A seaward prograding siliciclastic sequence from upper tidal flats to salt marsh facies (Southern North Sea)

Summary The uppermost part of the seaward prograding sequence in quartz sandy areas of the southern North Sea coast starts at the base with tidal flat layers, often strongly perturbated by burrowing endobenthic animals. This section is overlain by microbial mats intercalated by tempestites, and in part bioturbated by shaped burrows. The top consists of salt marsh facies strongly penetrated by roots. The seaward prograding sequence is characterized by numerous vertical changes in small-scale facies. The facies development and changes are caused by both organisms (halophytes, mat building microbes, benthic animals) and primary physical processes (erosion, transport and sedimentation, or sedimentation alone). The small-scale facies includes (i) bioturbation structures, (ii) biogenic growth structures caused by microbial mats, (iii) subaerial and subaqueous tempestites. Typical is the sudden breakdown of the biocoenosis by fast sedimentation due to tempestites or wind-blown sand sheets. Typical is also the renewal of the former biocoenosis in the new top section. Such sequences may be preserved by wind-blown sand sheets or by washover fans. The sequence is thus an important and unique tool for the identification of fossilized sequences of the intertidal-supratidal transition. It is also a useful mark for estimating the mean sea level and the level of the lower supratidal horizon within vertical sections. Finally the sequence indicates progress in island development governed by the interaction of biological components with physical processes.

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Zusammenfassung Die Verlandungssequenz sandiger Küsten der Nordsee besteht aus einer Abfolge, die von Wattenschichten mit überwiegend ungestalteter Verwühlung im Liegenden über Mikrobenmatten, in die Tempestite mit vorwiegend vertikal angelegten G?ngen eingeschaltet sind, zu supralitoralen Salzwiesen mit starker Durchwurzelung führt. Sie wird durch zahlreiche, oft nur zentimeterm?chtige Fazieswechsel charakterisiert. An der Entwicklung und am Wechsel der Fazies sind Organismen (benthische Fauna, mattenbildende Mikroorganismen und Halophyten) sowie prim?r physikalische, subaquatische wie subaerische Transport-und Sedimentationsprozesse beteiligt. Bezeichnend für die Verlandungssequenz sind wiederholte Zusammenbrüche der lokalen Bioz?nosen durch eingeschaltete Tempestite mit nachfolgender Entwicklung der gleichen Bioz?nose bei hinreichender sediment?rer Ruhezeit. Die beschriebene Sequenz ist ein diagnostisches Mittel zur Identifizierung flachmariner Verlandungsabfolgen. Sie erlaubt, die H?he der mittleren Tidehochwasserlinie festzulegen. Solche Sequenzen k?nnen durch Windsanddecken oder sturmflutbedingte Durchbruchsf?cher überdeckt und erhalten werden.

     

Late Paleozoic and Triassic bryozoans from the Tethys Himalaya (N India, Nepal and S Tibet)

New findings of Late Paleozoic and Triassic bryozoans from the Tethys Himalaya are reported. Fifteen species, including three undetermined, were described, while determinations at order, family or genus level were obtained on fragmentary material. The studied bryozoans were framed in a solid lithostratigraphic scheme spanning across the Tethys Himalaya for over 1500 km, from NW India (Zanskar and Spiti) through Nepal (Dolpo and Manang) to South Tibet; they are concentrated in correlatable stratigraphic intervals corresponding to the Upper Devonian-Tournaisian, Bashkirian, Sakmarian, Midian and Lower Norian. This study allowed us to integrate bryozoan occurrences reported from the literature, mostly referring to the Tournaisian, Bashkirian and Early Norian, and to refine the available biostratigraphic dates. Bryozoan-rich intervals are interpreted as associated to long-term transgressions, in turn driven by major climatic and/or tectonic events. Cosmopolitan genera which prevail in the Paleozoic, are replaced by provincial forms after the Triassic crisis.     

Molecular diversity of soil basidiomycete communities in northern-central New South Wales, Australia

Basidiomycete communities were profiled using terminal RFLP (TRFLP) and amplified ribosomal DNA restriction analysis (ARDRA) approaches at seven field sites under differing land use in northern-central New South Wales (NSW), Australia. TRFLP data indicated greater basidiomycete species richness at sites with natural vegetation. Sixty-seven basidiomycete ARDRA-types were detected. Various putatively ectomycorrhizal fungi were detected at all sites with native vegetation. Most ectomycorrhizal taxa had affinities to the genus Tomentella, while two Pisolithus taxa and putatively ectomycorrhizal Cantharellales taxa were also detected. Although soils under woodland or grassland communities supported a range of putatively saprotrophic taxa, only members of the Ceratobasidiales were detected in soils under agricultural land use. This study is the first investigation of fungal communities in soils of northern-central NSW, Australia.     

Fluvival tufa formation in a hard-water creek (Deinschwanger Bach, Franconian Alb, Germany)

Summary Cyanobacteria-dominated biofilms involved in tufa deposition in the hardwater creek Deinschwanger Bach, Bavaria, were investigated with regard to their effect on the carbonate equilibrium and fabric formation. Current tufa deposition is evident by up to 1.5 mm thick crusts that have formed on substrate plates placed in the creek for 10 months. Hydrochemistry data indicate that carbonate precipitation along the creek is physicochemically driven by CO₂ degassing, whereas photosynthetic carbon assimilation is without detectable effect on the macroscale carbonate equilibrium. However, stable isotope data indicate a minor photosynthetic effect, but only for the lower creek section where the pCO₂ already drops to the two-fold of the atmospheric level. Though the initial process of external nucleation on cyanobacterial sheaths in the lower creck section might be promoted of by a photosynthetically-induced microscale pH gradient, the effect is not strong enough to cause a CaCO₃ impregnation of the sheaths. The fabric of the laminated tufa crusts in the creek reflects the temporal alternation of porous microspariticPhormidium incrustatum-Phormidium foveolarum-diatom biofilms in spring, micrite-impregnatedPhormidium incrustatum-Phormidium foveolarum-diatom biofilms in summerautumn, and detritus-rich non-calcified diatom-biofilms in winter. By contrast, exopolymer-poor surfaces of cascade tufa mosses show large, euhedral spar crystals. Non-phototrophic bacteria, which occur in large numbers inPhormidium incrustatum-Phormidium foveolarums-diatom-communities, thrive on extracellular polymeric substances (EPS) and dead cells of the cyanobacteria and are unlikely to promote CaCO₃ precipitation.     

Prokaryotic aminopeptidase activity along a continuous salinity gradient in a hypersaline coastal lagoon (the Coorong, South Australia)

The relation between climatic parameters (relative air humidity) and the water activity of the Urmia Sea water determines the possible maximum evaporation of the lake. Using the Pitzer thermodynamic approach, the activity of the Urmia Lake water during evaporation was calculated and compared to the present relative air humidity above the water. Present climatic conditions allow the Urmia Sea water to evaporate down to water with activity of 0.55, corresponding to the lowest air humidity measured over the lake. This water activity falls in the range of halite precipitation, while carnalite precipitation starts at somewhat lower (a H₂O = 0.499) point. Our dynamic model predicts that for air humidity as low as 55% (reflecting present climate conditions), the Urmia Sea level may drop to as low as 1270 m (i. e., 1270 m above mean sea level). At that point, the lake water volume will have a volume of 11 km³. For the sake of comparison, at the beginning of 1990, the level of the lake was 1275 m, its volume was 25 km³, and its surface area was 5145 km².     

Non-skeletal carbonate production and stromatolite growth within a pleistocene deep ocean (Last glacial maximum, Red Sea)

Summary Quasi modern non-skeletal carbonates and stromatolites occur from the Red Sea shelf, proximal to the reef systems and continuous into the axial basin (512 to 2704 metres below present sea level). The lithified carbonates are intermixed with carbonate ooze forming a hard layer of 50 to 90 cm thickness. Decimetric platey fragments of lithified carbonate exhibit planar to columnar stromatolitic growth forms, lumpy microbial fabrics and internal brecciation features. The ultrastructures of lithified carbonates are formed by cryptocrystalline carbonate, mainly as aragonite spherulites, Mg-calcite peloids, anhedral mosaics of Mg-calcite and aragonite. Biogenic overgrowth, intercalations of calciturbidites and the type of interlocking relationships in the crystalline fabrics all indicate precipitation at the sea floor or close by. Morphological and mineralogical similarity with previously published microfabrics indicate microbial mediation of carbonate precipitation. The hard layer was formed during the last glacial maximum (LGM, approx. 23ka to 13ka), when pelagic sedimentation rates droped to a minimum due to high surface water salinities. Precipitation of the excess calcium carbonate in the deep ocean was strongly enhanced because the Hanish sill at the southern end of the Red Sea blocked input of cold bottom waters which in turn caused bottom water with high temperatures and salinities (>50 ‰), and low oxygen content. The scenario of a starved greenhouse-type ocean for the Red Sea during the LGM compliments models for the origin of ancient (Mesozoic and Palaeozoic) deepwater stromatolites.     

Modern cryptic microbialite/metazoan facies from Lizard Island (Great Barrier Reef,Australia) formation and concepts

Summary From shallow water caves of fringing reefs related to continental islands of the Lizard Island Section thrombolitic micritic microbialites were observed. The microbialites exhibit always a light decreasing facies succession. The succession starts with a coralgal community and ends with light independent microbial biofilms and benthos (coralline sponges). The sessile mineralized benthos community is constructed of crustose foraminifera, serpulids, thecidean brachiopods, bryozoans, and coralline sponges. The observed benthic community is very similar to those one observed in cryptic habitates of Aptian and Albian reefs of northern Spain. For longtime studies of the microbialite formation and growth rates of coralline sponges the specimens were stained in vivo, within their natural habitat with histochemical fluorochromes and nonfluorescent agents. Main results are a very slow growth of the microbialite and associated sponges (50–100 μm/y). Only few calcifying microbes are participators during microbialite formation. Calcifying acidic organic macromolecules are mainly responsible for microbialite formation by cementing detritical material. Fe/Mn-bacterial biofilms are responsible for strong corrosion of the microbialite. Beside the corrosive activity of the Fe/Mn-bacterial biofilms boring sponges (Aka, Cliona) are the main destructors. Geochemically the observed microbialites are composed of mainly high-Mg calcites and exhibit high positive δ¹³C (+3 to +4) values.     

Development of cyanobacterial build-up and evolution of river bed morphology in the chalk stream Eaulne (Upper-Normandy, France)

In some hardwater rivers of the Seine basin (France), the development ofan encrusting cyanobacterial microflora may gradually lead to a cementation ofriver bed sediments, to a reduction of spawning ground areas and to a loss ofbenthic floral and faunal diversity. Current methods for build-up management arebased on mechanical dredging of the stream bed. In the short term, the habitatdiversity and microfaunal diversity are improved, but in 1–3years the cyanobacterial growth resumes and the bed sediments arecemented again. The early growth stages of stromatolitic structures on newlyavailable substrata were studied for three years in the river Eaulne(Upper-Normandy, France) in relation with microfloral development, sedimentaryprocesses and water quality. Seasonal current velocity variations appeared tocontrol the construction process (colonization dynamics and dependency ofstromatolite growth to mat extension) through substratum availability andnutrient renewal. Under the conditions allowing an optimal microfloraldevelopment, the carbonate precipitation rates were inversely correlated withsubstratum grain size, i.e. the maximal encrusting biomass was hosted bygravels. Homogeneous substrata showed the highest short-term potentialities forhigh sediment cementation rate, whereas heterogeneous, mixed grain size had thehighest potentialities for long-term colonization by the encrusting microflora.     

Modern freshwater microbial carbonates: thePhormidium stromatolites (tufa-travertine) of southeastern Burgundy (Paris Basin,France)

Summary The relationships of microstructure and vegetal remains, obtained by decalcification, were studied in Modern tufa from Burgundy, in order to try to link a given species with a particular crystal habitus. The edifices have various shapes (coatings on floors; encrusted pebbles, shells, vegetal shoots, mosses; oncolites; hydrodynamically shaped tufts). The biological content is rich in algae and animals, mainly at the proximity of springs, even ifPhormidium incrustatum is the predominant species. It is associated with several species ofGongrosira, Schizothrix, andOocardium stratum, the latter only known by its specific crystallizations. Among the animals, we point the galleries ofPsychomiidae (Trichoptera= Phrygan) larvae. The algae and animals are associated within a “biological felt” (in the sense ofForel, 1901). Some species are encrusted by calcite crystals of typical habitus (micrite:Phormidium incrustatum, Gongrosira andSchizothrix, ssp; sparite:Oocardium andBatrachospermum), and there are very little diagenetic modifications. The fabric results in an alternation of seasonal light laminations composed of juxtaposed bundles ofPhormidium incrustatum α, and dark laminations due to parallel filaments ofPhormidium incrustatum β. The influence of other algal species on shape and the internal fabric of the laminations is negligible.Phormidium incrustatum tufa are common in Western Europe, and probably have some fossil analogue in the Upper Cretaceous and Tertiary; the strongly differ from most older stromatolitic microstructures. Half of the studied tufa can suffer summer exposure and winter frost but related particular features do not seem to be preserved in the stromatolitic edifices.     

New species of Vomerina Winterton (Diptera, Therevidae, Agapophytinae) from Australia

Two new species of Vomerina Winterton, 2007 (Vomerina comapenissp. n. and Vomerina micorasp. n.) are described from New South Wales (Australia).     

New species of the myrmecophile Polyplocotes Westwood (Coleoptera: Ptinidae) from South Australia

Six new species of the Australian myrmecophilous ptinid genus Polyplocotes are described from South Australia. Three are from the deserts of central Australia, one from the Franklin Islands in the Great Australian Bight, one from Eyre Peninsula and one from the Riverland region. Morphologically, the majority of these new species are conventional Polyplocotes , but two are less typical. The characters uniting the genus are explored in the discussion, and comparisons are made to related genera. Although the six new species described here have not been observed in the field, the species of this genus are known to be myrmecophilous, and ant – beetle interactions similar to those seen in other spider beetles might occur between these new species and their host ants.     

Lacustrine bioherms,spring mounds,and marginal carbonates of the Ries-impact-crater (Miocene,Southern Germany)

Summary The petrographic investigation of the Miocene Rieslake-carbonates gave rise to a modifiedDunham-scheme for classifying non-marine carbonates. If the fabric is not exclusively the result of hydromechanical or biogenic effects,Dunham-terms were extended by interpretative attributes describing processes responsible for the secondary fabric development (pedogenesis, early meteoric diagenesis). The lowermost investigated section reveals a distinct zonation of the lake shore during humid stages (carbonates of the infra-, eu-, and supralittoral), interrupted by playa-like interstages of arid conditions (desiccated mudflat). Dolomitic successions of sinter-veneered bioherms, built by green algae and cyanobacteria, form an incomplete ‘reef belt’ at the northern crater rim. Bioherm sequences were controlled by a seasonally oscillating lake level and fluctuations of higher order, which correspond to small-scale climatic fluctuations in the range of several hundreds to thousands of years. A superposed facies trend is recognized, which is the result of the decreasing eutrophy, alkalinity, and carbonate supersaturation. This reflects the climatic change to generally humid conditions at the end of Miocene. Originally thrombolitic sublacustrine spring mounds were caused by upwelling groundwater from permeable bedrock. Cement framestones of the mound core are considered to result from fabric alteration within the upwelling ground water and by emersions. Marginal carbonates of the Ries basin, inclusively bioherms, probably were originally Mg-calcitic. Aragonite was restricted to gastropod shells and sublacustrine spring mounds. Dolomitization is interpreted as essentially due to a fluctuating phreatic mixing-zone caused by meteoric groundwater, which underflowed saline water at the soda lake margin. The algal flora comprises cyanobacteria, possible cyanobacteria, green algae, few charophytes, endoliths, and problematic forms. A Recent contamination by endolithic fungi and lichens is evident. Occasionally preserved insect larval tubes, mass accumulations of pupal cases of flies, and arthropod eggs demonstrate that these groups were once a prominent part of the fossil soda lake ecosystem of the N?rdlinger Ries.     

Biomarker studies on microbial carbonates: Extractable lipids of a Calcifying Cyanobacterial mat (Everglades, USA)

Summary Biomarker investigations are applied to the free lipid fractions of a naturally grown freshwater microbial mat, constructed by calcifying cyanobacteria (Scytonema sp. andSchizothrix sp.). The absolute and relative concentrations of hydrocarbons, free alcohols and carboxylic acids are studied and their probable biological precursors are discussed. A significant signal of cyanobacterial lipids is recognized by the strong predominance ofn-heptadecane (C₁₇),n-heptadecene, two monomethyl-heptadecanes, and the pentacyclic triterpenoid diploptene. Their occurrences parallel the lipid distributions found in pure cultured cyanobacteria and in recent cyanobacterial mats grown in particular environments (hypersaline, lagoonal, hot spring). The observed compound signature appears to be a suitable reference for environments, where cyanobacteria are directly associated with theloci of carbonate precipitation and thus, rock formation. In the studied material, a significant contribution of organic matter from other sources, especially higher plants is characterized by the occurrence of several specific marker compounds, namely lup-20(29)-ene-3-ol, high molecular weightn-alkanes and carboxylic acids. Although these components comprise a notably high portion of the sample’s lipid inventory, they are shown to be distinguished easily from the signal left by the predominant mat building organisms.     

The ecology of pre-imaginal simuliidae (Diptera) in South-East Queensland,Australia

A study of the pre-imaginal simuliid fauna of South-East Queensland was conducted to elucidate some of the aspects of their ecology. A total of 17 species of three genera (Cnephia, Austrosimulium and Simulium) bred in the area. The highest diversity of species was found to occur in mountainous areas near the coast which had the following conditions: high rainfall, steep relief, cool temperatures, on the edge of forests with streams of the order 1–3 (using a 1 : 250,000 map).More detailed studies of A. bancrofti, S. nicholsoni and S. ornatipes were made to investigate microdistribution, colonization, drift, pupation timing and population changes. Current velocity was the most important factor determining the distribution of A. bancrofti, while the distribution of S. nicholsoni was influenced by a preference for vegetation substrate and current velocity. Late instar larvae of A. bancrofti and S. ornatipes occurred in faster currents than early instar larvae. Pupae of these two species primarily occurred on the downstream side of submerged substrates. Colonization of a particular stream was dependent on the oviposition preference of gravid females while drift, looping, or descent on silk threads was used for larval dispersal from the oviposition site. Early instars of A. bancrofti drifted from quiet reaches of mature rivers to rapids, while S. ornatipes larvae appeared to be more sessile with limited dispersal from site of egg masses. Drift occurred throughout 24 hours with little change in total numbers. Early instars of A. bancrofti however showed a definite diurnal tendency while the proportion of late instars increased at night. Pupation of S. ornatipes was diurnal under undisturbed conditions. The larvae of A. bancrofti and S. nicholsoni both developed in the Brisbane River system, however the populations of A. bancrofti peaked in late winter, a dry season with stable water conditions while S. nicholsoni larvae were most abundant from late summer, at the end of the rains to the early winter. The larvae of S. ornatipes, which occur in small streams down to temporary trickles, were most numerous during the warm rainy period.Department of Parasitology, University of Queensland     

Bioerosion along a bathymetric gradient in a cold-temperate setting (Kosterfjord, SW Sweden): an experimental study

In the cold-temperate setting of the Swedish Kosterfjord, a 2-year experiment was launched in order to assess bioerosion rates and to investigate the endolithic borer communities in relation to light availability (relative bathymetry), hydrography and exposure time. The inventory of microendolithic traces, studied by SEM analysis of epoxy resin casts of planted bivalve shells, yields diverse ichnocoenoses comprising a total of 21 traces produced by boring cyanobacteria (7), chlorophytes (4), fungi (6) and traces of uncertain affinity (4). The link between the endoliths (biotaxa) and the traces they leave (ichnotaxa) is evaluated by the study of the boring organisms in situ by transmission light microscopy of planted Iceland spar and bivalve shells. Additionally, the activity of various macroborers (foraminiferans, polychaetes, echinoids, gastropods and sponges) is documented, adding to a distinct diversity maximum at 7 m water depth. A highly condensed photic zonation, due to the high latitude (59°) and eutrophic conditions, is recorded by the measurement of the Photosynthetically Active Radiation (PAR) and is confirmed by the bathymetric range of the photic related ichnocoenoses. At 1 m water depth, a mature shallow euphotic ichnocoenosis dominated by cyanobacteria and at 7 m, a deep euphotic ichnocoenosis dominated by chlorophytes, respectively, is developed after as little as 12 months exposure. With the vanishing light availability from 15 m downwards, the ichnocoenoses development is significantly slowed and only immature dysphotic and aphotic borer communities (dominated by fungi) are encountered. Strong fluctuations of salinity (down to 8%) and temperature (0–20°C) in the euphotic zone indicate most phototrophs present to be considerably euryhaline and eurytherm, while most endolithic fungi appear preferentially in the deeper, more stable marine waters.     

The first native Pyrgodesmidae (Diplopoda, Polydesmida) from Australia

Three new genera and six new species of Pyrgodesmidae are described from Queensland: Asticopyrgodesmusgen. n., containing Asticopyrgodesmus lamingtonensissp. n. and Asticopyrgodesmus maialasp. n. (type species); Nephopyrgodesmusgen. n., with Nephopyrgodesmus eungellasp. n. (type and only species); and Notopyrgodesmusgen. n., with Notopyrgodesmus kullasp. n. (type species), Notopyrgodesmus lanosussp. n. and Notopyrgodesmus weirisp. n. Localities and specimen data are given in an Appendix for undescribed Australian Pyrgodesmidae occurring in wet forests from the Northern Territory south to New South Wales, and on Lord Howe Island.     

Four new species of the myrmecophile Diplocotes Westwood (Coleoptera: Ptinidae) from Queensland and South Australia

Abstract  Four new species of the Australian ptinid genus Diplocotes are described. Two of these species are from the dry tropical and subtropical areas of northern and central Queensland, while the other two are from the arid areas of South Australia. While the four new species described here have not been observed with ants in the field, the species of this genus are known to be myrmecophilous, and similar interactions may occur between the new species and their host ants. Additionally, many characters are shared with other unrelated myrmecophilous species, and may be convergent adaptations to the ant-associated lifestyle.