Invasive South American floating plants are a successful substrate for native Central African pleuston

Eichhornia crassipes, commonly known as water hyacinth, is a free-floating perennial aquatic plant native to South America, which has been widely introduced on different continents, including Africa. E. crassipes is abundant in both the Congo (Africa) and Amazon (South America) River catchments. We performed a comparative analysis of the ostracod communities (Crustacea, Ostracoda) in the E. crassipes pleuston in the Amazon (South America) and Congo (Africa) River catchments. We also compared the ostracod communities from the invasive E. crassipes with those associated with stands of the native African macrophyte Vossia cuspidata. We recorded 25 species of ostracods associated with E. crassipes in the Amazon and 40 in the Congo River catchments, distributed over 31 ostracod species in E. crassipes and 27 in V. cuspidata. No South American invasive ostracod species were found in the Congolese pleuston. Diversity and richness of Congolese ostracod communities was higher in the invasive (Eichhornia) than in a native plant (Vossia). The highest diversity and abundance of ostracod communities were recorded in the Congo River. The result of principal coordinates analysis, used to evaluate the (dis)similarity between different catchments, showed significant differences in species composition of the communities. However, a dispersion homogeneity test (PERMDISP) showed no significant differences in the variability of the composition of species of ostracods (beta diversity) within Congo and Amazon River catchments. It appears that local ostracod faunas have adapted to exploit the opportunities presented by the floating invasive Eichhornia, which did not act as “Noah’s Ark” by introducing South American ostracods in the Congo River.     

Ostracoda (Crustacea) as indicators for surface water quality: a case study from the Ledra River basin (NE Italy)

Wastewater discharges associated with urbanisations, farming activities and industry may dramatically reduce the ecological health of river ecosystems. During the reconstruction of the Friuli Venezia Giulia region following the 1976 earthquake, a lot of resources were used to build large numbers of wastewater treatment plants to minimize the impact of human activities on lotic ecosystems. Their efficiency is usually assessed through monitoring of the physical and chemical environment near the discharge point. However, discontinuous monitoring of the abiotic environment may fail to detect periodic malfunctioning and do not recognize indirect effects on the ecosystem. We assessed the potential of an alternative approach to assess the impact of wastewater discharges, based on the monitoring of ostracod density, richness and community composition. We repeatedly measured physical, chemical and microbial parameters and collected ostracod samples at stations up- and downstream from wastewater discharge points scattered over a 21-km stretch of the Ledra River (NE Italy). The results indicate that monitoring ostracods is a potentially valuable approach, for two reasons. Communities appeared to be well differentiated even in the small spatial area of this study, indicating that they can provide sufficient resolution to pick up even minor impacts. Secondly, despite the seasonal succession in species composition, spatial differentiation was consistent over time, suggesting that ostracods provide a time-integrated picture of the water quality. The traditional approach failed to detect any consistent impact of wastewater discharges, apart from an ambiguous increase in nutrient levels. The density and/or richness of the ostracod communities was altered by some wastewater discharges, but not by others. We identified a general trend for wastewater discharges to systematically replace regionally rare ostracod species with common species. In particular, the species Ilyocypris inermis was very sensitive to discharges, and may be used as an indicator species for good ecosystem health.     

Ostracod fauna of Duvensee,an ancient lake in Northern Germany

About 4000 ostracod valves have been analysed from a sediment core of a cultivated bog NW of Hamburg. The deepest deposits are sands free of subfossils, the uppermost layers consist of peat. In the sediment in between, there are three layers containing undestroyed valves. The ostracod assemblies of the older claygyttja (Late-glacial) and the two younger, fine detritus deposits (Post-glacial) are strikingly different. Cytherissa lacustris, Candona neglecta, Ilyocypris bradyi, Herpetocyrpis reptans, and two Limnocythere species were found in the Late-glacial layers. Changes in abundance of these species indicate alterations in climate, lake ground, water inflow and waterlevels. Postglacial layers are rich in Metacypris cordata valves associated with numerous Candona species, L. inopinata, Darwinula stevensi, and Cyclocypris laevis. These species are characteristic of a small lake with a large littoral zone. A similar development in ostracod assemblages is found in middle Europe by Absolon (1973), although the main Candona species is not C. neglecta but C. candida. Ostracod analysis cannot demonstrate an influence of anthropogenic impacts on ostracod successions.     

Pleuston communities are buffered from regional flood pulses: the example of ostracods in the Paraná River floodplain, Brazil

1. It is widely acknowledged that sudden, large‐scale flood pulses are drivers of benthic and planktonic biodiversity change in floodplains. The impact of such pulses on pleuston (biotic communities associated with root systems of floating plants) remains to be demonstrated. Here, we investigate the effects of local and regional drivers on seasonal changes in abundance and diversity of ostracod communities in pleuston. 2. Temporal and spatial distribution patterns of species richness, abundance, diversity and evenness of ostracods associated with the floating water hyacinth, Eichhornia crassipes, in a lentic environment from the upper Paraná River floodplain, were investigated in relation to local, as well as regional, environmental factors. Ostracods were sampled monthly over an annual cycle (March 2004–February 2005). Twenty‐seven species were found, representing the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Both diversity and abundance of ostracod communities showed seasonal changes, although species turn‐over during the year was limited. 3. We tested two hypotheses concerning the causality of these fluctuations: seasonal recruitment and influx of allochthonous ostracods during the flood pulse. Our results indicate that seasonal recruitment is more likely to be the driver of fluctuations in relation to the flood pulse. We postulate that pleuston communities are buffered against possible detrimental effects of flood pulses.     

Ostracods from the marginal coastal Lower Cretaceous (Aptian) of the Central Tunisian Atlas (North Africa): Paleoenvironment,biostratigraphy and paleobiogeography

This work provides the first detailed taxonomic study of ostracod species from the Lower Cretaceous (Aptian) marginal coastal deposits of the Central Tunisian Atlas, the Kebar Formation, as well as biostratigraphic, paleoecological and paleobiogeographic implications. The ostracod fauna provides new insights into the depositional environment and biostratigraphic framework of the Kebar Formation, and is represented mainly by freshwater and brackish-water species among them, Perissocytheridea tunisiatlasica nov. sp., is newly described. The environmental setting of this formation comprises marginal-littoral conditions in its lower part, thus not exclusively non-marine/continental as assumed previously. The ostracod associations from the studied locality, Jebel Ksaïra, indicate a minimum age of Early Aptian as recently attributed to the lower member of the Kebar Formation based on charophytes (presence of Late Barremian to Early Aptian Globator maillardii var. biutricularis Vicente and Martín-Closas, 2012), whereas an Early Albian age had been previously assigned to the Jebel Kebar site. The relative sea-level fall documented in the lower member of the Kebar formation at Jebel Ksaïra might correspond to the 3rd order cycle major eustatic sea-level fall event starting at the base of the Aptian. Paleobiogeographically, the non-marine ostracod fauna newly discovered in the Kebar Formation shows some affinities to contemporaneous faunas of southern and western Europe, e.g. that of the uppermost Weald Clay Group of southern England (Cypridea fasciata subzone of Horne, 1995), West Africa, and possibly to eastern South America (Brazil). Hence, the studied ostracods further support the hypothesis of supraregional faunal exchange by passive ostracod dispersal during the Early Cretaceous – between Europe and Northern Africa on the one hand, and eastern South America/western Africa and North Africa on the other hand. This leads to the hypothesis that the Peri-Tethyan islands could have worked as effective bridges for non-marine ostracods to become widely dispersed passively by “island-hopping” of larger animals and thus, ultimately, facilitated intercontinental faunal exchanges between South America and Europe – potentially even Asia – via North Africa during the Early Cretaceous.     

长江、黄河源头地区土壤中的齿梗孢属真菌

在进行长江、黄河源头地区土壤中暗色丝孢菌多样性研究的过程中,从该地区分离、鉴定出8种齿梗孢属真菌。其中,中华齿梗孢Scolecobasidium chinense、青海齿梗孢S. qinghaiense为新种,树状齿梗孢S. dendroides为中国新记录种。对新种及中国新记录种作了较详细的描述。研究菌株的干制培养物和活菌种保存在山东农业大学植物病理学标本室（HSAUP）。     

Freshwater ostracod assemblages and their relationship to environmental variables in waters from northeast Germany

An ecological calibration dataset for freshwater ostracods from 33 localities throughout West-Pomerania (Mecklenburg-Vorpommern, Germany) was evaluated using multivariate statistical methods. A total of 47 freshwater ostracod species were identified. Nine species were rediscovered after 100 years since the last published record and Candonopsis scourfieldi and Pseudocandona sucki was recorded for the first time in the study area. Special emphasis is put on the phenology of each species to gain information on the water characteristics at the time of their last moult. Canonical correspondence analysis (CCA) revealed that the ecological variables such as water temperature, Ca, Mg, and lake area were statistically most significant (p < 0.005; n = 72) in explaining variation in the distribution of ostracod assemblages. In addition, a transfer function was developed for paleolimnological approaches, based on a weighted-averaging (WA) model to calculate water temperature from the relative abundances of 22 selected ostracod species. This model was successfully applied to infer lake water temperature from subfossil ostracod assemblages collected from lacustrine deposits in northeast Germany (Lake Krakower See). Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

A new species of the genus <Emphasis Type="Italic">Sequoiadendron</Emphasis> Buchholz (Cupressaceae) from the Upper Cretaceous of the Enmyvaam River Basin,Central Chukotka

A new conifer species, Sequoiadendron tchucoticum A. Sokolova from the Emuneret Formation on the Enmyvaam River (Anadyr River Basin) is described. It is established based on a thorough study of the morphology and epidermal features of shoot impressions, using scanning electron microscopy. The new species has polymorphic shoots with helical branching and three main leaf types: scalelike, subulate, and falcate. Leaves are amphistomatic; amphicyclic stomata are mostly obliquely arranged; ordinary epidermal cells are rectangular, frequently with oblique end walls, and their length-to-width ratio reaches 15: 1. Shoots of the new species prevail among conifers of the Ust’-Emuneret Assemblage. The age of the deposits enclosing the assemblage is debated; according to the latest data, it is estimated as Santonian–Early Campanian.     

Late Glacial and Holocene Ostracoda of the Gulf of Gdańsk,the Baltic Sea,Poland

To trace environmental changes in water hydrology and salinity in the Late Glacial to Holocene of the Gulf of Gdańsk, a south‐eastern bay of the Baltic Sea within the maritime zone of Poland, the distribution of ostracod valves was studied in 20 sediment cores collected from both the shallow‐ and deep‐water zones (depth 10.9–67.5 m). The studied sediment sequences yielded ca. 3000 valves of 21 ostracod species, of which only five are known to live today in the Gulf, which has a present maximum depth of 118 m and water salinity up to 7–8‰. The majority of the studied sediment layers that contained ostracod valves corresponded to the period of the Late Glacial to Mid‐Holocene and was dominated by non‐marine species, of which the most common were Candona neglecta (present in 17 cores), Cytherissa lacustris (15 cores) and Candona candida (14 cores). By clustering classification five major ostracod assemblage types were recognised in the studied cores. Initial assemblage types dominated mostly by inhabitants of the profundal/sub‐littoral zones of modern oligo‐mesotrophic lakes (C. lacustris and C. neglecta) in some sediment sequences were replaced in stratigraphical order by the assemblages dominated by brackish‐water species (Cyprideis torosa or Cytheromorpha fuscata). The structure and species composition of the distinguished ostracod assemblage types as well as their successional transitions indicate that the studied sediments were deposited initially in the Late Glacial in freshwater lacustrine conditions, and subsequently, during the Holocene marine transgression, covered by marine sands. The present results confirm and consolidate inferences based on previously published data on ostracods from the western part of the Gulf of Gdańsk as well as on other biotic (molluscs, diatoms) and abiotic (seismoacoustic) indices from this area (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Free-living nematodes of the Tra Ly River in the Red River mouth,Vietnam

In samples of the Tra Ly River in the Red River mouth (Northern Vietnam), 46 species of free-living nematodes have been found, five of which are new to science. The species dominant in abundance were Ptycholaimellus adocius Dashchenko et Belogurov, 1984; Dichrocuadora affinis Gagarin et Nguyen Vu Thanh, 2011; and Tripyloides minor sp.n. The species composition of nematodes is listed and the new species Tripyloides minor sp. n. is described and illustrated. The nematode described and illustrated by Riemann (1970) from watercourses of Colombia as Tripyloides amazonicus (Gerlach, 1957) is recognized as a valid species (Tripyloides riemanni nom.n).     

Zooplankton in the Vychegda River

The species composition of plankton invertebrates was studied in the middle Vychegda River (the main tributary of the Northern Dvina River) in 2003–2005. A list of planktonic rotifers and lower crustaceans was made. The dominating complexes of zooplankton organisms were found. The quantitative characteristics of plankton communities in the river were described.     

Fish remains from the Plio-Pleistocene Shungura Formation, Omo River basin, Ethiopia

Thousands of vertebrate fossils have been recovered from the lower Omo River Valley, in southern Ethiopia, however, fishes have been poorly reported. Here we describe fossil fish remains deriving from the Shungura Formation, part of the Omo Group of deposits ranging in date from 1.8 to 3.4 my. Two new species are reported, Sindacharax omoensis (Characiformes) and Lates arambourgi (Perciformes), which suggest greater diversity of these genera than previously documented.     

Aquatic insects of the Neman River and its tributaries

The aquatic insects of the Neman River and its tributaries were studied. 178 species belonging to 9 orders were found: Collembola—2 species, Ephemeroptera—33, Odonata—16, Plecoptera—10, Heteroptera—20, Coleoptera—39, Megaloptera—2, Trichoptera—54, and Lepidoptera—2 species. Two species of aquatic insects new for the Belarusian fauna were found, Pomatinus substriatus (Ph. Müller, 1806) (Coleoptera) and Brachycercus europaeus Kluge, 1991 (Ephemeroptera).     

Theoretical habitat templets, species traits, and species richness: ostracods (Crustacea) in the Upper Rhône River and its floodplain

• 1 Ostracods occurring at two sections of the Upper Rhône River, France, were examined to determine relationships among species traits, habitat utilization, the relationship between species traits and habitat utilization, and trends in species traits and species richness in the context of spatial and temporal variability of habitats. Twenty regularly sampled species were used in this study and fifteen species traits were considered.
• 2 Throe groups can be distinguished according to their species traits: group 1 has species of mixed sizes with high reproductive rates, short life span, spherical shape, long swimming bristles, low thigmotactism, and high resistance to desiccation; group 2 has medium-sized species with low reproductive rates, long life span, low or no tolerance to desiccation, geometric (trapezoidal, triangular) or streamlined carapace shape, no swimming bristles, and a strong thigmotactism; group 3 has the largest species with parthenogenetic reproduction, medium-sized swimming bristles, and flattened or cylindric carapace shape.
• 3 Ostracod habitat utilization segregates the superficial and interstitial habitats along a gradient from the main channel to the abandoned arms and to the temporary waters.
• 4 The co-structure (= relationship) between species traits and habitat utilization indicates that the species use particular habitats with a particular set of species trait modalities. Species with long life spans, late maturity, low fecundity, and low migratory ability are restricted to the interstitial habitats; the epigean species with long life spans, large size, and parental care are more abundant in permanent flowing and standing surface waters; the epigean species with short life spans, high migratory ability, and high tolerance to desiccation are more abundant in temporary ponds.
• 5 The analyses of the distribution of the species traits in a river habitat templet of spatial and temporal variability emphasized that the main disturbance structuring the Rhône River ostracod assemblage is desiccation.
• 6 Of the trends predicted for species traits in the framework of the river habitat templet, five (size, body form, attachment, reproductive technique, and mobility) are clearly opposite for ostracods (because the predictions were mainly established for flood-related disturbances) but four (life span, number of reproductive cycles per year, age at first reproduction, and desiccation tolerance) are in agreement.
• 7 No trends in ostracod species richness in the framework of spatial–temporal habitat variability were evident.

     

Euxinocythere (Ostracoda, Cytheridae, Leptocytherinae) du Miocène supérieur du Bassin de Turiec (Slovaquie) : taxonomie et paléoécologie

Eight new species of the family Cytheridae have been identified in the Upper Miocene deposits of the Turiec Basin (Slovakia), a small isolated intermountain depression. Six species are new - Euxinocythere aphroditae, E. delicata, E. lactea, E. minuscula, E. quadricostata, E. satyrica - and two are kept in open nomenclature. Their attribution to the genus Euxinocythere is based on arrangement of the hinge elements and of anterior marginal zone. This genus is known from brackish ostracod assemblages of the Paratethys and the Eastern Mediterranean while the species from the Turiec Basin are associated to fresh-water assemblages. The Euxinocythere have been found in littoral as well in deep limnic environment.     

Combined effects of local environment and continental biogeography on the distribution of Ostracoda

Summary 1. The relationship between altitudinal gradients on small spatial scales and latitudinal gradients on broader scales has been repeatedly recognised in the biogeography of animals and plants. However, little is known about this topic in the ecology and biogeography of ostracod communities in Mediterranean flowing waters or the factors underlying these spatial patterns. 2. We analysed the ostracod assemblages of near‐natural headwater streams in the Betic and Pre‐Betic Mountains in the southern Iberian Peninsula to decipher the most important environmental gradients structuring ostracod communities on a local scale. In addition, the European altitudinal and latitudinal distributions of the most commonly found species were analysed with GIS and regression models to compare geographical effects from local to continental scales. 3. Forty sampling sites, distributed among six catchments and ranging in altitude between 150 and 1940 m a.s.l., were sampled seasonally. Limnological and geographical information was also recorded for each sample. Seventeen ostracod species were found, two of which were new findings for the Iberian Peninsula: Potamocypris fulva and Cypria reptans. The most common species were Potamocypris zschokkei, Candona neglecta, Herpetocypris brevicaudata, Cyclocypris ovum, Potamocypris villosa and Pseudocandona albicans. The distribution of these species in 918 European locations was analysed to test the hypothesised change in altitudinal distribution with varying latitude. 4. The best subset of logistic and linear regression models, selected by means of the information‐theoretic approach, found that oxygen content and the variables related with substratum and discharge were the most important variables with a negative influence on ostracod presence, abundance and species richness on a local scale. These findings suggest that the negative effect on benthic invertebrates of physical disturbances relates to high flow velocity and turbulences. 5. Multivariate ordination methods show how altitude and water chemistry are the most important variables to explain the distribution of ostracod assemblages on the small spatial scale. On a larger scale, differences in latitudinal distribution throughout Europe were significant for the six most common species found in Granada. In addition, four of these showed significant negative linear relationships between latitude and altitude in Europe, supporting the important effect of climate on local and continental scale distributions. While ostracod biogeographies are still poorly known, our results indicate the influence of Quaternary climate variability on ostracod dynamic colonisation and extinction in Europe in accordance with species‐specific temperature and water chemistry preferences.     

The effects of sand deposition upon the macroinvertebrate fauna of the River Camel, Cornwall

Erosion from a tributary of the River Camel deposited an estimated 10,000 m³ of sand in the main river over a period of 2 years. The poor incidence of plants and macro-invertebrates from the river was associated with the unstable shifting nature of the sand deposits, rather than turbidity or abrasion caused by particles in suspension. Sand deposition accounted for the low diversity of invertebrate species below the tributary, and resulted in the elimination of several species which were frequent upstream. Baetis rhodani, Rhithrogena semicolorata, and Tubificidae were abundant where sand deposition had occurred.     

Pliocene coastal palaeomorphology and ostracod faunas of the Bass Strait hinterland,southeast Australia

Early to late Pliocene sedimentary strata present across the northern Bass Strait hinterland, southeastern Australia yield extensive fossil proxy data relevant to the interpretation of high sea level coastal palaeomorphology. Within the Pliocene Whalers Bluff Formation exposed in coastal cliffs near the township of Portland, Victoria, marine microfossil faunas delineate two broad cycles of deposition. Both these sedimentary cycles are bound below by unconformity surfaces. Within the lower sedimentary cycle, a basal stress-tolerant (low diversity) marginal marine microfossil fauna devoid of ostracods and suggestive of bottom-water hypoxia, is succeeded by a diverse shallow marine ostracod fauna dominated by stenohaline species indicative of a sheltered (but open) oceanic embayment. This lower sedimentary cycle has an early Pliocene (Zanclean) age. Equivalent shallow marine (e.g. coastal embayment) deposits occur broadly across the coastal hinterland of southeastern Australia—reflecting the generally higher global sea levels of this time. The upper cycle in the cliff exposures at Portland is late Pliocene (Piacenzian) in age. Equivalent deposits across the Bass Strait hinterland are restricted to former incised river valley settings. Euryhaline estuarine/coastal lagoon Ostracoda are present throughout the upper cycle in the Portland cliffs. These are associated with a low diversity microfauna at the base of the upper cycle and a high diversity microfauna towards the top of the cycle. Early Pliocene coastal marine deposits can be distinguished from late Pliocene coastal marine deposits across the northern Bass Strait hinterland on the basis of the presence or absence of certain open marine (‘stenohaline’) ostracod species.     

Mid to Late Holocene palaeoenvironment of Lake Eastern Juyanze (north-western China) based on ostracods and stable isotopes

An exposed section of nearly 13 m thick was investigated in the ancient depression of Lake Eastern Juyanze, north-eastern China. The succession of lacustrine and aeolian deposits covers a period from about 5400 to 2700 cal. a BP as indicated by four radiocarbon ages of macro-plant debris. Fifteen ostracod taxa were identified of which Limnocythere inopinata and Darwinula stevensoni are by far the most abundant species. Stable isotope (O, C) data of ostracod calcite as well as ostracod species abundances and X-ray diffraction results of bulk sediment samples were used to reconstruct the history of Lake Eastern Juyanze. Highest lake levels (water depth ∼10 m) occurred between 5100 and 4100 cal. a BP and were succeeded by intermediate and low levels until about 3150 cal. a BP. Three short-term events of complete desiccation were recorded between 3150 and 2900 cal. a BP. The lake experienced relatively high levels again for some decades at about 3000 cal. a BP and for at least two centuries after 2900 cal. a BP. According to the ostracod and gastropod record and the high abundance of a large diatom (Campylodiscus clypeus) in the lake sediments oligohaline to slightly mesohaline conditions were reconstructed for most of the lake periods (4-6 g/l). Geochemical and palaeontological records of Lake Eastern Juyanze reveal the retreat of the Asian monsoon after China’s Hypsithermal culminating in climate instability at about 3000 cal. a BP.     

Globotalicypridea mirabilis sp. nov. – the first non-marine ostracod taxon from the Upper Cretaceous of the Haţeg Basin,Romania

A monospecific assemblage of Globotalicypridea mirabilis sp. nov. is reported from the Maastrichtian of the Ha?eg Basin, Romania. This new species is the first ostracod taxa described from the famous dinosaur-bearing continental deposits of the Ha?eg Basin. G. mirabilis sp. nov. is characterized by large, finely punctate, and posteriorly strongly inflated carapace with a few papillae on the anterior margin. This new species was restricted exclusively to freshwater (limnic-fluvial) environments. The identification in Ha?eg Basin of Globotalicypridea expands the known geographic distribution of the Talicyprideinae into Eastern Europe, creating a link between Western European and Asian occurrences.