Eduardo Vicente’s research while affiliated with University of Valencia and other places

The existing literature provides limited insights into the dynamics of phytoplankton communities and the spatial heterogeneity of physicochemical parameters in multisystem cascade reservoirs (interconnected reservoirs derived from different rivers). The existing studies are concentrated on cascade reservoirs (interconnected reservoirs derived from the same river). To address this knowledge gap, the aims of the present study were as follows: (1) investigate the spatial heterogeneity, within and between reservoirs, of geochemical parameters associated with the eutrophication process, considering total phosphorus, chlorophyll-a, pheophytin, and metals (chromium, copper, nickel, lead, zinc, iron, and manganese); (2) evaluate sediment quality at the designated locations; (3) assess differences in the richness and concentration of sedimentary photopigments between the reservoirs. Application of principal component analysis revealed discernible gradients for the abiotic variables, although the differences were not statistically significant (one-way PERMANOVA test, p > 0.05). The observations suggested a tendency towards spatial homogeneity within and between the reservoirs. The metal concentrations were consistent with regional reference values, while phosphorus levels in the sediment approached the threshold for classification as pollution (~ 2000 mg/kg). Analysis of pigments indicated low dissimilarity among the reservoirs, which could be mainly attributed to the eutrophication process and high connectivity of the sampled areas. To counteract ongoing biotic homogenization, it is essential to reduce nutrient inputs and invest in ecological protection and restoration programs. The analysis of sedimentary photopigments provides an efficient and cost-effective alternative way to assess phytoplankton communities.

Anthropogenic pressures and impacts caused by industrial, agricultural and urban activities can alter the functions of coastal wetlands, compromising the uses to which they can be subjected. Albufera of Valencia (Spain) is a representative case of pressure on water quality with a hypertrophic state since 1970s, but with a great heterogeneity. Remote sensing as a tool for monitoring water quality has great potential as a complementary strategy, remotely, frequently, and continuously over time. PeruSAT-1 stands as Peru's inaugural remote sensing satellite, delivering composite images comprised of 4 multispectral bands boasting a spatial resolution of 2.8 m, complemented by 1 panchromatic band with a spatial resolution of 0.7 m., which makes it an ideal sensor for capturing highly detailed products useful for different applications, especially in very heterogeneous waters. This study pretends to assess the potential of PerúSAT-1s’ multispectral images to generate maps of different variables to evaluate the ecological state of Albufera lagoon. The main objective is to develop specific algorithms to estimate water quality, using PerúSAT-1 images synchronic with a Albufera in situ database. During 5 field campaigns, samples were taken, and measurements of ecological indicators were made. All possible combinations of bands were obtained, which were then correlated by fitting a linear regression with the biophysical variables from 22 water samples. The best algorithms have an R2 of 0.76 for chlorophyll-a, 0.75 for Secchi disk depth, 0.84 for total suspended solids, 0.76 for inorganic fraction, and 0.87 for organic fraction of these suspended solids. A temporal and spatial analysis was obtained by applying these equations to Albufera lagoon images.

El Proyecto REmote Sensing Spectroscopy for wetlands BIOdiversity (RESSBIO) pretende llevar a cabo la evaluación y seguimiento del estado ecológico de diferentes sistemas acuáticos lénticos, a través de nuevas misiones de satélites de observación de la Tierra, equipadas con sensores hiperespectrales. Como parte del proyecto RESSBIO en este trabajo se ha llevado a cabo una evaluación de los algoritmos de corrección atmosférica (CA) desarrollados específicamente para dichos sensores, así como ACOLITE, un algoritmo ampliamente utilizado en estudios de aguas continentales. Además, también se ha realizado la evaluación de la estabilidad a lo largo del tiempo de la reflectividad entre datos de campo y la reflectividad de imágenes a través de una prueba t-Student aplicada entre espectros de diferentes imágenes Sentinel-3. Las diferencias entre algoritmos de CA se han interpretado de dos maneras: analizando todo el espectro en conjunto para las diferentes CA, y comparándolas por regiones espectrales. Finalmente, se sugiere que la elección de la CA depende de la región espectral en la que estemos interesados.

The historical impacts of eutrophication processes were investigated in six subtropical reservoirs (São Paulo, Brazil) using a paleolimnological approach. We questioned whether the levels of pigment indicators of algal biomass could provide information about trophic increase and whether carotenoid pigments could offer additional insights. The following proxies were employed: organic matter, total phosphorus, total nitrogen, photosynthetic pigments (by high-performance liquid chromatography), sedimentation rates, and geochronology (by 210 Pb technique). Principal component analysis indicated a gradient of eutrophication. In eutrophic reservoirs (e.g., Rio Grande and Salto Grande), levels of lutein and zeaxanthin increased over time, suggesting growth of Chlorophyta and Cyanobacteria. These pigments were significantly associated with algal biomass, reflecting their participation in phytoplankton composition. In mesotrophic reservoirs, Broa and Itupararanga, increases and significative linear correlations (r > 0.70) between pigments and nutrients are mainly linked to agricultural and urban activities. In the oligotrophic reservoir Igaratá, lower pigment and nutrient levels reflected lesser human impact and good water quality. This study underscores eutrophication's complexity across subtropical reservoirs. Photosynthetic pigments associated with specific algal groups were informative, especially when correlated with nutrient data. The trophic increase, notably in the 1990s, may have been influenced by neoliberal policies. Integrated pigment and geochemical analysis offers a more precise understanding of eutrophication changes and their ties to human factors. Such research can aid environmental monitoring and sustainable policy development.