Vertical distribution and diversity of bacteria and archaea in sulfide and methane-rich cold seep sediments located at the base of the Florida Escarpment

The bacterial and archaeal communities of the sediments at the base of the Florida Escarpment (Gulf of Mexico, USA) were investigated using molecular phylogenetic analysis. The total microbial community DNA of each of three vertical zones (top, middle and bottom) of a sediment core was extracted and the 16S rRNA genes were amplified by PCR, cloned and sequenced. Shannon–Weaver Diversity measures of bacteria were high in all three zones. For the archaea, diversity was generally low, but increased with depth. The archaeal clonal libraries were dominated by representatives of four groups of organisms involved in the anaerobic oxidation of methane (ANME groups). Phylogenetic analysis of bacteria suggests the dominance of -proteobacteria in the top zone, the -, - and -proteobacteria in the middle zone and the -proteobacteria in the bottom zone of the core. Members of the Cytophaga–Flexibacter–Bacteroidetes group, the Chloroflexi/green non-sulfur bacteria, the Gram+ (Firmicutes), the Planctomyces, candidate division WS3 and Fusobacterium were also detected. Our data suggest that the community structure and diversity of microorganisms can shift greatly within small vertical distances, possibly in response to changes in the physical and chemical conditions.     

The Roggeveldberge — Notes on a botanically hot area on a cold corner of the southern Great Escarpment, South Africa

Despite the Roggeveldberge comprising the montane heart of the celebrated Hantam-Roggeveld Centre of Plant Endemism (HRC), this section of the southern Great Escarpment in South Africa is botanically poorly known. A detailed physical, historical and phytogeographical overview of the Roggeveldberge is thus presented, and a checklist of 513 plant taxa is provided as a contribution towards a more complete flora for the Roggeveld-Komsberg Escarpment. The HRC is considered in detail, including various delimitations, and all species purported to be endemic to the HRC are reviewed and separated into actual endemics, near-endemics and species incorrectly considered as endemic.     

A phytogeographic assessment of the Nuweveldberge, South Africa

The Nuweveldberge forms the central and most arid component to the southern Great Escarpment in South Africa. Situated between the Sneeuberg in the east and the Hantam-Roggeveld in the west, the Nuweveldberge has elements of both the Succulent Karoo and Grassland Biomes. The Nuweveldberge has low endemism (0.5%) compared to the adjacent Sneeuberg (2.3%) and Roggeveldberge (ca. 8%). Following an extensive floristic survey of the Nuweveldberge, a contribution of 473 taxa is provided. Together with the flora by Rubin et al., 2001 for the Karoo National Park this provides a total flora of 1139 taxa for the Nuweveldberge. Numerous range extensions of (previous) Sneeuberg endemics and Drakensberg near-endemics onto the Nuweveldberge are recorded. Although the Nuweveldberge may have been a corridor facilitating the movement of species from the Cape Floristic Region via the Komsberg through the Nuweveldberge onto the Sneeuberg (and of Drakensberg elements westwards from the Sneeuberg) there is currently little evidence of such connectivity. This is postulated to be due to aridification of the Nuweveldberge since the Last Glacial Maximum, and also likely explains the low endemism on the Nuweveldberge.     

Natural Recover y and Restoration Potential of Severely Disturbed Talus Vegetation at Niagara Falls: Assessment Using a Reference System

The talus slope adjacent to the Niagara River at Niagara Falls (Ontario, Canada) has been severely disturbed over the course of the past century as the area has been increasingly developed for tourism. In addition the lower talus slope is disturbed by periodic ice scour, most recently one year prior to this study. Historical evidence suggests that the original vegetation was similar to that currently found on talus slopes of the Niagara Escarpment, which could, therefore, be used as a reference system and restoration target. The current community structure and physical environment were sampled in 75 randomly placed 1‐×‐1–m quadrats. A total of 137 species were found, of which 62%were aliens. ANOVA showed that species richness, woody debris cover, litter cover, soil depth, and photosynthetically active radiation changed along a gradient perpendicular to the river. Three different sections of the study area whose last severe disturbance dated back 100, 30, and 4 years, respectively, were similar in their physical environment but were significantly different in species richness. Ordinations of species frequencies showed that light levels and distance from the river were the principal gradients controlling the vegetation structure. The species composition of the section last disturbed 100 years ago was different from that of the more recently disturbed sections. Ordination and cluster analysis of the pooled data showed large differences between the Niagara Falls site and reference escarpment talus slopes. Natural escarpment vegetation was much more homogeneous and had more species and fewer aliens. By comparing reference talus with sections of the study area at Niagara Falls that were last disturbed at different times, we conclude that the trajectory of natural succession at Niagara Falls is leading to an alternative state, an urban forest dominated by aliens, and that active restoration will be required to return the talus to its original state.     

Evaluation of the Salinic I tectonic, Cancañiri glacial and Ireviken biotic events: Biochemostratigraphy of the Lower Siluriansuccession in the Niagara Gorge area, Canada and U.S.A.

Well-preserved brachiopods from the Niagara Gorge area, Anticosti Island, Britain, Gotland and Estonia were utilised to delineate a complex isotopic evolution for Llandovery-Wenlock seawater. The Sr-isotope record reflects the Salinic I tectophase of the Late Llandovery in the continuous increase in ⁸⁷Sr/⁸⁶Sr values from 0.708070 to 0.708346. The Salinic II tectophase is marked by relative constancy of Sr isotope values until the Late Wenlock when it rises from 0.708345 to 0.708430. The second tectonic phase was therefore likely only of a regional nature. The carbon isotopes during the Llandovery fall within a band of about − 1‰ to + 3‰, a range comparable to modern low-latitude brachiopods. A large positive δ¹³C excursion of about 3‰, identifies the Ireviken event/excursion, characterizes the Early Wenlock. The biotic crisis and the isotope excursion itself may be ultimately related to the onset and duration of the Cancañiri glaciation, although a direct causative scenario is as yet unknown. The oxygen isotopic trends of well-preserved brachiopods clearly reflect a warm climate interval during the latest Llandovery associated with the Silurian sea level highstand. Subsequently, in the Early Wenlock, the sea level fell with the onset of the Cancañiri glaciation in the southern hemisphere. This is reflected in a significant positive δ¹⁸O excursion, particularly in brachiopods from the Niagara Gorge area. Brachiopods from lower latitudes were awash in warm tropical currents and therefore exhibit somewhat more negative δ¹⁸O values, indicating a lesser cooling gradient.     

Environmental relations of the bryophytic and vascular components of a talus slope plant community

The environmental factors correlating with community structure of vegetation on talus slopes of the 785 km long Niagara Escarpment, southern Ontario, Canada, were studied using canonical correspondence and regression analysis. The bryophytes and higher vascular plants were analysed separately to see if their responses were similar or different. Both vascular plants and bryophytes responded similarly to the environmental variables that were measured. For both vegetation components, location from north to south explained most of the variance. When species richness was plotted against location for the complete vegetation and for the two components separately, the results showed that vascular plant species richness decreased with increasing latitude, while bryophyte richness increased. The magnitude of both of these trends was slight but consistent with the hypothesis that available environmental energy governs a significant amount of the variance in species richness. Since separate components of the talus vegetation were shown to respond differently to the same environmental variable, groups of taxa should not be excluded from community level studies without a consideration of the possible consequences of this bias.     

Time of application of Niagara 10637 for induction of maleness or femaleness inRicinus communis Linn.

Ethyl hydrogen-1-propylphosphonate (Niagara 10637) at concentrations of 500, 1000 and 2000 mg/l had two different effects on sex expression ofRicinus communis L. cvIari 132. Higher concentrations (1000 and 2000 mg/l), applied just before emergence of inflorescence i.e. to 90 day old plants, induced a marked increase in female flower number and reduced the number of male flowers on the first inflorescence. However, there was a tendency towards maleness on the second and third inflorescences. When applied to 60 day old plants, the test compound induced a high degree of maleness on the first and second inflorescences. Sex expression was not markedly altered with treatments at still younger stages (seeds and seedlings).     

Bryobartramia schelpei T.A.Hedderson,a new species to accommodate the South African populations of the genus

Abstract

South African populations of Bryobartramia have been treated as B. novae-valesiae, a species otherwise restricted to Australia. However, material from the two regions differs in a number of traits, and the African populations are here described as a new species, B. schelpei. The Cape species differs most obviously from B. novae-valesiae in the markedly prorate-papillose, narrow, thick-walled cells of the calyptra. Nested analysis of variance reveals further morphometric differences, including the relatively narrower, more cylindrical, calyptra with a longer rostrum, and the smaller leaf cells and spores. Bryobartramia schelpii is known only from arid portions of the winter rainfall region in the Northern and Western Cape Provinces of South Africa.     

Somatic embryogenesis and long term maintenance of embryogenic lines from fox grapes

In the present paper, a method for the induction and long-term maintenance embryogenic cultures for Vitis × Labruscana `Niagara' and `Fredonia' is reported. Embryogenic cultures from these two cultivars were induced in an embryogenesis establishment medium (CIM) from ovaries obtained from flowers 10–14 days pre-anthesis. The embryogenic lines obtained in this experiment have been stably maintained for more than 2 years, through repeated subcultures on a long-term maintenance medium (LTMM) without loss of embryogenic competence. Somatic embryo regeneration and maturation have been successfully achieved after 30 days of cultivating embryogenic cultures in an embryo regeneration medium (EDMM), supplemented with charcoal and polyethylene glycol. The somatic embryos were successfully germinated in two different media, `Fredonia' germination medium (FGM) and `Niagara' germination medium (NGM), and converted into normal looking plants on a conversion medium (CM). This revised version was published online in June 2006 with corrections to the Cover Date.