On the identity of broad-shelled mussels (Mollusca, Bivalvia, Mytilus) from the Dutch delta region

Late Quaternary (Eemian) deposits of the Netherlands contain shells that resemble those of living Mytilus galloprovincialis. Similar broad-shelled mytilids also occur in estuaries of the southwestern Netherlands together with slender individuals typical of M. edulis. We sampled living mussels along a depth gradient in the Oosterschelde to a) investigate whether a relation exists between shell shape and depth, b) test if the broad-shelled specimens might represent M. galloprovincialis (or a hybrid with M. edulis) and c) assess by inference if the Quaternary specimens might be attributed to M. galloprovincialis as well. In order to do so, we compared genetic (length polymorphism of Me 15/16, COIII sequences and AFLPs) and shell-morphological characteristics (juvenile L/W ratios and so-called Verduin parameters) of the same specimens. The obtained dataset indicates that all studied mussels from the Oosterschelde should be attributed to M. edulis, including those with broad shell outlines. No correlation of shell-morphology and depth-distribution was found. The worn and generally damaged state of the Eemian specimens precluded measurement of the Verduin parameters, while juvenile L/W ratios turned out not to be diagnostic. Therefore the shell characters examined in this study are insufficient to demonstrate the possible presence of M. galloprovincialis shells in Quaternary deposits of the Netherlands

Landscape evolution and depositional processes in the Miocene Amazonian Pebas lake/wetland system: Evidence from exploratory boreholes in northeastern Peru.

This study of the type and scales of depositional processes and landscape development in western Amazonia during the Miocene is based on the description and interpretation of three boreholes from the Marañon basin (Peru). The Miocene Pebas Formation, and the overlying Marañon Formation and underlying Chambira Formation are lithologically characterised. An age calculation model indicates an Oligocene age for the Chambira Formation, and an Early - early Late Miocene age for the Pebas Formation. The base of the Chambira Formation is placed at a sequence boundary and corresponds to the beginning of a regression. The succession was deposited in floodplains included in a RST and a LST under a seasonal climate with a pronounced dry season. The base of the Pebas Formation is placed at a TS. It represents TST and HST lacustrine and swamp settings at or near sealevel, formed in a tropical monsoon climate alike the present-day climate in the region. At the time, the area was a mosaic of lakes, swamps and fluvial belts, but experienced tidal influence as well. During apparently regularly recurring base level highstands, open aquatic settings (lakes at sea level) were widespread. The depositional system was driven by tectonic subsidence in the area, uplift and erosion in the Andean hinterland and the western rim of the Pebas system (the developing Subandean zone), delta lobe switching and river belt avulsions, as well as presumable Milankovitch scale precipitation/erosion cycles and eustatic sea level variation. The base of the Marañon Formation is placed at a sequence boundary. It represents the end of the Pebas lake/wetland system, and the change to permanent fluvial conditions during the Late Miocene RST and LST

The nature of aquatic landscapes in the Miocene of western Amazonia: An integrated palaeontological and geochemical approach

The Miocene Pebas Formation from the section Santa Rosa de Pichana (Loreto, Peru) was investigated using a combination of analyses of sedimentary facies, molluscan communities and taphonomy, and stable isotopes of both entire shells and growth bands in bivalves. Three sequences, comprising a succession of transgressive, maximum flooding and regressive/prograding intervals, are documented. Molluscs are most common in the transgressive/highstand intervals and are almost absent in regressive/prograding intervals. The fauna is dominated by endemic Pebasian species, such as Pachydon and Dyris spp. The nature of the deposits as well as the availability of oxygen varied in a predictable way within each of the sequences and determined the nature of the assemblages. Highest diversity was reached in the late transgressive phase before the development of dysoxia that was widespread during the late highstand and early regressive/prograding phase. The mollusc and isotope data show no indications of elevated salinities, in contrast to ichnofossils found in the section. This discrepancy is interpreted to result either from temporal separation of the ichnofossils and the mollusc fossils or from evolution beyond usual ecological tolerances of taxa that produced these ichnofossils into freshwater settings

On the identity of broad-shelled mussels (Mollusca, Bivalvia, Mytilus) from the Dutch delta region

Late Quaternary (Eemian) deposits of the Netherlands contain shells that resemble those of living Mytilus galloprovincialis. Similar broad-shelled mytilids also occur in estuaries of the southwestern Netherlands together with slender individuals typical of M. edulis. We sampled living mussels along a depth gradient in the Oosterschelde to a) investigate whether a relation exists between shell shape and depth, b) test if the broadshelled specimens might represent M. galloprovincialis (or a hybrid with M. edulis) and c) assess by inference if the Quaternary specimens might be attributed to M. galloprovincialis as well. In order to do so, we compared genetic (length polymorphism of Me 15/16, COIII sequences and AFLPs) and shellmorphological characteristics (juvenile L/W ratios and socalled Verduin parameters) of the same specimens. The obtained dataset indicates that all studied mussels from the Oosterschelde should be attributed to M. edulis, including those with broad shell outlines. No correlation of shell-morphology and depth-distribution was found. The worn and generally damaged state of the Eemian specimens precluded measurement of the Verduin parameters, while juvenile L/W ratios turned out not to be diagnostic. Therefore the shell characters examined in this study are insufficient to demonstrate the possible presence of M. galloprovincialis shells in Quaternary deposits of the Netherlands.

Using social network analysis to assess the Pontocaspian biodiversity conservation capacity in Ukraine

Social networks, defined as sets of relationships between stakeholder organizations, are important determinants of constructive actions for biodiversity conservation. Such actions are achieved through cooperation between various stakeholders, exchange of information, and joint planning and implementation. We used a mix of qualitative and quantitative social network analysis methods to investigate the interorganizational network of stakeholders in Ukraine, and the implications of network properties for the conservation of Pontocaspian biodiversity. Pontocaspian biota contains unique and endemic fauna, which are threatened by anthropogenic impacts; this makes effective conservation measures an urgent priority. We identified a well-connected, centralized network in Ukraine. However, the strong network has not resulted in effective conservation of Pontocaspian biodiversity. Suboptimal conservation action stems from the subordinate role of Pontocaspian species in the interorganizational interactions, likely due to lack of knowledge regarding Pontocaspian taxa. Social variables, such as funding scarcity and legal constraints, further limit the effectiveness of biodiversity conservation actions. We conclude that the current landscape of stakeholders in Ukraine is well placed to rapidly improve conservation actions if they are supplied with improved information and recognition of conservation needs of Pontocaspian taxa, combined with improved financial and legal conditions

Decline of unique Pontocaspian biodiversity in the Black Sea Basin: a review

Environmental Biolog

Метод интегрирования дифференциальных уравнений динамики электрических машин с вращающимся ротором

Для исследования переходных процессов в электротехнических системах, содержащих статические электромагнитные устройства, включенные в сложные электрические схемы, разработан программный комплекс Colo, функционирующий на основе магнитоэлектрических схем замещения в матричной форме. Главная матрица комплекса Colo содержит коэффициенты при искомых токах или магнитных потоках. Моделирование динамических процессов в электрических машинах с вращающимся ротором связано с интегрированием дифференциальных уравнений, в которые входят произведения искомых величин, поэтому непосредственно эти уравнения не могут решаться в программном комплексе Colo