Development of a prototype for submarine communications in shallow waters

The Telecommunications Marine Laboratory (TML) of the University of Cádiz takes part in a research project to study the intertidal sediments of the Bay of Cádiz. The collection of samples from the seabed and the transmission of data to the surface are performed by a Mini Profiler with four channels (MP4), which is supplied by UNISENSE. Each channel processes the samples collected by a single sensor. For power, control, and data transmission, a special wiring that connects the submerged subsystem with the surface subsystem is used. The tension transmitted by the cable to the MP4 structure makes its handling and positioning under water more difficult. This article explains the technological solution developed by the TML to replace some wiring from the MP4. For the prototype, two underwater acoustic modems have been used and an electronic system has been developed based on the Arduino platform, in order to multiplex, digitize, and transmit the data collected by the MP4 sensors, eliminating the need to use wiring. The submerged subsystem has an autonomous power supply by a battery.Peer Reviewe

Kinetics of Indigenous Nitrate Reducing Sulfide Oxidizing Activity in Microaerophilic Wastewater Biofilms

23 páginas.-- 10 figuras.-- 2 tablas.-- 74 referencias.-- Supporting Information: Dataset. in http://dx.doi.org/10.1371/journal.pone.0149096Nitrate decreases sulfide release in wastewater treatment plants (WWTP), but little is known on how it affects the microzonation and kinetics of related microbial processes within the biofilm. The effect of nitrate addition on these properties for sulfate reduction, sulfide oxidation, and oxygen respiration were studied with the use of microelectrodes in microaerophilic wastewater biofilms. Mass balance calaculations and community composition analysis were also performed. At basal WWTP conditions, the biofilm presented a double-layer system. The upper microaerophilic layer (~300 μm) showed low sulfide production (0.31 μmol cm-3 h-1) and oxygen consumption rates (0.01 μmol cm-3 h-1). The anoxic lower layer showed high sulfide production (2.7 μmol cm-3 h-1). Nitrate addition decreased net sulfide production rates, caused by an increase in sulfide oxidation rates (SOR) in the upper layer, rather than an inhibition of sulfate reducing bacteria (SRB). This suggests that the indigenous nitrate reducing-sulfide oxidizing bacteria (NR-SOB) were immediately activated by nitrate. The functional vertical structure of the biofilm changed to a triple-layer system, where the previously upper sulfide-producing layer in the absence of nitrate split into two new layers: 1) an upper sulfide-consuming layer, whose thickness is probably determined by the nitrate penetration depth within the biofilm, and 2) a middle layer producing sulfide at an even higher rate than in the absence of nitrate in some cases. Below these layers, the lower net sulfide-producing layer remained unaffected. Net SOR varied from 0.05 to 0.72 μmol cm-3 h-1 depending on nitrate and sulfate availability. Addition of low nitrate concentrations likely increased sulfate availability within the biofilm and resulted in an increase of both net sulfate reduction and net sulfide oxidation by overcoming sulfate diffusional limitation from the water phase and the strong coupling between SRB and NR-SOB syntrophic relationshipAC was funded by projects P06-RNM-01787, P11-RNM-7199, the PAI group RNM-214 from Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía and CTM2013-43857-R from the Spanish Ministry of Economy and Competitiveness. JMG was funded by the PAI group BIO-288 from Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

Trophic status of a coastal lagoon - marine harbor system: Potential outwelling rates to the Mesoamerican Barrier Reef southern region

Eutrophication is still a serious problem in many coastal areas, including the tropics, where river discharges of nutrients is usually high. The ecological stability and ecosystem services of the Mesoamerican Barrier Reef System (MBRS), the world's second-largest coral reef system, suffer a generalized impact by riverine discharge of sediment and organic and inorganic nutrients, which may lead to coastal eutrophication and a coral-macroalgal phase shift. However, few data exist on the MRBS coastal zone status, particularly in Honduras. Here, two in situ sampling campaigns were carried out (May 2017 and January 2018) in the Alvarado Lagoon and Puerto Cortés Bay (Honduras). Measurements included water column nutrients, chlorophyll-a (Chla), particulate organic and inorganic matter and net community metabolism, completed with satellite images analysis. The lagoon and bay environments are ecologically different systems and present different sensitivities to seasonal changes in precipitation as shown by the multivariate analysis. Nonetheless, net community production and respiration rates were neither different spatially, nor seasonally. In addition, both environments were highly eutrophic as shown by the TRIX index. Thus, the Puerto Cortés system represents an important source of dissolved nutrients and particulate matter to the coastal zone. Even though offshore, water quality, based on estimated outwelling rates from the Puerto Cortés system to the coastal waters of the southern MRBS region, improved considerably, concentrations of Chla and nutrients remained higher than those typically measured in non-polluted coral reefs in the Caribbean region and the suggested threshold values. In situ monitoring and assessment of these aspects are crucial to evaluate the ecological functioning of and threats on the MBRS, and elaborate and implement adequate policies for integrated management given its regional and global importance

Reduction of net sulfide production rate by nitrate in wastewater bioreactors. Kinetics and changes in the microbial community

15 páginas, 7 figuras, 5 tablas, 44 referencias.-- [email protected] addition stimulated sulfide oxidation by increasing the activity of nitrate-reducing sulfide-oxidizing bacteria (NR-SOB), decreasing the concentration of dissolved H2S in the water phase and, consequently, its release to the atmosphere of a pilot-scale anaerobic bioreactor. The effect of four different concentrations of nitrate (0.12, 0.24, 0.50, and 1.00 mM) was investigated for a period of 3 days in relation to sulfide concentration in two bioreactors set up at Guadalete wastewater treatment plant (Jerez de la Frontera, Spain). Physicochemical variables were measured in water and air, and the activity of bacteria implicated in the sulfur and nitrogen cycles was analyzed in the biofilms and in the water phase of the bioreactors. Biofilms were a net source of sulfide for the water and gas phases (7.22±5.3 μmol s−1) in the absence of nitrate dosing. Addition of nitrate resulted in a quick (within 3 h) decrease of sulfide both in the water and atmospheric phases. Sulfide elimination efficiency in the water phase increased with nitrate concentrations following the Michaelis–Menten kinetics (Ks=0.63 mM NO3 −). The end of nitrate addition resulted in a recovery or increase of initial net sulfide production in about 3 h. Addition of nitrate increased the activity of NR-SOB and decreased the activity of sulfate-reducing bacteria. Results confirmed the role of NR-SOB on hydrogen sulfide consumption coupled with nitrate reduction and sulfate recycling, revealing Sulfurimonas denitrificans and Paracoccus denitrificans as NR-SOB of great importance in this process.We acknowledge the support of the grants P06-RNM-01787, P11-RNM-7199, the PAI groups RNM-214 and BIO-288 from Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía, Spain and CTM2009-10736 from the Ministerio de Innovación y Ciencia, Spain, which include cofinancing from FEDER funds. S. Papaspyrou was funded by a JAE-Doc fellowship (Programa JAE, JAE-Doc109, Spanish National Research Council) and a Marie Curie ERG action (NITRICOS, 235005, European Union).Peer reviewe

Risk Factors and Predictive Score for Bacteremic Biliary Tract Infections Due to Enterococcus faecalis and Enterococcus faecium: a Multicenter Cohort Study from the PROBAC Project

Biliary-tract bloodstream infections (BT-BSI) caused by Enterococcus faecalis and E. faecium are associated with inappropriate empirical treatment and worse outcomes compared to other etiologies. The objective of this study was to investigate the risk factors for enterococcal BT-BSI. Patients with BT-BSI from the PROBAC cohort, including consecutive patients with BSI in 26 Spanish hospitals between October 2016 and March 2017, were selected; episodes caused by E. faecalis or E. faecium and other causes were compared. Independent predictors for enterococci were identified by logistic regression, and a predictive score was developed. Eight hundred fifty episodes of BT-BSI were included; 73 (8.5%) were due to target Enterococcus spp. (48 [66%] were E. faecium and 25 [34%] E. faecalis). By multivariate analysis, the variables independently associated with Enterococcus spp. were (OR; 95% confidence interval): cholangiocarcinoma (4.48;1.32 to 15.25), hospital acquisition (3.58;2.11 to 6.07), use of carbapenems in the previous month (3.35;1.45 to 7.78), biliary prosthesis (2.19;1.24 to 3.90), and moderate or severe chronic kidney disease (1.55;1.07 to 2.26). The AUC of the model was 0.74 [95% CI0.67 to 0.80]. A score was developed, with 7, 6, 5, 4, and 2 points for these variables, respectively, with a negative predictive value of 95% for a score # 6. A model, including cholangiocarcinoma, biliary prosthesis, hospital acquisition, previous carbapenems, and chronic kidney disease showed moderate prediction ability for enterococcal BT-BSI. Although the score will need to be validated, this information may be useful for deciding empirical therapy in biliary tract infections when bacteremia is suspected. IMPORTANCE Biliary tract infections are frequent, and a significant cause of morbidity and mortality. Bacteremia is common in these infections, particularly in the elderly and patients with cancer. Inappropriate empirical treatment has been associated with increased risk of mortality in bacteremic cholangitis, and the probability of receiving inactive empirical treatment is higher in episodes caused by enterococci. This is because many of the antimicrobial agents recommended in guidelines for biliary tract infections lack activity against these organisms. To the best of our knowledge, this is the first study analyzing the predictive factors for enterococcal BT-BSI and deriving a predictive score.8 página

Photosynthetic activity and community shifts of microphytobenthos covered by green macroalgae

Macroalgae blooms, a frequent consequence of eutrophication in coastal areas, affect the photosynthetic activity of sediments dominated by microphytobenthos (MPB). Light spectra, steady-state (after 1 h) microprofiles of O2, gross photosynthesis (Pg), community respiration in light (RL) and net community photosynthesis (Pn) were measured in diatom- and cyanobacteria-dominated communities below increasing layers of Ulva. Photosynthetic photon flux (PPF) decreased exponentially with increasing layers of algae and the light spectrum was increasingly enriched in the green and deprived in blue and red regions. Sediment Pg, Pn and RL decreased as the number of Ulva layers increased; however, 1.6 times higher macroalgal density was necessary to fully inhibit cyanobacteria Pg compared with diatoms, indicating that cyanobacteria were better adapted to this light environment. Long-term (3 weeks) incubations of diatom-dominated sediments below increasing layers of Ulva resulted in a shift in the taxonomic composition of the MPB towards cyanobacteria. Hence, changes in the light climate below macroalgal accumulations can negatively affect the photosynthetic activity of sediments. However, spectral niche differentiation of MPB taxonomic groups and concurrent changes in the MPB community may provide sediments with increased resilience to the detrimental effects of eutrophication.The research was funded by grants CTM 2009-10736 (Ministry of Education and Science, Spain), P06-RNM-01787 and P06-RNM-01637 (Andalusian Regional Government). E. García-Robledo was funded by a FPU grant (AP2005-4897) from Ministry of Education and Science and by the project ECOLAGUNES (SOE1/P2/F153, Interreg SUDOE, European Union). E.P.M. was funded by a project (FUNDIV, P07-RNM-2516) granted by the Andalusian Regional Government. S. Papaspyrou was funded by a JAE-Doc fellowship (Programa JAE, JAE-Doc109, Spanish National Research Council) and a Marie Curie ERG action (NITRICOS, 235005, European Union).Peer reviewe

Microbial community fingerprinting by differential display-denaturing gradient gel electrophoresis

4 pages, 2 tables, 2 figures, 29 references. We acknowledge Aguas de Jerez E.M.S.A. for the use of the Guadalete wastewater treatment plant and for technical assistance and E. Iglesias from Yara Iberian for providing Nutriox.Complex microbial communities exhibit a large diversity, hampering differentiation by DNA fingerprinting. Herein, differential display-denaturing gradient gel electrophoresis is proposed. By adding a nucleotide to the 3'ends of PCR primers, 16 primer pairs and fingerprints were generated per community. Complexity reduction in each partial fingerprint facilitates sample comparison.This work was supported mainly by grant P06-RNM-01787 from the Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía, Spain, and by projects CGL2009-12328/BOS and Consolider CSD2009-00006 from the Spanish Ministry of Science and Innovation.Peer reviewe

Venenos animales, fuente para el desarrollo de agentes terapéuticos

En la actualidad, el uso de animales y sus componentes se ha vuelto un recurso para el tratamiento de padecimientos en humanos. Los animales ponzoñosos, capaces de producir veneno, destacan como un grupo ampliamente utilizado, por lo que se han descrito más de doscientas mil especies de animales productores de veneno y su distribución ecológica abarca, casi en su totalidad, la variedad de ecosistemas de nuestro planeta. El estudio moderno de los venenos ha permitido el descubrimiento de agentes terapéuticos desde los años ochenta. Tal vez el más destacado sea el de la hipertensión arterial, denominado Captopril; sin embargo, el potencial de estos organismos para el descubrimiento de nuevos fármacos es enorme, puesto que existen más de diez millones de péptidos, en su mayoría aún no caracterizados, que podrían servir de plataforma para el desarrollo de nuevos agentes terapéuticos

Freeze-lysable inorganic nutrients in intertidal sediments: dependence on microphytobenthos abundance

9 páginas, 6 figuras, 3 tablas.Freezing is a common treatment for the preservation of sediment samples. To test the role of microphytobenthos (MPB) abundance in the release of intracellular nutrients to the pore water due to cell breakage after freezing, referred to as freeze-lysable inorganic nutrients (FL-IN), parallel extractions were carried out from intertidal sediment cores collected in winter and summer from Cádiz Bay. After the determination of net production and dark respiration rates with O2 microsensors, sediment cores were subcored and sliced into several layers. The samples were divided into 2 fractions; the first was centrifuged to extract pore water (fresh) and the other was frozen at –80°C, thawed and centrifuged to extract pore water after freezing. NO2–, NO3–, NH4+ and PO43– were measured in the pore water extracted by both procedures. Chlorophylls a and c were extracted from the same sediment fractions. Freezing produced a significant increase in the pore water concentrations of all inorganic nutrients. Therefore, if the variable of interest is the inorganic nutrient concentration, pore water should be extracted from fresh samples. In addition, FL-IN correlated significantly with chlorophylls a and c (p < 0.01), r2 ranged from 0.54 for NO3– to 0.94 for NH4+, indicating that most FL-IN were released from MPB biomass. The relationships between chlorophyll a and FL-IN in winter and summer were significantly different, suggesting that nutrient accumulation by MPB changes seasonally and might affect nutrient cycling in intertidal sediments.The research was funded by grants CTM2006-04015 and CTM2009-10736 (Ministry of Education and Science, Spain) and P06-RNM-01787 (Junta de Andalucía) to A.C., and a FPU grant (AP2005-4897) from the Ministry of Education and Science to E.G. and a JAE-DOC fellowship to S.P. fellowship to S.PPeer reviewe

Benthic foraminiferal community changes and their relationship to environmental dynamics in inter tidal muddy sediments (bay of cádiz, SW Spain)

The temporal and vertical variability of live intertidal benthic foraminifera was studied in parallel to environmental variables such as porewater and overlying water nutrients, salinity, temperature, sedimentary pigments and organic carbon. About 80% of benthic foramini - fera were concentrated in the upper 0-4 mm sediment layer, which was also the maximum oxygen penetration depth under light conditions as determined by oxygen microsensor measurements. Significant changes in the composition of the foraminiferal community over the course of the study were found in the surface layer (0-2 mm), whereas no differences were detected in the deepest sediment layers (10-30 mm). Univariate measures, such as abundance, species richness and diversity showed few differences over time and little relation to environmental variables. On the other hand, multivariate regression analysis for the whole community assemblage showed that the significant community composition changes over time in the surface layer could be related to fluctuations of several environmental variables, mainly those related to sediment food availability. The macroalgal bloom that occurred during the winter months had no detectable effect on benthic foraminiferal abundance or community patterns. Overall, the intertidal foraminiferal community in the Bay of Cádiz showed a highly dynamic character and a clear vertical distribution which could be effectively captured by studying the uppermost sediment layer at sub-centimetric vertical resolution. © Inter-Research 2013.Peer Reviewe