Biologia Evolutiva, Ecologia i Ciències Ambientals

Taxonomic accuracy and complementarity between bulk and eDNA metabarcoding provides an alternative to morphology for biological assessment of freshwater macroinvertebrates

Wed, 15 Apr 2026 07:51:38 GMT

Taxonomic accuracy and complementarity between bulk and eDNA metabarcoding provides an alternative to morphology for biological assessment of freshwater macroinvertebrates Múrria i Farnós, Cesc; Wangensteen Fuentes, Owen S. (Simon); Somma, Simona; Väisänen, Leif O. S; Fortuño Estrada, Pau; Arnedo Lombarte, Miquel Àngel; Prat i Fornells, Narcís Determining biological status of freshwater ecosystems is critical for ensuring ecosystem health and maintaining associated services to such ecosystems. Freshwater macroinvertebrates respond predictably to environmental disturbances and are widely used in biomonitoring programs. However, many freshwater species are difficult to capture and sort from debris or substrate and morphological identification is challenging, especially larval stages, damaged specimens, or hyperdiverse groups such as Diptera. The advent of high throughput sequencing technologies has enhanced DNA barcoding tools to automatise species identification for whole communities, as metabarcoding is increasingly used to monitor biodiversity. However, recent comparisons have revealed little congruence between morphological and molecular-based identifications. Using broad range universal primers for DNA barcode marker cox1, we compare community composition captured between morphological and molecular-based approaches from different sources — tissue-based (bulk benthic and bulk drift samples) and environmental DNA (eDNA, filtered water) metabarcoding — for samples collected along a gradient of anthropogenic disturbances. For comparability, metabarcoding taxonomic assignments were filtered by taxa included in the standardised national biological metric IBMWP. At the family level, bulk benthic metabarcoding showed the highest congruence with morphology, and the most abundant taxa were captured by all techniques. Richness captured by morphology and bulk benthic metabarcoding decreased along the gradient, whereas richness recorded by eDNA remained constant and increased downstream when sequencing bulk drift. Estimates of biological metrics were higher using molecular than morphological identification. At species level, diversity captured by bulk benthic samples were higher than the other techniques. Importantly, bulk benthic and eDNA metabarcoding captured different and complementary portions of the community — benthic versus water column, respectively — and their combined use is recommended. While bulk benthic metabarcoding can likely replace morphology using similar benthic biological indices, water eDNA will require new metrics because this technique sequences a different portion of the community.

Suitability mapping and management monitoring in Castilian organic and conventional wheat fields with Sentinel-2 and spatial data.

Wed, 15 Apr 2026 07:41:13 GMT

Suitability mapping and management monitoring in Castilian organic and conventional wheat fields with Sentinel-2 and spatial data. Segarra, Joel; Araus Ortega, José Luis; Kefauver, Shawn Carlisle The Mediterranean region is a climate change hotspot due to projected precipitation decreases, soil erosion, and rising temperatures in the coming decades. In such a context, wheat productivity is expected to decrease; thus, all available croplands will need to be farmed to meet food demands. It is therefore crucial to have adequate management to help balance wheat production and environmental protection in specific target environments. With this aim, we present a study in Castile and Leon (Spain) in which we assess conventional and certified organic wheat grain yield and quality. Moreover, we spatially define wheat cultivation suitability categories and monitor crop rotation practices. For wheat suitability mapping, a fuzzy interference system was used to standardize topographic (height and slope), edaphic (pH, soil erosion, organic matter, and texture), and climatic (rainfall and temperature) variables and create marginal, suitable, and very suitable wheat cultivation suitability categories. We calculated the area of wheat suitability categories with confidence intervals and discussed factors affecting productivity. Additionally, we assessed the performance of certified organic and conventionally managed fields with organic and chemical fertilization. We also examined crop rotations using Sentinel-2 data over two seasons (2020−21). Certified organic management yielded 50% less than conventional management in similar environments while maintaining grain quality. Besides management, the main causes of the yield gap are the growing environment and variety. In conventional wheat management, organic fertilization achieves comparable yields to chemical fertilization. Crop rotation practices are uncommon, and over 50% of fields rotate wheat-to-barley or wheat-to-wheat, indicating poor soil management. The region has 25% of cropland classified as marginal wheat croplands (163,503 ± 33,796 ha) producing <2500 kg/ha. Wheat organic agriculture has decreased yield gaps in marginal croplands compared to more productive areas. By farming organic wheat in marginal croplands, the best croplands might be used for more productive farming.

Assessing the effects of salinity on microbial communities and pollutantremoval in urban wastewater treatment plants

Tue, 14 Apr 2026 12:16:31 GMT

Assessing the effects of salinity on microbial communities and pollutantremoval in urban wastewater treatment plants Moyano Salcedo, Alvaro Javier; Cañedo-Argüelles, Miguel; Kaushal Sujay S.; Ciriero-Cebrián, Eva Maria; Pérez-Blanco, Adrià; Salvadó i Cabré, Humbert This study assessed the impact of electrical conductivity (EC) on the microeukaryotic community and pollutant removal efficiency in full-scale wastewater treatment plants (WWTPs) in Catalonia, Spain. Monthly samples from seven WWTPs (2010 2021) were collected, with microbial communities identified by microscopy and effluent quality parameters measured. Linear mixed-effects models (LMER), indicator species analysis (IndVal), and structural equation modeling (SEM) were used to evaluate the effects of EC on WWTP operation and microbial communities. EC levels varied widely among WWTPs (800 to 15,000 μS cm1), with mean removal rates generally low, not exceeding 26 %. EC removal was inversely correlated with organic matter removal (p < 0.05). IndVal analysis revealed distinct microbial communities associated with each WWTPs along the EC gradient (e.g., Beggiatoa spp. and Epistylis sp. were associated with high and low EC, respectively). High EC and peaks negatively affected the abundance of certain microorganisms (e.g., Acineria uncinata) (p < 0.05). Ciliate genera were most affected by EC peaks, with different species showing different salinity tolerance ranges (e.g. Holophyra discolor was affected by EC > 3000 μS cm-1). Seasonal variations did not significantly alter community sensitivity to salinity (p > 0.05). LMER and SEM analyses revealed strong adverse effects of high EC and EC peaks on microbial diversity, richness, and the efficiency of organic matter and TKN removal (p < 0.05). This highlights the importance of monitoring and controlling EC levels in WWTP influent to maintain optimal treatment performance and the need for effective technologies or biological processes to mitigate saline discharges into rivers.

Long-term monitoring of dwarf eggs in clutches of Yellow-legged Gulls (Larus michahellis) breeding in a western Mediterranean colony

Mon, 13 Apr 2026 06:31:40 GMT

Long-term monitoring of dwarf eggs in clutches of Yellow-legged Gulls (Larus michahellis) breeding in a western Mediterranean colony Bosch Mestres, Marc The present study provides data on clutches with dwarf eggs from a large sampling in a colony of Yellow-legged Gulls(Larus michahellis) over 31 years. Their occurrence was very low, with a global percentage of 0.26%. Significant variations were not detected among periods of 10 or 11 years. In all the cases, only one dwarf egg was found per clutch. Mean volume of dwarf eggs was 34% of that of non-dwarf eggs. Their content was mostly albumen and a very reduced quantity of yolk, and they were infertile. Several results of the study (the laying order of the dwarf eggs, their mean clutch size and the mean size of the non-dwarf eggs from clutches with dwarf eggs) support the hypotheses that runt eggs occur from a temporary disturbance to the reproductive tract