Luis Dominguez-Granda

High-income countries, such as China, have shifted from traditional household-based production (for self-consumption or local markets) to large-scale-intensive industrial operations aimed at increasing productivity and economic efficiency in the sector (Lu et al. 2020). However, concentrated swine farming generates large volumes of organic solid waste, nutrient-rich wastewater, and greenhouse gases that often exceed the natural attenuation of pollutants in ecosystems. Consequently, inadequate waste management in intensive farming operations can lead to pollution of water, soil, and air, thereby disrupting ecological balance (Leca et al. 2023). In Ecuador, pig farming is an expanding industry, with an estimated population of 1.9 million pigs distributed across both high-tech and domestic farms (APE, 2011). The intensification of pig production has contributed to a sharp increase in organic waste generation, prompting growing concern regarding environmental sustainability (Martínez Medina, 2020) To exemplify, during the fattening stage (approximately 70 kg of live weight), each pig produces around 4 to 5 kg/day of organic waste (Sánchez Saldarriaga, 2020). Approximately 90% of this waste is feces and 10% is urine, making the wastewater generated from cleaning operations a primary vector of contamination. This situation is exacerbated by the fact that around 90% of wastewater in Ecuador—whether agricultural or industrial—is discharged untreated or only partially treated into natural water bodies. The swine effluents, rich in nutrients such as potassium (K), phosphorus (P), nitrogen (N), and ammonia (NH3), poses a serious threat to aquatic ecosystems through eutrophication, and also is a source of gases and bad odors near farming facility (Sánchez Saldarriaga, 2020). Effluents from pig farms can be better valued as a growth medium for microalgae and cyanobacteria, by providing continuous aeration in a biological process downstream of physical pre-treatment (Lim et al. 2021). Among the microalgae, Spirulina platensis has shown considerable promise due to its capacity to assimilate excess nutrients, particularly nitrogen and phosphorus, while producing a high-value biomass that can be harvested for use in animal feed or other bioproducts (Díaz et al. 2024). This approach enables the bioremediation of swine effluents, as algae also release oxygen through photosynthesis while simultaneously assimilating excess nitrates as primary nitrogen source, leading to the production of nutrient-rich biomass (Mezzomo et al. 2010).

Background Wastewater-based epidemiology (WBE) is increasingly applied to monitor SARS-CoV-2 and other viral pathogens at the community level, particularly in settings with limited access to clinical surveillance. By capturing aggregated population-level pathogen shedding, this approach complements traditional case-based reporting and provides near–real-time information on infection dynamics in resource-limited settings. Methods We conducted a one-year longitudinal wastewater monitoring study in Guayaquil, Ecuador, between June 2021 and June 2022. We targeted SARS-CoV-2 and three enteric viruses—human adenovirus F (HAdV-F), rotavirus A (RVA), and hepatitis A virus (HAV)—using RT-qPCR. Viral concentrations were normalized using Pepper Mild Mottle Virus (PMMoV) to account for variations in fecal load and environmental dilution. Statistical analyses were performed using Spearman’s rank correlation to compare wastewater signals with clinical reports. Findings SARS-CoV-2 RNA concentrations showed a significant correlation with reported COVID-19 cases (Spearman’s ρ = 0·69, p < 0·001) which increased approximately one week before the Omicron surge in early 2022. RVA and HAdV-F were consistently detected throughout the surveillance period, reflecting sustained community circulation, whereas HAV was rarely observed. The lack of granular clinical data for acute gastroenteritis limited formal comparisons for enteric viruses, highlighting gaps in traditional surveillance. Interpretation These findings demonstrate that multiviral WBE can characterize temporal patterns of community infection and provide early warning signals of epidemic waves in tropical, high-density urban areas. Integrating environmental surveillance into public health frameworks strengthens outbreak preparedness in regions where clinical testing capacity is inconsistent.

Mangrove conservation and restoration are increasingly implemented for nature-based coastal defence. Mangrove stems and above-ground root systems attenuate wind waves, tidal currents and storm surge heights, by exerting drag on water flow. This drag scales directly with the underwater frontal area of the mangrove structures, defined as the projected plant surface area in the vertical plane perpendicular to the flow. However, existing field methods to quantify frontal area are often time-consuming, require expensive equipment that is difficult to deploy on typically unstable mangrove soils, or provide only coarse estimates. Here, we present a method that avoids these limitations, using a LiDAR-equipped smartphone to generate detailed 3D reconstructions of the stilt root systems of Rhizophora mangle, enabling direct quantification of their frontal area. The resulting frontal area estimates are among the highest reported for mangroves and provide realistic drag estimates, supported by a strong agreement between modelled and observed tidal water levels along a 400 m cross-shore transect through a mangrove forest. This approach provides an accurate, low-cost, and time-efficient method to quantify frontal area in Rhizophora-dominated mangroves, allowing improved parameterization of mangrove drag in hydrodynamic and coastal flood models, as such assisting the assessment of nature-based coastal defence programs using mangroves. This method is also promising for potential broader applications, such as assessments of carbon stocks in mangrove biomass and monitoring of the success rate of mangrove afforestation or restoration projects.

Nutrient inputs from human activities, such as agriculture and sewage discharge, influence algal blooms in water bodies. In Ecuador, the Daule River receives wastewater discharges. In addition, poor agricultural practices, including the unsuitable use of fertilisers in combination with soil erosion and surface runoff processes, increase the nutrient load to the river. Considering this, the objective of this study was to evaluate environmental and biological variables using statistical analysis to identify the parameters that influence algal blooms in the main stem of the Daule River. The methodology consisted of two phases: (i) data collection, including water sampling and laboratory work for the analysis of nutrients and phytoplankton, and (ii) statistical analysis, which includes univariate, bivariate, inferential and multivariate analysis (STATICO technique). The results showed that pH and dissolved oxygen were the main drivers of diatoms (Polymyxus coronalis and Aulacoseira granulate) and the charophyte Mougeotia sp. Similarly, ammonium-N was the main driver of the diatom Ulnaria ulna and the cyanobacteria Planktothrix cf. agardhii. The outcomes of this study identified the main environmental variables driving blooms of the five most abundant species, providing a basis for the development of ecological models in the context of land use and climate change.

Mangrove conservation and restoration have been increasingly recognized as cost‐effective and sustainable strategies to mitigate the increasing coastal flood risks. As surge or tidal waves propagate through river deltas and estuaries, mangroves can lower peak water levels by exerting friction on the water flow, which results in within‐wetland attenuation of high water levels, and by providing flood storage, resulting in along‐channel attenuation. While the impact of channels and vegetation on the friction effect has been studied before, the impact on the storage effect is not. Here we present a hydrodynamic model in a tropical subestuary, calibrated and verified with field observations. Through a scenario analysis, we show that with a denser network of secondary subchannels and less dense vegetation, the storage effect becomes stronger, leading to higher along‐channel attenuation. The opposite can be observed for the friction effect: we simulate lower within‐wetland attenuation rates in case of higher channel drainage density and lower vegetation density. If 2 km wide mangroves fringe the channels, we found the strongest along‐channel attenuation in case of a dense network of secondary subchannels with low vegetation density. In contrast, when the mangrove extent is limited, for instance due the presence of aquaculture, a dense network of channels or sparse vegetation can result in the amplification of peak water levels. Future conservation and restoration efforts should consider this trade‐off between within‐wetland and along‐channel attenuation in order for nature‐based flood protection to safeguard both human settlements behind unchanneled wetlands and along deltaic channels fringed by mangroves.

Mangroves are more and more recognized for nature‐based mitigation of flood risks in low‐lying coastal zones, which host a disproportionately large part of the global population. Aerial roots, branches, and canopy of mangrove trees exert friction on the water flow, thereby reducing the propagation of high water levels through the forest. Field measurements of high water level attenuation rates are limited so far to mangrove forests situated at higher‐latitude subtropical settings, where aerial roots are much sparser and lower than in low‐latitude tropical mangroves. Here, for the first time, we measured high water level attenuation in a tropical Rhizophora forest, where aerial roots are several meters high and water levels never exceeded the aerial root height. Our measurements reveal attenuation rates between 42 ± 9.8 and 46 ± 9.8 cm km⁻¹, which are the highest attenuation rates ever recorded in a mangrove forest, but an exponential rate is more suited to quantify high water level attenuation. In contrast to observations inside the mangrove forest, our observations showed that the propagation of high water levels through a 20 km long tidal channel fringed by wide mangrove areas was amplified, but that high water level amplification was reduced for higher tides with deeper flooding of the fringing mangroves. Our results provide the first empirical assessment of flood protection by tropical Rhizophora mangroves. As Rhizophora is globally the most common genus among mangroves, we propose that our reported high attenuation rates should be incorporated in future assessments of nature‐based flood risk mitigation by mangroves.

Mangrove conservation and restoration has been increasingly recognized as cost-effective and sustainable strategies to mitigate the increasing coastal flood risks. As surge or tidal waves propagate through river deltas and estuaries, mangroves can lower peak water levels by exerting friction on the water flow, which results in within-wetland attenuation of high water levels, and by providing flood storage, resulting in along-channel attenuation. While the impact of channels and vegetation on the friction effect has been studied before, the impact on the storage effect is not. Here we present a hydrodynamic model in a tropical subestuary, calibrated and verified with field observations. Through a scenario analysis, we show that with a denser network of secondary subchannels and less dense vegetation, the storage effect becomes stronger, leading to higher along-channel attenuation. The opposite can be observed for the friction effect: we simulate lower within-wetland attenuation rates in case of higher channel density and lower vegetation density. If a wide 2 km mangrove band fringes the channels, we found the strongest along-channel attenuation in case of a dense network of secondary subchannels with low vegetation density. In contrast, when the mangrove extent is limited, for instance due the presence of aquaculture, a dense network of channels or sparse vegetation can result in the amplification of peak water levels. Future conservation and restoration efforts should consider this trade-off between within-wetland and along-channel attenuation in order for nature-based flood protection to safeguard both human settlements behind unchanneled wetlands and along deltaic channels fringed by mangroves.

The flagfin mojarra (Eucinostomus currani) is an important subsistence fishery resource in local Ecuadorian markets; however, very little is known about the early life history and reproductive biology of this species. In 2016 and 2017, E. currani larvae were collected at 3 sandy beaches in the Gulf of Guayaquil, Ecuador, and identified using DNA barcoding. Standard lengths ranged from 4.00–15.78 mm. We also collected otoliths to better understand the early life history of E. currani. Otoliths were used to estimate the age, population growth rate (±SE), hatch dates, and reproductive period. On average, the fish were 16.5 ± 4.5 days old, while the average growth rate was 0.70 ± 0.05 and 0.22 ± 0.16 mm per day in March and May, respectively. In the Gulf of Guayaquil, most hatch dates and the presumed reproductive activity of E. currani occurred during the wet season (December–April) when warmer water prevailed. To our knowledge, this is the first study to estimate the hatch dates and larval growth rate for a species of the family Gerreidae in the Pacific Ocean.

High-elevation tropical streams are under increasing threat from human activities and climate change. Specifically, Ecuadorian Andean streams require priority actions such as bioassessment (e.g., biodiversity and functional ecology of macroinvertebrates) in order to generate adequate environmental management policies. Therefore, we investigated the distribution and composition of the macroinvertebrate taxa and their functional feeding groups in relation to the environmental variables in the Antisana river basin (Andean–Ecuadorian Region). We sampled macroinvertebrates from 15 locations to assess ecological conditions (ECs), expressed as the Biological Monitoring Working Party Colombia (BMWP-Col) classes, the Andean Biotic Index (ABI) and the Andean–Amazon Biotic Index (AAMBI). Results indicate that dissolved oxygen saturation, elevation, nutrient concentration and conductivity contributed significantly to the composition of the taxa and functional feeding groups (FFGs). Taxa diversity and FFGs were more abundant in the best EC sites. Shredders (SH) were, overall, dominant and abundant at sites with medium-high ECs. Scrapers constituted the second most prevalent assemblage, exerting dominance at moderate ecological conditions (high altitude and high oxygen saturation). Collector–gathers (CGs) are less sensitive to contamination than the previous two groups but were equally abundant at medium-high EC sites. Collector–filterers (CFs) and parasites (PAs) were less abundant, although the presence of the former was slightly related to better environmental conditions. Predators (PRs) were almost absent throughout the study, but they were collected from poor EC sites. CGs, PAs and PRs showed more tolerance to the presence of human disturbances (e.g., hydraulic constructions or slope erosion). The BMWP-Col index seems to be the best fit for this ecosystem, showing a significant difference in FFG between the index classes, compared to the other indices evaluated. The results of this investigation may be regarded as a fundamental starting point and used in future bioassessment work in other similar ecosystems, particularly high-altitude tropical Ecuadorian streams.