Efectos ecológicos del acúmulo de valvas de mejillón debido a la acuicultura sobre la comunidad de invertebrados bentónicos

España es el segundo productor de mejillón en el mundo, concentrándose la producción en la parte NO del país. Los altos niveles de producción conllevan a la acumulación de valvas, modificando la complejidad de los hábitats bentónicos, forzando cambios en el bentos y favoreciendo el aumento masivo en la abundancia del decápodo Pisidia longicornis, cuando se compara con áreas distantes a las bateas. El objetivo del presente estudio es estimar el aumento poblacional de P. longicornis debido a la acumulación de valvas de mejillón en el bentos, utilizando unidades experimentales localizadas bajo la influencia de bateas, en comparación con una zona cercana a las bateas (control). Las unidades experimentales se depositaron durante 5 meses, las cuales consisten en bolsas de malla rellenas con valvas de mejillón defaunadas (30 litros de volumen de ocupación), que simulan el sustrato existente debajo de las bateas. Además, la tasa metabólica de esta especie se estimó utilizando la respiración. El experimento se realizó midiendo la tasa de consumo de oxígeno y la producción de CO2 por organismos de dos tamaños diferentes, usando botes cerrados para medir el consumo de ambos parámetros durante una hora. El oxígeno se midió a través de un oxímetro, y la producción de CO2 se midió usando una valoración total de carbono con Titrisol HCl en dos rangos de pH. Los resultados mostraron un aumento significativo de la abundancia de P. longicornis, hasta 12,000 ind/m2 en las zonas con acumulaciones de valvas de mejillón, siendo la abundancia de alrededor de 10 ind/m2 en sedimento de control. Los resultados mostraron una tasa metabólica fuertemente dependiente de la temperatura, tamaño y alimentación natural, con valores de consumo de O2 entre 15 y 796 mmol/g/día dependiendo del tamaño del organismo. Los efectos de la acumulación de valvas producen un aumento en la abundancia de invertebrados como P. longicornis, que encuentran un hábitat óptimo en dichas zonas. La alta tasa metabólica y la gran abundancia, pueden aumentar el consumo de materia orgánica y evitar su acumulación en el hábitat bentónico afectado por la acuicultura de mejillón, aumentando la capacidad de carga de los hábitats bentónicos

A 50-year (1971–2021) mesozooplankton biomass data collection in the Canary Current System: Base line, gaps, trends, and future prospect

Mesozooplankton have been widely used as a bioindicator of marine ecosystems due to their key position in ocean food webs, rapid response to environmental changes, and ubiquity. Here, we show mesozooplankton biomass values in the Canary Current System from 1971 to 2021 in three different areas in relation to mesoscale activity: (1) scarcely affected by mesoscales structures (North of the Canary Islands), (2) affected by mesoscale activity and the presence of the islands (South and around the islands), and (3) close to the Northwest African coastal upwelling system (Upwelling influenced). A Generalized Additive Mixed Model (GAMM) was used to analyze the general mesozooplankton biomass trend throughout the studied period discriminating differences in biomass between the areas, annual cycle, and day-nighttime periods. The GAMM showed a significant negative biomass tendency North of the Canary Islands over the 50-year time-series compared to the South and around the islands, and significant differences between day and nighttime periods (p < 0.001) and the annual cycle (p < 0.0001). Linear regression analyses showed different tendencies depending on the area, season, and period. When comparing biomass data of the most oligotrophic zone (north of the islands) with other tropical-subtropical time-series stations in Hawaii (HOTS) and Bermuda (BATS), we obtained increasing biomass tendencies for both fixed time stations but decreasing tendency for our time-series

Mesozooplankton size structure in the Canary Current System

Changes in plankton composition influences the dynamics of marine food webs and carbon sinking rates. Understanding the core structure and function of the plankton distribution is of paramount importance to know their role in trophic transfer and efficiency. Here, we studied the zooplankton distribution, abundance, composition, and size spectra for the characterization of the community under different oceanographic conditions in the Canaries-African Transition Zone (C-ATZ). This region is a transition zone between the coastal upwelling and the open ocean showing a high variability because of the physical, chemical, and biological changes between eutrophic and oligotrophic conditions through the annual cycle. During the late winter bloom (LWB), chlorophyll a and primary production were higher compared to that of the stratified season (SS), especially in the upwelling influenced area. Abundance distribution analysis clustered stations into two main groups according to the season (productive versus stratified season), and one group sampled in the upwelling influenced area. Size-spectra analysis showed steeper slopes during daytime in the SS, suggesting a less structured community and a higher trophic efficiency during the LWB due to the favorable oceanographic conditions. We also observed a significant difference between day and nighttime size spectra due to community change during diel vertical migration. Cladocera were the key taxa differentiating an Upwelling-group, from a LWB- and SS-group. These two latter groups were differentiated by Salpidae and Appendicularia mainly. Data obtained in this study suggested that abundance composition might be useful when describing community taxonomic changes, while size-spectra gives an idea of the ecosystem structure, predatory interactions with higher trophic levels and shifts in size structure

Non-volatile tuning of normally-on and off states of deep depletion ZrO2/O-terminated high voltage diamond MOSFET

Based on the stability of the deep depletion regime in diamond and the outstanding properties of this promising material for its use in power devices, p-channel deep depletion metal oxide semiconductor field effect transistors were fabricated on a (001) Ib nitrogen-doped high pressure high temperature diamond substrate. Taking advantage of the new concept of the non-volatile diamond-based photo switch, it is demonstrated that it is possible to tune the normally-on and normally-off states of the transistor by configuring the pn-junction space charge region. The devices under study was designed following an interdigital-like and a circular-like architectures presenting low threshold voltages (between 3 V and −3 V), an on/off ratio of 107 and a critical electric field numerically assessed of 9 MV.cm−1 at room temperature. This new degree of freedom opens the route for diamond based power electronics.8 página

Swimbladder properties of Cyclothone spp. in the northeast Atlantic Ocean and the Western Mediterranean Sea

Non-migratory bristlemouth fishes (Cyclothone spp.) are the most abundant vertebrates on Earth and play an important role in the biological carbon pump by remineralizing organic carbon in deep ecosystems. Acoustic data and net sampling are often used in combination to estimate fish and zooplankton biomass, but this procedure may be subject to several sources of error when applied to mesopelagic species. For instance, the allocation of echoes to species has often been biased by not considering Cyclothone spp. due to the use of nets targeting larger fish. Furthermore, the acoustic properties of the target organisms must be well understood to convert acoustic density into numerical density. The characteristics of a fish’s swimbladder are the most relevant features necessary to assess its acoustic properties. This study provides information on the swimbladder properties of six Cyclothone species inhabiting the meso- and bathypelagic layers in the North Atlantic Ocean and Mediterranean Sea, including swimbladder location within the body, fat tissue content, morphology, morphometry (only available for C. braueri and C. pseudopallida), and fish body-mass density (only available for C. braueri, C. pseudopallida, C. pallida, and C. pygmaea). The studied species showed a functional physoclistous swimbladder, with well-developed gas glands and rete mirabile and numerous capillaries in the case of the shallower species C. braueri and C. pseudopallida (mainly distributed from 400 to 600 m depth), and a fat-invested swimbladder in species with deeper vertical distribution (C. livida, C. microdon, C. pallida, and C. pygmaea). The fat content in the swimbladder (C. pallida and C. microdon) increased with depth and latitude, reducing the space in the swimbladder that could contain gas. Changes in swimbladder size and volume during growth were analyzed for shallower species, where swimbladder volume and equivalent radius followed negative allometric growth in relation to body length. Finally, values of body-mass density (ρ) and gas content required for neutral buoyancy (VG) were estimated for C. braueri and C. pygmaea collected between 350 and 550 m (ρ = 1.052–1.072 g·cm−3, VG = 2%–4%; ρ = 1.052–1.062 g·cm−3, VG = 3.6%), and for C. pallida and C. pseudopallida sampled in the 450–700 m layer (ρ = 1.052–1.062 g·cm−3, VG = 2.6–3.1%; ρ = 1.052–1.062 g·cm−3, VG = 2.8%–3.25%). Results in this study highlight the change in scattering behavior of Cyclothone species from gas-bearing organisms (those that contain gas in their swimbladder) in the upper mesopelagic zone to the fluid-like scattering (with fat-filled swimbladders) of the deeper and northern individuals. The data presented in this manuscript are important for parametrizing acoustic backscattering models built to estimate the echo of Cyclothone species, although further work is needed, particularly for individuals with partially invested swimbladders with an irregular fat-free shape

Suplementación con calcio, densidad mineral ósea y contenido mineral óseo. Predictores de cambios en la masa ósea en madres adolescentes a los 6 meses postparto

We determined the effect of calcium supplementation on bone mineral density (BMD) and bone mineral content (BMC) and identified predictors of bone mass changes in adolescent mothers 6 months postpartum. A prospective, analytical, clinical study was performed in adolescent mothers (≤19 years old; n=37) from La Plata, Argentina. At 15 days postpartum, mothers were randomly assigned into one of two groups and started with calcium supplementation; one group received dairy products (932 mg Ca; n=19) and the other calcium citrate tablets (1000 mg calcium/day; n=18). Weight, height and dietary intake were measured and BMD was determined by DEXA at 15 days (baseline) and 6 months postpartum. BMC, total body BMD and BMD were assessed in lumbar spine, femoral neck, trochanter and total hip. Regression models were used to identify the relationship of total body BMD and BMC with independent variables (calcium supplementation, months of lactation, weight at 6 months, percent weight change, lean mass at 6 months, percent lean mass change, total calcium intake). Results showed that changes in BMD and BMC at the different sites were similar in both groups, and changes in percent body weight and total calcium intake were the main predictive factors. In conclusion, the effect of calcium was similar with either form of supplementation, i.e., dairy products or tablets, and changes in percent body weight and total calcium intake were predictors of total body BMD and BMC changes.El objetivo del estudio fue determinar el efecto de dos formas de suplementare calcio sobre la densidad mineral ósea (DMO) y el contenido mineral óseo (CMO), e identificar predictores de cambios en la masa ósea en madres adolescentes a los 6 meses postparto. Se realizó un estudio prospectivo, analítico y clínico en madres adolescentes (≤19 años; n=37) de la ciudad de La Plata, Argentina. A partir de los 15 días postparto, las adolescentes fueron distribuidas al azar en 2 grupos y comenzaron con la suplementación con calcio; un grupo recibió productos lácteos (932 mg Ca; n=19) y el otro citrato de calcio (1000 mg calcio/día; n=18). Se midió peso, altura y consumo de alimentos y se determinó la DMO por DEXA a los 15 días (línea de base) y a los 6 meses postparto. También se determinó CMO, DMO corporal total y DMO de columna lumbar, cuello femoral, trocánter y cadera total. Se usaron modelos de regresión para identificar relaciones entre DMO corporal total y CMO con variables independientes (tipo de suplementación, meses de lactancia, peso a los 6 meses, porcentaje de cambio de peso, masa magra a los 6 meses, porcentaje de cambio de masa magra, consumo total de calcio). Los resultados muestran que los cambios en DMO y CMO en los distintos sitios fueron similares en ambos grupos, y que los cambios en los porcentajes de peso corporal e ingesta total de calcio fueron los principales factores predictivos. En conclusión, el efecto del calcio fue similar tanto con productos lácteos como con comprimidos. Los cambios porcentuales en peso corporal e ingesta total de calcio resultaron factores predictivos de los cambios de la DMO corporal total y el CMO.Facultad de Ciencias Médica

Efectos ecológicos del acúmulo de valvas de mejillón debido a la acuicultura sobre la comunidad de invertebrados bentónicos

España es el segundo productor de mejillón en el mundo, concentrándose la producción en la parte NO del país. Los altos niveles de producción conllevan a la acumulación de valvas, modificando la complejidad de los hábitats bentónicos, forzando cambios en el bentos y favoreciendo el aumento masivo en la abundancia del decápodo Pisidia longicornis, cuando se compara con áreas distantes a las bateas. El objetivo del presente estudio es estimar el aumento poblacional de P. longicornis debido a la acumulación de valvas de mejillón en el bentos, utilizando unidades experimentales localizadas bajo la influencia de bateas, en comparación con una zona cercana a las bateas (control). Las unidades experimentales se depositaron durante 5 meses, las cuales consisten en bolsas de malla rellenas con valvas de mejillón defaunadas (30 litros de volumen de ocupación), que simulan el sustrato existente debajo de las bateas. Además, la tasa metabólica de esta especie se estimó utilizando la respiración. El experimento se realizó midiendo la tasa de consumo de oxígeno y la producción de CO2 por organismos de dos tamaños diferentes, usando botes cerrados para medir el consumo de ambos parámetros durante una hora. El oxígeno se midió a través de un oxímetro, y la producción de CO2 se midió usando una valoración total de carbono con Titrisol HCl en dos rangos de pH. Los resultados mostraron un aumento significativo de la abundancia de P. longicornis, hasta 12,000 ind/m2 en las zonas con acumulaciones de valvas de mejillón, siendo la abundancia de alrededor de 10 ind/m2 en sedimento de control. Los resultados mostraron una tasa metabólica fuertemente dependiente de la temperatura, tamaño y alimentación natural, con valores de consumo de O2 entre 15 y 796 mmol/g/día dependiendo del tamaño del organismo. Los efectos de la acumulación de valvas producen un aumento en la abundancia de invertebrados como P. longicornis, que encuentran un hábitat óptimo en dichas zonas. La alta tasa metabólica y la gran abundancia, pueden aumentar el consumo de materia orgánica y evitar su acumulación en el hábitat bentónico afectado por la acuicultura de mejillón, aumentando la capacidad de carga de los hábitats bentónicos

A 50-year (1971-2021) mesozooplankton biomass data base in the Canary Current System

Mesozooplankton have been widely used as a bioindicator of marine ecosystems due to their key position in ocean food webs, rapid response to environmental changes, and ubiquity. Here, we present the compilation of mesozooplankton biomass values in the Canary Current System over 50 years (1971-2021) in three different areas in relation to mesoscale activity: (1) scarcely affected by mesoscales structures (North of the Canary Islands), (2) affected by mesoscale activity and the presence of the islands (South and around the islands), and (3) close to the Northwest African coastal upwelling system (Upwelling influenced). This dataset contains the reference where mesozooplankton biomass values were obtained (indicated when not published), latitude, longitude, area, date, fraction, station number, net type and sampled period

Otolith morphological measures of stranding mesopelagic fishes in the Canary Islands during June 2021

Otolith of mesopelagic fishes stranded in the Canary Islands during June 2021 were measured. This dataset contains the standard length (SL, mm) of each species, as well as the otolith length (OL, in mm) and width (OW, in mm), the aspect ratio (OAR = OW/OL) and the otolith relative length (ORL = (100*(OL/SL)) for each specimen. The species were identified using the external morphological identification and the otoliths analysis. We used the AFORO website for the identification of species using the otolith contour (Lombarte et al. 2006)