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A Tentative Model for the Origin of A-Type Granitoids
No full textA-type granites are typically formed in stable intra-plate, back-arc or postcollisional settingsand are characterized by highly ferroan and potassic major element compositions, and by strong enrichment in incompatible trace elements. Unlike I-, S- and M-type granites, where the letters denote the dominant source material (igneous, sedimentary or mantle derived), there is no consensus on the source and processes giving rise to A-type magmas. In this contribution, a conceptual model for the origin of A-type granitoids, using the Bornholm A-type granitoid complex in southern Fennoscandia as an example, is presented. In this model, underplated mantle-derived basaltic magma may develop into intermediate and siliceous A-type magma, which is ferroan, potassic and highly enriched in incompatible trace elements, through a combination of fractional crystallization leading to cumulate formation, and partial melting and crustal assimilation, in a process akin to zone refining in metallurgy. The key factor is a relatively stable tectonic environment (postcollisional, anorogenic, or extensional), where there is little or no replenishment of more primitive basaltic magma to the system, allowing it to attain more evolved, enriched and extreme compositions. The A-type granitoids may then be viewed as a more evolved counterpart of subduction-related I-type granitoids
Effect of hunting and by-catches on the observed rate of growth of the Baltic sea grey seal population.
No full textNew taxa, records, and data for vesicomyid bivalves from Cenozoic strata of the North Pacific region
No full textNew discoveries of Cenozoic deep-water hydrocarbon seep deposits and continued collecting at previously documented sites in the North Pacific region have resulted in additional fossils of vesicomyid bivalves and necessitate a systematic review. We report five new vesicomyid species, including four species from western Washington State, USA: Isorropodon humptulipsense sp. nov. from middle to upper Eocene strata of the Humptulips Formation and the “Siltstone of unit B”, the oldest record for Isorropodon, Pleurophopsis thieli sp. nov. from upper Eocene to lowermost Oligocene strata of the Lincoln Creek, Makah, and Pysht formations, and Pliocardia? guthrieorum sp. nov. and Squiresica plana sp. nov. from Oligocene strata of the Lincoln Creek and Pysht formations. The new species Squiresica yooni sp. nov. is from the Middle Miocene Duho Formation in South Korea. We report possibly the as-yet oldest Vesicomya from a lower Oligocene seep deposit in the Lincoln Creek Formation in western Washington. Pliocardia kawadai was previously only known from Lower to Middle Miocene strata in Japan; with our new record from the Lower to Middle Miocene Astoria Formation in western Washington, this species represents the first fossil vesicomyid species with a trans-Pacific distribution. The large and elongated Pleurophopsis chinookensis is restricted to upper Eocene strata; previous Oligocene records are shown to belong to other species.Field work by SK was financially supported by the Swedish Research Council (Vetenskapsrådet) through grant 2016-03920</p
Bird nest boxes infested with Carnus hemapterus (Diptera: Carnidae): A perfect arena for the study of trophic interplays with a special focus on parasitoid Hymenoptera
No full textBirds' nests hold rich and diverse communities of invertebrates with complex interspecific interactions whose study could improve our understanding of food webs and resource dynamics. To reach this goal, identification of the participants of such interactions is basic but current knowledge on some key groups such as hymenopteran parasitoids is admittedly poor and unreliable. Here we describe the invertebrate fauna in nests of the Eurasian wryneck Jynx torquilla Linnaeus, 1758 (Piciformes: Picidae) and the relative importance of various trophic guilds. We found a rich community where ectoparasitic Diptera of birds, parasitoid wasps and scavenger Diptera had a prominent representation. We specifically studied the natural enemies of the most abundant bird ectoparasite Carnus hemapterus Nitzsch, 1818 (Diptera: Carnidae), which revealed that Kleidotoma caledonica Cameron, 1888 (Hymenoptera: Figitidae) is a specialized and frequent parasitoid of the ectoparasite. Information on the association between other parasitoid wasps, parasitoid flies and their hosts is also offered. Such associations could result in trophic cascades with remarkable consequences for the avian host
High diversity and early radiation of organic-walled phytoplankton in southern Baltica during the Middle-Late Ordovician – evidence from the Borenshult-1 drillcore of southern Sweden
No full textHighly diverse and well preserved organic-walled phytoplankton were recorded from the Darriwilian–early Katian interval of the Borenshult-1 drillcore. We identified 154 species in 53 genera, and three assemblages were distinguished; Assemblage A of a late Darriwilian age, Assemblage B of a Sandbian age (further subdivided into sub-assemblages B1 and B2), and Assemblage C dated as Katian. Taxa with “Silurian affinities” with previous first appearance datum in the early Silurian, Hirnantian, such as Metaleiofusa and Visbysphaera, are here recorded from the late Darriwilian and Sandbian respectively. These occurrences question the relationship between the appearance of pioneering phytoplankton morphotypes and the Hirnantian glaciation. Other taxa with no pre-Silurian records such as Visbysphaera pirifera subsp. minor, Petaloferidium cazurrum and Dorsennidium cf. D. estrellitae are here present in the Sandbian, where bentonite beds are intercalated. The diversity curve of acritarchs shows similarities with those proposed for the Darriwilian-Katian of Baltica with main differences in the interval with bentonite beds representing an intense volcanic activity. The species Metaleiofusa arcuata Wall is here emended and a new combination is proposed: Petaloferidium cazurrum (Cramer) comb. nov. The genus Fankea is recorded for the first time from Swedish strata, suggesting a dominant high- to middle latitudinal distribution instead of a Perigondwanan distribution. We contend that the location of paleo-southern Sweden contributed to the great diversity seen, since a middle-low latitude provided a suitable habitat with warm, shallow water, rich in nutrients.Funding is acknowledged from Fondo para la Investigación Científica y Tecnológica (FONCYT), PICT 2017–0532 (C. Rubinstein) This is a contribution to the IGCP Project 735 ‘Rocks and the Rise of Ordovician life’.PlantEr
First report of Sphenothallus Hall, 1847 from the lower Cambrian of North China
No full textSphenothallus is a tubular organism that is one of the most widely distributed and longest-ranging genera through the Palaeozoic. Despite its apparent cosmopolitan distribution, the genus has never been reported from North China. New specimens of Sphenothallus sp. have been discovered in the upper part of the Houjiashan and base of the Mantou formations (early to middle Age 4, Epoch 2, Cambrian) in Jiangsu Province, North China. The specimens are small tubes (up to 5 mm long) and have typical Sphenothallus characteristics, such as a multilayered lamellar structure, and subcircular to elliptical transverse cross-section with a pair of longitudinal thickenings situated at the widest diameter. Our material shows that both the rate of apertural expansion and the curvature of the tubes are significantly larger in early growth stages than in the later growth stages. As the diameter of the aperture increases, the transverse cross-section of the Sphenothallus sp. tube changes from subcircular at the proximal end to elliptical or lenticular at the distal end, and its wall thickness changes from uniform to thickening longitudinally. The discovery of Sphenothallus sp. from the North China Platform represents an extension of its palaeogeographic range during the Cambrian.This work was financially supported by the National Natural Science Foundation of China [NSFC Nos. 41890844, 41720104002 and 41621003 to Zhang Zhifei]. We also thank the Department of Science and Technology of Shaanxi Province [2022TD–11] and the 111th project [D17013] at Northwest University.</p
The first U–Pb age for shocked zircon from the Mien impact structure, Sweden, and implications for metamictization‐induced zircon texture formed during impact events
No full textPer- and polyfluoroalkyl substances (PFAS) within the Swedish Monitoring Programme for Contaminants in Marine Biota
No full textThe aim of the report is three-fold. Firstly, to evaluate to what extent phase-out of certain per- and polyfluoroalkyl substances (PFAS) first initiated in the early 2000s are reflected in the biota concentration within the Baltic Sea. Secondly, to investigate the spatial differences of PFAS across the Baltic Sea, which has not previously been evaluated, and couple these results to PFAS observations in other matrices to better understand the flow of PFAS through the Baltic Sea ecosystem. Lastly, to investigate the implication of a proposed PFAS EQS dossier on the evaluation of Good Environmental Status in the Baltic Sea. We use data on PFAS from the Swedish Monitoring Program for Contaminants in Marine Biota covering 40 years for the longest time series (four Time Trend Stations) and 26 stations at present day. The program covers stations from the Bothnian Bay in the north to Skagerrak at the Swedish west coast (referred to as the Greater Baltic Sea) and PFAS is analyzed in four fish species and three bird species. The target compounds are perfluoroalkyl sulfonic acid (PFSA; C4-C8), perfluoroalkyl carboxylic acid (PFCA; C6-C15) and FOSA. In the data evaluation, observations from other monitoring programmes and research campaigns are included (river, marine surface water, sediment, and top predators) to set the observations from the Swedish Monitoring Program for Contaminants in Marine Biota into context. After an initial exponential increase in PFAS concentrations, we found that PFAS displayed a rapid response to phase-out and regulations in the early 2000s. As a result, PFAS concentrations stabilized (rather than displaying an immediate decrease). This is linked to the few removal pathways of the long lived PFAS homologues in the Baltic Sea water column. However, within the last decade PFAS has started to show significant declines at many stations, the exception being a few PFAS homologues (PFOA (C8) and PFNA (C9)). Two distinct water masses are present in the Greater Baltic Sea, North Sea water and Baltic Sea water, the latter with origin in the Baltic Sea drainage basin. Differences in the PFAS loads of these water masses likely drives geographical differences seen in the PFAS concentrations and homologue distribution between fish in Kattegat and the Baltic Sea. Different water mass lifetimes in the Baltic Sea basins further affect the concentration and response time with regards to changes in external sources for individual homologues. A proposed PFAS EQS dossier presents an EQS (with the PFAS sum expressed as PFOA-equivalents) a factor 100 lower than the current PFOS EQS. We find that PFOS, PFNA and PFUnDA contribute more than 80% to the sumPFAS-equivalent. PFNA is the only homologue that is currently increasing in some parts of the Baltic Sea and special attention should be on this homologue in the future. Despite the slow recovery with regards to PFAS concentrations over the past decade the biota PFAS concentrations are still 5-230 times higher than the threshold proposed in the PFAS EQS dossier. Screening studies has further identified a range of PFAS in the Greater Baltic Sea not currently part of the Swedish Monitoring Program for Contaminants in Marine Biota. As an example the cyclic PFECHS has been found at various trophic levels in the food web at concentrations indicating biomagnification potential. These findings indicate that PFAS is still affecting the Greater Baltic Sea environment negatively and the development in concentrations of individual homologues should be followed closely over the coming decade both for those PFAS included in the current program but also the emergence of novel PFAS through screening program
Historic Sampling of a Vanishing Beast: Population Structure and Diversity in the Black Rhinoceros
No full textThe black rhinoceros (Diceros bicornis L.) is a critically endangered species historically distributed across sub-Saharan Africa. Hunting and habitat disturbance have diminished both its numbers and distribution since the 19th century, but a poaching crisis in the late 20th century drove them to the brink of extinction. Genetic and genomic assessments can greatly increase our knowledge of the species and inform management strategies. However, when a species has been severely reduced, with the extirpation and artificial admixture of several populations, it is extremely challenging to obtain an accurate understanding of historic population structure and evolutionary history from extant samples. Therefore, we generated and analyzed whole genomes from 63 black rhinoceros museum specimens collected between 1775 and 1981. Results showed that the black rhinoceros could be genetically structured into six major historic populations (Central Africa, East Africa, Northwestern Africa, Northeastern Africa, Ruvuma, and Southern Africa) within which were nested four further subpopulations (Maasailand, southwestern, eastern rift, and northern rift), largely mirroring geography, with a punctuated north–south cline. However, we detected varying degrees of admixture among groups and found that several geographical barriers, most prominently the Zambezi River, drove population discontinuities. Genomic diversity was high in the middle of the range and decayed toward the periphery. This comprehensive historic portrait also allowed us to ascertain the ancestry of 20 resequenced genomes from extant populations. Lastly, using insights gained from this unique temporal data set, we suggest management strategies, some of which require urgent implementation, for the conservation of the remaining black rhinoceros diversity