Distribution Of Ostracod Species Research Articles

Evidence for Conductivity- and Macroinvertebrate-Driven Segregation of Ostracod Assemblages in Endorheic Depression Wetlands in North West Province of South Africa

Our knowledge of the ecology of non-marine Ostracoda inhabiting endorheic wetlands (pans) of the semi-arid regions of South Africa is very scarce. The present study investigates the distribution of ostracod species in grass, open, and salt pans in the central part of the North West province and tests ostracod response to abiotic and biotic predictor variables operating at a local scale. Distance-based linear models revealed three variables (pan type, water electrical conductivity and abundance of macroinvertebrate predators, and collector-gatherers) that best explained variation in the ostracod dataset. Ostracod assemblages from the three studied pan types differed by the dominance structure rather than by the species composition. Salt pans with high conductivity and high ratio of predaceous macroinvertebrates were dominated by Heterocypris giesbrechti, with accessory presence of Plesiocypridopsis newtoni. In open pans with low conductivities and the lowest ratio of predators (but highest ratio of collector-gatherers) Potamocypris mastigophora was typically a dominant species, while in grass pans, all the three mentioned species had similar relative abundances. Although our findings lend provisional support to some models of ostracod assemblage diversity across different pan types, more studies replicating endorheic depression wetlands in other regions are required before generalizations can be made.

Spatio-temporal distribution of ostracod species in saline inland lakes (Mansfeld lake area; Central Germany).

Ostracods are a diverse group of microcrustaceans with a ubiquitous distribution in a wide array of aquatic habitats and are common constituents of lake sediments. Inferences on the temporal-spatial distribution of ostracod species is a prerequisite for reconstructions of palaeoenvironmental conditions. This requires a precise knowledge not only about ecological preferences and specific life histories, but also the understanding how (local) ecological parameters affect ostracod species assemblages (abundance and composition). Generally, these studies are rare and often characterized by an insufficient differentiation of living specimens from the total amount of valves of the modern population leading to uncertainties in species occurrences and diversity data. Modern ostracod populations were sampled from 12 water bodies within a relatively small study area (Mansfeld lake area, Central Germany). Physico-chemical parameters (temperature, oxygen content, conductivity, pH) were measured in situ and the uppermost 2 cm of sediment were collected in different seasons (April, June, September). Relative abundances of ostracods (living and dead), differentiated for adults and juveniles, were used for statistical analyses (Spearman‘s rank correlation, Canonical correspondence analysis, Cluster analyses, Fisher’s α), to investigate relationships between species distribution and environmental factors as well as to identify habitat similarities and ostracod species assemblages. In total, 27 ostracod species (20 living species) were identified. Majority of them are considered as very common (cosmopolitan) freshwater species. Only two species are usually known from brackish water (Cytheromorpha fuscata and Cyprideis torosa). This is the first confirmation of living C. torosa in German inland waters. The relative abundances of ostracods show strong fluctuations during the study period and differences in composition of the ostracod species assemblages between and within the water bodies. There are also strong differences between bio- and taphocoenoses. The measured physico-chemical parameters which are usually considered as most important drivers on ostracod species distribution do not contribute to explain the observed temporal-spatial distribution of the ostracod species. Differences in taphocoenoses show, that taphonomic processes can be very local and the sampling site, as well as the sampling time, is crucial. Biodiversity of ostracods is biased by sampling time, the variability of the ostracod assemblages between sampling month and the relationship between abundance of valves and living ostracods is not straightforward. Therefore, without precise knowledge of the ecological requirements of a species at a local scale, uncertainties may exist for the palaeoecological indication of a species.

Mapping the observed and modelled intracontinental distribution of non-marine ostracods from South America

Ecological niche modelling (ENM) has been used to quantify the potential occurrence of species, by identifying the main environmental factors that determine the presence of species across geographical space. We provide a large-scale survey of the distribution of ostracod species in South America, by using the domains of 25 river basins. From 221 known ostracod species, we estimate the potential distribution of 61 species, using ENM. Ten clusters of potential distribution patterns were found. Clusters 8 and 9 grouped most of the species, which presented high similarity of niche between them. Heterocypris paningi Brehm, 1934 (group 1) obtained higher niche variability. The minimum temperatures of the coldest month and the mean elevation of the river basin were most important to predict the potential distribution of ostracods of most groups. South America has a complex pattern of elevation, which affects species distributions indirectly through changes in local factors. For instance, the Andes mountains might impose a barrier for ostracod distribution in the southern part of South America because of the low temperatures and precipitation. The ENM indicated that some regions and/or basins of South America might be susceptible to the entry of several ostracod species, presently absent, including non-native species.

Distribution and Taxonomy of Shallow Marine Ostracods from the Western Coast of the Red Sea, Egypt

A total 5849 individuals of ostracods constituting twenty species were collected from five shallow marine sites along the area from El-Quseir to Marsa Alam on the West Coast of the Red Sea. The twenty ostracod species belonging to sixteen genera and ten different families. The three genera; Loxoconcha, Neonesidea and Xestoleberis have high species diversity. Furthermore, the species Loxoconcha ghardaqensis, Xestoleberis rotunda, Paranesidea fracticorallicola, Tanella gracilis and Neonesidea schulzi were the best recognized in the collecting region. Otherwise, the distribution of the collected ostracod species in relation to environmental variables and plants were discussed in detail here. Based on this, it is concluded that, vegetation type appears to be the most important factor controlling the distribution of ostracod species in the investigated area. Also, other factors such as, water temperature, salinity, dissolved oxygen, pH and electrical conductivity play an important role. Scanning electron microscope images of valves are delivered of the recorded taxa. These fauna displays close affinities to those of the Red Sea and the Indo- Pacific region.

The role of watercourse versus overland dispersal and niche effects on ostracod distribution in Mediterranean streams (eastern Iberian Peninsula)

The processes behind the heterogeneous distribution of species involve a combination of environmental and spatial effects. In the spatial context, stream networks constitute appropriate systems to compare the relative importance of two dispersal modes in aquatic organisms: overland and watercourse dispersal. In the present study, we analyzed the distribution of ostracod species in a river network in the eastern Iberian Peninsula, with variation partitioning between environmental and spatial factors, using Moran and Asymmetric Eigenvector Maps (MEMs, AEMs) as spatial variables. Our aims were to determine the relative importance of environmental and spatial control and to compare the importance of overland and watercourse dispersal for species distribution of passively-dispersing aquatic organisms. Our results suggest that watercourse was the most important dispersal mode, favoring mass-effects. The role of species sorting was significant and related to temperature, stream width and water quality, measured as a biotic index (IBMWP). These results stress the major importance of connectivity, besides niche-related factors, in structuring riverine communities of passively-dispersing aquatic organisms.

Living Ostracod Species From Permanent and Semi-Permanent Ponds of Bardenas Reales De Navarra (Northern Spain) With Remarks on Their Ecological Requirements

Abstract. Ostracod species living in 13 ponds (25 sample points) in Bardenas Reales de Navarra Natural Park and World Biosphere Reserve are studied for the first time. Nineteen species were identified, nine of them being the most abundant. According to statistical analyses (cluster and Correspondence Analysis), the distribution of ostracod species in this semi-arid area is mainly controlled by water conductivity and pH. The hydroperiod, sediment type, dissolved oxygen, altitude and vegetation cover play a secondary role. Thus, in semi-permanent waters with conductivity between 4.5 and 5.4 mS/cm and pH from 7.95 to 8.73 the most abundant species is Sarscypridopsis aculeata (Costa). In ponds with water conductivity from 0.3 to 2 mS/cm, pH between 7.1 and 7.78 and dissolved oxygen from 0.1 to 7.95 mg/l, Cypridopsis vidua (Muller) s the most abundant species. When the vegetation cover increases in this type of ponds, Limnocythere inopinata (Baird) and Potamocypris villosa (Jurine) appear as more abundant. Fin...

CCA Inferred Environmental Implications of Common Ostracods on the Qinghai‐Tibetan Plateau

Abstract103 surface sediment samples in 71 water bodies, such as lakes with different salinity, swamps, shallow puddles and rivers on the Qinghai‐Tibetan Plateau (QTP), were collected to study the ecological distribution of living ostracods and their environmental implications. Total of 12 genus and 45 species living ostracods are identified. According to the frequencies and abundance of ostracods occurrence, Limnocythere dubiosa, Limnocytherellina kunlunensis, Ilyocypris bradyi, Condona candida, Eucypris rischtanica and Leucocythere dilatata are the common species on the QTP, with occurrence frequency of more than 8 and abundance of more than 570 in the 71 water bodies. Among them, L. dubiosa, occurring in 28 water bodies with 2177 shells, is the most widely distributed ostracod in this research. Canonical Correspondence Analysis (CCA) indicates high correlation between species and environmental variables, suggesting that the occurrence of species is strongly related to the changes in ecological conditions of habitats. Among eight environmental factors, salinity and pH value are the most affective variables that influence the species occurrence. L. kunlunensis is positively correlated with salinity while E. rischtanica is negatively correlated with salinity. C. candida has a positive correlation with salinity, as does I. bradyi although there is not such a strong correlation. L. dubiosa displays a positive correlation with pH value. Consequently, we discuss the environmental implications of the common living ostracods on the QTP based on the CCA as well as the distribution of ostracod species in different salinity and pH values water. L. dubiosa, L. kunlunensis and E. rischtanica are euryhaline species, among which, L. dubiosa is the most adaptable species on the QTP with large occurrence in sundry salinity water and the most widely adaptive range for pH values. L. kunlunensis prefers to saline water while E. rischtanica prefers to fresh water. Both L. kunlunensis and E. rischtanica can live in water from faintly acid to alkaline, in contrast, L. dubiosa only appears in neutral and alkaline water bodies. I. bradyi only occurs in fresh water and oligohaline water with a large pH tolerance range tolerance range from weakly acidic water to alkaline water weakly acidic water to alkaline water. C. Candida lives in freshwater, with pH value above eight. The six common species reach maximum abundance in alkaline water (pH 8–10) except for Ilyocypris bradyi.

On some Recent non-marine ostracods from northern China, with description of one new species

Preliminary investigations of urban waters in Beijing City and small water-bodies in Inner Mongolia yielded a total of 12 living ostracod species. Five species are new records for China:Candona quasiakainaKaranovic & Lee, 2012,Fabaeformiscandona myllainaSmith & Kamiya, 2007,Heterocypris auricularissp. nov. (previously known asHeterocypris sanukiensisOkubo, 2004 nomen nudum),Ilyocypris mongolicaMartens, 1991 andPlesiocypridopsis newtoni(Brady & Robertson, 1870).Bradleycypris vittata(Sars, 1903),Ilyocypris angulataSars, 1903,Limnocythere stationisVávra, 1891 andPhysocypria kraepeliniG. W. Müller, 1903 are the first records for Palaearctic China.Cypridopsis vidua(O. F. Müller, 1776),Heterocypris incongruens(Ramdohr, 1808) andLimnocythere inopinata(Baird, 1843) are also reported in this paper, although they had already been found in China before. Of the above species,B. vittata,I. angulataandI. mongolicaare re-described. The present study expands our knowledge on the taxonomy and geographical distribution of ostracod species.

Les ostracodes et foraminifères associés des dépôts de l’Éocène moyen et supérieur de la coupe de Jebel Serj (Tunisie centrale). Intérêt biostratigraphique, paléoécologique et paléobiogéographique

The ostracod fauna collected from the Cherahil formation that crops out at the Jebel Serj section (central Tunisia) contains 24 species belonging to 12 genera. These ostracods are associated with 9 genera of benthic Foraminifera (including 4 Nummulites species) and 7 genera of planktonic Foraminifera. The biostratigraphic study of ostracod assemblages results to the recognition of 6 biozones which are correlated with Lutetian-Priabonian. The Shannon Weaver, Margalef and equitability indices point to internal platform netritic conditions, with minor fluctuations in depth and oxygenation. The palaeobiogeographic distribution of ostracod species found in the study area of Central of Tunisia establishes a good connexion with the basins developed in Northern Africa (Tunisia, Algeria, Libya and Mauritania) and the Middle East (Egypt and Jordan).

The Impact of Environmental Factors on Diversity of Ostracoda in Freshwater Habitats of Subarctic and Temperate Europe

In this study, we compared the ostracod species diversity in selected inland-water habitats of Lapland and Poland, and assessed the relationships between ostracod occurrence and abiotic environmental variables. In total, 41 species were collected, of which only 15 species were found in Lapland, as compared with 35 in Poland. Almost all species collected from the Lapland sites were eurybiontic and no clear differences were found between ostracod assemblages inhabiting different habitat types. We hypothesize that this homogeneity might be a consequence of the raised water level during the springtime snow melt, temporarily connecting various waterbodies. The main factors limiting distribution of ostracod species in Lapland appeared to be low pH and low ionic content of water. In Poland,predominantly stenobiontic species were observed. In temporary waters and peat-bogs of this area useful indicator species were identified.

Middle and Upper Jurassic Ostracods from Western Kachchh, Gujarat, India: Biostratigraphy and paleobiogeography

This paper presents a study of the Middle and Upper Jurassic Ostracods from Western Kachchh, India. The first part discusses the biochronological importance of the Ostracod assemblages, while the second part reports the paleobiogeographical results.Benthic foraminiferal biozones are used to calibrate the biostratigraphical distribution of ostracod species and genera from sections in the Aalenian–Tithonian interval located in Western Kachchh (or Kutch) (Mundham Anticline, Jumara Dome, Jhurio Dome and Habo Dome) and on Pachchham Island (Khavda Nala), Gujarat, India. A total of 71 species are listed, including 32 previously published species and 38 species in open nomenclature, belonging to 23 genera. The ostracod assemblages indicate that faunal communication was first established during the Bathonian and Callovian (Middle Jurassic) and continued until the early Cretaceous. These faunal exchanges occurred between Laurasia (USA, Europe, Russia and Siberia) and the Indo-East African Province, extending along the Western Tethyan carbonate shelves (bordering West and East Gondwana) through to the Pacific Ocean margin of West Gondwana.

Distribution of Recent ostracods in inland waters of Sicily (Southern Italy)

From 2003 to 2005, freshwater ostracods were sampled in 67 water bodies of mainland Sicily (Provinces of Agrigento, Caltanisetta, Catania, Enna, Palermo, Messina, Ragusa, Siracusa and Trapani) located from sea level up to 1300 m a.s.l. This survey took into account streams, springs, wells, but especially temporary and ephemeral habitats (e.g., flooded meadows, temporary ponds). The aim of this research was to give the first comprehensive picture of the regional ostracod fauna and establish relationships between the distribution of ostracod species and some habitat features. Altogether, 21 ostracod taxa belonging to five families (Candonidae, Ilyocyprididae, Cyprididae, Notodromadidae, and Limnocytheridae) were identified. A maximum of four species was found in a single sample. The most frequent species was Heterocypris incongruens, followed by Eucypris virens. The following ten taxa have been found only once: Candona lindneri, Ilyocypris decipiens, Notodromas persica, Trajancypris clavata, Herpetocypris brevicaudata, Heterocypris salina, Cypridopsis cf. elongata, Cypridopsis vidua, Potamocypris cf. villosa, and Limnocythere inopinata. The faunal assemblage of Sicily is compared with the known ostracod distribution in some Mediterranean areas.

The Ostracoda community in hypersaline channels in Al-Khiran, Arabian Gulf

Abstract. A community of ten ostracod species characterizes the hypersaline channels of Khor Al-Mufateh and Khor Al-Mamlaha. The dominant species in Khor Al-Mufateh are Loxoconcha (Loxoconcha) indica Jain, 1978; Gibboborchella venosa Gumey, 1979; Gibboborchella alata Gurney, 1979; and Hemicytheridea paiki Jain, 1978. L.(L.) indica, along with Neomonoceratina sp., dominate Khor Al-Mamlaha. Other species ranging from common to rare, include Carinocythereis (Carinocythereis) batei Jain, 1978; Callistocythere cf. flavidofusca intricatoides (Ruggieri), 1953; Loxoconcha (Loxoconcha) multiornata Bate & Gurney, 1981; Tanella cf. gracilis Kingma, 1948; and Xestoleberis rotunda Hartmann, 1964.Khor Al-Mufateh and Al-Mamlaha are divided into zones according to the distribution of ostracod species, which are dependant upon the richness and distribution of algae and the type of sediment. The ten ostracod species are salinity-tolerant and occur in the upper third of Khor Al-Mufateh and the lower half of Khor Al-Mamlaha with salinity ranging between 55–70‰ and 45–70‰, respectively. These zones are rich in algal growth with sediments varying from muddy carbonate sands to sandy mud. Most ostracod species are found in abundance during the summer exhibiting a rich diversity of algae genera and species.