Ostracod Diversity Research Articles

Microfossil assemblages and geochemistry for interpreting the incidence of the Jenkyns Event (early Toarcian) in the south-eastern Iberian Palaeomargin (External Subbetic, SE Spain)

Abstract. By studying the facies, geochemistry, and microfossil assemblages of the uppermost Pliensbachian and lower Toarcian of the Cueva del Agua section, I was able to appraise the impact of the Jenkyns Event in the eastern part of the South Iberian Palaeomargin (Western Tethys). Depleted oxygen conditions are envisaged for the Polymorphum–Serpentinum Zone boundary (lower Toarcian), represented by dark marls, precisely in a laminated interval. The decrease in the α diversity of foraminifera and ostracods, along with greater proportions of opportunists such as Lenticulina, Eoguttulina, and Cytherella just before the negative carbon isotopic excursion (CIE), would indicate a disturbance of the environmental conditions during the initial phase of the biotic crisis. The peak of the biotic crisis is characterized by an absence of trace fossils, increased organic matter content, an increased Mo∕Al ratio, and negative CIE and δ18O, as well as fewer specialist forms and more opportunists. This biotic crisis peak is related to oxygen-depleted conditions in the bottom waters and in the sediment pore water, while warming negatively affected microfauna – to the point of leaving a barren benthic horizon in the record. Recovery is evidenced by the occurrence of carbonate layers with hummocky cross-stratification and a decrease in organic matter content, the Mo∕Al ratio, and the trace fossil record. In terms of microfauna, the first phase of recovery shows highly abundant foraminifera, ostracods, and microgastropods, mainly opportunist forms. After the proliferation of opportunist forms, a second phase of recovery is marked by a progressive increase in α diversity.

Ostracods from the end‐Permian mass extinction in the Aras Valley section (north‐west Iran)

AbstractThe Aras Valley section (north‐west Iran) exposes a sedimentary succession that allows the study of ostracod diversity patterns during/across the end‐Permian mass extinction. For the present study, 59 samples were investigated for their ostracod abundances, which ranged from 4 to 31 500 specimens per 500 g. In 45 sample horizons, the ostracods were identified to the species level. In total, 3 425 specimens were determined and 62 species were identified, of which one genus and ten species are described for the first time: Fabalicypris veronicae Gliwa, sp. nov., Orthobairdia capuliformis Gliwa, sp. nov., Araxobairdia formosa Gliwa, gen. et sp. nov., Bairdiacypris kathleenae Gliwa, sp. nov., Eumiraculum mettei Gliwa, sp. nov., Liuzhinia julfensis Gliwa, sp. nov., Carinaknightina hofmanni Gliwa, sp. nov., Cavellina fosteri Gliwa, sp. nov., Cavellina hairapetiani Gliwa, sp. nov. and Hungaroleberis striatus Forel, sp. nov. The assemblages show, at the end‐Permian mass extinction event, a complete turnover from a low‐diversity Fabalicypris‐dominated pre‐extinction community to a more diverse Bairdiacypris‐dominated post‐extinction community. The turnover coincides with the significant temperature increase that was previously recorded from north‐west Iranian sections. The low diversity in the horizon immediately below the extinction horizon indicates that environmental changes, such as thermal stress, may have had an impact on the ostracod assemblages prior to the extinction event. In comparison with other diverse ostracod assemblages from the Palaeotethyan realm, the ostracods of the Aras Valley section are not associated with microbialites.

Habitat factors differentiating the occurrence of Ostracoda (Crustacea) in the floodplain of a small lowland River Krąpiel (N-W Poland)

We analysed the occurrence of ostracods in a small river, taking into account all the types of water bodies in the floodplain − these included helocrenes, oxbow lakes, and ponds, as well as the main river channel. The objective of the study was to investigate the variation in ostracod communities and identify those factors determining species distribution. The environmental factors considered were the type of water body, responsible for 17% of the variance, the physical and chemical water properties (29%), and the biotic and abiotic factors associated with the substrate type (23%). Among the factors associated with the substrate, sediment sorting, plant coverage and insolation were the most important. The ostracod fauna of the helocrenes differed from that of the other water bodies in the floodplain. In the water bodies of the Krąpiel valley and in the main river channel, 33 ostracod species were recorded, of which 26 were found in the main river channel. Refugia in the floodplain were the main source of the diversity and abundance of ostracods in the main river channel. The mean density in the main river channel was very low, at 330 indiv. m−2, while in the water bodies of the floodplain it was the greatest, reaching up to 5568 indiv. m−2.

An updated checklist of Recent ostracods (Crustacea: Ostracoda) from inland waters of Sicily and adjacent small islands with notes on their distribution and ecology

Because of its position in the middle of the Mediterranea Sea and a complex geological history that has promoted repeated waves of biological colonization, Sicily (Southern Italy) is of particular interest from a biogeographical perspective. A number of previous investigations, dating back as far as the end of the 19th century, have contributed to gather information about the occurrence of Recent non-marine ostracods in Sicily, making this region one of the most intensively studied areas of the Central Mediterranean. Published data on ostracod distributions have been integrated through an extensive field survey on mainland Sicily and surrounding small islands and archipelagos. Altogether, 271 ostracod samples and 11 sediment samples from dry water bodies were analysed from 218 sites visited between 2002 and 2017. Sampling sites were selected to encompass all the most common types of freshwater aquatic habitats, both natural and artificial, present in the area. Thirty-nine ostracods were identified at species level and 12 at supraspecific level. The present study reports four species (Cypria subsalsa, Eucypris mareotica, Physocypria kerkyrensis, Vestalenula boteai) and one genus (Vestalenula) as new for both peninsular Italy and adjacent islands, and three species (Candonopsis novaezelandiae, Ilyocypris inermis, Neglecandona neglecta) and two genera (Candonopsis and Physocypria) as new for Sicily. The updated checklist of the study area now includes at least 46 nominal species and other taxa identified at supraspecific level, belonging to 28 genera in 8 families (Candonidae, Cyprididae, Cytherideidae, Darwinulidae, Hemicytheridae, Ilyocyprididae, Limnocytheridae and Notodromadidae). The present investigation represents a significant addition to the knowledge of the ostracod diversity and distribution in the Sicilian area and in Italy as a whole. It also provides a sound baseline data for further comparative faunal studies aimed at investigating the affinities and origins of the central Mediterranean inland-water ostracod faunas, and to analyse their biogeographic patterns.

The filter-feeders signal: response of ostracods to marine environmental changes in the Devonian F–F event

The percentage of filter-feeder species in benthic ostracod assemblages shows evident changes during the Late Devonian Frasnian–Famennian (F–F) transition with two sharp rises in the event stratal interval based on materials collected from the Yangdi section, South China. Neither anoxia nor oligotrophy, eustasy should have been the only primary cause of filter-feeders signal in the F–F event. The sea level fall and rise would create deteriorative environmental conditions such as lower oxygenation and less nutrients, which altogether reduced the diversity and abundance of the benthic ostracods in the F–F transition. The percentage of filter-feeders showed a decrease during the regression, and vice-versa. Therefore, the filter-feeders may be potentially an indicator of sea level changes in the F–F event.

Comparative analyses of non-marine ostracods (Crustacea) among water basins in Turkey

Total of 26, 22 and 32 sites in Konya, Antalya and West Mediterranean basins in Turkey, respectively, were sampled twice during 2017 to compare the non-marine ostracod diversity. A total of 1787 individuals belonging to 31 species were recorded from all basins. Of which, nine species are common among basins when Fabaeformiscandona fragilis is new for Turkey. High species diversity was found at middle elevational intervals. The highest and lowest Shannon diversity index values were recorded for both Konya (H = 2.19) and Antalya (H = 1.90) basins, respectively. The highest beta diversities values are encountered between closed the Konya and other open basins. Species and environmental variables composition among basins and elevational intervals showed significant differences (p < 0.05, ANOSIM). Of species, cosmopolitans (e.g., Candona neglecta, Ilyocypris bradyi, Psychrodromus olivaceus) provide an important contribution to the differences in diversities among basins and elevational intervals. According to Canonical Correspondence Analysis, elevation appeared to be the common influential variables in all basins. Results suggest that alpha diversity is under the control of local and regional factors when beta diversity is primarily affected by regional factor. Although cosmopolitan species are positive indicators, they seem to make a significant contribution to alpha and beta diversities of ostracods.

Response of Ostracods (Crustacea) to the Devonian F—F event: Evidence from the Yangdi and Nandong sections in Guangxi, South China

Abstract This study focuses on the Late Devonian ostracods and their responses to the F—F (Frasnian-Famennian) event based on abundant materials collected from the Yangdi and Nandong sections in South China. More than half (53%) of the benthic ostracod species disappeared at the F—F boundary in the Yangdi section of slope facies, whereas most benthic ostracod species survived the F—F crisis in the Nandong section of basinal facies, with the extinction of some pelagic entomozooidea. In view of a higher extinction rate (more than 65%) of ostracod species in the shallow-water Xikuangshan section, we deduce that ostracods in varied environments responded to the F—F event differently. Namely, from the carbonate platform, slope, to basinal settings, the extinction rate of benthic ostracods at the F—F transition decreased with increasing water depth. Nevertheless, the F—F event caused substantial loss among pelagic entomozooidea lineages. The extinction pattern of benthic and pelagic ostracods in F—F event in South China is similar to the situation in Europe. But the extinction rates of benthic ostracods in shallow water and slope in Europe seems to be higher than that in the same situation in South China. The abundance and diversity of ostracods decreased and some species even disappeared in anoxic environments across the F—F boundary in South China, when there were rapid changes in the palaeotemperature of surface sea water.

ASSESSMENTS OF ENVIRONMENTAL VARIABLES AFFECTING THE SPATIOTEMPORAL DISTRIBUTION AND HABITAT PREFERENCES OF LIVING OSTRACODA (CRUSTACEA) SPECIES IN THE ENEZ LAGOON COMPLEX (ENEZ-EVROS DELTA, TURKEY)

The present study analyzed the spatiotemporal changes of Ostracoda fauna in eight coastal lagoons in the Enez-Evros delta (Tuzla Lake 1, Tuzla Lake 2, Tuzla Lake 3, Taz, Işık, Dalyan, Kuvalak, and Taşaltı), located along the northern Aegean Sea coastline of Turkey. Recent ostracod samples collected from the eight lagoons were analyzed, and 16 living ostracod species (belonging to 14 genera) were identified during the sampling periods. The most abundant species were found to be Cyprideis torosa and Loxoconcha elliptica. C. torosa, a cosmopolitan and opportunistic species of Ostracoda, was found in all the studied coastal lagoons. All ostracod species determined in the lagoons were grouped into three assemblages: Group 1: halophilic continental freshwater species (F. fabaeformis, C. vidua, D. stevensoni, E. virens, H. salina, I. biplicata, I. bradyi, L. inopinata, and S. aculeata); Group 2: euryhaline and typical brackish water species (C. torosa and L. elliptica); Group 3: marine (coastal: A. convexa, L. rhomboidea, C. elongata, and X. communis) and brackish (lagoonal: L. lacertosa) water species. These species of Ostracoda were shown to be affected by environmental conditions. Analyses with the physicochemical variables and species (Spearman’s rank correlation coefficient and Canonical Correspondence Analysis) confirmed that ostracod distribution in the Enez lagoons are controlled by seawater–freshwater inputs and by salinity. The purpose of this work is about to present data about of the Enez lagoons, and analyze the diversity of ostracods of them.

Radiation, diversity and environmental expansion of Early Ordovician ostracods: a view from the Southern Hemisphere

Radiation, diversity and environmental expansion of Early Ordovician ostracods: a view from the Southern Hemisphere

Composition and distribution patterns of marine planktonic ostracods (Crustacea, Ostracoda) in the Adriatic Sea - a historical perspective

This study provides the first comprehensive results on species composition, seasonal and horizontal distribution of the planktonic ostracod community in the open waters of the whole Adriatic Sea. Samples were collected during the “Andrija Mohorovičić” oceanographic expedition (1974-1976) in all four seasons at 35 stations located along eight latitudinal transects in the northern, central and southern part of the Adriatic Sea. Fifteen ostracod species and two subspecies belonging to the family Halocyprididae were identified. The dominant species were Archiconchoecia striata, Porroecia spinirostris and Proceroecia macroprocera. Additionally, Paraconchoecia oblonga was recorded for the first time in the Adriatic Sea. The highest abundance and diversity of planktonic ostracods were found in the deep South Adriatic. Conversely, ostracods were scarce in the shallow North Adriatic area. As the transitional zone between these two regions, the Central Adriatic was characterized by high ostracod diversity, but a short period of dominance in the zooplankton assemblage. The horizontal distribution of planktonic ostracods in the Adriatic Sea could be linked to periodical ingressions of Eastern Mediterranean water masses and gyre currents, especially in the Central and the South Adriatic.

Diversity of marine planktonic ostracods in South China Sea: a DNA taxonomy approach

Ostracods (Crustacea, Ostracoda) are small bivalved crustaceans, contributing over 200 described species to the marine zooplankton community. They are widely distributed and are relatively abundant components of the mesozooplankton, playing an important role in the transport of organic matter to deep layers. However, identification of ostracods based on micro-morphological characters is extremely difficult and time-consuming. Previous fragmentary taxonomic studies of ostracods in the South China Sea (SCA), were based solely on morphology. Here, by analysing the mitochondrial COI gene, we explore the taxa across the SCA using molecular tools for the first time. Our results show that sequence divergence among species varies within a large range, from 12.93% to 35.82%. Sixteen of the taxonomic units recovered by DNA taxonomy agree well with morphology, but Paraconchoecia oblonga, Conchoecia magna and Halocypris brevirostris split into two clades each, each of which contains cryptic species.

Diversity and paleoenvironmental significance of Middle Triassic ostracods (Crustacea) from northern Thailand: Pha Kan Formation (Anisian, Lampang Group)

The Pha Kan Formation that crops out at the Phra That Muang Kham section, south of Lampang city, was measured and sampled for ostracod analysis. We here report the occurrence of 29 species distributed among 14 genera. Four new species are described: Triassocypris phakanella Forel nov. sp., Leviella lampangensis Forel nov. sp., Bektasia yawella Forel nov. sp. and Hungarella poli Chitnarin nov. sp. The present data represent the first detailed report of Middle Triassic (Anisian) ostracods from the Sukhothai terrane and the first insight into diversity dynamics following the end-Permian extinction in this area. The ostracod assemblages of the Phra That Muang Kham section are discussed and document an important shift from siliciclastic to carbonate conditions, from a protected to an open marine environment, followed by a slight regressive trend up-section associated with repeated salinity fluctuations. This fauna illustrates the post-crisis recovery during the Middle Triassic and some hypothesis are issued on the distribution pathways of several taxa.

Periphytic community structure of Ostracoda (Crustacea) in the river-floodplain system of the Upper Paraná River

Abstract Aim: We assessed the effect of environmental factors on the structure of periphytic ostracods communities along the river-floodplain system of the Upper Paraná River. We predict that the higher distance from Porto Primavera dam downstream would lead to higher diversity and density of the ostracods. Methods Periphytic ostracods (associated with root systems of the floating Eichhornia spp) were sampled during November 2013 to May 2015. Three samples were collected at each sampling site (channel of the Paraná River, tributaries and lakes). Eichhornia plants were removed from the water by hand and the plants were placed in a plastic bucket. Roots were washed for the removal of ostracods, and samples were filtered through a hand net with 160 µm mesh size. Results The faunistic survey recorded 44 ostracods species and richness estimators indicated that sampling effort appears to be suitable to reveal the diversity of ostracods in this studied area. The highest richness and density were observed in the stretch downstream of the dam in the main channel of Paraná River and in the lakes. Beta diversity was not significantly different along the longitudinal gradient downstream and higher similarity of ostracods species composition was observed in the lakes located in the stretch downstream of the dam. Conclusions An increase in the richness and density of ostracods were recorded in the sections downstream of the Paraná River, evidencing the importance of undammed tributaries on the ostracods community. The similarity of beta diversity amongst sampling sites may be owing to permanent hydrological connectivity amongst these environments, favouring the exchange of organisms mainly through the drift of free-floating macrophytes, and owing to the passive dispersal of drought resistant eggs of ostracods. Local abiotic factors had significant effects on abundance and distribution of some ostracod species.

Species diversity of ostracods (Crustacea: Ostracoda) from rice fields in Northeast Thailand, with the description of a new Tanycypris species.

The species diversity of ostracods in rice fields from Northeast Thailand was studied. Fifty-two samples were collected from 43 rice fields during 2010-2016. This investigation revealed 23 genera and 52 species, including one new to science (Tanycypris eugenkempfi n. sp.) and 21 endemic species: endemic to the Oriental region (14 species), Southeast Asia (two species) and Thailand (five species). In addition, two species that were restricted to rice fields in this study were recognized: Bradleytriebella tuberculata (Hartmann, 1964) and Notodromas sinensis Neale & Zhao, 1991. The most diverse genus was Pseudostrandesia, followed by Strandesia with eight and five species, respectively. The most widely distributed species were Pseudocypretta maculata Klie, 1932 and Strandesia kraepelini (G.W. Müller, 1906) occurring in 48.8 % of the total of surveyed rice fields. The number of species in individual rice fields ranged from none to 18. Most of the samples contained three species, but one rice field showed very high species richness (18 species). Most of the species recorded in this study were also found in several types of water bodies and reported from several zoogeographical regions. The main distinguishing characters between Tanycypris eugenkempfi n. sp. and other Tanycypris species are the more tumid carapace in dorsal view, the distinctly arched dorsal margin of the carapace in lateral view, the presence of a subapical dorsal seta on the first segment of the first antenna, the smooth large bristles on the third endite of the maxillula, the absence of c-seta on the first thoracopod, and the long proximal claw (Gp) of the caudal ramus.

Biodiversity of ostracod communities (Crustacea, Ostracoda) in a tropical floodplain

Neotropical floodplains harbour both floating and rooted plants and are associated with rich ostracod communities. After dry seasons, flooding causes recruitment in 2 ways: floods bring in allochthonous macrophytes with associated pleuston communities, and these rising water levels rehydrate plants and attached (ostracod) eggs that dried at the onset of the dry season. We analysed the ostracods communities in the Araguaia River floodplain (Brazil) during 2 hydrological periods (dry and rainy) and evaluated the species distribution in relation to abiotic and biotic factors. We compared the ostracod fauna of 6 lakes in the dry and rainy period and 17 lakes in the rainy period. We tested the hypothesis that the highest values of ostracod community attributes (richness, density, and evenness) occur in the rainy season owing to the influx of allochthonous individuals and the rehydration of the dried autochthonous macrophytes. We indeed observed the highest richness and diversity of ostracods in the rainy season; the homogenizing effect of the flood pulse at the onset of the rainy season caused a more homogeneous fauna (lower beta diversity) during that hydrological period. The distribution of species showed a significant effect of both abiotic factors (local) and hydrological period (regional).

Distribution, diversity and some ecological characteristics of ostracods (Crustacea: Ostracoda) in Gökçeada (Imbros) Island (Northern Aegean Sea, Turkey)

AbstractThe aim of this study was to determine the environmental factors affecting distribution and diversity of ostracods (Crustacea: Ostracoda) in the inland waters of the northern Aegean Sea island of Gökçeada (Imbros), Turkey. Over a period of one year, sampling of ostracods was performed in order to estimate the composition, richness, and diversity of the ostracod assemblages from the Gökçeada Island. A total of 18 ostracod species were identified from 28 sampling sites during the course of the study. In both winter and summer seasons,

Morphological and molecular diversity of Lake Baikal candonid ostracods, with description of a new genus.

Uncoupling between molecular and morphological evolution is common in many animal and plant lineages. This is especially frequent among groups living in ancient deep lakes, because these ecosystems promote rapid morphological diversification, and has already been demonstrated for Tanganyika cychlid fishes and Baikal amphipods. Ostracods are also very diverse in these ecosystems, with 107 candonid species described so far from Baikal, majority of them in the genera Candona Baird, 1845 and Pseudocandona Kaufmann, 1900. Here we study their morphological and molecular diversity based on four genes (two nuclear and two mitochondrial), 10 species from the lake, and 28 other species from around the world. The results of our phylogenetic analysis based on a concatenated data set, along with sequence diversity, support only two genetic lineages in the lake and indicate that a majority of the Baikal Candona and Pseudocandona species should be excluded from these genera. We describe a new genus, Mazepovacandona gen. n., to include five Baikal species, all redescribed here. We also amend the diagnosis for the endemic genus Baicalocandona Mazepova, 1972 and redescribe two species. Our study confirms an exceptional morphological diversity of Lake Baikal candonids and shows that both Baikal lineages are closely related to Candona, but only distantly to Pseudocandona.

Pannonian ostracods from the southwestern Transylvanian basin

Pannonian (Late Miocene) ostracods were investigated from 7 outcrops, exposing deep-water lacustrine sediments along the western margin of the Transylvanian Basin. Sedimentological patterns in the outcrops indicate deposition in sublittoral to profundal environments where fine-grained, suspension fall-out sediments are intercalated with various types of mass transport deposits, most commonly turbidites. The ostracod fauna, consisting of 30 taxa, is dominated by endemic species of the brackish Lake Pannon. The assemblages indicate a mixture of deep-water (sublittoral to profundal) species, such as Paratethyan Candoninae, and shallow-water (littoral) species, belonging to Cyprideis, Loxoconcha, Amnicythere and Hemicytheria. The mixed character of the assemblages is most probably a consequence of the reworking of littoral specimens into deeper environments, a phenomenon also observed in the molluscan fauna from some of the investigated outcrops. Alternatively, some endemic and extinct species of the littoral genera might have adapted to the deep-water environment. A significant decrease in the abundance and diversity of ostracods from west to east is interpreted reflecting increasingly distal environments. The ostracod fauna indicates the Hemicytheria hungarica (2 outcrops), Hemicytheria tenuistriata (3 outcrops), and Propontoniella candeo Zones (2 outcrops) of the lower Pannonian Slavonian Substage.

Freshwater ostracods (Crustacea) and environmental variability of polygon ponds in the tundra of the Indigirka Lowland, north-east Siberia

Freshwater ostracods (Crustacea, Ostracoda) are valuable biological indicators. In Arctic environments, their habitat conditions are barely known and the abundance and diversity of ostracods is documented only in scattered records with incomplete ecological characterization. To determine the taxonomic range of ostracod assemblages and their habitat conditions in polygon ponds in the Indigirka Lowland, north-east Siberia, we collected more than 100 living ostracod individuals per site with a plankton net (mesh size 65 µm) and an exhaustor system from 27 water bodies and studied them in the context of substrate and hydrochemical data. During the summer of 2011, a single pond site and its ostracod population was selected for special study. This first record of the ostracod fauna in the Indigirka Lowland comprises eight species and three additional taxa. Fabaeformiscandona krochini and F. groenlandica were documented for the first time in continental Siberia. Repeated sampling of a low-centre polygon pond yielded insights into the population dynamics of F. pedata . We identified air temperature and precipitation as the main external drivers of water temperatures, water levels, ion concentrations and water stable isotope composition on diurnal and seasonal scales. Keywords: Arctic limnology; permafrost; patterned ground; ecological indication; freshwater ostracods. (Published: 1 March 2016) To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools). Citation: Polar Research 2016, 35 , 25225, http://dx.doi.org/10.3402/polar.v35.25225

Diversity of ostracod communities (Crustacea, Ostracoda) across hierarchical spatial levels in a tropical floodplain

Assessing and evaluating the mechanism and patterns of species distribution across multiple hierarchical spatial levels, such as in floodplains, are important for understanding the factors that influence the structure of communities. The species composition may vary at these spatial levels or between the spatial levels along the hierarchical scale. Thus, using the additive partitioning in species richness, Shannon index, and Simpson coefficient, we tested the hypothesis that the alpha and beta components of ostracod diversity are unevenly distributed along the hierarchical spatial levels in the Upper Parana River floodplain (Brazil). The results obtained by PCoA and diversity partitioning allowed us to conclude that dispersal is efficient, and that at higher spatial levels (floodplain, systems, and environments), the establishment of a new population of ostracods depends on both abiotic and biotic factors. However, at lower levels, spatial factors such as plants architecture and other biotic factors, e.g., competition, may have greater influence on community structure.