Comparative study of gonadal development of Ruditapes philippinarum (Adams and Reeve) and Ruditapes decussatus (L.) (Mollusca: Bivalvia): Influence of temperature

Laboratory experiments were used to study the influence of temperature on the reproductive behaviour of two species of clam, Ruditapes decussatus and Ruditapes philippinarum, during their adaptation to the temperature conditions of Galician coastal waters. In both species the rate of gonadal development was directly related to the increase in temperature. At 14ºC the reproductive behaviour was similar, both species needing over 2 months to mature. At 18ºC, the rate of gonadal development of R. philippinarum was greater than that of R. decussatus. Nevertheless, the results of this study confirm that both species have adapted perfectly to the temperature conditions of the Galician Rias, though certain differences between the reproductive behaviour of these species were detected. R. philippinarum accumulates oocytes prior to their partial or total emission, while in the case of R. decussatus gametes are liberated continuously. In the early phases of its development, the gonad of R. philippinarum is highly heterogeneous in nature, with up to 3 reproductive states being present at the same time, while in R. decussatus gonadal development is much more uniform. Another major difference concerns the phenomenon of reabsorption, common in R. philippinarum but very rare in R. decussatus. These characteristics may well result in a greater reproductive activity in R. philippinarum than in R. decussatus, and a longer reproduction period in the former. They may also represent a certain advantage for the adaptation of the foreign species (R. philippinarum) over the native species (R. decussatus) to the temperature conditions of the Galician Rias.Se llevaron a cabo experiencias de laboratorio para estudiar la influencia de la temperatura en el comportamiento reproductivo de dos especies de almeja, R. philippinarum y R. decussatus, en su adaptación a las condiciones térmicas en las costas de Galicia. En ambas especies la tasa de desarrollo gonadal está directamente relacionada con el incremento de temperatura. A 14ºC el comportamiento reproductivo es similar y ambas especies necesitan cerca de 2 meses para madurar. A 18ºC, la tasa de desarrollo gonadal de R. philippinarum es mayor que en R. decussatus. No obstante, los resultados de este estudio confirman que ambas especies se han adaptado perfectamente a las condiciones térmicas de las rías de Galicia, si bien, se detectan ciertas diferencias en su comportamiento reproductivo. Así, mientras R. philippinarum acumula ovocitos antes de su emisión parcial o total, en el caso e R. decussatus los gametos se liberan continuamente. En las primeras fases de su desarrollo, el aspecto de la gónada de R. philippinarum es muy heterogéneo, presentándose hasta 3 estados reproductivos simultáneamente, mientras que en R. decussatus el desarrollo gonadal es bastante más uniforme. Otra diferencia concierne al fenómeno de la reabsorción, común en R. philippinarum, pero muy raro en R. decussatus. Estas características pueden sustentar una mayor actividad reproductiva en R. philippinarum comparado con R. decussatus, y un mayor periodo reproductivo en el caso de la primera. Ello puede también representar una cierta ventaje adaptativa, de la especie foráneas (R. philippinarum) frente la especie nativa (R. decussatus), a las condiciones térmicas de las rías de Galicia

Reporte inicial de las investigaciones arqueológicas en el tercer claustro del antiguo convento de Santa Clara de Asís

Este trabajo propone una nueva lectura del tercer claustro del edificio del antiguo convento de Santa Clara de Asís de la Habana Vieja, sede del Centro Nacional de Conservación, Restauración y Museología (CENCREM). Los antecedentes de los que se parte críticamente son la importante investigación publicada por el historiador Pedro Herrera (2006), así como los reportes de las investigaciones arqueológicas llevadas a cabo en las áreas del edificio durante unos cincuenta años. Durante los últimos cinco años las investigaciones fundamentales realizadas por el grupo de arqueología del CENCREM en lo tocante al proyecto investigativo general del convento han estado dedicadas a las instalaciones hidráulicas del primer claustro y a los cambios constructivos del tercer claustro. Como consecuencia de las investigaciones en el tercer claustro se ha identificado una capilla no reportada en la bibliografía o en fuentes documentale

Comparative study of gonadal development of Ruditapes philippinarum (Adams and Revé) and Ruditapes decussatus (L.) (Mollusca, Bivalvia): Influence of temperature

Laboratory experiments were used to study the influence of temperature on the reproductive behaviour of two species of clam, Ruditapes decussatus and Ruditapes philippinarum, during their adaptation to the temperature conditions of Galician coastal waters. In both species the rate of gonadal development was directly related to the increase in temperature. At 14°C the reproductive behaviour was similar, both species needing over 2 months to mature. At 18°C, the rate of gonadal development of R. philippinarum was greater than that of R. decussatus. Nevertheless, the results of this study confirm that both species have adapted perfectly to the temperature conditions of the Galician Rias, though certain differences between the reproductive behaviour of these species were detected. R. philippinarum accumulates oocytes prior to their partial or total emission, while in the case of R. decussatus gametes are liberated continuously. In the early phases of its development, the gonad of R. philippinarum is highly heterogeneous in nature, with up to 3 reproductive states being present at the same time, while in R. decussatus gonadal development is much more uniform. Another major difference concerns the phenomenon of reabsorption, common in R. philippinarum but very rare in R. decussatus. These characteristics may well result in a greater reproductive activity in R. philippinarum than in R. decussatus, and a longer reproduction period in the former. They may also represent a certain advantage for the adaptation of the foreign species (R. philippinarum) over the native species (R. decussatus) to the temperature conditions of the Galician Rias

Energy balance of mussels Mytilus galloprovincialis: the effect of length and age

Clearance and ingestion rates, absorption efficiencies and respiration rates were measured in mussels Mytilus galloprovincialis Lmk of different lengths (53 to 89 mm) and age (10 to 24 mo) from cultivation rafts in the Ría de Arosa (Galicia, Spain). The experiments were carried out either in the laboratory, using monoalgal food (Isochrysis galbana) with an organic content of 91%, or under natural conditions of food availability in cultivation rafts with seston, the organic content of which ranged from 33 to 69%. Food concentrations ranged from 0.57 to 1.00 mg l-1 of total particulate matter (TPM), a load which is below the threshold for the production of pseudofaeces in Mytilus. These experiments proved that the ingestion rate (IR = mg TPM h-1) of food increases with the size of the mussel (measured as g of soft-tissue dry weight [DW]) according to the power equation IR = 12.661DW0.619, this model accounting for over 90% of the variance of the IR. Behavioural patterns that tended to maintain constant IR regardless of the density of the food were observed. Absorption efficiency (AE) is positively related to the organic content (OC) of the food according to the following hyperbolic equation: AE = 1.015 - 0.163(1/OC) (r = 0.940). AE is independent of mussel size for most of the size range used in this study, but there is a critical length around 85 mm, above which there is a noticeable decrease of AE. Metabolic expenditure, measured in terms of oxygen consumption standarized per unit of dry weight of flesh, tends to increase with the age of the mussel. The results obtained led to the conclusion that physiological traits such as the regulation of ingestion or differences in AE between groups do not explain the differences in growth between mussels of the same age. These differences must therefore be due to the limited food and space available as a result of the large numbers of mussels on the cultivation rafts and the agglomeration of mussels on the cultivation ropes.Versión de editor

Joint recording of EEG and audio signals in hyperscanning and pseudo-hyperscanning experiments.

Hyperscanning is an emerging technique that allows for the study of brain similarities between interacting individuals. This methodology has powerful implications for understanding the neural basis of joint actions, such as conversation; however, it also demands precise time-locking between the different brain recordings and sensory stimulation. Such precise timing, nevertheless, is often difficult to achieve. Recording auditory stimuli jointly with the ongoing high temporal resolution neurophysiological signal presents an effective way to control timing asynchronies offline between the digital trigger sent by the stimulation program and the actual onset of the auditory stimulus delivered to participants via speakers/headphones. This configuration is particularly challenging in hyperscanning setups due to the general increased complexity of the methodology. In other designs using the related technique of pseudo-hyperscanning, combined brain-auditory recordings are also a highly desirable feature, since reliable offline synchronization can be performed by using the shared audio signal. Here, we describe two hardware configurations wherein the real-time delivered auditory stimulus is recorded jointly with ongoing electroencephalographic (EEG) recordings. Specifically, we describe and provide customized implementations for joint EEG-audio recording in hyperscanning and pseudo-hyperscanning paradigms using hardware and software from Brain Products GmbH.•Joint EEG-audio recording configuration for hyperscanning and pseudo-hyperscanning paradigms.•Near zero-latency playback of auditory signal captured by a microphone.•Precise alignment between EEG and auditory stimulation

The Hartree-Fock state for the 2DEG at filling factor 1/2 revisited: analytic solution, dynamics and correlation energy

The CDW Hartree-Fock state at half filling and half electron per unit cell is examined. Firstly, an exact solution in terms of Bloch-like states is presented. Using this solution we discuss the dynamics near half filling and show the mass to diverge logarithmically as this filling is approached. We also show how a uniform density state may be constructed from a linear combination of two degenerate solutions. Finally we show the second order correction to the energy to be an order of magnitude larger than that for competing CDW solutions with one electron per unit cell.Comment: 14 pages, no figures, extended acknowledgements, two new references include

ESQUEMA METODOLÓGICO PARA EL ANÁLISIS DE LA SITUACIÓN SOCIO-HABITACIONAL EN UNA CIUDAD.

En este trabajo se propone un esquema metodológico para analizar el comportamiento de la ciudad en función de la situación socio-habitacional. Este esquema permite definir modelos de comportamiento espacial de una ciudad con relación a la situación socio-habitacional, apoyados en el uso de los SIG a escala territorial, los cuales tienen la cualidad de enfocar el carácter multidimensional que posee el desarrollo urbano y su dimensión social a partir de la determinación de las variables estratégicas socio-habitacionales. Los modelos resultantes permiten focalizar los centros críticos donde se sintetizan los problemas; son ordenados y jerarquizados en función de la importancia o peso que realmente poseen en la explicación de la problemática, a partir de dichas variables. El esquema metodológico diseñado se ha aplicado en la ciudad Camagüey, capital de la provincia de igual nombre. Para la realización del trabajo se utilizó una gama de bibliografía tanto nacional, como internacional

Simple approach to the mesoscopic open electron resonator: Quantum current oscillations

The open electron resonator, described by Duncan et.al, is a mesoscopic device that has attracted considerable attention due to its remarkable behaviour (conductance oscillations), which has been explained by detailed theories based on the behaviour of electrons at the top of the Fermi sea. In this work, we study the resonator using the simple quantum quantum electrical circuit approach, developed recently by Li and Chen. With this approach, and considering a very simple capacitor-like model of the system, we are able to theoretically reproduce the observed conductance oscillations. A very remarkable feature of the simple theory developed here is the fact that the predictions depend mostly on very general facts, namely, the discrete nature of electric charge and quantum mechanics; other detailed features of the systems described enter as parameters of the system, such as capacities and inductances

Applying Fishers' Ecological Knowledge to Construct Past and Future Lobster Stocks in the Juan Fernández Archipelago, Chile

Over-exploited fisheries are a common feature of the modern world and a range of solutions including area closures (marine reserves; MRs), effort reduction, gear changes, ecosystem-based management, incentives and co-management have been suggested as techniques to rebuild over-fished populations. Historic accounts of lobster (Jasus frontalis) on the Chilean Juan Fernández Archipelago indicate a high abundance at all depths (intertidal to approximately 165 m), but presently lobsters are found almost exclusively in deeper regions of their natural distribution. Fishers' ecological knowledge (FEK) tells a story of serial depletion in lobster abundance at fishing grounds located closest to the fishing port with an associated decline in catch per unit effort (CPUE) throughout recent history. We have re-constructed baselines of lobster biomass throughout human history on the archipelago using historic data, the fishery catch record and FEK to permit examination of the potential effects of MRs, effort reduction and co-management (stewardship of catch) to restore stocks. We employed a bioeconomic model using FEK, fishery catch and effort data, underwater survey information, predicted population growth and response to MR protection (no-take) to explore different management strategies and their trade-offs to restore stocks and improve catches. Our findings indicate that increased stewardship of catch coupled with 30% area closure (MR) provides the best option to reconstruct historic baselines. Based on model predictions, continued exploitation under the current management scheme is highly influenced by annual fluctuations and unsustainable. We propose a community-based co-management program to implement a MR in order to rebuild the lobster population while also providing conservation protection for marine species endemic to the Archipelago