soils had lower methane consumption. The mean methane flux observed was −0.022 mg CH4‐C m−2 hr−1, and methane was consumed at all timepoints, with lower consumption in saturated soils. Our data show that month studied, and the correlation between soil type and month significantly drove methane flux trends. Our data indicate that ENSO cycles may impact biogenic methane fluxes, mediated by soil moisture conditions. Climate projections for Central America show dryer conditions and increased El Niño frequency, further exacerbating predicted drought. These trends may lead to negative climate feedbacks, with drier conditions increasing soil methane consumption from the atmosphere.National Science Foundation/[DEB‐1624623]/NSF/Estados UnidosNational Science Foundation/[DEB‐1442537]/NSF/Estados UnidosNational Science Foundation/[DEB‐1624658]/NSF/Estados UnidosNational Science Foundation/[DEB‐1442714]/NSF/Estados UnidosUnited States Department of Agriculture-National Institute of Food and Agriculture/[CA‐R‐PPA‐5093‐H/1005159]/USDA NIFA/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Estructuras Microscópicas (CIEMIC

Diversity of Aerobic Bacteria Isolated from Oral and Cloacal Cavities from Free-Living Snakes Species in Costa Rica Rainforest

Costa Rica has a significant number of snakebites per year and bacterial infections are often complications in these animal bites. Hereby, this study aims to identify, characterize, and report the diversity of the bacterial community in the oral and cloacal cavities of venomous and nonvenomous snakes found in wildlife in Costa Rica.The snakes where captured by casual encounter search between August and November of 2014 in the Quebrada Gonzalez sector, in Braulio Carrillo National Park. A total of 120 swabs, oral and ´ cloacal, were taken from 16 individuals of the Viperidae and Colubridae families. Samples were cultured on four different media at room temperature. Once isolated in pure culture, colonies were identified with the VITEK 2C platform (bioMerieux). In order to ´ test the identification provided on environmental isolates, molecular analyses were conducted on 27 isolates of different bacterial species. Specific 16S rDNA PCR-mediated amplification for bacterial taxonomy was performed, then sequenced, and compared with sequences of Ribosomal Database Project (RDP). From 90 bacterial isolates, 40 different bacterial species were identified from both oral and cloacal swabs. These results indicate the diversity of opportunistic pathogens present and their potential to generate infections and zoonosis in humans.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET

Snake diversity (squamata: Serpentes) in Quebrada González sector of Braulio Carrillo National Park, Costa Rica

Within Braulio Carrillo National Park (BCNP) of Costa Rica, there is a lack of quantitative data regarding the snake community despite its informally reported abundance and relevance to human health. The objective of this research was to document the diversity of snakes within the Quebrada González sector of BCNP. We searched for snakes using visual encounter surveys along several trails, as well as in quadrants and transects within the forest interior. We captured 272 individual snakes across 28 species and five families. Bothrops asper (Fer-de-Lance) and Bothriechis schlegelii (Eyelash Viper), both Viperids, were the most abundant species encountered, most likely due to their generalist habits. Most other snake species were found in smaller numbers but with roughly equal frequency to each other. Snake species richness and relative abundance were similar between the sampled trails but did show temporal variation during the study period with higher values during the rainy season from April to August. Species composition between the sampled trails was similar, but we did detect some differences likely due to differing habitat characteristics. The species diversity identified here may have been positively affected by the location of the site along an elevational and habitat gradient with high temperatures and precipitation, but likely remains incomplete due to the preliminary nature of the survey and the difficulty of detecting many snake species. A species accumulation curve suggests that the inventory was approximately 81% complete; additional, less abundant species would likely be identified with increased sampling effort and additional survey techniquesEn el Parque Nacional Braulio Carrillo (PNBC) existe una carencia de datos cuantitativos de la comunidad de serpientes presentes, a pesar de su abundancia e importancia médica reportada informalmente. El objetivo de este estudio fue documentar la diversidad de serpientes en el sector Quebrada González del PNBC. Realizamos búsquedas mediante relevamiento por encuentro visual en los senderos del parque, así como en cuadrantes y transectos en áreas dentro del bosque. Capturamos 272 individuos, pertenecientes a 28 especies y cinco familias. Bothrops asper (Terciopelo) y Bothriechis schlegelii (Bocaracá), ambas de la familia Viperidae, fueron las especies más abundantes, probablemente debido a sus hábitos generalistas. Las otras especies fueron encontradas en una abundancia menor, pero equitativa entre sí. La riqueza y abundancia relativa de las serpientes fue similar entre los senderos, sin embargo varió temporalmente durante el período de estudio con los valores más altos en la época lluviosa entre abril y agosto. La composición de especies fue similar entre los senderos, sin embargo se detectaron algunas diferencias debido probablemente a que las características del hábitat en estos difieren entre sí. La diversidad observada podría estar afectada positivamente por la presencia del sitio de estudio en un gradiente altitudinal y de hábitat, con altas temperaturas y tasas de precipitación, sin embargo aún es incompleto debido a su naturaleza preliminar y a la dificultad de observar algunas especies de serpiente. La curva de acumulación de especies muestra que se completó el 81% del inventario; adicionalmente, podrían encontrarse especies menos abundantes si se aumentara el esfuerzo y se diversificaran las técnicas de muestreoUniversidad Nacional, Costa RicaUniversidad Técnica Nacional, Costa RicaUniversity of Hartford, Estados UnidosEscuela de Ciencias Biológica

Welcome to the Atta world: A framework for understanding the effects of leaf‐cutter ants on ecosystem functions

1. Leaf‐cutter ants are a prominent feature in Neotropical ecosystems, but a comprehensive assessment of their effects on ecosystem functions is lacking. We reviewed the literature and used our own recent findings to identify knowledge gaps and develop a framework to quantify the effects of leaf‐cutter ants on ecosystem processes. 2. Leaf‐cutter ants disturb the soil structure during nest excavation changing soil aeration and temperature. They mix relatively nutrient‐poor soil from deeper layers with the upper organic‐rich layers increasing the heterogeneity of carbon and nutrients within nest soils. 3. Leaf‐cutter ants account for about 25% of all herbivory in Neotropical forest ecosystems, moving 10%-15% of leaves in their foraging range to their nests. Fungal symbionts transform the fresh, nutrient‐rich vegetative material to produce hyphal nodules to feed the ants. Organic material from roots and arbuscular mycorrhizal fungi enhances carbon and nutrient turnover in nest soils and creates biogeochemical hot spots. Breakdown of organic matter, microbial and ant respiration, and nest waste material decomposition result in increased CO2, CH4, and N2O production, but the build‐up of gases and heat within the nest is mitigated by the tunnel network ventilation system. Nest ventilation dynamics are challenging to measure without bias, and improved sensor systems would likely solve this problem. 4. Canopy gaps above leaf‐cutter ant nests change the light, wind and temperature regimes, which affects ecosystem processes. Nests differ in density and size depending on colony age, forest type and disturbance level and change over time resulting in spatial and temporal changes of ecosystem processes. These characteristics remain a challenge to evaluate rapidly and non‐destructively. 5. Addressing the knowledge gaps identified in this synthesis will bring insights into physical and biological processes driving biogeochemical cycles at the nest and ecosystem scale and will improve our understanding of ecosystem biogeochemical heterogeneity and larger scale ecological phenomena.National Science Foundation/[DEB-1442568]/NSF/Estados UnidosNational Science Foundation/[DEB-1442537]/NSF/Estados UnidosNational Science Foundation/[DEB-1442622]/NSF/Estados UnidosUniversidad de Costa Rica/[801-B4-527]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Salud::Facultad de Medicina::Escuela de MedicinaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Estructuras Microscópicas (CIEMIC