Feeding Habits of the Invasive Weakfish (Cynoscion regalis) in the Gulf of Cadiz

Weakfish (Cynoscion regalis) has been present in Iberian waters since at least 2011, when it was first recorded in the Guadalquivir estuary. Little is known about the preferences and feeding strategies of weakfish outside of its native range; therefore, in this work, we carried out a comprehensive study between March 2021 and September 2021 to elucidate these matters. In total, the stomach contents of 300 fish were examined. The fish were collected in spring and summer in the Gulf of Cadiz (Spain), with individuals caught ranging from 185 to 590 mm in total length. Due to the sampling period and size range of individuals, ontogenic and seasonal (spring–summer) variations in the diet were also explored. Overall, fish and crustaceans were the dominant groups consumed by weakfish. The European anchovy (Engraulis encrasicolus) and caramote prawn (Penaeus kerathurus) were the most abundant prey in each group. While no differences were found in the percentage of occurrence of fish in the non-empty stomachs analyzed in spring and summer (83%), a small increase was found in the percentage of occurrence of crustaceans from spring (20%) to summer (29%). In addition, the analysis of the results also suggested that weakfish of smaller sizes feed more on crustaceans, while bigger individuals feed mainly on fish. Our findings indicate that weakfish is a fully carnivorous species with a preference for fish. All this is in line with the diet and strategy that weakfish exhibits in its native area and with the first assessment made with the existing population in the Sado Estuary (Portugal). In recent years, due to the appearance of non-native species, there is increasing concern among local fishermen and the local authorities about the reduction in captures of certain species such as Penaeus kerathurus; therefore, this study could help researchers to understand the role of weakfish concerning this matter. The present study contributes to the ecological knowledge about this species in the Iberian Peninsula and the Gulf of Cadiz, helping the local authorities to establish, if needed, an appropriate management program to cope with this recently introduced species

Paleo and historical seismicity in Mallorca (Baleares, Spain): a preliminary approach

The island of Mallorca is subject to low seismic activity. The instrumental record shows that current seismicity is surficial (La isla de Mallorca presenta una actividad sísmica baja. El registro instrumental muestra que la sismicidad actual es superficial

Electrochemical Interaction of Few-Layer Molybdenum Disulfide Composites vs Sodium: New Insights on the Reaction Mechanism

The direct observation of real time electrochemical processes is of great importance for fundamental research on battery materials. Here, we use electron paramagnetic resonance (EPR) spectroscopy to monitor the electrochemical reaction of sodium ions with few-layer MoS2 and its composite with carbon nanotubes (CNTs), thereby uncovering new details of the reaction mechanism. We propose that the sodiation reaction takes place initially in structural defects at the MoS2 surface that have been created during the synthetic process (ultrasonic exfoliation), leading to a decrease in the density of Mo5+ at low symmetry sites that can be related to the electrochemical irreversibility of the process. In the case of the few-layer MoS2/CNTs composite, we found metallic-type conduction behavior for the electrons associated with the Mo paramagnetic centers and improved electrochemical reversibility. The reversible nature of the EPR spectra implies that adsorption/desorption of Na+ ions occurs on the Mo5+ defects, or that they are neutralized during sodiation and subsequently created upon Na+ extraction. These effects help us to understand the higher capacities obtained in the exfoliated samples, as the sum of electrosorption of ions and faradaic effects, and support the suggestion of a different reaction mechanism in the few-layer chalcogenide, which is not exclusively an insertion process

Optical Photometry of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex in IC 5179

We present UBVRIz lightcurves of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex, both located in the galaxy IC 5179. SN 1999ee has an extremely well sampled lightcurve spanning from 10 days before Bmax through 53 days after peak. Near maximum we find systematic differences ~0.05 mag in photometry measured with two different telescopes, even though the photometry is reduced to the same local standards around the supernova using the specific color terms for each instrumental system. We use models for our bandpasses and spectrophotometry of SN 1999ee to derive magnitude corrections (S-corrections) and remedy this problem. This exercise demonstrates the need of accurately characterizing the instrumental system before great photometric accuracies of Type Ia supernovae can be claimed. It also shows that this effect can have important astrophysical consequences since a small systematic shift of 0.02 mag in the B-V color can introduce a 0.08 mag error in the extinction corrected peak B magnitudes of a supernova and thus lead to biased cosmological parameters. The data for the Type Ib/c SN 1999ex present us with the first ever observed shock breakout of a supernova of this class. These observations show that shock breakout occurred 18 days before Bmax and support the idea that Type Ib/c supernovae are due to core collapse of massive stars rather than thermonuclear disruption of white dwarfs.Comment: 55 pages, 15 figures, accepted by the Astronomical Journa

Neutrino Electron Scattering and Electroweak Gauge Structure: Future Tests

Low-energy high-resolution neutrino-electron scattering experiments may play an important role in testing the gauge structure of the electroweak interaction. We propose the use of radioactive neutrino sources (e.g. $^{51}$Cr) in underground experiments such as BOREXINO, HELLAZ and LAMA. As an illustration, we display the sensitivity of these detectors in testing the possible existence of extra neutral gauge bosons, both in the framework of E_6 models and of models with left-right symmetry.Comment: 22 pages, revtex, 4 figures included, accepted for publication in Phys. Rev.

Hyperbolicity of the Kidder-Scheel-Teukolsky formulation of Einstein's equations coupled to a modified Bona-Masso slicing condition

We show that the Kidder-Scheel-Teukolsky family of hyperbolic formulations of the 3+1 evolution equations of general relativity remains hyperbolic when coupled to a recently proposed modified version of the Bona-Masso slicing condition.Comment: 4 pages. Several changes. Main corrections are in eqs. 4.9 and 4.1

Recruitment of the exotic weakfish at its southernmost limit in Europe: a preliminary assessment.

Since its first record in Europe as an exotic species back in 2009 at the Schelde estuary (Belgium), the weakfish Cynoscion regalis -native from North America East coast- has increased its presence in the Iberian Peninsula waters. Identified for the first time in the Guadalquivir River estuary (2011) and later in the Sado estuary (2014), C. regalis population is increasing in the Gulf of Cadiz and is becoming a fisheries resource. Its introduction into Europe probably occurred through maritime transatlantic trade. Morais et al (2017) suggested that weakfish could have been introduced through multiple independent ballast water release events. The Guadalquivir, Sado and Schelde estuaries show similar transoceanic ship traffic to upstream important commercial ports, supporting multiple direct or secondary transatlantic introductions among European ports. The first genetic studies suggest that C. regalis populations in southern European estuaries are connected and come from a single transoceanic commercial route. Currently, the Gulf of Cadiz maintains a well-established population with frequent catches by artisanal fishing, especially in coastal waters and the estuary, where it is sold in local markets of the surrounding cities. The population in the area is constituted by mature specimens (ranging from 234 to 453 mm) that are using the estuary as a spawning area, where larvae and juvenile have also been found. In recent years, an increase in the abundance of larvae and juvenile has been observed through monthly samplings in the estuary, which indicates the culmination of the complete life cycle in the Gulf of Cadiz. These findings represent new evidence that the Guadalquivir estuary constitutes a remarkable nursery habitat for this species. This could have effects on native fauna and the ecosystem, which is why it is currently under study and evaluation (EcoInvadiz project) for helping the local Administration to establish, if needed, an appropriate management program

Molecular epidemiology of enterovirus 71, coxsackievirus A16 and A6 associated with hand, foot and mouth disease in Spain

Producción CientíficaHand, foot and mouth disease (HFMD) is a childhood illness frequently caused by genotypes belonging to the enterovirus A species, including coxsackievirus (CV)-A16 and enterovirus (EV)-71. Between 2010 and 2012, several outbreaks and sporadic cases of HFMD occurred in different regions of Spain. The objective of the present study was to describe the enterovirus epidemiology associated with HFMD in the country. A total of 80 patients with HFMD or atypical rash were included. Detection and typing of the enteroviruses were performed directly in clinical samples using molecular methods. Enteroviruses were detected in 53 of the patients (66%). CV-A6 was the most frequent genotype, followed by CV-A16 and EV-71, but other minority types were also identified. Interestingly, during almost all of 2010, CV-A16 was the only causative agent of HFMD but by the end of the year and during 2011, CV-A6 became predominant, while CV-A16 was not detected. In 2012, however, both CV-A6 and CV-A16 circulated. EV-71 was associated with HFMD symptoms only in three cases during 2012. All Spanish CV-A6 sequences segregated into one major genetic cluster together with other European and Asian strains isolated between 2008 and 2011, most forming a particular clade. Spanish EV-71 strains belonged to subgenogroup C2, as did most of the European sequences circulated. In conclusion, the recent increase of HFMD cases in Spain and other European countries has been due to a larger incidence of circulating species A enteroviruses, mainly CV-A6 and CV-A16, and the emergence of new genetic variants of these viruses

Spatio-temporal trends of the bottom trawling activity in a mud volcano field of the north-eastern Gulf of Cádiz (south-western Iberian Peninsula)

Multi-species bottom trawl fisheries are one of the human activities with a great impact on the benthic habitats and their associated biota. This study provides estimates of the bottom trawling activity (effort), catches and landings of the main commercial species as well as an estimation of the total revenue (TR) generated inside a mud volcano field located in the Spanish margin of the Gulf of Cádiz, during a time series from 2007 to 2012. To date, no studies have been carried out to analyse the temporal evolution of bottom trawling activity and TR in a mud volcano fied, or the economic consequences of possible potential bottom trawling regulation of certain sectors harbouring vulnerable and/or threatened habitats. In this study, Vessel Monitoring System data, logbooks and sales slips were used. The spatial distribution of the bottom trawling activity, catches and TR were related to the seafloor morphology and specific bottom types of the mud volcano field. During the time series, a high bottom trawling activity and associated catches was detected in flat sandy and muddy bottoms, including the Anastasya sector and between the Guadalquivir and Cádiz Diapiric Ridges. Low bottom trawling activity and catches were detected in the deepest areas but also in areas with hard and detritic bottoms such as Gazul and Chica sectors as well as in the Diapiric Ridges. A similar spatial pattern was detected for the TR asociated with these bottom trawling fisheries. An increase in bottom trawling activity was detected during the time series, mainly at the end, probably for increasing the TR and mantaining the economic profit due to the instability and increases in fuel prices and offset the increased costs. Based on the obtained information, bottom trawling regulations should be implemented in certain sectors harboring singular and/or threatened habitats and species. In some of these sectors, a low TR from bottom trawling was detected and, bottom trawling regulation may potentially have a low socioeconomic impact. This specific bottom trawling regulation could provide a sustainable balance between bottom trawling activities and habitat conservation in this mud volcano field according to the aims of the Habitats Directive (92/43/EEC) and the European Marine Strategy Framework Directive (2008/56/EEC).En prens