Palaeoenvironmental analysis of Early Pleistocene brackish marshes in the Rieti and Tiberino intrapenninic basins (Latium and Umbria, Italy) using ostracods (Crustacea)

Recent palaeontological and sedimentological studies on the Upper Pliocene–Lower Pleistocene continental deposits of the Rieti and Tiberino basins (Latium and Umbria, Italy) showed the existence of brackish marshes influenced by the Early Pleistocene Tyrrhenian sea. The micropaleontological analyses carried out on five sections cropping out in the northern sector of the Rieti Basin and on one section cropping out in the southwestern branch of the Tiberino Basin showed the repeated alternance of two ostracod assemblages. The first is characterized by a very abundant ostracod association dominated by Cyprideis torosa, typical of brackish waters; the second one is less rich in specimens and dominated by several species of freshwater Candoninae. This alternance allowed the recognition of several changes in the water salinity that could be related to many Early Pleistocene sea-level changes. Palaeosalinities were estimated for both the Tiberino and the Rieti Basin using the morphological analysis of the shell of Cyprideis torosa (ornamentation, nodosities and percentages of sieve-type pore canals). The obtained palaeosalinity values, ranging from freshwater to oligohaline, show slightly higher salinities for the Tiberino Basin, located nearer the ancient coastline, than for the Rieti Basin.     

Distribution of Cyprideis torosa (Ostracoda) in Quaternary Athalassic Sediments in Germany and its Application for Palaeoecological Reconstructions

Cyprideis torosa (Jones , 1850) is a very common brackish water ostracod of the German coasts, but, despite empty valves are found occasionally in surface sediments of some modern inland waters, C. torosa could not be found living in modern athalassic waters of Germany so far. During interglacial periods, including the Holocene, however, fossils of this species are quite common in Central Germany, at a distance of more than 300 km away from the coasts of the Baltic and North Seas. All 31 Quaternary localities with C. torosa known so far from Germany are documented. C. torosa is an indicator for brackish waters and widely used as index‐fossil in palaeosalinity reconstructions relying on water chemistry bound morphological changes (nodes, sieve‐pores). The comparisons imply a general underestimation of palaeosalinity in oligo‐ to mesohaline athalassic waters if using nodes and sieve‐pores of C. torosa as proxy. A water chemistry (ionic composition) driven morphological response is assumed instead one by salinity only. Palaeosalinity estimations for athalassic waters, relying on morphological variability alone, should therefore be used with caution. Palaeosalinity trends, however, can be detected. Distinguishing thalassic and athalassic sediments with C. torosa is possible by using the associated ostracod fauna as a discriminator. Regarding the ecology and distribution of C. torosa, permanent, brackish, and shallow water bodies under relatively warm conditions are required for its settlement. The source of the salt are brines originating from Zechsteinian or Triassic underground evaporites. Warm and relatively dry climates could enhance the process for such water bodies of becoming salty, a situation present in Holocene Central Germany. The occurrence of C. torosa can therefore be used for palaeoclimatological studies. The most probable migration path of this ostracod species to athalassic waters is by avian transport. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The ontogeny of appendages of Heterocypris salina (Brady, 1868) Ostracoda (Crustacea)

The post-embryonic development of the appendages of the Cyprididae ostracod Heterocypris salina (Brady, 1868) are described in detail and compared with those of other podocope species documented in previous studies. Generally, the appearence of limbs during onotgeny of H. salina is similar to that of other species, but small differences in limb morphologies were identified between H. salina and other Cyprididae species, including other Heterocypris species. Some features appear either earlier or later in the development of H. salina compared with other species, even species of the same genus. These features may be useful characters for phylogenetic analyses at the genus and family levels.     

Distribution and community structure of Ostracoda (Crustacea) in shallow waterbodies of southern Kenya

The current study presents the ostracod communities recovered from 26 shallow waterbodies in southern Kenya, combined with an ecological assessment of habitat characteristics. A total of 37 waterbodies were sampled in 2001 and 2003, ranging from small ephemeral pools to large permanent lakes along broad gradients in altitude (700–2 800 m) and salinity (37–67 200 µS cm^?1). Between 0 and 12 species were recorded per site. Lack of ostracods was associated with either hypersaline waters, or the presence of fish in fresh waters. Three of the 32 recovered ostracod taxa, Physocypria sp., Sarscypridopsis cf. elizabethae and Oncocypris mulleri, combined a wide distribution with frequent local dominance. Canonical correspondence analysis on species–environment relationships indicated that littoral vegetation, altitude, surface water temperature and pH best explain the variation in ostracod communities. Presence of fish and water depth also influence species occurrence, with the larger species being more common in shallow waterbodies lacking fish. Based on Chao’s estimator of total regional species richness, this survey recovered about two-thirds (60–68%) of the regional ostracod species pool. Scanning electron micrographs (SEM) of the valve morphology of 14 ostracod taxa are provided, in order to facilitate their application in biodiversity and water-quality assessments and in palaeoenvironmental reconstruction.     

Ecological characteristics of the freshwater Ostracoda in Bolu Region (Turkey)

Total of 40 ostracod taxa obtained from 141 different sampling locations in Bolu were examined to determine relationships between habitat preferences of species and their ecological characteristics from June to August 2006. According to the first axis of Canonical Correspondence Analysis (CCA), 52% of the relationships between species and five most influential environmental variables with 36.2% of variances were explained. Although the first four variables, air temperature, water temperature, pH, and electrical conductivity had significant influence (P?P?=?0.47) was relatively low. Spearman correlation analyses indicated that some species had weak to strong positive correlation with electrical conductivity, whereas some others had a significant negative correlation with pH and redox potential. Only two species (Herpetocypris chevreuxi and Ilyocypris inermis) had strong correlation to the habitat type (P?Heterocypris incongruens, I. bradyi, Candona neglecta, and C. candida) had high Environmental Tolerance Index (ETI) values for at least six different environmental variables. Thus, cosmopolitans are highly adaptable within a wide range of environmental conditions and geographical distribution.     

Ostracods and the Holocene palaeolimnology of Lake Qarun, with special reference to past human–environment interactions in the Faiyum (Egypt)

We present an ostracod record covering the past two millennia from an 8.25-m core taken from Lake Qarun, in the Faiyum Depression of Egypt. The occurrence of ostracod species in the lake is controlled primarily by variations in solute composition, which are in turn related to shifts in catchment land use. At times when the Faiyum Depression supported thriving agriculture, lake water contained Na⁺–Cl^? brine, and Cyprideis torosa dominated the ostracod assemblage. When the Faiyum Depression experienced periods of environmental and economic decline, lake water contained Na⁺–HCO₃ ^? brine, and Limnocythere inopinata dominated. The relative abundance of other ostracod species provides additional information about past conditions in Lake Qarun including salinity and lake level changes. Overall, the ostracod assemblages provide evidence for human influences in the Faiyum, which extend back before instrumental or detailed observational records began.     

Subcellular preservation in giant ostracod sperm from an early Miocene cave deposit in Australia

Cypridoidean ostracods are one of a number of animal taxa that reproduce with giant sperm, up to 10 000 µm in length, but they are the only group to have aflagellate, filamentous giant sperm. The evolution and function of this highly unusual feature of reproduction with giant sperm are currently unknown. The hypothesis of long-term evolutionary persistence of this kind of reproduction has never been tested. We here report giant sperm discovered by propagation phase contrast X-ray synchrotron micro- and nanotomography, preserved in five Miocene ostracod specimens from Queensland, Australia. The specimens belong to the species Heterocypris collaris Matzke-Karasz et al. 2013 (one male and three females) and Newnhamia mckenziana Matzke-Karasz et al. 2013 (one female). The sperm are not only the oldest petrified gametes on record, but include three-dimensional subcellular preservation. We provide direct evidence that giant sperm have been a feature of this taxon for at least 16 Myr and provide an additional criterion (i.e. longevity) to test hypotheses relating to origin and function of giant sperm in the animal kingdom. We further argue that the highly resistant, most probably chitinous coats of giant ostracod sperm may play a role in delaying decay processes, favouring early mineralization of soft tissue.     

Microvertebrates from unit G/layer 17 of the archaeological site of Hummal (El Kowm,Central Syria): Preliminary results

We present a first look at the microvertebrate fauna of the Middle Pleistocene site of Hummal in Central Syria. Some 2000 microvertebrate remains (1200 mammalian; 230 reptilian; 600 unidentified) were found in unit G/layer 17 by screen-washing sediments in an area of 4 m². The following taxa have been identified: Reptilia: Agaminae indet., Gekkota indet., Lacertidae indet. (2–3 taxa), Eryx sp., Natricinae indet.; and Mammalia: Crocidurinae indet., Chiroptera indet., Lepus sp., Arvicolinae indet., Ellobius sp., Microtus sp., Murinae indet. (large form), Mus sp., Meriones sp., Gerbillus sp. The presence of Ellobius indicates a Middle Pleistocene age of the fauna. This genus does not occur in Syria today, but is recorded in Israel in Late Acheulean to Early Mousterian sites. In North Africa, the occurrence of this genus is restricted to the early part of the Middle Pleistocene. The ecological requirements of the nearest living relatives of the recorded taxa indicate mainly open habitats, but also the presence of vegetation and wet conditions, at least close to the site. Lepus, Ellobius, Meriones, Gerbillus, and Eryx live to various extents in steppes, semi-deserts, and deserts. Various extant species of large murids that come into consideration occupy a variety of wooded habitats, grassland and savannah and require the presence of water. Hummal offers the most detailed Pleistocene portrait yet of hominin palaeoenvironment in an area that, at the end of the Pleistocene, became known as part of the Fertile Crescent.     

Zooplankton (Cladocera, Ostracoda), Chironomidae and other benthic faunal remains in sediment cores from nine North African wetland lakes: the CASSARINA Project

Palaeolimnological studies were carried out on sediment cores from nine North African wetland lakes. The lakes represented a variety of habitats ranging from freshwater to mixohaline conditions and with and without direct connections to the sea. Sediment cores were examined for records of recent environmental change during the 20th century period. Faunal remains analysed in the sediments included those of Cladocera, Ostracoda, Chironomidae, Mollusca and, at the sites with marine connections, Foraminifera. Cyprideis torosa littoralis was the most common ostracod, occurring in sediments from the seven sites linked with the sea and also in brackish water Sidi Bou Rhaba. In acid Megene Chitane ostracods were scarce, being represented by a single species (Cypria ophtalmica). Candona neglecta completely disappeared at two sites (Sidi Bou Rhaba and Bokka) during the 20th century. Of the Cladocera, Chydorus sphaericus was common in the moderately mixohaline sites and but Heterocypris salina occurred only where marine salinities were occasionally achieved (in Zerga, Ichkeul and Korba). Microinvertebrate assemblages in the Nile Delta lake cores and to a less extent in Zerga showed a clear response indicative of more fresher conditions occurring during the latter part of the 20th century. However the freshening trend began prior to construction of the Aswan High Dam (mid 1960s).With the exception of the most saline site (Korba), microinvertebrate communiuties at all the CASSARINA sites have experienced major disturbances during the 20th century. Changes in freshwater availability associated with increased human usage of water resources is perceived as a major factor regulating the abundance and occurrence of aquatic microinvertebrate species at these sites     

Land use and ostracod community structure

Ostracods are important members of the benthos and littoral communities of lake ecosystems. Ostracods respond to hydrochemistry (water chemistry) which is influenced by climatic factors such as water balance, temperature, and chemicals in rainfall runoff from the land. Thus, at local scales, environmental preferences of ostracods and characteristics of lakes are used to infer changes in climate, hydrology, and erosion of lake catchments. This study addresses potential drivers of ostracod community structure and biodiversity at multiple spatial scales using NMS, CART^?, and multiple regression models. We identified 23 ostracod species from 12 lake sites. Lake area, maximum depth, spring conductivity, chlorophyll a, pH, dissolved oxygen, sedimentary carbonate, and organic matter all influence ostracod community structure based on our NMS. Based on regression analysis, lake depth, chlorophyll a, and total dissolved solids best explained ostracod richness and abundance. Land uses are also important community structuring elements that varied with scale; locally and regionally agriculture, wetlands, and grasslands were important. Nationally, using regression tree analysis of lakes sites in the North American Non-marine ostracod database (NANODe), row-crop agriculture was the most important predictor of biodiversity. Low agriculture corresponded to low species richness but greater landscape heterogeneity produced sites of high ostracod richness.     

Les Ostracodes et le Quaternaire d’Aigion (golfe de Corinthe, Grèce)

The Upper Pleistocene and the Holocene of Aigion have delivered an abundant microfauna with 35 ostracode species. The Pleistocene from Aigion borehole generally provides Ostracodes from oligohaline environment with Cyprideis torosa, Candona angulata and Tyrrhenocythere amnicola while, in the Holocene, marine infralittoral species dominate with Cytheridea neapolitana, Carinocythereis whitei, Loxoconcha ovulata and Cytherois frequens. The marine sedimentation occurred at depth from some meters to some tens of meters. In the Aghios Constantinos section, the lagoonal marls are characterised by Euxinocythere schuldtae and a dwarf species of Xestoleberis. Then, a drastic environmental change occurs around the Pleistocene-Holocene boundary and presumably affected the whole Corinth gulf.     

The biogeochemistry and zoogeography of lakes and rivers in arctic Alaska

Water samples from 45 lakes and 8 rivers in arctic Alaska were analyzed for major anions, cations, nutrients, chlorophyll, zooplankton, and benthos. The waters were dilute (conductivities of 30 to 843 μS cm⁻¹), and their composition varied from Na-Ca-Cl waters near the Arctic Ocean to Ca-Mg-HCO₃ waters further inland. Sea salt input in precipitation was important in determining the chemistry of coastal lakes, partly because of low groundwater flow and less time for water to react with shallow unfrozen soils. Further inland, variations in water chemistry among sites were related mainly to differences in bedrock, the age of associated glacial drift, and the input of wind blown sediment. Variations in zooplankton species composition among the lakes were related more to latitude, lake morphometery, and biotic interactions than to water chemistry. The presence of fish as predators mostly determined the overall size structure of the zooplankton community. The chironomid taxa identified have been previously reported from the Neararctic, except for Corynocera oliveri which is a new record. The abundance of the widely distributed chironomid Procladius appears to be controlled by sculpin predation.     

Benthic macrophyte metrics as bioindicators of water quality: towards overcoming typological boundaries and methodological tradition in Mediterranean and Black Seas

Benthic macrophyte communities of different substratum types (soft, hard) were studied in eleven differently impacted sites belonging in two different water typologies (transitional waters: Lesina Lagoon, Varna Lake; coastal waters: Varna Bay) and two ecoregions (Mediterranean Sea, Black Sea). Species lists were compiled for each study site, 20 taxa were found at Lesina and Varna Lake and Bay, and the abundance of each taxon was determined at each site. The relationship between nine metrics related to community structure [species richness, % of total coverage, dry biomass (g/m^?2), and cluster and multi-dimensional scaling plot of Bray–Curtis similarity] and function [Ecological Status Group I % coverage, ESG II % coverage, Ecological Evaluation Index (EEI-c) and Ecological Index (EI_EEI)] and key abiotic factors and an anthropogenic stress index (EnII) were studied. A strong relationship (Spearman rank correlation coefficient ρ ≤ ?0.89; R ² ≥ 0.89) between anthropogenic stress and functional indices, EEI-c and EI_EEI, was found. The structural index ‘species richness’ correlated negatively with EnII and positively with salinity, demonstrating a freshwater and confinement influence on species diversity. EEI-c and EI_EEI indices classified the studied sites and locations in different Ecological Status Classes in accordance with the anthropogenic stress gradient.     

Intra- and infra-specific morphological variation in selected coccolithophore species in the equatorial and subequatorial Pacific Ocean

The ecological preferences of morphological groups within major coccolithophore taxa were studied in surface water samples from the equatorial and subequatorial Pacific Ocean. Emiliania huxleyi was subdivided into three morphological groups: Type A, Type C, and variety corona. The most probable factors limiting the occurrence of E. huxleyi Types A and C were high temperatures and low nutrient concentrations, respectively. E. huxleyi var. corona had an affinity for oligotrophic conditions. Calcidiscus leptoporus ssp. small was adapted to fertile waters. Umbilicosphaera foliosa and Umbilicosphaera sibogae preferred mesotrophic upwelling waters and stratified marginal waters surrounding the upwelling front, respectively. Among the three Umbellosphaera tenuis morphotypes observed in this study (Types I, III, and IV), only Type I was found in very warm tropical surface. Both Types III and IV were found in subtropical waters, and Type III differed from Type IV in that its distribution was constrained to hemi-pelagic waters. Habitat segregation among the morphotypes of major taxa indicates that the observed global distributions of these major taxa are, in fact, combinations of discrete morphological groups.     

Ecological differentiation and cladogenesis of Baldellia (L.) Parl. (Alismataceae)

The Iberian Peninsula is home to a large number of endemic species that often show strong genetic subdivisions which indicate possible isolation of populations in the past. Numerous phylogeographic and phylogenetic studies on Iberian flora and fauna have revealed this territory to be the origin of genetic differentiation during the Pleistocene Ice Age. To better understand the influence of Plio-Pleistocene climatic oscillations on the cladogenesis and population structuring of refugial taxa restricted to freshwaters of the Iberian Peninsula, we studied the evolutionary history of the small European genus Baldellia, both from a phylogenetic/phylogeographic perspective and regarding its ecological characteristics. Molecular analyses were based on four plastid regions and nuclear ITS2 ribosomal spacer from individuals belonging to geographically isolated Baldellia populations, while the relationships between climate and Baldellia species distribution was investigated by redundancy analysis applied to the climatic data with the occurrence of Baldellia species as external variables. The absence of a clear phylogenetic signal most likely reflects a common and recent cladogenesis for Baldellia. In contrast, the more rapidly evolving plastid sequences indicate a recent phylogeographic history of refugial repartition and ecological segregation probably occurring during the last glaciation, a scenario well supported by marked differences in species?? ecological preferences and climate analysis.     

Evaporation effects as reflected in freshwaters and ostracod calcite from modern environments in Central and Northeast Yakutia (East Siberia,Russia)

Taxonomical and geochemical investigations on freshwater ostracods from 15 waters in Central and Northeast (NE) Yakutia have been undertaken in order to estimate their potential usefulness in palaeoenvironmental reconstructions based on regional fossil records. Higher variability in environmental factors such as pH, electrical conductivity, and ionic content was observed in thermokarst-affected lakes in Central Yakutia than in NE Yakutia lakes. Species diversity of freshwater ostracods reached up to eight taxa per lake, mostly dominated by Candona weltneri Hartwig 1899, in Central Yakutia, whereas in NE Yakutian waters the diversity was lower and Candona muelleri jakutica Pietrzeniuk 1977 or Fabaeformiscandona inaequivalvis (Sars 1898) had highest frequencies. Coupled analyses of stable isotopes (δ¹⁸O, δ¹³C) and element ratios (Sr/Ca, Mg/Ca) were performed on both host waters and ostracod calcite, aiming to estimate the modern relationships. Correlations between host waters and ostracod calcite of single species were found for δ¹⁸O, δ¹³C and Sr/Ca and Mg/Ca ratios. The relationships between δ¹⁸O, Mg/Ca and Sr/Ca ratios and electrical conductivity (salinity) as an expression of solute concentrations in the waters mainly controlled by evaporation are more complicated but evident, and may be useful in future interpretation of geochemical data from fossil Siberian ostracods. Handling editor: K. Martens     

Influence of environmental variables on algal associations from a floating vegetation mat (Schwingmoor Lake Lunzer Obersee,Austria)

In 2002, periphyton samples were collected 14 times from six stations within a floating vegetation mat in Lake Lunzer Obersee, a small mountain lake in Austria. Water temperature, conductivity, pH, alkalinity, Ca²⁺- and total-hardness were measured and quantitative samples were taken for algal biomass and chlorophyll-a analysis. Algal biomass results clearly indicated the dominance of green algae. Cluster analyses were carried out, based on both algal data and environmental parameters. The algal data separated sites, whereas the abiotic clustering revealed a temporal aspect. An indicator species analysis determined the characteristic taxa for each species group. Indicator species were then related to environmental factors using a redundancy analysis (RDA). Both pH and conductivity were significant factors, whereas water temperature, alkalinity, Ca²⁺- and total-hardness were not. The results of the RDA show that three species groups could be identified along a gradient of pH. One group was positively correlated with high alkalinity and another group occurred at higher values of conductivity.     

First record of non-marine ostracods from the Paleogene “hamadian deposits” of Méridja area,west of Bechar (southwestern Algeria)

A new non-marine ostracod fauna from the Paleogene “hamadian deposits” outcropping west of Bechar (southwestern Algeria) has been recovered from lacustrine to fluvial deposits of the Oued Méridja section and fluvial deposits on the southern edge of the Hamada de Méridja section. Recently, these sections have been dated as late Thanetian – early Ypresian (latest Paleocene to earliest Eocene) and Ypresian – earliest Lutetian (early to earliest middle Eocene), respectively, based on charophytes. The associated ostracod fauna recovered consists of relatively mostly moderately to badly preserved specimens and comprises 14 taxa, none of which could be identified to species level in view of its poor state of preservation; we have nevertheless been able to identify and describe the following taxa: Herpetocypris sp., Cyprinotus? sp., Heterocypris? sp. 1 and sp. 2, Cypris? sp., Ilyocypris sp., Cytheroidea indet. sp. 1 and sp. 2, Limnocytheridae indet. sp. 1, Cypridoidea indet. sp. 1, Cyprididae indet. sp. 1, and Ostracoda indet. sp. 1, 2 and 3. Only Heterocypris sp. 1 occurs in both sections. Although the fauna can as yet not be related to the few other contemporaneous faunas reported from the wider palaeogeographic area, it adds important new information to our poor knowledge on Eocene non-marine ostracods in North Africa and southern Europe. The Méridja sections and area are promising regarding the discovery of more, better preserved material and further studies, and one main limitation to the correlation of the fauna is the hitherto insufficient taxonomic knowledge on many faunal elements of Eocene non-marine ostracods to which our section contributes considerably.     

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 (Çetin Bey and Çaygökp?nar 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.     

Size and environmental salinity in the modern euryhaline ostracod Cyprideis torosa (Jones, 1850), a biometrical study

Samples from living populations of the ostracod Cyprideis torosa, taken at various inland brackish-water localities in The Netherlands, are biometrically analyzed. A negative correlation is found between the mean size of the carapace (adult females) and the salinity level of the environment. The results are discussed and compared with published data on the size-salinity relationship in ostracods.