Ostracod Record Research Articles

Changes in the Early Holocene lacustrine environment inferred from the subfossil ostracod record in the Varangu section, northern Estonia

The Varangu section is located on the southern slope of the Pandivere Upland in northern Estonia. A silty clay bed formed in the study area at 11 200–9300 cal yr BP, according to ostracod subfossils (e.g. Tonnacypris estonica, Leucocythere mirabilis, Limnocytherina sanctipatricii) in an oxygen-rich cool and oligotrophic profundal lacustrine environment, with an inflow of surface waters through springs. The record of specific ostracods (e.g. Cyclocypris ovum, Cypridopsis vidua, Metacypris cordata) reflects littoral environments, ongoing eutrophication, temperature increase and a progressive shallowing of the lake in the early Holocene (9300–7400 cal yr BP) when the tufa bed accumulated. A slight cooling and productivity decrease at 9100– 8600 cal yr BP preceded further temperature rise and water level lowering, leading to the development of a eutrophic lake and cease of tufa precipitation (8600–7400 cal yr BP).

Early Eocene marine ostracods from the Crescent Formation, southwestern Washington State, USA

Abstract. An assemblage of eleven species of Early Eocene marine intertidal and sublittoral ostracods has been found in the Crescent Formation in the Black Hills, Thurston County, Washington State, USA. The ostracods are subtropical and tropical taxa, such as Bairdoppilata, Cytherella and Neomonoceratina, which are found south of Washington today. Based on the geological age of the formation, the fauna corresponded to the Early Eocene Climatic Optimum. Five new species are recognized: Acanthocythereis olympiana sp. nov., Ambostracon irizukii sp. nov., Bairdoppilata crescentana sp. nov., Coquimba washingtonensis sp. nov. and Cytherelloidea squiresi sp. nov. This new assemblage from the Crescent Formation is the northernmost record of Early Eocene ostracods for the entire Pacific Basin.

Ostracods as tsunami tracers in Holocene sequences

This review analyses the ostracod record in Holocene tsunami deposits, using an overview of the 2004 Indian Ocean tsunami impact on its recent populations and the associated tsunamigenic deposits, together with results from numerous investigations of other Holocene sequences. Different features such as the variability of the local assemblages, population density, species diversity, age population structure (e.g., percentages of adults and juvenile stages) or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high-energy events in marshes, lakes, lagoons or shallow marine areas.

Climate controlled ostracod preservation in Lake Ohrid (Albania, Macedonia)

Lake Ohrid (Albania, Macedonia) is probably the oldest existing lake in Europe and thus of great interest for palaeo-environmental and genetic studies. Within more than 220 endemic faunal species known to live in the lake, ostracods are outstanding due to the potentially very long fossil record. They can provide geochemical information over a period exceeding the entire Quaternary and direct evidence for radiation. Here we discuss the ostracod record and the calcite concentration along a 10-m-long sediment core taken at 100 m water depth in the south-eastern, Albanian part of Lake Ohrid. Well preserved ostracod valves representing in-situ fauna only occur from 0 cm to 105 cm and from 476 cm to 933 cm core depth, corresponding to the last interglacial and the Holocene, respectively. Those periods are also characterized by high concentrations of endogen calcite. There is no significant difference in the faunal composition of the two periods separated by several tens of thousand years and we found non-calcitic ostracod remains, especially the strongly chitinised mandibles, throughout the glacial period. Therefore, we conclude that ostracods were present in the lake throughout the entire period represented by the sediment core, but with poor or lacking preservation of their calcite valves during the glacial period. Calcite precipitation and ostracod preservation were most likely inhibited by the complete interruption of Calcium supply from karsts springs, which were inactive during the glacial periods due to permafrost in large parts of the calcareous mountains.

Reconstruction of a latest Paleocene shallow-marine eutrophic paleoenvironment at Sidi Nasseur (Central Tunisia) based on foraminifera, ostracoda, calcareous nannofossils and stable isotopes (d13C, d18O)

In order to unravel faunal and paleoenvironmental parameters in shallow marine settings prior to the Paleocene- Eocene thermal maximum, we investigated the Sidi Nasseur section (NAS) in Central Tunisia. This section exposes Paleocene to lower Eocene shales and marls of the El Haria Formation. The uppermost Paleocene part of the Sidi Nasseur section is marked by poor to moderately rich, but fairly diversified nannofossil associations, containing the typical latest Paleocene taxa of the top of NP9a. The ostracode record displays an almost continuous record in the uppermost Paleocene part of the section. Representatives of Aegyptiana, Paracosta, Reticulina and Reymenticosta make up the major part of the ostracode fauna. The benthic foraminiferal assemblage consists of numerous small calcareous benthic foraminifera, like Anomalinoides midwayensis and Lenticulina spp. and many large Frondicularia phosphatica, Pyramidulina spp. These, together with the non-calcareous agglutinated foraminifera and the rare planktic foraminifera, indicate an inner neritic to coastal environment with eutrophic conditions, regularly interrupted by oxygen deficiency. The dominance of non-calcareous benthic foraminifera between intervals with abundant calcareous benthic foraminifera suggests post-mortem dissolution. The foraminiferal d13C record (based upon Pyramidulina latejugata) of the latest Paleocene in the Sidi Nasseur area is very similar to these from coeval sediments at Gebel Duwi and Gebel Aweina in Egypt. Oxygen isotopic ratios indicate a marine setting with a water composition affected by evaporation. During the latest Paleocene, the highly productive shallow water environment evolved to shallower water depths with higher salinity and increasing dominance of A. midwayensis.

Extinction pattern of marine Ostracoda across the Pliensbachian-Toarcian boundary in the Cordillera Ibérica, NE Spain: Causes and consequences

This paper discusses the extinction pattern of the Pliensbachian-Toarcian boundary (PTB) ostracod assemblages at the Almonacid de la Cuba section (Cordillera Ibérica, NE Spain), which has been recently proposed as auxiliary boundary stratotype for the PTB. The ostracod record shows that the main Early Jurassic ostracod extinction event occurred not at the end of the Pliensbachian, but near the top of the Mirabile ammonite Subzone, Tenuicostatum ammonite Zone (Early Toarcian). On the basis of the evaluation of PTB ostracod record, a new causal explanation for the Early Toarcian ostracod turnover is proposed. This paper suggests that a reorganization of surface and deep-water circulations caused by the opening of the Hispanic Corridor could have generated a mild cooling episode, finally affecting the survival of healdioid ostracods.

Ostracods in the Palaeozoic?

The attribute traditionally used to recognise the occurrence of ostracods in the Palaeozoic stratigraphic record has in essence been the presence of a bivalved arthropod carapace of small size. Discoveries offering unparalleled insight into the soft part palaeobiology of tiny bivalved Palaeozoic arthropods, when taken together with the notion that a bivalved carapace is a convergent phenomenon within the Arthropoda, have in the last decade revolutionised our understanding of the nature and stratigraphic record of the major groups of ostracod present in the Palaeozoic. Evidence from appendages and other soft parts is crucial in determining systematic affinity. Evidence from the soft part anatomy of bradoriids and phos-phatocopids has undermined the record of ostracods in the Cambrian, but molecular and fossil evidence implies that they may be present at that time. In the absence of soft parts the case that lepetditicopids (Ordovician-Devonian) are ostracods remains uncertain. Myodocopes certainly occur in the Palaeozoic, as determined on a wealth of new palaeobiological evidence. As yet, supposed Palaeozoic podocopes are represented in practical terms only by fossil shells. The systematic affinity of palaeocopes — a major group in the Palaeozoic and hitherto recognised as a coherent taxon — remains enigmatic, and they may turn out to represent an artificial grouping.

Brood care in a Silurian ostracod.

An exceptionally preserved new ostracod crustacean from the Silurian of Herefordshire, England, preserves eggs and possible juveniles within its carapace, providing an unequivocal and unique view of parental brood care in the invertebrate fossil record. The female fossil is assigned to a new family and superfamily of myodocopids based on its soft-part anatomy. It demonstrates a remarkably conserved egg-brooding reproductive strategy within these ostracods over 425 Myr. The soft-tissue anatomy urges extreme caution in classifying 'straight-hinged' Palaeozoic ostracods based on the carapace alone and fundamentally questions the nature of the shell-based Palaeozoic ostracod record.

Ostracods (Crustacea) from thermal waters, southern Altiplano, Argentina

Research Article| January 01, 2006 Ostracods (Crustacea) from thermal waters, southern Altiplano, Argentina Cecilia Laprida; Cecilia Laprida 1Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina, Ciudad Universitaria, Pab. 2, 1° piso. 1428 Ciudad de Buenos Aires, Argentina, email: chechu@gl.fcen.uba.ar Search for other works by this author on: GSW Google Scholar Analia Díaz; Analia Díaz 2Cátedra Zoología Invertebrados I, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Argentina, email: ostracodiaz@fcnym.unlp.edu.ar Search for other works by this author on: GSW Google Scholar Norma Ratto Norma Ratto 3Museo Etnográfico, Facultad de Filosofía y Letras, Universidad de Buenos Aires. Buenos Aires, Argentina, email: nratto@ciudad.com Search for other works by this author on: GSW Google Scholar Micropaleontology (2006) 52 (2): 177–188. https://doi.org/10.2113/gsmicropal.52.2.177 Article history received: 12 Jul 2005 accepted: 13 Mar 2006 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Cecilia Laprida, Analia Díaz, Norma Ratto; Ostracods (Crustacea) from thermal waters, southern Altiplano, Argentina. Micropaleontology 2006;; 52 (2): 177–188. doi: https://doi.org/10.2113/gsmicropal.52.2.177 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyMicropaleontology Search Advanced Search Abstract The ostracod fauna from la Terma hot spring (26°55′31″ S −68° 08′45.7″W, 4026m above sea level), Southern Altiplano, Argentina, is described and the pool itself characterized. The occurrence of ostracods in this type of environments is registered for the first time in Argentina. Six species were found, two of which are new to the fauna of Argentina: Penthesilenula incae (Delachaux) and Hemicypris panningi (Brehm). Two species were found for the first time in the Altiplano: H. panningi (Brehm) and Cypridopsis fuhrmanni (Méhes). Some comments concerning how and when these species could spread to populate the Dry Altiplano are discussed briefly taking into account paleoclimatic data. This paper provides the first record of recent ostracods from the Southern Altiplano, Argentina. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Holocene paleohydrology of Little Salt Spring, Florida, based on ostracod assemblages and stable isotopes

Ostracod assemblages and the δ 18O and δ 13C records of Cytheridella ilosvayi provide a ∼12,000 yr paleohydrological reconstruction of Little Salt Spring, a sinkhole lake and underwater archaeological preserve in west central Florida. The ostracod record documents relative changes in water temperature and hydrologic characteristics of the lacustrine system that are the result of warming air temperatures, changes in the relative contributions of input waters (shallow vs. deep groundwater), rainfall patterns and relative sea level rise during the Holocene. The data indicate that LSS was initially supplied by relatively low amounts of direct rainfall and surface runoff as the spring's location was closer to the recharge area and far from the freshwater/saltwater interface. At about 11,000 yr BP, LSS became groundwater supported, initially by a shallow freshwater aquifer with low δ 18O composition until ∼5700 yr BP, and after that time by 18O-enriched and increasingly mineralized groundwater originating from a deeper, carbonate aquifer as the regional water table rose bringing the saltwater interface closer to the location of LSS which at this time was becoming a groundwater discharge area. The data also shows that the most abrupt and pronounced hydrologic changes occurred during the Late Holocene with an interval of low δ 18O values (∼− 2.86‰) between 2700 and 2000 yr BP, followed by a stepped increase in δ 18O composition with maximum values (∼− 1.46‰) between 1100 and 900 yr BP. Over these periods to the present time the ostracod assemblage is characterized by brackish species ( Cyprideis spp. and Limnocythere floridensis). It is inferred that the interval of decreased isotopic values indicates mixing with saline water during dry climatic conditions, while the interval of more enriched isotopic values suggest saltwater intrusion during a period of, presumably, a sea level highstand. Although some discrepancies exist between other records from the northern Caribbean region and the one from LSS with regards to the exact timing for the Late Holocene drying and subsequent increase in rainfall conditions, the differences between the records may be explained by greater continental influences on ocean–atmosphere interactions on the Florida peninsula, a highly complex groundwater mixing balance in LSS, and by a better constrained age-model in the other records.

The impact of 150 years of anthropogenic pollution on the shallow marine ostracode fauna, Osaka Bay, Japan

Coastal bays adjacent to metropolitan areas are commonly polluted heavily, and the direct and indirect results of pollution (e.g., heavy metal pollution, eutrophication, and hypoxia) seriously influence metazoan benthos. Historical metazoan trends, however, remain poorly documented and understood. Using the ostracode record of the past 150 years ( 210Pb and 137Cs age information), we show that anthropogenic impacts during industrialization seriously influenced the benthic metazoan ecosystem in a bay adjacent to a metropolis (Osaka Bay, Japan). Ostracode absolute abundance decreased by 90% from ca. A.D. 1910–1920 to ca. A.D. 1960–1970 as a result of Japan's rapid industrial development, coinciding with a rapid increase in concentration of various pollutants and the Osaka City population. The ostracode abundance has not recovered despite environmental legislation enforced after ca. A.D. 1960–1970.

First record of ostracods (Crustacea) in Baltic amber

Ostracods were found in two pieces of Baltic amber for the first time. The animals belong to the freshwater genus Cyclocypris. Since Baltic amber was formed during Eocene times in southern Scandinavia, the age of the specimens is estimated at 42–54 million years. As aquatic organisms, ostracods are seldom trapped in amber; it is considered that one specimen, already dead and dried, was either blown onto sticky resin on a plant stem, or washed there by a high flood level, while the other was probably splashed, alive, in a drop of water against the flowing resin, again probably during a flood. Associated faunal remains, including other crustaceans, suggest a coastal palaeoenvironment with some marine as well as freshwater influence.

A Late Quaternary lake record from the Qilian Mountains (NW China): lake level and salinity changes inferred from sediment properties and ostracod assemblages

Two sediment cores (length 13.94 and 12.93 m) have been drilled from the small alpine Lake Luanhaizi in the eastern central Qilian Mountains and correlated by means of magnetic susceptibility (MS). This paper focuses on the lithology and chronology of the longer core, on the results of loss on ignition (LOI), element concentration, thermomagnetic as well as magnetic hysteresis loop measurements, and on the ostracod record. The recovered sediments represent three types of depositional environment: a shallow intermittent lake, a deeper permanent lake and a true playa lake. Three stages of a higher lake level and permanence of the water body are reconstructed. The lowermost stage of a permanent lake and inferred favourable environmental conditions occurred probably about 45 14C ka BP. The second stage of a deeper permanent lake occurred either shortly before or, more likely, following the LGM. Most favourable environmental conditions and highest water levels were reconstructed for the uppermost stage comprising the Holocene. Considering the lake record, glaciers have not reached the lake site at 3200 m altitude during the LGM, providing further evidence against a large ice sheet on the Tibetan Plateau.

First record of ostracods as natural intermediate hosts of Anguillicola crassus, a pathogenic swimbladder parasite of eels Anguilla spp.

The ostracod Physocypria nipponica (Ostracoda: Candonidae) was found (prevalence 14.2%) to be the only intermediate host of the nematode Anguillicola crassus (Nematoda: Anguillicolidae), a pathogenic swimbladder parasite of eels, in a greenhouse-heated culture pond at Isshiki, Aichi Prefecture, Japan. Japanese eels Anguilla japonica from the same pond were found to be infected by adult A. crassus (prevalence 71.8%, intensity 1 to 6). This indicates that A. crassus could complete its life cycle under conditions of modern eel-culture technology where copepods were absent due to the unfavorable water quality for them, by utilizing ostracods as the intermediate host.

Deep‐sea ostracods as indicators of palaeoceanographic changes: a case history from the middle–late Miocene of southern Italy (Central Mediterranean)

ABSTRACT The middle–late Miocene palaeoceanography of the Central Mediterranean was investigated using bio‐chronostratigraphically constrained (estimated ages are based on plancktonic foraminifers) ostracod faunas from the Tremiti Islands and the Hyblean Plateau (southern Italy). Specifically, differences and similarities between the hydrographical evolution of the two study areas, inferred from the ostracod record, are herein used to provide new insights into the evolution of the Mediterranean deep‐water circulation. Ostracod assemblage compositions suggest a simultaneous progressive trend from deep thermospheric towards psychrospheric conditions in both the areas during the Langhian. However, this trend seems to have developed fully only in the Hyblean Plateau. Notably, the first sign of an oceanic deep water‐mass supply is shown by the almost synchronous entry of the upper psychrospheric genus Agrenocythere in the middle Langhian. The youngest reliable evidence of deep oceanic influences (common occurrence of Agrenocythere) in the Central Mediterranean comes from the Tremiti Islands and dates back to the earliest Serravallian. Similarities between the two study areas suggest large‐scale modifications in the Central Mediterranean deep basins. This hypothesis is discussed in the context of the global middle Miocene oceanographic scenario.

Ostracode turnover and sea-level changes associated with the Paleocene-Eocene thermal maximum

The ostracode response to oceanographic changes during the Paleocene-Eocene thermal maximum (PETM, ca. 55 Ma) is largely unknown. The Gebel Duwi section (Egypt) provides a detailed ostracode record across the PETM in a middle neritic setting. Quantitative analysis of this record reveals two significant results. (1) The PETM is marked by a sharp faunal turnover, as indicated by abundance changes, local extinctions, and immigrations. This turnover punctuated a gradual basin-wide faunal transition. (2) During the ∼60 k.y. period prior to the PETM, relative sea level fell rapidly by ∼15 m. This sea-level fall was followed by an ∼20 m sea-level rise during the PETM. A possible eustatic control on these fluctuations suggests the presence of a cryosphere and variations in its size during this time of global warmth.

Ostracods and palaeobotany from the middle Permian of Oman: implications on Pangaea reconstruction

Discovery of a middle Permian ostracod fauna in the marine Khuff Formation (Sultanate of Oman), combined with palaeobotanical data from the immediately underlying continental Gharif Formation, supports new interpretations of the palaeobiogeography of the Tethys during the late Palaeozoic. A mixed ostracod fauna existed on the Arabian platform. This new record of Permian ostracods, combined with recent data obtained in other Tethyan areas, emphasizes the close relationship between the south‐western Tethys realm and South China. The macro‐ and microfloral assemblages of the continental Gharif Formation demonstrate that this palaeoflora represents a true mixed association in which Gondwanan, Cathaysian and Euramerian elements are intermingled. Two main models exist for the reconstruction of Pangaea during the late Palaeozoic. Both ostracods and palaeobotanical evidence favour the reduction of the oceanic area between South China and Arabian plate as in the B Pangaea model favoured by recent palaeomagnetic data.

The ostracode record from Harris Lake, southwestern Saskatchewan: 9200 years of local environmental change

Holocene paleoenvironments of Harris Lake, southwestern Saskatchewan, are reconstructed from the ostracode stratigraphy of a 10.4 m sediment core. Twenty three taxa, representing nine genera, were identified and counted from 113 samples. At each depth, a theoretical faunal assemblage was derived from the raw counts. The mean and variance of chemical, climatic and physical variables were inferred from modern analogues of the fossil assemblages, using existing autecological data from 6720 sites, mostly in western Canada. These data suggest four paleoenvironments: an early-Holocene (9240–6400 years BP) variable climate supporting aspen parkland vegetation; the warm dry hypsithermal (6400–4500 years BP); a short transitional period of ameliorating climate and expanding subboreal forest (4500–3600 years BP); and the present environment since 3600 years BP. A change in regional climate with the draining of Glacial Lake Agassiz (ca. 8500 years BP) and landsliding in the watershed (ca. 4000 years BP) caused relatively rapid environmental change. The ostracode record generally corroborates the interpretations of other proxy data previously published for Harris Lake. Most of the discrepancy involves the timing and severity of maximum Holocene warmth and aridity. Peak aridity interpreted from the pollen data is earlier than in the other proxy records. Both the diatoms and ostracodes indicate highest paleosalinity between ca. 6500 and 5000 years BP, but maximum salinity in the diatom record occurs between ca. 6000–5700 years BP, whereas the ostracode-inferred salinity is relatively low at this time and peaks later at ca. 5000 years. Neither of these reconstructions suggests the short episodes of hypersalinity interpreted from the mineralogy.

Ostracode stratigraphy and paleoecology from surficial sediments of Lake Tanganyika, Africa

We report here on the first detailed ostracode stratigraphic record to be obtained from late Holocene sediments of Lake Tanganyika. We analyzed four cores, three from the northern lake region and a fourth from a more southern lake locality, that collectively record ostracode assemblages under a variety of disturbance regimes. These cores provide a stratigraphic record of ostracode abundance and diversity, as well as depositional changes over time periods of decades to millennia. We have investigated the fossil ostracodes in these cores by looking at temporal changes of species diversity and population structure for the species present. All four cores provided distinct patterns of ostracode diversity and abundance. BUR-1, a northern lake core obtained close to the Ruisizi River delta, yielded a sparse ostracode record. Karonge #3, another northern core from a site that is closely adjacent to a river delta with high sediment loading, yielded almost no ostracodes. The third core 86-DG-14, taken from a somewhat less disturbed area of the lake, suggests that there have been recent changes in ostracode populations. Through most of the lower portion of this core, ostracode abundance is low and species richness is relatively constant. Above 7 cm there is a marked increase in ostracode abundance and a corresponding decrease in species richness, probably signaling the onset of a major community disturbance, perhaps due to human activities. The southernmost core, 86-DG-32, is from a site that is well removed from influent rivers. Ostracode abundance varies erratically throughout the core, whereas species richness is relatively constant and high throughout the core. The temporal variation evident in ostracode community makeup both within and between the studied cores may be a result of naturally patchy distributions among ostracodes, coupled with local extinctions and recolonizations, or it may reflect inadequate sampling of these high diversity assemblages. In either case, these cores illustrate the potential to obtain high resolution ostracode records from the rich, endemic fauna of Lake Tanganyika that can be used to address questions about the history of community structure and human impacts in this lake.

The late Pleistocene ostracod record of the crater lake sediments from Lago di Albano (Central Italy): changes in trophic status, water level and climate

Four cores (ranging between ca. 9 and ca. 14 m in length) from Lago di Albano in Central Italy were studied for their ostracod content, as well as algal and bacterial pigments, CaCO3 and concentration of organic matter. Cores PALB 94 1E and PALB 94 1C from Site 1, located at the bottom of a steep slope at 70 m water depth, where oxygen concentration is below 6 mg l-1, spans the Holocene and the late Pleistocene until 28 kyr B.P. (calibrated age). The other cores, PALB 94 6A and PALB 94 6B taken at a depth of 30 m, where oxygen is 7--11 mg l-1, represent mainly Pleistocene deposits.