RESUMO

Soil quality indices (SQI) used for assessing soil degradation are often developed using additive scoring functions. However, these SQI may lack reference values for interpreting their outputs and the capacity to differentiate changes in specific variables. To overcome these limitations, this study introduces SQI using Log Response Ratios (LRR) as measures of size effects caused by land use in physical, chemical, and microbiological soil quality indicators. LRR vectors projected 2D polygons with condensed change measures along their perimeters. This method was tested in andosols within the southeastern region of Antioquia, Colombia. These soils were subjected to contrasting stages of degradation determined by the extent of A-horizon removal due to land use practices. This study shows that mining and agriculture have detrimental effects on soil organic carbon and water contents, and that size effects vary significantly between land uses (p < 0.05). Microbiological features also exhibit distinct size effects, such as populations of culturable mesophilic bacteria and fungi, microbial basal respiration, spore density of arbuscular mycorrhizal fungi (AMF), their diversity, and total glomalin-related soil proteins (p < 0.05). The SQI proposed exhibited a negative correlation with SQI computed from scoring additive functions either considering the entire dataset (R2 = 0.87) or a minimum dataset (R2 = 0.90). This approach underscores the utility of using LRR geometrical analysis to assess global soil quality differences among land uses (p < 0.01), offering a visual, quantifiable representation of the effects of each land use over specific soil quality indicators.

Assuntos

RESUMO

Amphipods belonging to the Hyalella genus are macroinvertebrates that inhabit aquatic environments. They are of particular interest in areas such as limnology and ecotoxicology, where data on the number of Hyalella individuals and their allometric measurements are used to assess the environmental dynamics of aquatic ecosystems. In this study, we introduce HyACS, a software tool that uses a model developed with the YOLOv3's architecture to detect individuals, and digital image processing techniques to extract morphological metrics of the Hyalella genus. The software detects body metrics of length, arc length, maximum width, eccentricity, perimeter, and area of Hyalella individuals, using basic imaging capture equipment. The performance metrics indicate that the model developed can achieve high prediction levels, with an accuracy above 90% for the correct identification of individuals. It can perform up to four times faster than traditional visual counting methods and provide precise morphological measurements of Hyalella individuals, which may improve further studies of the species populations and enhance their use as bioindicators of water quality.

Assuntos

RESUMO

RESUMEN Los lagos altoandinos son ecosistemas afectados por múltiples presiones antrópicas que alteran la calidad del agua y las comunidades bióticas, siendo los macroinvertebrados acuáticos excelentes bioindicadores para estos ecosistemas. El presente trabajo analiza la dinámica de la comunidad de macroinvertebrados asociada a Egeria densa, la relación con las variables fisicoquímicas, los índices bióticos y la interacción predador-presa en el litoral del Lago de Tota. Este trabajo se desarrolló en tres campañas sobre nueve estaciones de muestreo en el perímetro del lago. Dentro de los hallazgos, Hyallela sp. (30 %) y Dicrotendipes sp.(27 %) son los taxones más abundantes y dominantes del estudio, siendo bioindicadores de presencia de materia orgánica en descomposición y disminución en la calidad del agua. El análisis ANOVA de las variables fisicoquímicas del agua y los nutrientes de Egeria densa mostró diferencias significativas a nivel temporal. Los índices bióticos mostraron diferencias en la calidad del agua, determinando una posible zonificación de este parámetro en el litoral. Finalmente, para identificar las relaciones de la comunidad, se presenta un modelo predador-presa, con Hyalella sp. como presa e Ischnura sp. como predador a través de las ecuaciones Lotka-Volterra, encontrando que hay concordancia entre el comportamiento de las abundancias medidas y las simuladas. De esta forma, la dinámica trófica contribuye a entender las comunidades y su proyección en el tiempo con relación a las condiciones ambientales de la zona litoral.

ABSTRACT High Andean lakes are ecosystems affected by multiple anthropogenic pressures that alter water quality and biotic communities, and aquatic macroinvertebrates are excellent bioindicators for these ecosystems. The present work analyzes the dynamics of the macroinvertebrate community associated with Egeria densa, the relationship with physicochemical variables, biotic indices, and predator-prey interaction in the littoral of Lake Tota. This work was developed in three campaigns on nine sampling stations on the perimeter of the lake. Among the findings, Hyallela sp. (30 %) and Dicrotendipes sp. (27 %) are the most abundant and dominant taxa of the study, being bioindicators of the presence of decomposing organic matter and decrease in water quality. ANOVA analysis of the physicochemical variables of water and nutrients of Egeria densa showed significant differences at the temporal level. The biotic indices showed differences in water quality, determining a possible zoning of this parameter along the coast. Finally, to identify community relationships, a predator-prey model is presented, with Hyalella sp. as prey and Ischnura sp. as predator through the Lotka-Volterra equations, finding that there is agreement between the behavior of measured and simulated abundances. In this way, the trophic dynamics contribute to understand the communities and their projection in time in relation to the environmental conditions of the littoral zone.

RESUMO

Changes in soil fungal communities caused by land use have not been sufficiently studied in South American Andosols, which are considered key food production areas. Since fungal communities play an important role in soil functionality, this study analysed 26 soil samples of Andosols collected from locations devoted to conservation, agriculture and mining activities in Antioquia, Colombia, to establish differences between fungal communities as indicators of soil biodiversity loss using Illumina MiSeq metabarcoding on nuclear ribosomal ITS2 region. A non-metric multidimensional scaling allowed to explore driver factors of changes in fungal communities, while the significance of these variations was assessed by PERMANOVA. Furthermore, the effect size of land use over relevant taxa was quantified. Our results suggest a good coverage of fungal diversity with a detection of 353,312 high-quality ITS2 sequences. We found strong correlations of Shannon and Fisher indexes with dissimilarities on fungal communities (r = 0.94). These correlations allow grouping soil samples according to land use. Variations in temperature, air humidity and organic matter content lead to changes in abundances of relevant orders (Wallemiales and Trichosporonales). The study highlights specific sensitivities of fungal biodiversity features in tropical Andosols, which may serve as a basis for robust assessments of soil quality in the region.