Production of C2-symmetrical phenazines by some actinomycetes

The C₂-symmetrical phenazines produced by Microbispora and Streptosporangium were identified as 1,6-phenazinediol-5,10-di-N-oxide (φd-dioxide) and 1,6-phenazinediol (φ-diol). Both oxidation of φ-diol to φd-dioxide and reduction of φd-dioxide to φ-diol were detected with M. amethystogenes and M. parva. No albino mutants lacking φ-diol-oxidation ability were isolated from cultures of Microbispora incubated in the presence of acridine orange, or those incubated at sublethal temperatures.     

Correlation of shape and habit with sediment grain size for selected species of the bivalve Anadara

Burrowing ability was experimentally determined for a range (3–150 g) of sizes of the blood ark, Anadara ovalis , in sieved sediments ranging from very coarse sand (-1 φ) to silt (>4 φ). Small individuals (<5 g) could penetrate the complete range of sieved sediments, but the ability to reburrow apparently decreases with size (age) so that adults larger than 50 g can only reburrow in fine sands (2.5–3.0φ). This semi-infaunal species has a length/height ratio of 1.16 and is most commonly found in sand. The infaunal A. cheninitzi and A. braziliana , with L/H values of 1.10 and 1.18, respectively, are also most common in sands. The ovate (L/H ratio = 1.07–1.25) forms of the Pliocene A. trilineata from the Kettleman Hills of California are inferred to have been infaunal, based on the absence of muricid boreholes and the infrequent occurrence of epizoans. Ovate specimens are restricted to fine sands (2–3φ) in the Etchegoin and San Joaquin Formations, sediment textures into which the adults could probably reburrow. Elongated shell morphotypes (L/H = 1.5–1.67) have muricid boreholes and epizoans concentrated posterodorsally on the inferred exposed portion of the shells in life position. Populations of elongated shells were associated with gravelly, sandy and silty sediments, as is the living epibyssate A. lienosa (L/H = 1.72) and A. transversa (L/H = 1.48).□ Anadarids, burrowing, epifounal, infaunal, Pliocene, sediment influence .     

A new encrusting interstitial marine fauna from Brazil

Abstract. This paper reports the second occurrence of a sand‐grain encrusting interstitial epifauna dominated by bryozoans and polychaetes at a site thousands of kilometers from the first described occurrence of such a fauna 20 years ago. Such faunas seem to have gone almost unrecorded in the marine ecological literature, but they are potentially geographically widespread and ecologically significant, deserving recognition and further study by benthic ecologists. Although rooted‐erect and free‐living lunulitiform bryozoans can be abundant in soft‐bottom habitats, the presence of encrusting forms was, until recently, considered to be limited to patches of hard substrata. In 1985 and 1988, a new and seemingly unique habitat for encrusting bryozoans and other organisms on single grains of shell or sand was reported from the coastal waters of Florida, USA. Here we report a second discovery of an interstitial encrusting fauna from the continental shelf off the state of São Paulo, Brazil. In addition to the cupuladriid Discoporella umbellata, several species of bryozoans (9 cheilostomes, 3 ctenostomes, and 1 cyclostome) were found encrusting on or boring into sand grains from the 4 stations examined. Four species were found exclusively on sand to gravel size grains. The most abundant colonies, with ～1300–1500 colonies m^?2, belonged to a new species of Cleidochasma. New species of Trypostega and Reginella, each with up to 200–300 colonies m^?2, were also discovered. The grain‐encrusting bryozoans were characterized by their small size, and by the fact that sexual reproduction was initiated very early in colony growth; brood chambers (for the development of embryos into larvae) occurred in colonies having only a few zooids. Colonies of boring ctenostome and cheilostome bryozoans were even more abundant than those of grain encrusting forms, being present in almost every piece of shell (～5000–5500 colonies m^?2). The fauna also included representatives of other groups of encrusting organisms, especially tubeworms (11,000–13,000 tubes m^?2). Planned work on samples from additional stations on the São Paulo shelf will no doubt yield a larger number of species from various taxa and perhaps show some overlap in sand fauna species between the Brazilian and Floridian sites. In addition to the unique species of single grain encrusters, colonies of bryozoan species characteristic of larger subtidal hard substrata were also found on sand or gravel size grains, indicating that an interstitial refuge may be available to some epifaunal taxa and suggesting that this interstitial refuge, which remains almost completely unknown to benthic ecologists, may play a large role in determining distributions of those taxa.     

Density and environmental effects on shell size in some sand dune snail populations

Populations ol three species of land snail, Helicella itala. Candidula intersecta and Cochlicella acuta are studied on sand dunes on Coll in the Inner Hebrides.
Population density and mean shell size were estimated on 18 sample sites. The sites were ranked for six environmental factors. Environmental factors which are related to the dune vegetational succession account for much of the variation in the densities of C. intersecta and C. acuta . The density of H. itala , however, shows no strong association with these factors. Both snail density and shell size are reactively independent of total soil calcium levels. For each of the three species, mean shell size is negatively associated with population density; the environmental factors account for little of the variation in shell size.
Four possible mechanisms are suggested to account for the variation of shell size with density. It is argued that a direct influence of density on shell size, possibly mediated by mucus conditioning of the environment is the most probable mechanism. There is some evidence to suggest an inter-specific effect whereby C. intersecta density affects H. itala shell size.     

Effect of taphonomic processes on dental microwear

Taphonomic processes have the potential to affect microscopic wear on teeth and to modify the wear patterns so as to confound dietary reconstructions based on dental microwear which was formed during the lifetime of an animal. This study describes a series of experiments which were conducted to simulate various taphonomic agents and to record their effect on dental microwear. Three types of experiment were carried out in order to explain anomalous microscopic wear that had been found on the dentition of several hominoid specimens from the 15 M.a. site of Pasalar in Turkey. The effect of two different acids-citric and hydrochloric acid-on dental microwear was investigated. Modification to microscopic wear caused by alkali (carbonatite ash) was examined in the second set of experiments. Lastly, the effect of abrasion by three different size classes of sediment from the site of Pasalar-quartz pebbles (grain size varied from 2,000-11,000 microm), coarse sand (grain size ranged from 500-1,000 microm), and medium-sized sand (grain diameters were between 250 and 500 microm)-was investigated. Results confirm previous findings that the taphonomic modification of dental microwear is readily identifiable and causes the obliteration rather than secondary alteration of microwear features. The experiments show that both citric and hydrochloric acid affect dental microwear but to varying degrees, whereas alkali did not cause any modification of microscopic features. The different size classes of sediment also had different effects on the dental microwear. The largest size sediment (quartz pebbles) polished the enamel and removed finer microwear features. The coarse sand, however, did not have any effect on the microwear. The greatest amount of abrasion was caused by the smallest sediment particles -the medium-sized sand. Several hominoid dental specimens from Pasalar display similar microscopic wear to the two types of acid erosion and the abrasion caused by the medium-sized sands.     

Plant functional traits and diversity in sand dune ecosystems across different biogeographic regions

Plant species of a functional group respond similarly to environmental pressures and may be expected to act similarly on ecosystem processes and habitat properties. However, feasibility and applicability of functional groups in ecosystems across very different climatic regions have not yet been studied. In our approach we specified the functional groups in sand dune ecosystems of the Mediterranean, Hyrcanian and Irano-Turanian phytogeographic regions. We examined whether functional groups are more influenced by region or rather by habitat characteristics, and identified trait syndromes associated with common habitat types in sand dunes (mobile dunes, stabilized dunes, salt marshes, semi-wet sands, disturbed habitats). A database of 14 traits, 309 species and 314 relevés was examined and trait-species, trait-plot and species-plot matrices were built. Cluster analysis revealed similar plant functional groups in sand dune ecosystems across regions of very different species composition and climate. Specifically, our study showed that plant traits in sand dune ecosystems are grouped reflecting habitat affiliation rather than region and species pool. Environmental factors and constraints such as sand mobility, soil salinity, water availability, nutrient status and disturbance are more important for the occurrence and distribution of plant functional groups than regional belonging. Each habitat is shown to be equipped with specific functional groups and can be described by specific sets of traits. In restoration ecology the completeness of functional groups and traits in a site may serve as a guideline for maintaining or restoring the habitat.     

Sand as a medium for transmission of vibratory signals of prey in antlions Euroleon nostras (Neuroptera: Myrmeleontidae)

Abstract.  European pit-building antlions ( Euroleon nostras / Geoffroy in Fourcroy/) detect their prey by sensing the vibrations that prey generate during locomotory activity. The behavioural reactions and some of the physical properties of substrate vibrations in sand are measured to observe signal transmission through the substrate. The frequency range of the signals of four arthropod species ( Tenebrio molitor , Pyrrhocoris apterus , Formica sp. and Trachelipus rathkei ) is 0.1–4.5 kHz and acceleration values are in the range 400 μm s⁻² to 1.5 mm s⁻². Substrate particle size and the frequency of prey signals both influence the propagation properties of vibratory signals. The damping coefficient at a frequency 300 Hz varies from 0.26 to 2.61 dB cm⁻¹ and is inversely proportional to the size of the sand particle. The damping coefficient is positively correlated with the frequency of the pulses. Vibrations in finer sand are attenuated more strongly than in coarser sand and, consequently, an antlion detects its prey only at a short distance. The reaction distance is defined as the distance of the prey from the centre of the pit when the antlion begins tossing sand as a reaction to the presence of prey. The mean reaction distance is 3.3 cm in the finest sand (particle size ≤ 0.23 mm) and 12.3 cm in coarser sand (particle size 1–1.54 mm). The most convenient sands for prey detection are considered to be medium particle-sized sands.     

Endomycorrhizae in plant colonization on coastal sand-dunes at Cooloola,Queensland

Soil, fungi, including species forming endomycorrhizae, appear to be important to pioneer plants colonizing coastal sand-dunes in the subtropics. In three mobile dunes at Cooloola, Queensland, networks of fungal hyphae were very common in the surface 0-20 cm of bare sand of the colonizing zones. These networks, consisting of long threads of hyphae, extend out into the bare sands from the roots of pioneer seedlings, most of which are endomycorrhizal. The fungi intermesh sand-grains to form aggregates which appear to be an important factor in stabilizing these loose sands. The sands are dominantly quartz grains partly covered by thin sesquioxide coatings which contain some phosphorus. Phosphorus held by sesquioxide is generally regarded as being unavailable to most plants. However, the close attachment of hyphae to these coatings, the lack of alternative sources of phosphorus and the prominence of endomycorrhizal fungi are consistent with these fungi obtaining phosphorus from these surfaces. These fungi appear to be important in plant colonization of these dunes and could have appliction in revegetaton of disturbed areas.     

Recent advances and synthesis in biodiversity and biogeography of arenicolous Collembola

Synthesis and new data on interstitial Collembola-fauna in littoral and continental sand sediments. Collembola biodiversity in supralitoral and inland sands can not be compared to the biodiversity developed in mineral soils or leaf litter, and Collembola biodiversity in intertidal sands is lower. The problem of the dispersial of these littoral sand Collembola is considered. A number of species appear have a trans-oceanic dispersal on considerable distances on or in sea water.     

Particulate matter filtration and seasonal nutrient dynamics in permeable carbonate and silicate sands of the Gulf of Aqaba,Red Sea

This study compares mineralization in permeable silicate and carbonate sands in the shallow shelf of the Gulf of Aqaba. From July 1999 to March 2000, we monitored concentrations of inorganic nutrients in water and pore water at two neighboring sites, one dominated by silicate, the other by carbonate sand. Although the carbonate was coarser than the quartz sand, organic matter, dissolved inorganic nitrogen (DIN), and ortho-phosphate concentrations in the biogenic carbonate sediment always exceeded those in the terrigenic silicate sands (factor 1.5–2.0 for organic matter, 1.7–14.0 for nutrients). Higher nutrient concentrations in the water column during winter months caused increases in pore-water nutrient concentrations in both sediments down to 10 cm depth with no significant delay, emphasizing the effect of advective transport of solutes and particles into permeable sands. An experiment was conducted where sieved clean quartz and carbonate sands of same grain size (250–500 µm) were incubated in-situ. Although exposed to the same water and boundary current conditions, the sieved carbonate sand accumulated more organic matter and developed higher nutrient concentrations than the incubated silicate sediment. We conclude that the mineralogical characteristics of the carbonate sand (higher porosity, sorption capacity and pH buffer capacity) enhance the filtration capacity, and the biocatalytic conversion efficiency relative to the smooth crystalline quartz grains.     

Density and environmental effects on shell size in some sand dune snail populations

Populations ol three species of land snail, Helicella itala. Candidula intersecta and Cochlicella acuta are studied on sand dunes on Coll in the Inner Hebrides. Population density and mean shell size were estimated on 18 sample sites. The sites were ranked for six environmental factors. Environmental factors which are related to the dune vegetational succession account for much of the variation in the densities of C. intersecta and C. acuta. The density of H. itala, however, shows no strong association with these factors. Both snail density and shell size are reactively independent of total soil calcium levels. For each of the three species, mean shell size is negatively associated with population density; the environmental factors account for little of the variation in shell size. Four possible mechanisms are suggested to account for the variation of shell size with density. It is argued that a direct influence of density on shell size, possibly mediated by mucus conditioning of the environment is the most probable mechanism. There is some evidence to suggest an inter-specific effect whereby C. intersecta density affects H. itala shell size.     

The sedimentary facies of <Emphasis Type="Italic">Posidonia oceanica</Emphasis> seagrass meadows from the central Mediterranean Sea

Sedimentary facies of seven Posidonia oceanica meadows of western Mediterranean Sea were investigated. Five meadows are located in the Tyrrhenian coast, two are placed in the western coast of Sardinia and Corsica. These meadows develop on soft and hard substrates, often forming “mattes”, in areas characterized by different oceanography, morphology, and terrigenous inputs produced by coastal erosion and fluvial runoff. A total of five sedimentary facies have been recognized ranging from pure terrigenous to bioclastic: terrigenous sand to gravelly sand, bioclastic sands, skeletal gravelly sands, mixed siliciclastic–carbonate sands, well to moderately sorted skeletal siliciclastic sands. All of the sedimentary facies associated with P. oceanica are in the sand grain size. The gravelly fraction is generally subordinated and variable, whereas the muddy fraction is generally low. The very low frequencies of the muddy fraction can be attributed to re-suspension processes and to the lack of carbonate mud production. The rate of epiphytic carbonate production obtained by two of the investigated meadows averages 400 g m^?2 year^?1. This value is in the range of temperate Mediterranean as well as of tropical and subtropical seagrasses. The epiphytic carbonate production plus the calcareous biota living on seagrass substrate contributes to form mixed siliciclastic–carbonate sediments of the nearshore environment of the Mediterranean. Lastly, the carbonate production associated with seagrass was derived by biota belonging to the heterozoan assemblage, where aphotic organisms are dominant, together with oligophotic biota such as coralline algae and symbiont-bearing foraminifera. Consequently, in the well-illuminated seagrass settings, the prevalent skeletal assemblages is represented by the heterozoan association while the components of the photozoan assemblages are absent or subordinate. This a key point for the paleoenvironmental reconstruction of the photic zone in the fossil record. Because the skeletal components of many seagrass dwellers greatly contribute to the carbonate sediment production of photic shallow-water environments, the seagrass meadows became substantial places of carbonate production and C (organic and inorganic) sequestration during the Cenozoic.     

Importance du sédiment dans la distribution des Lingules

Log-probability curves of grain-size distribution have been analysed of sediments collected in three previously described localities occupied by either Lingula anatina or L. reevei (Brachiopoda, Inarticulata). The grain-size population transported by saltation (average about 92–223 μm), generally associated with traction load population, determines Lingula distribution. The two preferential substrates of both studied species (density > 100 individuals/m^-2) are compact and stable sediments under moderate water currents: either coarse sands and gravels clogged by fine and very fine sands, or fine, very fine and clay sands (saltation populations more than 60%). As soon as the suspension population and/or traction increase in the sediment to the detriment of the saltation population, the density of Lingula decreases rapidly. Nevertheless, if grain-size distribution and populations have a primordial function for Lingula , other ecological features (i.e. the environmental fauna, high occurrence of digging species, the available nutrients) will affect the distribution and sometimes become prevailing. The absence of important changes in the shell shape of Lingula since its origin suggests that the grain-size requirements remained about the same.     

Chlamydia bacteriophages

Phages are called “good viruses” due to their ability to infect and kill pathogenic bacteria. Chlamydia are small, Gram-negative (G?) microbes that can be dangerous to human and animals. In humans, these bacteria are etiological agents of diseases such as psittacosis or respiratory tract diseases, while in animals, the infection may result in enteritis in cattle and chronic bowel diseases, as well as miscarriages in sheep. The first-known representative of chlamydiaphages was Chp1. It was discovered in Chlamydia psittaci isolates. Since then, four more species of chlamydiaphages have been identified [Chp2, Chp3, φCPG1 φCPAR39 (φCpn1) and Chp4]. All of them were shown to infect Chlamydia species. This paper described all known chlamydiaphages. They were characterised in terms of origin, host range, and their molecular structure. The review concerns the characterisation of bacteriophages that infects pathogenic and dangerous bacteria with unusual, intracellular life cycles that are pathogenic. In the era of antibiotic resistance, it is difficult to cure chlamydophilosis. Those bacteriophages can be an alternative to antibiotics, but before this happens, we need to get to know chlamydiaphages better.     

Diversity and Transport of Microorganisms in Intertidal Sands of the California Coast

Forced by tides and waves, large volumes of seawater are flushed through the beach daily. Organic material and nutrients in seawater are remineralized and cycled as they pass through the beach. Microorganisms are responsible for most of the biogeochemical cycling in the beach; however, few studies have characterized their diversity in intertidal sands, and little work has characterized the extent to which microbes are transported between different compartments of the beach. The present study uses next-generation massively parallel sequencing to characterize the microbial community present at 49 beaches along the coast of California. In addition, we characterize the transport of microorganisms within intertidal sands using laboratory column experiments. We identified extensive diversity in the beach sands. Nearly 1,000 unique taxa were identified in sands from 10 or more unique beaches, suggesting the existence of a group of “cosmopolitan” sand microorganisms. A biogeographical analysis identified a taxon-distance relationship among the beaches. In addition, sands with similar grain size, organic carbon content, exposed to a similar wave climate, and having the same degree of anthropogenic influence tended to have similar microbial communities. Column experiments identified microbes readily mobilized by seawater infiltrating through unsaturated intertidal sands. The ease with which microbes were mobilized suggests that intertidal sands may represent a reservoir of bacteria that seed the beach aquifer where they may partake in biogeochemical cycling.     

Germination requirements and seedling responses to water availability and soil type in four eucalypt species

We conducted experiments on seed germination, seedling survival and seedling growth of four Eucalyptus species to identify factors that might explain why they are restricted to the two major soil types in southwestern Australia, deep sands (E. macrocarpa, E. tetragona) and lateritic loam (E. loxophleba, E. wandoo). At high temperatures (28 °C), germination in darkness was lower for the two ‘loam species’ than for the ‘sand species’, while there were no differences in light or at low temperatures (10 °C). Germination commenced earlier, and was faster in the sand species than in the loam species, but was almost inhibited in all species by –1.0 MPa. E. tetragona proved the most drought-tolerant in terms of germination level and seedling survival. Seedlings of the sand species had much longer roots two weeks after germination in the absence of water stress, and the roots of more seedlings continued to elongate under moderate water stress (–1.0 MPa), than the two loam species. Roots were longer in all species, except E. macrocarpa, at –0.5 MPa than at –0.1 MPa, despite seedlings having a smaller mass and hypocotyl length. As water availability declined, there was a tendency for the sand species to survive longer on sand than on loam while soil type had no effect on the loam species. Pattern and duration of seedling survival of the loam species was similar to that of the sand species despite their smaller seeds. We conclude that seedlings from the large-seeded sand species are able to penetrate the soil profile faster and deeper, but that they are not less prone to drying soils than seedlings from the small-seeded loam species. Instead, seed size and germination speed are important prerequisites to cope successfully with unstable soil surfaces and to exploit the rapidly descending water in deep sands.     

Modelling nearshore intertidal habitat use of young-of-the-year Pacific sand lance (Ammodytes hexapterus) in Barkley Sound, British Columbia, Canada

The Pacific sand lance (Ammodytes hexapterus) is an ecologically important prey species for many vertebrate marine predators in the Pacific Northwest. In this study, we examined the use of intertidal habitat by young of the year (YOY) sand lance in Barkley Sound, British Columbia. We selected 14 of the original 29 independent environmental variables for modelling based on univariate analysis for variable selection. These were then used to model sand lance presence-absence using a classification tree approach. Based on our models we found that sand lance avoided mud and intertidal eelgrass. For sites that had very little mud and no intertidal eelgrass, sand lance preferred sediment size mean ≥1,918 μm or sites with sediment size mean ≤1,918 μm but with relatively well sorted sediment (sorting values ≤2.56 SDs, used as a heterogeneity index of the substrate grain size). Adjacent subtidal characteristics were not found to be important at this scale of study. This suggests intertidal substrate characteristics and presence-absence of intertidal eelgrass are the main influences on occurrence of YOY in the intertidal. Our results support the hypothesis that sand lance are associated with particular sediment types, however intertidal sediment types used by sand lance in our study differ from known preferences of sand lance for subtidal sediment types. This difference may be due to unique habitat constraints for intertidal versus subtidal regions. Although it is unknown if the results of this study are widely applicable, the results begin to identify intertidal habitat features that are important for Pacific sand lance.     

Differentiating pollen of Betula species from Iceland

Subfossil pollen from two co‐existing Betula species in Iceland, B. nana and B. pubescens, is frequently found in sediments and peat. Interpretation of the findings often depends on the ability to differentiate between the two species according to pollen size and structure. Fresh pollen samples were prepared from 70 individual trees/shrubs which had been identified to species by chromosome number. Grain diameters and pore depths were measured and ratios of grain diameter to pore depth (D/P ratios) were calculated. The mean grain diameters of pollen from diploid B. nana and tetraploid B. pubescens were 20.42 and 24.20?µm, whereas mean pore depths were 2.20 and 2.81?µm respectively. Mean D/P ratios were therefore 9.55 for B. nana and 8.85 for B. pubescens. The difference between species was statistically significant for all three pollen parameters. Grain diameter appeared to be the most useful parameter, as only about 20% of the samples were in the overlapping region of the species distributions. Pollen size (grain diameter) was also positively correlated to tree morphology, which was evaluated using species‐specific botanical characters. Pollen samples from different locations/populations in Iceland varied slightly in mean size and ratio. The size difference between pollen of B. nana and B. pubescens in this study is less than other papers have reported, which may be due to the effect of introgressive hybridisation between the two birch species in Iceland.     

Effects of soil characteristics and human disturbance on tiger beetle oviposition

Abstract 1. Understanding species‐specific habitat requirements is important in insect ecology. Co‐occurrence of closely related species can provide insight into microhabitat segregation. Tiger beetles are well suited for such studies, as they occur in multi‐species assemblages, exhibit species‐specific habitat requirements, and are sensitive to anthropogenic modifications of the environment. 2. This study investigated ovipositional microhabitat choice of two sympatric tiger beetles at Point Reyes National Seashore, California, U.S.A., and evaluates how human activity affects that choice. Cicindela oregona is widespread and common whereas C. hirticollis, an undescribed subspecies, is locally threatened. Laboratory experiments tested oviposition‐site selection of the two species in response to variations in moisture, pH, salinity, and grain size. Field experiments tested larval burrow location in response to experimental shading and experimental human disturbance. 3. Laboratory results indicated that while C. hirticollis females preferred a narrow range of moisture levels and fine sands, C. oregona females had more specific pH and salinity requirements and preferred coarser sands. They also differed in timing of activity. Preferences are probably related to prevention of fungal or bacterial infection and avoidance of desiccation and immersion. 4. In the field, significantly more larval burrows were found under experimental shading for both species. In addition, repeated human compaction of the sand significantly decreased the number of larval burrows. 5. Results suggest that protection of microhabitat, restoration of native plants, and limitation of human traffic are vital in the conservation management of tiger beetles.     

Characeae-derived carbonate deposits in Lake Ganau, Kurdistan Region, Iraq

Characeae, a family of calcifying green algae, are common in carbonate-rich freshwaters. The southwestern shoreline of Lake Ganau (Kurdistan Region, northeastern Iraq) harbors dense and thick mats of these algae (genus Chara). On the lake bottom and along the shore, carbonate sands and rocks rich in the remains of stems, branches, nodes, and whorls of Chara are deposited. These deposits show all stages of growth and degradation of characean algae, including replacement and lithification into limestone. The replacement of the fragments by fine-grained calcite preserved delicate microstructures of Chara, such as cortical walls, cell shape, inner and outer layers of the stems, and reproductive organs. Based on roundness, sorting, the degree of lithification, and preserved microstructures of the grains (fragments), three facies were recognized. The first is represented by a newly formed lime sand facies showing elongated grains, poor sorting, and reduced roundness, with pristine preservation of characean surface microstructures. The second is a weathered lime sand facies, which shows better sorting and good roundness, whereas internal structures of characean fragments are still well preserved. The third is comprised of a lithified lime sand facies (grainstone), with very well sorted and rounded grains, and poorly preserved external and internal structures of the characeans. As compared to the newly formed lime sand facies, the grainstone facies shows an increase in grain size by more than 30 %, owing to precipitation of micritic lamina of possible microbial origin. Eventually, the Characeae-derived lime sands are lithified into oolitic limestones with sparry calcite cement, forming a grainstone microfacies. The present study has important implications for the interpretation of pre-Quaternary environments, as it records all stages of the fossilization process of characean green algae and highlights the role of these algae in the formation of oolitic carbonate rocks.