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- Modulation of biofilm growth by shear and fluctuations in turbulent environmentsPublication . Pizzi, Federico; Peters, Francesc; Sorribes, Elena; Marín Beltrán, Isabel; Romera-Castillo, Cristina; Grau, Joan; Rahmani, Mona; Jofre, Lluís; Capuano, FrancescoThis work investigates the role of shear and turbulent fluctuations on multi-species biofilm growth. The study is mostly motivated by understanding biofouling on microplastics (MPs) in oceanic environments. By increasing particle stickiness, biofilms promote MP aggregation and sinking; therefore, a thorough understanding of this multi-scale process is crucial to improve predictions of the MPs fate. We conducted a series of laboratory experiments using an oscillating-grid system to promote biofilm growth on small plastic surfaces under homogeneous isotropic turbulence with grid Reynolds numbers between 305 and 2220. Two configurations were analyzed: one where plastic samples move along with the grid (shear-dominated) and another one where the samples are kept fixed downstream the grid, thus experiencing turbulence but no mean flow (shear-free). Biofilm formed in all cases in a time scale of days, then the biomass formed on the plastic pieces was carefully measured and analyzed as a function of the turbulence level. The shear-free results were further interpreted using a parsimonious physical model, coupling the nutrient uptake rate within the biofilm (Monod kinetics) with the turbulent diffusion of the surrounding bulk liquid. Results show that: (i) under shear-dominated conditions, the biofilm mass initially grows with turbulence intensity before decaying, presumably due to shear-induced erosion; (ii) in the shear-free experiments, the mass increases monotonically following an enhanced availability of nutrients, and then saturates due to uptake-limited kinetics. This latter behavior is well reproduced by the physical model. Furthermore, a subset of plastic pieces were analyzed with a scanning electron microscope, revealing that turbulence also affects the microscopic configuration of biofilm clusters, increasing their compactness as the amplitude of turbulent fluctuations increases. These results contribute not only to our fundamental understanding of biofilms under flow, but can also inform global models of MP transport in marine environments.
- Editorial on the themed issue in honor of Carlos Gutiérrez Merino: forty years of research excellence in the field of membrane proteins and bioenergeticsPublication . Samhan-Arias, Alejandro K.; López-Sánchez, Carmen; Aureliano, ManuelProf. Carlos Gutiérrez-Merino has led over 30 research projects funded by national and international agencies and, under his guidance, numerous researchers have developed their doctoral theses, contributing to the growth of biomedical research in Extremadura.
- Under pressure: deep-sea elasmobranchs experience high mortality and stress in a crustacean trawling fisheryPublication . Graça Aranha Carvalho Ramos, Sofia; Teodosio, Maria; Marsili, Tiago; Pires da Rocha, Pedro; Modesto, Teresa; Guerreiro, Pedro Miguel; Tambutte, Aurélien; Carvalho Alves, Alexandra; Relvas, Paulo; Dias, EsterCrustacean bottom trawling in southern Portugal is an economic and culturally important fishing activity but may result in considerable bycatch of deep-sea elasmobranchs (DSE). Due to DSE life-history strategies, at-vessel mortality (AVM) rates in crustacean bottom trawl fisheries are expectedly high but require further investigations. This study assessed the at-vessel condition of 18 species of DSE, and AVM rates and stress of four deep-sea shark species (Etmopterus pusillus, E. spinax, Galeus melastomus, and Scymnodon ringens), to understand the impact of bottom trawling on these animals. Opportunistic sampling on a crustacean trawler in the southern Portuguese coast, revealed that 95% of specimens were either dead (n = 1,258) or in poor condition (n = 224) upon collection, underscoring their minimal chance of post-release survival. General linear model analyses showed that AVM was species-specific and highest in smaller sharks, as well as in those from hauls that exhibited larger temperature dierences between bottom and surface waters, and those caught in hauls with heavier codend weight using a 55 mm codend mesh (targeting shrimp and prawns) instead of those caught in hauls using a 70 mm codend mesh (targeting Norway lobster). Stress, evaluated through metabolites and electrolytes levels in sharks’ plasma, indicated significant dierences in potassium, urea, and magnesium levels between live and deceased specimens of E. pusillus and G. melastomus, suggesting these as reliable mortality markers. Elevated lactate levels in G. melastomus further pointed to high post-release mortality risk. These findings highlight an urgent need to find solutions to mitigate the impacts of bottom trawling on those DSE, which are thoroughly discussed. A coordinated, multi-stakeholder approach involving researchers, the fishing industry, and regulatory bodies is crucial for developing and implementing eective, and more sustainable fisheries management and protection of DSE populations.
- Transdisciplinary ecohydrology for water management solutions and sustainabilityPublication . Elfithri, Rahmah; Zalewski, Maciej; Arduino, Giuseppe; Chicharo, LuisEcohydrology is a transdisciplinary and applied science, a sub-discipline of hydrology that seeks to understand and apply the natural ecological processes controlled by the hydrological cycle and vice versa1. This ‘dual regulation’2–4 knowledge is used to develop solutions restoring impacted aquatic ecosystems at the entire river system, where a starting point for the regulation of processes is the identification of a hierarchy of drivers at different ecosystems5. It is a solution-oriented science for reducing anthropogenic impacts, enhancing aquatic ecosystems and their catchment sustainability, improving water resources, bioproductivity and biodiversity, ecosystem services6 and resilience at the whole mesocycle, while the involvement of society through water culture and water education will be crucial for effective implementation. The continuous development of science-based solutions must be accompanied by dissemination and education about the concept of ecohydrology and its potential application and solutions.