Finn A. Viehberg

The Ecology of Ostracoda Across Levels of Biological Organisation from Individual to Ecosystem: A Review of Recent Developments and Future Potential

Abstract Palaeoenvironmental and palaeoclimatic applications of fossil ostracods rely on a uniformitarian approach underpinned by knowledge of the biology and ecology of living species. This review reveals that in recent decades, major advances have been made in the understanding of species’ abiotic niches in relation to their preferences for different water chemistries and temperatures. However, the underlying ecophysiological mechanisms for such preferences are still largely unknown. Only a few works analyse in detail aspects of population growth or species interactions (competition, predation) in the framework of classical ecological theories. Similarly, the role of Ostracoda in the assembly and functioning of aquatic biological communities is just starting to be recognised. We finally stress the relevance of Quaternary research on ostracod palaeoecology for testing ecological theories of community succession and dynamics in the long term, which may provide answers that standard ecological studies on living communities cannot, due to an inappropriate timescale.

Quantitative Transfer Function Approaches in Palaeoclimatic Reconstruction Using Quaternary Ostracods

Abstract Quantifying (palaeo-)environmental changes is a key challenge for aquatic biological proxies, but the number of published transfer functions is increasing rapidly for the main palaeoecologically relevant groups such as diatoms and chironomids, and several transfer functions have also been developed during the past decades based on ostracod findings. The main environmental variables influencing the species assemblage composition in ostracod training sets are specific ion concentrations or ratios, salinity, water temperature and/or water depth. The available transfer functions and training sets are globally scattered, but often regionally restricted in their application. The most common numerical methods in ostracod transfer functions are weighted averaging and weighted averaging partial least squares regression and calibration. Here, we discuss the specific prerequisites to set up new datasets for ostracods and review available transfer functions and their interpretation.

Quaternary coastline evolution of Lake Ohrid (Macedonia/Albania)

Lake Ohrid (between FYR of Macedonia and Albania), situated in an active tectonic region of the Balkanides, is characterized by N — S trending active faults. To reconstruct the Holocene shoreline evolution we investigated the coastline using sediment cores and geophysical methods to image sedimentary and tectonic structures. We revealed areas of differing sedimentation regimes. The plains north and south of the lake are dominated by clastic input related to climate variations and uplift/erosion, whereas the steep western and eastern margins are controlled by recent tectonics. Furthermore, no evidence for a much higher lake-level during the Holocene was found in the plains north and south of the lake, except rare temporary floodings. This is supported by mappings of the limestone cliffs around Lake Ohrid, which yielded no evidence for abrasional platforms or notches as indicators for past highstands.

New methods for collecting Ostracoda (Crustacea) in stony sediments with methodological remarks on the separation of ostracods from sediment

New methods for sampling ostracods are described specifically for hyporheic environments and coarse sediments (i.e., pebbles and rocks). The main module is a diaphragm pump that establishes an artificial current strong enough to force individuals from their habitat. Two other methods are presented for separating living ostracods from sediment samples taking advantage of their biological and physical properties: (1) emigration out of a basket; (2) harvesting ostracods floating on the water surface.

Living Ostracoda (Crustacea) from the town moat of Bremen, Germany

Between 2009 and 2014 we collected 23 ostracod species in the historical town moat of Bremen, Germany. Today, the moat is part of an urban park, separated into six basins by various bridges. Brackish water, pumped from the Weser River into the moat, regulates the water level and is the main factor controlling the various physical and chemical parameters of the basins. Brackish water ostracod species originate from this artificial inflow, but only a minority of these species establishes stable populations. The Bremen moat ostracod assemblages are compared with the moat of Greifswald. The different environmental setting (e.g., water current) and the number of studied localities can explain the differences in the occurrence of ostracods in these two localities.

Ostracoda as Proxies for Quaternary Climate Change: Overview and Future Prospects

Abstract Ostracod crustaceans are excellent Quaternary palaeoclimate proxies. As microfossils they supply evidence of past climatic conditions via indicator species, transfer function and mutual climatic range methods as well as the trace-element and stable-isotope geochemistry of their shells. We provide an overview of 17 contributions to the book Ostracoda as proxies for Quaternary climate change , highlight some of the emerging innovations and concerns, and assess the future prospects for ostracod applications in the field of Quaternary palaeoclimatology. The science of using ostracods as Quaternary palaeoclimate proxies has matured, well beyond the pioneering stage, and their application now needs to be tempered with critical awareness of their limitations. Key areas for future attention include palaeogenetics, improving knowledge of the ecology of living ostracods and the factors influencing their shell geochemistry, the establishment of global distributional databases and, as a necessary corollary to the last-mentioned, a programme of taxonomic harmonisation on a global scale. Finally, we emphasise the need for multi-proxy testing of methods, comparing ostracod-inferred climatic parameters with those derived from other proxies such as beetles, chironomids and foraminifera.

Late Quaternary salinity variation in the Lake of Siebleben (Thuringia, Central Germany) – Methods of palaeoenvironmental analysis using Ostracoda and pollen

We test several methods of ostracod-based palaeoenvironmental reconstruction using indicator species approach, mutual ecological/climatic range methods, transfer functions, modern analogue technique and morphological variation within Cyprideis torosa in reconstructing the site evolution of a late Quaternary small lake basin in Thuringia, Central Germany. Sediment sections containing a diverse ostracod fauna were studied and compared with those from modern water bodies of Thuringia. Palynological investigations were executed to reconstruct the environmental conditions in the catchment area and for a obtaining a biostratigraphical framework. The brackish water ostracod Cyprideis torosa as well as the foraminifer Haplophragmoides indicate phases of saline groundwater influence, fed by salt bearing sediments of the Triassic basement. The accompanying freshwater ostracod fauna, however, reflects only low variations of salinity and temperature. Environmental changes in salinity, temperature and ecological stability indicated by microfossils and pollen are caused by an interplay of climatic shifts and the local geological and hydrological setting.