Effects of pulsed discharges from a hydropower station on summer diel feeding activity and diet of brown trout (Salmo trutta Linnaeus, 1758) in an Iberian stream.

The influence of pulsed discharges associated with hydroelectric power generation (i.e. hydropeaking) on feeding activity and diet composition of adult brown trout (Salmo trutta) was studied during the summer by comparing two sites: upstream (control site) and downstream from a power plant (hydropeaking site). Twenty fish were captured from each study site by electrofishing at 4-hour intervals for two consecutive days and stomach contents were collected with pulsed gastric lavage. Hydropeaking events affected brown trout feeding behaviour as well as prey availability. Feeding intensity, measured by the stomach Fullness Index, showed pronounced variations with maximum values after flow pulses, which were linked to variations in prey availability because of increased drift rates of invertebrates. In contrast, brown trout living at the control site showed smoother variations in feeding activity not linked to invertebrate drift. Overall, brown trout at the hydropeaking site had higher food consumption rates and a more generalist and heterogeneous diet than trout from the control site, indicating an opportunistic feeding behaviour during flow pulses. Therefore, the hydrological disturbance caused by hydropeaking did not appear to cause direct negative impacts on feeding of adult brown trout. However, reduced trout density and imbalanced size structure in the hydropeaking site were detected, requiring further research to clarify the spatial influence of hydropeaking on other factors that could negatively affect brown trout populations

Feromones: el paper de l'olor en la comunicació animal

Chemical perception is considered one of the first senses used as a communication system between living organisms. Such communication is based on the emission of signals between a sender and a receiver; if the communication is chemical, these signals are called pheromones. These signals have evolved via natural selection through a mechanism known as ritualization, which converts cues (which are not adapted to communication and which the receiver picks up regardless of the interests of the sender) into signals (information that the sender transmits as an adaptative response to its previously developed perception of the receiver). When communication has evolved between actors (sender and receiver) with common interests, the honesty of the signal is taken for granted, since both want the same thing (i.e., there is no reason to deceive). If the actors have conflicting interests, however, then the possibility of deception seeps into the possible array of adaptations. This can be observed in the case of communicative mimicry. However, in other situations natural selection imposes conditions that screen the possible signals, allowing only those that meet the requirement of honesty to stabilize. These include indices and added-cost signals. The emission of pheromones plays a variety of roles in the life processes of living beings. It facilitates encounters between individuals of the same species and is heavily involved in the mechanisms of recognition of relatives. It also fosters behaviours such as altruism (cooperation between individuals that share a percentage of their genetic inheritance). In many species, including humans, chemical communication works behind the scenes to guide the choice of a sexual partner

The effect of 22^{22}Ne diffusion in the evolution and pulsational properties of white dwarfs with solar metallicity progenitors

Because of the large neutron excess of $^{22}$Ne, this isotope rapidly sediments in the interior of the white dwarfs. This process releases an additional amount of energy, thus delaying the cooling times of the white dwarf. This influences the ages of different stellar populations derived using white dwarf cosmochronology. Furthermore, the overabundance of $^{22}$Ne in the inner regions of the star, modifies the Brunt-V\"ais\"al\"a frequency, thus altering the pulsational properties of these stars. In this work, we discuss the impact of $^{22}$Ne sedimentation in white dwarfs resulting from Solar metallicity progenitors ($Z=0.02$). We performed evolutionary calculations of white dwarfs of masses $0.528$, $0.576$, $0.657$ and $0.833$ M_{\sun}, derived from full evolutionary computations of their progenitor stars, starting at the Zero Age Main Sequence all the way through central hydrogen and helium burning, thermally-pulsing AGB and post-AGB phases. Our computations show that at low luminosities (\log(L/L_{\sun})\la -4.25), $^{22}$Ne sedimentation delays the cooling of white dwarfs with Solar metallicity progenitors by about 1~Gyr. Additionally, we studied the consequences of $^{22}$Ne sedimentation on the pulsational properties of ZZ~Ceti white dwarfs. We find that $^{22}$Ne sedimentation induces differences in the periods of these stars larger than the present observational uncertainties, particularly in more massive white dwarfs.Comment: Accepted for publication in ApJ. 8 pages, 6 figure

Fluvio-deltaic record of increased sediment transport during the Middle Eocene Climatic Optimum (MECO), Southern Pyrenees, Spain

The early Cenozoic marine sedimentary record is punctuated by several brief episodes (&lt;200 kyr) of abrupt global warming, called hyperthermals, that have disturbed ocean life and water physicochemistry. Moreover, recent studies of fluvial–deltaic systems, for instance at the Palaeocene–Eocene Thermal Maximum, revealed that these hyperthermals also impacted the hydrologic cycle, triggering an increase in erosion and sediment transport at the Earth's surface. Contrary to the early Cenozoic hyperthermals, the Middle Eocene Climatic Optimum (MECO), lasting from 40.5 to 40.0 Ma, constitutes an event of gradual warming that left a highly variable carbon isotope signature and for which little data exist about its impact on Earth surface systems. In the South Pyrenean foreland basin (SPFB), an episode of prominent deltaic progradation (Belsué–Atarés and Escanilla formations) in the middle Bartonian has been usually associated with increased Pyrenean tectonic activity, but recent magnetostratigraphic data suggest a possible coincidence between the progradation and the MECO warming period. To test this hypothesis, we measured the stable-isotope composition of carbonates (δ13Ccarb and δ18Ocarb) and organic matter (δ13Corg) of 257 samples in two sections of SPFB fluvial–deltaic successions covering the different phases of the MECO and already dated with magnetostratigraphy. We find a negative shift in δ18Ocarb and an unclear signal in δ13Ccarb around the transition from magnetic chron C18r to chron C17r (middle Bartonian). These results allow, by correlation with reference sections in the Atlantic and Tethys, the MECO to be identified and its coincident relationship with the Belsué–Atarès fluvial–deltaic progradation to be documented. Despite its long duration and a more gradual temperature rise, the MECO in the South Pyrenean foreland basin may have led, like lower Cenozoic hyperthermals, to an increase in erosion and sediment transport that is manifested in the sedimentary record. The new data support the hypothesis of a more important hydrological response to the MECO than previously thought in mid-latitude environments, including those around the Tethys.</p

Origin and propagation of sedimentary sequences throughout the Escanilla fluvial routing system (South Pyrenean foreland basin)

EGU2020: Sharing Geoscience Online, 4-8 may 2020During middle Eocene, the Escanilla fluvial system transported and deposited material from East to West in the southern Pyrenees foreland basin. The paleogeography and sedimentology of the source to sink system is well established. The temporal framework is made of scattered low resolution magnetostratigraphies, and a robust temporal framework in the most distal (Olson) and most proximal (Sis) parts of the system. We built a new high resolution magnetostratigraphy from the middle part of the system, the Lascuarre section. The correlation of Lascuarre with the high resolution magnetostratigraphies and the integration of these data with other available chronological constraints results into a robust complete temporal framework from source to sink. Sedimentological analyses of the Lascuarre section allow recognizing a set of sedimentary sequences throughout the record. Here we present the result of the analyses, and discuss the relative weight of the different forcing. Particularly, we elucidate the role of tectonics in relation to subsidence distribution patterns, and also the distinct expression of climate. Eventually, we identify and explore the signal propagation mechanisms of climate aberrations and of quasi-regular orbital variations along the routing system

The Effect of a Mediterranean Diet on the Incidence of Cataract Surgery

Background: Cataract is a leading cause of vision impairment worldwide, and surgery is the only available treatment. The process that initiates lens opacification is dependent on the oxidative stress experienced by the lens components. A healthy overall dietary pattern, with the potential to reduce oxidative stress, has been suggested as a means to decrease the risk of developing cataract. We aimed to investigate the hypothesis that an intervention with a Mediterranean diet (MedDiet) rather than a low-fat diet could decrease the incidence of cataract surgery in elderly subjects. Methods: We included 5802 men and women (age range: 55–80 years) from the Prevención con Dieta Mediterránea study (multicenter, parallel-group, randomized controlled clinical trial) who had not undergone cataract surgery. They were randomly assigned to one of three intervention groups: (1) a MedDiet enriched with extra-virgin olive oil (EVOO) (n = 1998); (2) a MedDiet enriched with nuts (n = 1914), and a control group recommended to follow a low-fat diet (n = 1890). The incidence of cataract surgery was recorded yearly during follow-up clinical evaluations. Primary analyses were performed on an intention-to-treat basis. Cox regression analyses were used to assess the relationship between the nutritional intervention and the incidence of cataract surgery. Results: During a follow-up period of 7.0 years (mean follow-up period: 5.7 years; median: 5.9 years), 559 subjects underwent cataract surgery. Two hundred and six participants from the MedDiet + EVOO group, 174 from the MedDiet + Nuts group, and 179 from the control group underwent cataract surgery. We did not observe a reduction in the incidence of cataract surgery in the MedDiet groups compared to the control group. The multivariable adjusted hazard ratios were 1.03 (95% confidence interval [CI]: 0.84–1.26, p = 0.79) for the control group versus the MedDiet + EVOO group and 1.06 (95% CI: 0.86–1.31, p = 0.58) for the control group versus the MedDiet + Nuts group. Conclusions: To our knowledge, this is the first large randomized trial assessing the role of a MedDiet on the incidence of cataract surgery. Our results showed that the incidence of cataract surgery was similar in the MedDiet with EVOO, MedDiet with nuts, and low-fat diet groups. Further studies are necessary to investigate whether a MedDiet could have a preventive role in cataract surgery

10 Myr evolution of sedimentation rates in a deep marine to non-marine foreland basin system: Tectonic and sedimentary controls (Eocene, Tremp–Jaca Basin, Southern Pyrenees, NE Spain)

The propagation of the deformation front in foreland systems is typically accompanied by the incorporation of parts of the basin into wedge-top piggy-back basins, this process is likely producing considerable changes to sedimentation rates (SR). Here we investigate the spatial-temporal evolution of SR for the Tremp–Jaca Basin in the Southern Pyrenees during its evolution from a wedge-top, foreredeep, forebulge configuration to a wedge-top stage. SR were controlled by a series of tectonic structures that influenced subsidence distribution and modified the sediment dispersal patterns. We compare the decompacted SR calculated from 12 magnetostratigraphic sections located throughout the Tremp–Jaca Basin represent the full range of depositional environment and times. While the derived long-term SR range between 9.0 and 84.5 cm/kyr, compiled data at the scale of magnetozones (0.1–2.5 Myr) yield SR that range from 3.0 to 170 cm/kyr. From this analysis, three main types of depocenter are recognized: a regional depocenter in the foredeep depozone; depocenters related to both regional subsidence and salt tectonics in the wedge-top depozone; and a depocenter related to clastic shelf building showing transgressive and regressive trends with graded and non-graded episodes. From the evolution of SR we distinguish two stages. The Lutetian Stage (from 49.1–41.2 Ma) portrays a compartmentalized basin characterized by variable SR in dominantly underfilled accommodation areas. The markedly different advance of the deformation front between the Central and Western Pyrenees resulted in a complex distribution of the foreland depozones during this stage. The Bartonian–Priabonian Stage (41.2–36.9 Ma) represents the integration of the whole basin into the wedge-top, showing a generalized reduction of SR in a mostly overfilled relatively uniform basin. The stacking of basement units in the hinterland during the whole period produced unusually high SR in the wedge-top depozoneAgència de Gestió d'Ajuts Universitaris i de Recerca, Grant/Award Number: 2017SGR596; Secretaría de Estado de Investigación, Desarrollo e Innovación, Grant/Award Number: BES-2015-073302 and CGL2014-55900-P; Swiss National Science Foundation, Grant/Award Number: 200020_18201