77 research outputs found
Ostrakoden und Foraminiferen aus athalassischen Gewässern und deren Anwendung für die Rekonstruktion quartärer Ökosysteme
Athalassic waters are characterised by elevated salinity and continental location with full separation from the sea. Faunal assemblages of athalassic waters are individually distinct and characteristic for specific salinity ranges. They are never, however, identical to fully marine assemblages. Athalassic taxa derive from the marginal marine, intertidal zone, where instable ecological conditions require a high adaptability of species. The present thesis identifies, documents and classifies athalassic foraminifer and ostracod associations and applies them for palaeoenvironmental reconstructions. The classification of athalassic waters based on ostracod and foraminifer assemblages needs a specialised methodology because of generally low diversity and high ecological tolerances of typical species, especially towards salinity. Additional methods allow to compensate for this weakness; morphological features as malformations in foraminifer tests as well as noding and sieve pore variability in Cyprideis torosa are applicable for reconstructing salinity changes of the past. Athalassic waters of the low salinity range are characterised by brackish water and tolerant freshwater taxa, dominance of brackish water species, however, is typical for higher salinities. Hypersaline waters are inhabited by a few euryhaline species only, often occurring in very high numbers because of lacking competing species. Some species of marginal marine origin, often associated with salinity-tolerant freshwater species, are typical for athalassic waters, as a generally low diversity as well. If Foraminifera occur, a high proportion of their tests is malformatted. Climatically generated athalassic waters are located in arid climate zones while those with geogenic salinity are typical for humid climate zones because of a high precipitation/evaporation ratio. Hypersaline waters are of climatogenic type and characterised by very low diversity and the exclusive occurrence of euryhaline taxa
Holocene coastal stratigraphy, coastal changes and potential palaeoseismological implications inferred from geo-archives in Central Chile (29–32° S)
Coastal geomorphology and the stratigraphy of coastal geoarchives record past coastal and fluctuations
of coastal environments. In addition, these archives potentially store traces of past extreme events
such as earthquakes and tsunamis, severe storms, and major flfl oodings of the coastal hinterland, e.g. due to
El Niño conditions. Studying their characteristics may thus improve the knowledge of past frequency and
magnitude patterns of such extreme events. For instance, large scaled spatial information about past earthquakes
is needed for the understanding and estimation of seismo-tectonic processes. Misinterpretations in
the size of preceding earthquakes may lead to incorrect strain balance estimations along megathrusts. Thus,
fundamental research on the occurrence of past earthquakes is needed, which can be reflected in sudden or
long-term coastal changes.
Using sedimentological, geomorphological and microfaunal evidence, coeval geomorphodynamic and
palaeoenvironmental changes at four different locations between 29° 50′ and 32° 20′ S in Central Chile were
identififi ed in estuary systems, coastal swamps and coastal plains. The results may represent possible indirect
evidence for palaeoseismicity, affecting the coastal system by vertical tectonic movements. Changes
of coastline elevation, morphodynamic activity and/or coastal environments, as well as the formation of a
liquefaction layer took place during the last c. 400 years. Moreover, major flfl ooding events related to strong
El Niño conditions are assumed to have influenced the coastal stratigraphy by depositing high energy fluvial
deposits. Our results suggest that the coastal environment, geomorphology and stratigraphy are considerably
inflfl uenced by tectonic processes in the study area; a relation of the presented fifi ndings to the 1730 Great Valparaíso
Earthquake is assumed. In general, the findings may encourage the implementation of comparable
detailed studies, which may ultimately contribute to a better understanding of the Holocene coastal evolution
and its relation to palaeoseismicity in Central Chile
Comment on the letter of the Society of Vertebrate Paleontology (SVP) dated April 21, 2020 regarding 'Fossils from conflict zones and reproducibility of fossil‑based scientific data': Myanmar amber
Recently, the Society of Vertebrate Paleontology (SVP) has sent around a letter, dated 21st April, 2020 to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). The signatories of this letter request significant changes to the common practices in palaeontology. With our present, multi-authored comment, we aim to argue why these suggestions will not lead to improvement of both practice and ethics of palaeontological research but, conversely, hamper its further development. Although we disagree with most contents of the SVP letter, we appreciate this initiative to discuss scientific practices and the underlying ethics. Here, we consider different aspects of the suggestions by Rayfield et al. (2020) in which we see weaknesses and dangers. It is our intent to compile views from many different fields of palaeontology, as our discipline is (and should remain) pluralistic. This contribution deals with the aspects concerning Myanmar amber. Reference is made to Haug et al. (2020a) for another comment on aspects concerning amateur palaeontologists/citizen scientists/private collectors
Nonmarine Ostracoda as proxies in (geo‐)archaeology — A review
Ostracods as bioindicators are extremely useful for reconstructing palaeoenvironment and palaeoclimate and can also indicate the provenance of sediments and materials, for example, in studies on ancient commercial networks. Ostracods are small crustaceans that live in almost all aquatic habitats, both natural and man‐made. Due to their calcitic carapace, they have high fossilization potential, and their use in geoarchaeology has been steadily increasing during the last decades. Their small size needs mean that only small volumes of sediment samples are needed, and species‐specific ecological tolerances and preferences allow detailed palaeoenvironmental reconstructions. Typical methods of their application are palaeoecological analyses of associations based on ecological information and taphonomy, morphometric variability and stable isotope and chemistry analyses of their shells. The present paper aims to present an overview of applications of non‐marine ostracods in (geo‐)archaeological research, recommending sampling and analytical techniques for addressing archaeological research questions on palaeoclimate, habitat and landscape changes, water availability and quality, land use and other anthropogenic impacts, the provenance of materials and commercial networks to promote the application of Ostracoda in geoarchaeology/environmental archaeology.International Max Planck Research School for the Science of Human Histor
Ostracod fauna associated with Cyprideis torosa - an overview
The ostracod Cyprideis torosa (Jones) tolerates a wide range of salinity from fresh to brackish water-transition to hyperhaline values. The species often dominates ostracod assemblages in oligohaline and hyperhaline waters. For a more precise determination of controlling ecological factors, mainly the salinity, the accompanying ostracod fauna needs to be investigated. In oligohaline inland water bodies of humid climates, C. torosa is associated with tolerant non-marine ostracods. In coastal lagoons the mostly very low-diversity ostracod assemblages are characterized by brackish taxa accompanying C. torosa. In saline lakes of arid climatic zones non-marine and brackish species occur together, but brackish ostracods frequently dominate the assemblages. Monospecific occurrences of C. torosa are realized mainly in hypersaline environments. Examples are given that represent typical ostracod taxa that co-occur with C. torosa
Salinity-dependent sieve pore variability in Cyprideis torosa: an experiment
Salinity-dependent sieve pore variability in Cyprideis torosa (Jones) is tested and confirmed through a culture experiment investigating valves from a salinity range between 0.6 and 14.8. In contrast to results from a previous study, the proportion of sieve pore shapes shows a slight offset at higher values probably caused by relatively lower calcium concentrations in our microcosms. Besides ion concentration, salinity variability and ion composition are assumed to be driving factors for sieve pore shapes, as for the case of noding in Cyprideis torosa. Despite some limitations in using sieve pore shapes as a proxy in quantitative salinity reconstructions in athalassic water bodies, an application for detecting trends and salinity changes in fossil associations and for quantitative reconstructions in marginal marine waters is feasible and adds a valuable salinity proxy, especially for the oligohaline to mesohaline salinity range
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