Seasonal variations of water system distribution and flow patterns in the southern sea area of Hokkaido,Japan

Hydrographic data and composite current velocity data (ADCP and GEK) were used to examine the seasonal variations of upper-ocean flow in the southern sea area of Hokkaido, which includes the “off-Doto” and “Hidaka Bay” areas separated by Cape Erimo. During the heating season (April–September), the outflow of the Tsugaru Warm Current (TWC) from the Tsugaru Strait first extends north-eastward, and then one branch of TWC turns to the west along the shelf slope after it approaches the Hidaka Shelf. The main flow of TWC evolves continuously, extending eastward as far as the area off Cape Erimo. In the late cooling season (January–March), part of the Oyashio enters Hidaka Bay along the shallower part of the shelf slope through the area off Cape Erimo, replacing almost all of the TWC water, and hence the TWC devolves. It is suggested that the bottom-controlled barotropic flow of the Oyashio, which may be caused by the small density difference between the Oyashio and the TWC waters and the southward migration of main front of TWC, permits the Oyashio water to intrude along the Hidaka shelf slope.     

Reconstruction of annual winter rainfall since A.D.1579 in central-eastern Spain based on calcite laminated sediment from Lake La Cruz

We present the first winter (December to March) rainfall reconstruction based in a novel proxy, the thickness of annual calcite laminations preserved in Lake La Cruz (central–eastern Spain). A previous calibration analysis between laminae thickness and the instrumental data series (1950 to present) indicated a highly significant correlation with winter rainfall. Therefore this study attempts the winter rainfall reconstruction since the onset of laminations (1579 a.d.) by means of the calibration function previously developed. The verification analysis between inferred annual values and earlier instrumental data (1859–1949) confirms the suitability of this novel proxy and the reliability of the series reconstructed. The reconstructed series show the fluctuating character of winter rainfall in the western Mediterranean area; interdecadal dry periods alternated with wetter periods following, in a board sense, the pattern recorded by documentary sources in other regions of the Iberian Peninsula. At present times regional winter rainfall anomalies are highly correlated with the phase of the North Atlantic Oscillation (NAO). However the time series analysis showed the dominance of nonstationary components at high frequencies of the climate signal over the last four centuries suggesting that the connection between winter rainfall and the NAO has not been stable over time and also other modes of variability, not only NAO, may have conditioned winter rainfall variability.     

New Approach to Study Extended Evolution of Supergranular Flows and Their Advection of Magnetic Elements

Using velocity and magnetogram data extracted from the full-disk field of view of MDI during the 1999 Dynamics Program, we have studied the dynamics of small-scale magnetic elements (3–7 Mm in size) over time periods as long as six days while they are readily visible on the solar disk. By exploiting concurrent time series of magnetograms and Doppler images, we have compared the motion of magnetic flux elements with the supergranular velocity field inferred from the correlation tracking of mesogranular motions. Using this new method (which combines the results from correlation tracking of mesogranules with detailed analysis of simultaneous magnetograms), it is now possible to correlate the motions of the velocity field and magnetic flux for long periods of time and at high temporal resolution. This technique can be utilized to examine the long-term evolution of supergranulation and associated magnetic fields, for it can be applied to data that span far longer time durations than has been possible previously. As tests of its efficacy, we are able to use this method to verify many results of earlier investigations. We confirm that magnetic elements travel at approximately 350 m s ^–1 throughout the duration of their lifetime as they are transported by supergranular outflows. We also find that the positions of the magnetic flux elements coincide with the supergranular network boundaries and adjust as the supergranular network itself evolves over the six days of this data set. Thus we conclude that this new method permits us to study the extended evolution of the supergranular flow field and its advection of magnetic elements. Since small-scale magnetic elements are strongly advected by turbulent convection, their dynamics can give important insight into the properties of the subsurface convection.     

The observation of intrinsically different emergences for large and small active regions

The analysis of high-resolution H and white-light observations on the emergence of 73 active regions shows an intrinsically different behaviour for both the large and small ones. The small active regions (magnetic flux as 5 × 10²¹ Mx) display circular structures of supergranular size with pores only at the borders, whereas the large active regions show elongated structures with pores which develop at the center and later migrate towards the extremes. These observations are used to suggest two different models for the emergence of these two kinds of active regions: the small ones are produced by the superficial convective concentration of loosely packed dux and the large ones are the result of tightly wound flux ropes.     

Till fabric and grain-size analysis of glacial sequences in the Upper Sil River Basin,Cantabrian Mountains,NW Spain

Fabric and grain-size analysis of eight deposits present in the Upper Sil River Basin palaeoglacial system of northwest Spain were used to interpret till types and to reconstruct the glacial paleoprocess history of this region. They are represented by lodgement, deformation, and melt-out tills. The first, representative of glacial advance stages, present cluster fabrics and are generally composed of poorly sorted and finer sediments. Melt-out and deformation tills, representative of stages of glacial stability followed by fast recession, present transitional to girdle fabrics and are composed of poorly sorted coarser sediments. In any case, multiple criteria, including lithological, clast-shape, or structural data, support these directional and grain-size observations. These sequences, most of them located in the snout area of the Sil palaeoglacier, are important in the reconstruction of glacial dynamics due to poor preservation of landforms related to the maximum glacial advance. This palaeoglacial system was formed by multiple tributaries and had an extension of over 450 km², with the Sil paleoglacier being 51 km long during its maximum glacial advance.     

Variations in the pallial organ sizes of the invasive oyster, Crassostrea gigas, along an extreme turbidity gradient

Spatial size variations of labial palps, gills and the adductor muscle of the invasive feral oyster, Crassostrea gigas, were studied along two gradients of suspended particulate matter (SPM) concentrations in the temperate macrotidal Bourgneuf Bay, (annual mean SPM concentration gradient of 21.0–154.0 mg l⁻¹) and the adjacent Loire Estuary (annual mean SPM concentration gradient of 24.1–630.4 mg l⁻¹) on the French Atlantic Coast. The gill-to-palp (G:P) ratios decreased with increasing turbidity, both in the bay and the estuary. Changes in G:P ratios were chiefly related to palp area variations, increasing gradually from low turbidity to very high-turbidity sites, while gill area showed no clear relationship with turbidity conditions. The G:P ratio, showing a significant relationship (r² = 0.97) with SPM concentrations, is proposed as a pallial organ index of oyster acclimation to turbidity conditions. The area of the striated part of the adductor muscle was always greater than that of the smooth one, and adductor muscle area tended to decrease when SPM concentration increased. These observations show the morphological capacity of the oyster C. gigas to tolerate SPM concentrations above the feeding cessation thresholds previously determined experimentally. They also suggest that pallial organ size variations could help explain the success of recent feral oyster invasions in temperate turbid ecosystems.     

Cyanobacterial blooms in estuarine ecosystems: characteristics and effects on Laeonereis acuta (Polychaeta, Nereididae)

In January of 2003, a cyanobacterial bloom in the Patos' Lagoon (Southern Brazil) (32 degrees 05'S-52 degrees 12'W) was observed. Water samples were taken to identify the composition and abundance of the bloom, as well as the occurrence of toxins. The effects of this occurrence on the estuarine worm Laeonereis acuta (Polychaeta, Nereididae) was also evaluated. Predominance of cyanobacteria, particularly Anabaena trichomes ( approximately 2.5.10(6) individuals per liter) was observed, and low concentrations of microcystins and anticholinesterasic toxins were detected. Augmented levels of lipid hydroperoxides (LPO) and glutathione-S-transferase activity, and lowering of total protein content were also observed in organisms collected during the bloom event. Although non-toxic, the cyanobacterial bloom could augment the cycle of hyper-oxygenation and hypoxia in the water. During hyperoxia, L. acuta, an oxyconformer, should consume more oxygen, thus augmenting the rate of reactive oxygen species generation. A repeated cycle of hyper-oxygenation and hypoxia would finally induce oxidative stress, as evidenced by the high levels of LPO and glutathione-S-transferase activity.     

The INTEGRAL complete sample of type 1 AGN

In this paper we discuss the broad-band X-ray characteristics of a complete sample of 36 type 1 active galactic nuclei (AGN), detected by INTEGRAL in the 20–40 keV band above the 5.5σ level. We present, for all the objects in the sample, the broad-band (1–110 keV) spectral analysis obtained by using INTEGRAL / Swift /Burst Alert Telescope observations together with XMM–Newton , Chandra , ASCA and Swift /X-Ray Telescope data. We also present the general average properties of the sample, i.e. the distribution of photon indices, high-energy cut-offs, reflection fractions and absorption properties, together with an in-depth analysis of their parameter space. We find that the average Seyfert 1 power law has an index of 1.7 with a dispersion of 0.2. The mean cut-off energy is at around 100 keV, with most objects displaying E _c in the range 50–150 keV; the average amount of Compton reflection is 1.5 with a typical dispersion of 0.7. We do not find any convincing correlation between the various parameters, an indication that our analysis is not strongly dependent by the interplay between them. Finally, we investigate how the results presented in this work fit into current frameworks for AGN spectral modelling and cosmic diffuse X-ray background synthesis models.     

Comparative phylogeography and population genetic structure of three widespread mollusc species in the Mediterranean and near Atlantic

Although several studies have evaluated the genetic structure and phylogeographic patterns in many species of marine invertebrates, a general model that applies to all of them remains elusive. For example, some species present an admixture of populations with high gene flow, whereas others exhibit more complex patterns characterized by small‐scale unstructured genetic heterogeneity, even at a local scale. These differences are thought to be due to clear biological aspects such as direct versus indirect development, or the presence of lecithotrophic versus planktotrophic larvae, but few studies compare animals with similar distributions and life modes. Here, we explore the phylogeographic and genetic structure patterns in two chiton (Chiton olivaceus and Lepidopleurus cajetanus) and one abalone (Haliotis tuberculata) species co‐occurring in the same habitat. Samples were obtained from shallow rocky bottoms along the Iberian Peninsula (Atlantic and Mediterranean coasts), Italy, Croatia and Greece, and the mitochondrial markers COI and 16S rRNA gene were sequenced. Our data show evidence of admixture and population expansion in C. olivaceus and H. tuberculata, whereas L. cajetanus exhibited a ‘chaotic patchiness’ pattern defined by a high genetic variability with locality‐exclusive haplotypes, high genetic divergence, and a lack of geographic structure. Shared haplotypes were sampled in both coasts of Iberia (for H. tuberculata) and in the Western and Eastern Mediterranean (for C. olivaceus), potentially indicating high dispersal ability and a recent expansion. The processes underlying the fine‐scale structuring in L. cajetanus remain a mystery. These results are especially interesting because the reproductive mode of the two chitons is similar but differs from that of the abalone, with a veliger larva, while instead the genetic structure of C. olivaceus and H. tuberculata are similar, thus contrasting with predictions based on the life history of the three molluscs and showing that the genetic patterns of marine species may be shaped by many factors, including historical ones.