Ilyocypris Bradyi Research Articles

A PRELIMINARY STUDY ON OSTRACODA (CRUSTACEA) FAUNA OF THE ISTRANCA STREAMS-TURKEY

To determine the Ostracoda fauna of the Istranca region, this preliminary study was performed and seven stream, Kuzuludere, Buyukdere (Cilinkozdere), Sultanbahcedere, Papucdere, Elmali, Kisla and Efendi stream, located in Istranca region, were investigated. In this way, ten spe-cies; Ilyocypris bradyi Sars, 1890; Pseudocandona albicans (Brady, 1864); Candona sp; Candonopsis kingsleii (Brady & Robertson, 1870); Physocypria kraepelini G. W. Muller, 1903; Heterocypris salina (Brady, 1868); Psychrodromus fontinalis (Wolf, 1920); Cypridopsis vidua (O.F. Muller, 1776); Potamocypris variegata (Brady & Nonman, 1889); Limnocythere inopinata (Baird, 1843) were identified. The highest species number was found in Sultanbahce stream. Also Pseudocandona albicans is new record for Thrace region of Turkey.

Ecological Succession of Freshwater Ostracoda (Crustacea) in A Newly Developed Rheocrene Spring (Bolu, Turkey)

Six species of ostracod (Candona neglecta, Heterocypris incongruens, Ilyocypris bradyi, Darwinula stevensoni, Pseudocandona compressa, and Psychrodromus olivaceus) were collected from a newly developed spring between October 2001 and October 2004. The first 5 species have cosmopolitan distribution in the Holarctic region. The ratio of non-cosmopolitan to cosmopolitan species (called 'pseudorichness') was 0.2, suggesting dominance of cosmopolitan species. Among the species, C. neglecta displayed the highest tolerance to 6 different environmental variables, although its estimated optimum values varied. Except foor redox potential and salinity, optimum values for H. incongruens were the highest. High tolerance and optimum values seemed to provide more advantages for cosmopolitan species to increase their survival in a variety of habitats. Considering that this spring is newly developed, the ostracod species' composition may be demonstrating the first stages of ecological succession, in which the first invader animals can be cosmopolitan species due to their wide-ranging tolerance.

Comparative ecology of Ostracoda (Crustacea) in two rheocrene springs (Bolu, Turkey)

A total of ten taxa belonging to the class Ostracoda of the Crustacea (Darwinula stevensoni, Candona neglecta, Cypria ophthalmica, Ilyocypris bradyi, Prionocypris zenkeri, Herpetocypris chevreuxi, Psychrodromus olivaceus, Heterocypris incongruens, Scottia pseudobrowniana, Eucypris sp.) were collected from two rheocrene Darwinula stevensoni springs (Cetin Bey and Caygokpinar springs) on 15 separate occasions between November 2002 and November 2004. Almost all of the species identified exhibit cosmopolitan distributions – at least in the Holarctic region. The presence of Scottia pseudobrowniana represents the second recording of this species in the ostracod fauna of Turkey. The dominant taxa in both springs was Cy. ophthalmica, I. bradyi, Pr. zenkeri and Ca. neglecta. Correlation analyses suggested a significant positive relationship in relative abundance between I. bradyi, Pr. zenkeri and Cy. ophthalmica. Species composition differed significantly between the upper and lower study sites for each spring, but differences could not be detected between sites at the same elevation across sites. Environmental tolerance index (ETI) values suggest that species with high optima and tolerance ranges show cosmopolitan characteristics.

Ecological requirements of freshwater Ostracoda (Crustacea) in two limnocrene springs (Bolu, Turkey)

Ecological requirements of ostracods in two limnocrene springs (Usta and Cetin Bey) were investigated between January 2000 and July 2002 in Bolu, Turkey. Ten taxa (Candona neglecta, Darwinula stevensoni, Eucypris virens, Eucypris sp., Heterocypris incongruens, Herpetocypris sp., Ilyocypris bradyi, Potamocypris sp., Scottia pseudobrowniana, Tonnacypris lutaria) were found. Canonical correspondence analysis (CCA) showed that species with wide cosmopolitan distribution could tolerate high levels of changes in environmental variables. CCA explained about 80 % and 77 % of the relationships between species and environmental variables in Usta and Cetin Bey springs, respectively. Electrical conductivity and dissolved oxygen were the two most influential factors on species occurrence in each spring. According to Spearman correlation analysis, there were no significant relationships between the numbers of species and environmental variables in both springs. When dissolved oxygen showed significant negative correlations to electrical conductivity, water and air temperature in Usta spring, such correlation was only negatively significant (P <0.05, r = -0.46) between electrical conductivity and dissolved oxygen in Cetin Bey spring. Clustering analysis (UPGMA) of presence/absence data divided species into four main groups. Results may suggest that anthropogenic activities were responsible for decreasing water quality of these springs and reducing species richness. Although increasing incentives for conservation of natural springs were proposed, Cetin Bey spring and especially Usta spring are now highly degraded.

The impact of late Holocene environmental change on lacustrine Ostracoda in Armenia

Lake Sevan, Armenia, is an ancient lake, although it evolved into its present form only in the Holocene. The ostracod population was dominated by extant, spatially widespread species that have been recorded throughout Europe and Asia (e.g. Limnocythere inopinata, Ilyocypris bradyi, Cyprideis torosa, Candona candida and Candona neglecta), although a small proportion of the association is restricted to the Caucasus (e.g . Fabaeformiscandona caucasica). Diversity appears to reflect the gradual increase in water depths and environmental heterogeneity during the Sub-boreal European climatic phase (late in the Khvalynian climatic phase of the Caspian region). The muds, silts and sands penetrated by the boreholes contain shallow water ostracods indicating water depths of about 5 to 20 m. None of the boreholes penetrated deeper water deposits, so that Fabaeformiscandona dorsobiconcava, which lives at depths below c.40 m in the modern lake, was not found. Salinity was no greater than oligohaline; and water temperatures appear to have been cool. As is the case today, there were a number of streams transporting ostracods (such as Prionocypris zenkeri and Ilyocypris bradyi) into the lake and weeds were abundant. The Holocene association of Lake Sevan is unusual in that it is one of the few in which bisexual populations of Limnocythere inopinata occur.

Factors affecting the occurrence of ostracoda (crustacea) in the Yumrukaya reedbeds (Bolu, Turkey)

I assessed the relationship between ostracod occurrence and ecological variables in the Yumrukaya reedbeds (Bolu, Turkey), describing how differences in water conditions affcted the composition of ostracod assemblages in this small freshwater wetland. Between May 2000 and July 2002, seven ostracod taxa (Cypridopsis vidua, Ilyocypris bradyi, I. gibba, Heterocypris incongruens, Eucypris virens, Candona neglecta, Pseudocandona sp.) were collected. All the ostracods had cosmopolitan characteristics, with broad ranges of tolerance to the variations in ecological variables and the capacity to either resist desiccation or to recolonize newly flooded habitats. The number of ostracods found in Yumrukaya reedbeds was about 50% lower than the average number of ostracods in similar sized habitats of Turkey. The Unweighted Pair Group Mean Averages (IPGMA) clustering analysis based on presence/absence data displayed three groups of ostracods and suggested that cosmopolitan species might have similar life cycles and ecological preferences. Correlation analyses indicated that salinity and percent oxygen saturation were significantly associated with species richness.

The influence of biological and environmental factors on the stable isotopic composition of ostracods – the Late Pleistocene record from Lake Albano, Central Italy

The stable oxygen and carbon isotopic composition of ostracod valves is the result of the interaction of several variables. Understanding and identifying the biological and ecological factors influencing the life of these animals improves the interpretation of isotopical data, and leads to better paleoenvironmental reconstructions. Ostracod biostratigraphy and determinations of oxygen and carbon stable isotopes on ostracod valves were carried out on a short sequence of the Last Glacial Maximum from Lake Albano (Central Italy). The oxygen isotopic composition of adults of Candona neglecta ranged between 0.5‰ and 1.5‰, and in Ilyocypris bradyi between –2‰ and –0.5‰ . Isotopic values from adults of C. neglecta fell within the range –1.5‰ to –0.8‰ when corrected for vital effect. The carbon isotopic signal ranged from 9.4‰ to 10.8‰ in adults and juveniles of C. neglecta, and from 9.8‰ to 11.3‰ in I. bradyi. Differences between left/right valve and gender were negligible, whereas there appeared to be a marked influence of life stage and species-specific factors related to vital effect and differences in microhabitat and seasonality. We combined analyses on carbon and oxygen isotopes with information deriving from ostracod ecology to reconstruct short term oscillations in past lake water level. Seasonal changes in either the temperature or the isotopic composition of the lake water were also identified. Relatively high δ18O values in ostracod valves were probably associated with the lake location and source of moisture, while high δ13C values were most probably related to the input of volcanic CO2 into the lake.

Palaeoecological studies of Holocene lake sediments from west Greenland

Colonisation by plants and animals and subsequent biotic development in west Greenland was studied by analyses of macrofossils in four Holocene lake sequences. One of the lake basins, located near the outer coast, was deglaciated shortly after the transition from the last glacial stage to the Holocene, and a basal date of 12,100–11,300 cal. years BP was obtained. Two of the lake basins located near the margin of the Greenland ice sheet were deglaciated several millennia later. The oldest sediments contain low-diversity floras and faunas. Some of the first immigrants were Chironomidae and Daphnia pulex, soon followed by other insects, crustaceans and other invertebrates. Water mosses, Ranunculus confervoides, Hippuris vulgaris and Potamogeton filiformis were among the first plants that colonised the lakes. The earliest Holocene terrestrial flora in west Greenland was probably entirely herbaceous, with Salix herbacea and Empetrum nigrum being some of the first woody plants to arrive. A number of invertebrates are new to the fossil fauna of Greenland, and the ostracod Ilyocypris bradyi that was found in one sequence, from 7000 to 6500 cal. years BP, has not been recorded from Greenland before.

ECOLOGY AND DISTRIBUTION OF OSTRACODS ASSOCIATED WITH FLOWING WATERS IN THE EASTERN IBERIAN PENINSULA

ABSTRACT The ostracod fauna of the three main rivers of the central Mediterranean slope of the Iberian Peninsula was studied, with special attention being paid to ecology and distribution. Forty-six stations were sampled in spring and autumn 1995 and thirty ostracod species were collected, two of these (Trujancypris serrata and Heterocypris reptans) new to the Iberian fauna. The most common species were Ilyocypris bradyi, Herpetocypris brevicaudata, Cypridopsis vidua, and Limnocythere inopinata. Cluster analysis showed that these species, together with Ilyocypris inermis and Sarscypridopsisspp. form the most widespread ostracod assemblage in the area, although its widespread distribution is not related to any of the environmental variables monitored. However, factors such as altitude, mean January air temperature, distance from source, flow discharge, water quality, and degree of organic pollution play an important role in explaining the occurrence of less common species. One species group was linked to high elevations and BMWP' biotic index values and low winter temperatures. Candona neglecta best characterizes this assemblage. In the opposite part of this environmental gradient, Ilyocypris gibba, associated with lower altitudes, epitomizes the third species group. Heterocypris salina and Heterocypris incongruens were the species that were most tolerant of organic pollution. Our results are compared with those reported in studies from different habitats (e.g., springs) and latitudes. The implications of our findings for paleoenvironmental reconstruction and water resources management are discussed.

Trace-element chemistry of non-marine ostracods as a means of palaeolimnological reconstruction: An example from the Quaternary of Kashmir, northern India

Recent work has demonstrated the use of Sr/Ca and Mg/Ca ratios in the calcite of ostracod shells for reconstructing the palaeosalinity and palaeotemperature of lakes. In this study, the technique was applied to a lacustrine sequence of late Quaternary age (the upper Karewa Formation) in Kashmir, northwest Himalaya. Ostracods are the only fossils found in abundance in the upper Karewa sediments and are thus important for the reconstruction of upper Karewa palaeoenvironments. Trace-element analyses of multiple-shell samples of the ostracod Ilyocypris bradyi Sars 1890 were performed using inductively coupled plasma-atomic emission spectrometry. The results show that the palaeo-lake was even more dilute than the modern residual lakes in Kashmir. Reconstructed molar Sr/Ca ratios for the palaeo-lake waters vary between 30·10 −4 and 42·10 −4 compared with observed values of (46–110)·10 −4 for the modern residual lakes. Changes in the molar Mg/Ca ratios with unchanging Sr/Ca are attributed to variations in water temperature. The palaeo-lake probably receded from the study site at between 116 and 80 ka and lacustrine sedimentation gave way to subaerial loess deposition. The lack of any increasing trend in the reconstructed Sr/Ca values, together with structural and sedimentological evidence, suggests that the lake was drained by tectonic tilting or warping of the basin floor rather than by climatically-induced desiccation.