Improving the remote estimation of soil organic carbon in complex ecosystems with Sentinel-2 and GIS using Gaussian processes regression.

Background and aims: The quantitative retrieval of soil organic carbon (SOC) storage, particularly for soils with a large potential for carbon sequestration, is of global interest due to its link with the carbon cycle and the mitigation of climate change. However, complex ecosystems with good soil qualities for SOC storage are poorly studied. Methods: The interrelation between SOC and various vegetation remote sensing drivers is understood to demonstrate the link between the carbon stored in the vegetation layer and SOC of the top soil layers. Based on the mapping of SOC in two horizons (0-30 cm and 30-60 cm) we predict SOC with high accuracy in the complex and mountainous heterogeneous páramo system in Ecuador. A large SOC database (in weight % and in Mg/ha) of 493 and 494 SOC sampling data points from 0-30 cm and 30-60 cm soil profiles, respectively, were used to calibrate GPR models using Sentinel-2 and GIS predictors (i.e., Temperature, Elevation, Soil Taxonomy, Geological Unit, Slope Length and Steepness (LS Factor), Orientation and Precipitation). Results: In the 0-30 cm soil profile, the models achieved a R2 of 0.85 (SOC%) and a R2 of 0.79 (SOC Mg/ha). In the 30-60 cm soil profile, models achieved a R2 of 0.86 (SOC%), and a R2 of 0.79 (SOC Mg/ha). Conclusions: The used Sentinel-2 variables (FVC, CWC, LCC/Cab, band 5 (705 nm) and SeLI index) were able to improve the estimation accuracy between 3-21% compared to previous results of the same study area. CWC emerged as the most relevant biophysical variable for SOC prediction. Supplementary Information: The online version contains supplementary material available at 10.1007/s11104-022-05506-1.

Draft genome assembly for the colombian freshwater bocachico fish, Prochilodus magdalenae.

We report the first draft genome assembly for Prochilodus magdalenae, the leading representative species of the Prochilodontidae family in Colombia. This 1.2-Gb assembly, with a GC content of 42.0% and a repetitive content of around 31.0%, is in the range of previously reported characid species genomes. Annotation identified 34,725 nuclear genes, and BUSCO completeness value was 94.9%. Gene ontology and primary metabolic pathway annotations indicate similar gene profiles for P. magdalenae and the closest species with annotated genomes: blind cave fish (Astyanax mexicanus) and red piranha (Pygocentrus nattereri). A comparative analysis showed similar genome traits to other characid species. The fully sequenced and annotated mitochondrial genome reproduces the taxonomic classification of P. magdalenae and confirms the low mitochondrial genetic divergence inside the Prochilodus genus. Phylogenomic analysis, using nuclear single-copy orthologous genes, also confirmed the evolutionary position of the species. This genome assembly provides a high-resolution genetic resource for sustainable P. magdalenae management in Colombia and, as the first genome assembly for the Prochilodontidae family, will contribute to fish genomics throughout South America.

Multi-predictor mapping of soil organic carbon in the alpine tundra: a case study for the central Ecuadorian páramo.

BACKGROUND: Soil organic carbon (SOC) affects essential biological, biochemical, and physical soil functions such as nutrient cycling, water retention, water distribution, and soil structure stability. The Andean páramo known as such a high carbon and water storage capacity ecosystem is a complex, heterogeneous and remote ecosystem complicating field studies to collect SOC data. Here, we propose a multi-predictor remote quantification of SOC using Random Forest Regression to map SOC stock in the herbaceous páramo of the Chimborazo province, Ecuador. RESULTS: Spectral indices derived from the Landsat-8 (L8) sensors, OLI and TIRS, topographic, geological, soil taxonomy and climate variables were used in combination with 500 in situ SOC sampling data for training and calibrating a suitable predictive SOC model. The final predictive model selected uses nine predictors with a RMSE of 1.72% and a R2 of 0.82 for SOC expressed in weight %, a RMSE of 25.8 Mg/ha and a R2 of 0.77 for the model in units of Mg/ha. Satellite-derived indices such as VARIG, SLP, NDVI, NDWI, SAVI, EVI2, WDRVI, NDSI, NDMI, NBR and NBR2 were not found to be strong SOC predictors. Relevant predictors instead were in order of importance: geological unit, soil taxonomy, precipitation, elevation, orientation, slope length and steepness (LS Factor), Bare Soil Index (BI), average annual temperature and TOA Brightness Temperature. CONCLUSIONS: Variables such as the BI index derived from satellite images and the LS factor from the DEM increase the SOC mapping accuracy. The mapping results show that over 57% of the study area contains high concentrations of SOC, between 150 and 205 Mg/ha, positioning the herbaceous páramo as an ecosystem of global importance. The results obtained with this study can be used to extent the SOC mapping in the whole herbaceous ecosystem of Ecuador offering an efficient and accurate methodology without the need for intensive in situ sampling.

Effect of ibuprofen in vivo and in vitro on the sperm quality of the striped catfish Pseudoplatystoma magdaleniatum.

Because ibuprofen is a high consumption drug, which has the waters as its final destination, causing alterations in the aquatic environment, specifically in fish. However, there is not enough knowledge about the effect it can have on neotropical fish. This study aimed to evaluate the impact of different concentrations of ibuprofen on sperm quality, both in vivo and in vitro, of the striped catfish Pseudoplatystoma magdaleniatum, and analyze its effects on the reproduction of this critical extinction endangered species. For this purpose, three groups of fish, with a mean weight of 2.3 ± 0.6 kg and mean total length of 62.9 ± 6.1 cm, were placed in tanks (3 fish/tank) with water at concentrations of 0 (control), 25, and 50 µg/L of ibuprofen for 4 months. For the analysis of sperm quality for each treatment (in vivo), the males were selected in the spermiation phase. Also, the semen from the control group was used for in vitro tests and activated with type I water solutions containing 0, 25, and 50 µg/L of ibuprofen. In the in vivo and in vitro tests, when fish and semen were treated to 50 µg/l, the seminal quality of striped catfish was statistically different from the other treatments. For this study, it was shown that ibuprofen at concentrations of 50 µg/L can cause a significant reduction in sperm quality and, therefore, a threat to the reproduction of P. magdaleniatum.