The Global Paleomonsoon as seen through speleothem records from Asia and the Americas

The regional monsoons of the world have long been viewed as seasonal atmospheric circulation reversal—analogous to a thermally-driven land-sea breeze on a continental scale. This conventional view of monsoons is now being integrated at a global scale and accordingly, a new paradigm has emerged which considers regional monsoons to be manifestations of global-scale seasonal changes in response to overturning of atmospheric circulation in the tropics and subtropics, and henceforth, interactive components of a singular Global Monsoon (GM) system. The paleoclimate community, however, tends to view ‘paleomonsoon’ (PM), largely in terms of regional circulation phenomena. In the past decade, many high-quality speleothem oxygen isotope (δ¹⁸O) records have been established from the Asian Monsoon and the South American Monsoon regions that primarily reflect changes in the integrated intensities of monsoons on orbital-to-decadal timescales. With the emergence of these high-resolution and absolute-dated records from both sides of the Equator, it is now possible to test a concept of the ‘Global-Paleo-Monsoon’ (GPM) on a wide-range of timescales. Here we present a comprehensive synthesis of globally-distributed speleothem δ¹⁸O records and highlight three aspects of the GPM that are comparable to the modern GM: (1) the GPM intensity swings on different timescales; (2) their global extent; and (3) an anti-phased inter-hemispheric relationship between the Asian and South American monsoon systems on a wide range of timescales.     

Effect of galvanic distortions on the series and parallel magnetotelluric impedances and comparison with other responses

The series and parallel impedances of the magnetotelluric tensor are appraised in relation to their relative immunity to galvanic electric distortions. The distorted responses are modeled using the Groom-Bailey decomposition of the tensor in terms of twist, shear, statics and strike direction. These four parameters and the undistorted responses are normally considered as unknowns, and are obtained from field data through the solution of an inverse problem. In the present work we use the decomposition as a forward model to simulate distorted sounding curves. Starting with undistorted 2-d te and tm responses, the tensor is distorted by assuming arbitrary values of twist, shear, static and strike direction. By default, both series and parallel responses are immune to the strike direction because they are invariants under rotation. In addition, series responses are immune to twist and shear and parallel responses only to twist. The dependence of the latter on shear is in the form of a real factor that shifts downwards the amplitude curves. On the other hand, the effect of statics on both series and parallel responses is more complicated than that on the impedance tensor because it cannot be accounted for by a simple shift of the curves. On the whole, there is a positive balance on the part of the series and parallel impedances over the te and tm responses because some of the distortions are filtered out by the invariants. It is shown that invariance is not sufficient to be immune to any of the distortions. The example chosen is Eggers’ eigenvalues, which are immune only to the by-the-fault strike direction. Invariance is not necessary either, as evidenced by the phase tensor, whose elements depend on strike but are immune to all distortions. The derivations are illustrated using soundings from the synthetic coprod2s1 and field-recorded coprod2 and bc87 data sets.     

Temporal and spatial variation of soil erosion in wooded rangelands of southwest Spain

Changes in land use are common in Mediterranean areas and are reported as having produced changes in the intensity of soil erosion. Dehesas are rangelands with a disperse tree cover, widespread in the south-western part of the Iberian Peninsula and similar ecosystems are also common in other areas with a Mediterranean climate. The aim of the present study is to analyse temporal and spatial variations of soil erosion rates estimated along three hillsides, located in two farms (Buitrera and Parapuños) in southwest Spain. To understand the temporal variation, soil erosion rates were studied in light of land use-management changes that took place during the last few centuries. Results indicate very low erosion rates prior to the 18^th century in both farms. In Buitrera, a first increase of soil loss rates was identified during the period 1831-1897, amounting to 7.4 t ha^-1 y^-1. A further increase took place during the 20^th century, reaching a mean erosion rate of 29.1 t ha^-1 y^-1. In Parapuños, data points to a significant increase from 1881 onwards, with an estimated mean erosion rate of 18.5 t ha^-1 y^-1. Those increases were presumably connected with an intensification of land use, such as cultivation and excessive livestock populations. Regarding spatial variation, the bare surface and the erosive power of run-off along the hillsides accounts for 76% of the soil erosion rates dispersion. At a local scale, the variability of erosion rates could not be explained, because of (i) uncertainty related to the micromorphology of the past soil surface and (ii) the role of tillage erosion in the past. However, the results obtained offer valuable data on the temporal and spatial variation of erosion rates in dehesas at the hillslope scale and a similar approach could be used for other rangelands with a disperse tree cover. © 2019 John Wiley & Sons, Ltd.     

Assessment of predictions of the response of the Hualien containment model during forced vibration tests

Blind predictions for the response of the 1/4-scale reinforced concrete Hualien (Taiwan) containment model during forced vibration tests are compared with the observed data. The predictions obtained by the CLASSI approach reflect the experimental conditions prior to and after backfill of the soil surrounding the embedded foundation. The experimental data show a strong and unexpected coupling between the response in the NS and EW directions which is not present in the results for the axisymmetric theoretical models. Also, significant differences can be seen between the experimental responses in the two orthogonal horizontal directions which minimize cross-axis coupling. Although these differences are not accounted for in the theoretical models, the discrepancies between predictions and observations are within the uncertainty of the structural and geotechnical data. The obtained differences between predictions and observations give an excellent measure of the prediction error that can be expected in this type of analysis from uncertainty in the data. A detailed assessment of the initial structural and geotechnical data based on extensive comparisons with the results of previous identification studies is also presented. Finally, comparisons between the observed response and calculations based on revised models for the structure and the soil show that current methods of analysis can account accurately for the observed response.     

Hierarchical classification of marine rocky landscape as management tool at southeast Mediterranean coast

The existence and distribution of European marine reef habitat (1170), defined as rocky substrates and biogenic concretions in the UE habitats Directive, remain incomplete especially for the Mediterranean region. It is necessary to cartography the habitats but also it is important to classify and develop tools to asses at adequate management scales. Rocky habitats occur in a variety of spatial configurations and pattering landscape. It is necessary to define a typology of landscape to permit a realistic comparison of similar units recognizing, for example, its favourable conservation status. The aim of this study is to identify the rocky landscape units and to propose a hierarchical classification, for identifying the units with a favourable conservation status, based on the presence of listed species. Non-parametric multivariate techniques were used to classify the 88 landscape units based on presence of different biocoenoses and environmental factors. A hierarchical typology was recognised according to the increase of complexity. The study comprises six sorts of landscape typologies included in two major groups. High correlations of selected environmental variables with biocenosis composition were obtained depending on the scale of analysis. We observed that both geomorphologic structure and depth influence presence of biocenosis. The reef landscape typology proposal can be the base for the definition of reference ecological conditions or the favourable conservation state of the habitats, it is also an interesting tool for decision-making in the marine management.     

Evaluation of policy options for the live reef food fish trade in the province of Palawan,Western Philippines

The live reef food fish (LRFF) trade has an estimated annual retail value of US$1 billion in the Asia-Pacific region and at least US$30 million in the Philippines. Palawan Province is the trade's center accounting for as much as 55% of the commodity's total export. Concern about the LRFF trade has caused the Palawan Provincial government to take action to regulate the trade. Four key policy options to address the short-term policy objective of developing a sustainable LRFF industry through the reduction of threats associated with destructive fishing and overfishing were proposed. These four policy options and associated analyses were presented to stakeholders at three separate policy consultations. The stakeholders reached a consensus that a regulated LRFF trade was the most sensible option. As a result, the Provincial Government of Palawan took action to enact “The Palawan Live Reef Fish Ordinance of 2006”, which provides for the sustainable and integrated regulation of the LRFF industry. This provincial ordinance will assist in crafting a national policy for the LRFF trade and may also be useful in revising the 1998 Philippine Fisheries Code. The key challenge is how to translate the ordinance provisions into effective on-the-ground actions.     

Influence of nutritional stress on digestive enzyme activities in juveniles of two marine clam species, Ruditapes decussatus and Venerupis pullastra

The potential use of digestive activities as indicators of the nutritional status in bivalves is discussed in relation to the results obtained in two clam species exposed to starvation and refeeding. Activities of some digestive enzymes (amylase, laminarinase, cellulase, and protease) were measured in juveniles of two commercially interesting species of clams, Ruditapes decussatus and Venerupis pullastra. The specimens were fed normally, being after subjected to a 15-days starvation and a further refeeding period. Samples were obtained at different moments of such feeding schedule to evaluate enzymes as well as weight (live, dry and organic) and length, in order to calculate growth rates and feeding efficiencies. Starvation led to a major decrease in clam growth as measured by dry weight and a negative growth as measured by organic weight, this coinciding with a certain degree of growth of the shell and a consumption of soft tissue. This response occurred more rapidly in R. decussatus but was of a lower magnitude than in V. pullastra. Activity of carbohydrases decreased rapidly in both species with starvation, although protease activity was maintained in R. decussatus. Recovery after the end of starvation was not similar in both species; while R. decussatus attained similar growth rates and enzyme activities to those measured prior to nutritional stress, V. pullastra only recovered 50% of its initial values. For both species of bivalves it can be concluded that digestive enzymes, and more specifically amylase, could be used as indicative of their nutritional condition.