Influence of natural and anthropogenic factors on the hydrophilic flora of water ecosystems of the southern part of the Ob-Irtysh interfluve

Factors of negative anthropogenic impacts on hydrophilic flora are analyzed in detail and classified. Natural local and regional changes dependent on the climatic factors of the study region are considered. Vanishing and endangered species are identified.     

A contribution to the rust flora (Uredinales) on Aizoaceae in southern Africa

Rust fungi on Aizoaceae in southern Africa have been examined and reported based on 27 specimens collected during a biodiversity study and previously collected herbarium specimens. Eight species including five new species have been recognized, and they are described in detail and illustrated. Together with two additional species in literature, ten species of rust fungi are now recognized on Aizoaceae in southern Africa. Part 223 in the series “Studies in Heterobasidiomycetes” from the Botanical Institute, University of Tübingen.     

Phytoplankton flora in the Warri/Forcados Estuary of southern Nigeria

The phytoplankton flora of the Warri/Forcados estuary varied from typical fresh and brackish water forms to purely distinct marine species. These were made up of members of the Bacillariophyta (about 80 species), Chlorophyta (over 90 species), Cyanophyta (16 species), Dinophyceae (10 species) and the Euglenophyta (8 species). The bulk of the species belonging to the Chlorophyta, Cyanophyta and the Euglenophyta were almost exclusively fresh-water in distribution, being limited to habitats of less than 0.5 salinity. Members of the Bacillariophyta were found in all habitats, occurring freely in freshwater, estuarine, and marine ecosystems. In all cases, no true examples of euryhalinity were recorded. The majority of dinoflagellates encountered, as well as a number of marine diatoms, manifested stenohaline peculiarities as they could not tolerate a wide salinity range.The overall influence of the periodic shift in salinity and some physico-chemical parameters along the stretch of the estuary brought about by strong tidal effects and the variable seasonal volume of water discharge or runoff on the pattern and limit of distribution of phytoplankton species is highlighted.     

High-resolution studies on vegetation succession, hydrological variations, anthropogenic impact and genesis of a subrecent lake in southern Ecuador

A lake sediment record from Laguna Campana at 2,488 m a.s.l. in the eastern Ecuadorian Andes allows the reconstruction of local environmental conditions over the past ~500 years. A high-resolution multi-proxy approach using pollen, spore, charcoal and XRF analyses provides information about lake genesis, hydrological variations and the development of the surrounding vegetation. Results suggest that Laguna Campana originated from a landslide, which are naturally common and anthropogenically promoted in the study area. Human activities, e.g. deforestation or slash and burn cultivation, impacted the local vegetation development and biodiversity during the recorded period. After a first dense layer of pioneer grasses developed on open soil around the small lake, successional stages of secondary upper mountain rainforest forest mainly composed of Alnus and Weinmannia were observed. The record shows no signs of dense forest regeneration but rather open vegetation with trees and a grassy understory. Especially since ca. a.d. 1980, the proportion of forest in the area was reduced, most probably by fire use for pastures, cultivation and wood extraction. Hydrological variability was derived from differences in minerogenic input and variations in Botryococcus braunii and Sphagnum occurrence. After wettest conditions at the study site, probably triggering the landslide, humid conditions persisted until a time of drier conditions between a.d. 1900 and 1960. A subsequent return to wetter conditions was observed over the last decades. XRF analyses suggest an increase in deposition of atmospherically derived lead since the formation of the lake.     

Oligochaete communities at the mouth of the Neva and their relationship to anthropogenic impact

Changes in the oligochaete community of the Neva Mouth for the period 1982–1993 are discussed in relation to anthropogenic impacts. A number of community parameters such as species composition, biomass and diversity were generally stable, although local changes were noted. Predominance of eutrophic species, i.e. L. hoffmeisteri, T. tubifex, P. hammoniensis was enhanced, whereas mesotrophic and oligotrophic species — L. isoporus, S. heringianus, T. newaensis disappeared or became less numerous at some stations. The reverse trend was observed at other stations. These phenomena were accompanied by a sharp increase in the variability of biomass and/or diversity, which is regarded as exceeding normal annual fluctuations. The oligochaete community is recognized as a promising indicator of the ecological situation in the Neva Mouth.     

Nitrogen cycling and anthropogenic impact in the tropical interamerican seas

We discuss the mechanisms leading to nutrient limitation in tropical marine systems, with particular emphasis on nitrogen cycling in Caribbean ecosystems. We then explore how accelerated nutrient cycling from human activities is affecting these systems.Both nitrogen and phosphorus exert substantial influence on biological productivity and structure of tropical marine ecosystems. Offshore planktonic communities are largely nitrogen limited while nearshore ecosystems are largely phosphorus limited. For phosphorus, the ability of sediment to adsorb and store phosphorus is probably greater for tropical carbonate sediments than for most nearshore sediments in temperate coastal systems. However, the ability of tropical carbonate sediments to take up phosphorus can become saturated as phosphorus loading from human sources increases. The nature of the sediment, the mixing rate between nutrient-laden runoff waters and nutrient-poor oceanic waters and the degree of interaction of these water masses with the sediment will probably control the dynamics of this transition.Nearshore tropical marine ecosystems function differently from their temperate counterparts where coupled nitrification/denitrification serves as an important mechanism for nitrogen depuration. In contrast, nearshore tropical ecosystems are more susceptible to nitrogen loading as depurative capacity of the microbial communities is limited by the fragility of the nitrification link. At the same time, accumulation of organic matter in nearshore carbonate sediments appears to impair their capacity for phosphorus immobilization. In the absence of depurative mechanisms for either phosphorus or nitrogen, limitation for both these nutrients is alleviated and continued nutrient loading fuels the proliferation of nuisance algae.     

The species composition and distribution of diatoms in sphagnum bogs of European Russia: Ecosystems of the Volga Upland

The species composition of diatoms in ten sphagnum bogs of the Volga Upland (Penzenskaya oblast) was studied. A systematic and ecologo-geographical analysis of flora was performed. A great number of algae were found (291 species and intraspecific taxon) that differ in specific ecological features and frequency of occurrence in samples. The horizontal heterogeneity of diatom communities in the sphagnum cover was established, and a decrease in the number of species from the center to the bog periphery was determined.     

Historical changes in anthropogenic lead fallout in southern Ontario,Canada

A quantitative historical record of anthropogenic lead deposition has been determined for the Haliburton region of southern Ontario from a) the relative change in lead concentration in undisturbed sediment cores, and b) the total anthropogenic lead deposition measured in the region. The first parameter was measured on two sediment cores from a meromictic lake. Total lead deposition was assumed to be the average of that measured for eight other lakes in the study area. The validity of this historical record was tested on sediment cores from nearby dimictic lakes. Predicted lead concentration profiles closely resembled observed profiles.     

The role of anthropogenic and natural factors in changes in mesophilic rodent distribution in steppes between the Ural and Volga Rivers

A rapid increase in the average annual temperature (mainly due to rise in temperature during the cold season) and total annual precipitation is observed against the background of climate warming in the Northern Hemisphere as a whole and in the steppe zone between the Ural and Volga Rivers in particular. This has resulted in a change in many natural processes. As the dynamics of climate parameters is ostensibly regional in character, it is expedient to describe these changes in the course of regional studies. We demonstrate this phenomenon using the change in the distribution of mesophilic rodents in steppes of Zavolzh’ye as an example. We also show the role of flood-lands of steppe rivers, dammed beds of hollows and of roadside, field-sheltering, and other forest belts in provision for expansion processes.     

Functional ecology and palaeolimnology: using cladoceran remains to reconstruct anthropogenic impact

The field of lake palaeoecology has undergone significant changes. Powerful quantitative techniques have been developed to investigate anthropogenic impacts on lakes. Inclusion of zooplankton and benthic chydorid cladocerans has provided previously unavailable information on the historical development of planktivorous fish populations, submerged macrophytes and lake production, and has been used to document exotic species introductions, rapid genetic evolution and human disturbance of lakes. In particular, new techniques now allow a more complete evaluation of changes in past and present trophic structure to be made, and provide insights on the rapid evolutionary responses of aquatic invertebrate communities to anthropogenic perturbation of lakes.     

Elevational patterns in the vascular flora of a highly diverse region in southern Mexico

We examined general and family-specific patterns of vascular plant richness along a large elevational gradient (0?C3,670?m a.s.l.), assessed the continuity of these patterns and analysed their potential underlying causes in a high diversity region of the Sierra Madre del Sur, Oaxaca, Mexico. We used a vascular plant database constructed previously. The gradient was divided into 18 200-m elevation belts. To examine elevational patterns of richness, we used both observed and estimated (interpolated) species richness, as well as genus and family observed richness, for each belt. A generalised linear model (GLM) was used to assess the effect of altitude on area-corrected species richness (standard area?=?100?km²), and a numerical classification of the elevational belts based on species richness was performed. Overall, richness at the three taxonomic levels decreased with elevation, but some individual families departed from this pattern. A sharp drop in species richness was observed at 1,800?m, and the dendrogram separated two elevational floristic groups at this elevation. The GLM revealed a significant negative effect of elevation on species richness. Despite this overall decreasing pattern for vascular plants along this extensive gradient, an examination of some family-specific patterns revealed the existence of other elevation?Cdiversity relationships, indicating taxon-specific responses to elevation. The most noticeable discontinuity in species richness, at ca. 1,800?m, is likely related to a critical temperature isocline.     

The response of herbaceous-layer vegetation to anthropogenic disturbance in intermittent stream bottomland forests of southern Indiana,USA

Between 1993 and 1995 we sampled herbaceous layer vegetation on 84 plots in Platanus/Asarum Wet-Mesic Bottomland forests to determine how these forests have responded to human disturbance. Four different disturbance types were sampled (abandoned agricultural are as, clearcuts, group-selection openings, and single-tree selection openings), and uncut 80–100 year-old reference stands were sampled for comparison. Detrended Correspondence Analysis (DCA), distance analyses (chord distance and normalized Euclidean distance) and similarity analysis (Bray-Curtis similarity coefficient) suggest that agricultural use has shifted herbaceous-layer vegetation composition away from that typical of the reference forests, but that clearcutting, group-selection harvest, and single-tree selection harvest have not greatly shifted herbaceous composition. This shift in vegetation on abandoned agricultural land resulted from a loss of indicator species, such as Cardamine concatenata (Michx.) Sw., Stellaria pubera Michx., and Laportea canadensis (L.) Weddell and an influx of disturbance, exotic, and nonforest species (e.g., Lycopodium complanatum L., Lonicera japonica Thunb. and Senecio aureus L.). However, only two species found in reference stands, Erigenia bulbosa (Michx.) Nutt. and Sphenopholis obtusata (Michx.) Scribn., were missing from clearcuts, group-selection openings, and single-tree selection openings. The species richness values of abandoned agriculture, clearcut, and group-selection plots were generally greater than those of single-tree selection and reference plots. Abandoned agricultural areas had much greater total species richness because of the influx of dry-site, exotic, disturbance, and non-forest species.     

Analysis of the biodeteriogenic vascular flora at the Royal Palace of Portici in southern Italy

A study was carried out on the biodeteriogenic vascular flora at the Royal Palace of Portici in southern Italy. In all, 160 species were found on the building, which represents approximately 35.5% of the flora found in the whole grounds (449 taxa). Ecological analysis of the plant population highlighted the decisive role of xeric climatic conditions, the lack of substrate, use of the site, and ordinary and restorative maintenance work. Therophytes (48.8%) broadly prevail over other biological forms. Most of the taxa censused (38.8%) may be considered ubiquitous and hence found at the same time on different types of substrate. Measured against the Hazard Index (HI), 62.5% of the species detected may be considered low-hazard (HI 0-3), 31.9% medium-hazard (HI 4-6), and 5.6% very hazardous (HI 7-10). Ailanthus altissima (Mill.) Swingle (HI 10), Ficus carica L. (HI 10), and Quercus ilex L. subsp. ilex (HI 9) were the species that had the most impact of the architectural structures in question.     

Nyssa talamancana (Cornaceae), an addition to the remanant Laurasian Tertiary flora of southern Central America

A new species,Nyssa talamancana, with fruits larger than those of any other, either living or fossil, is described from Costa Rica and Panama. In size, number of germination valves, and surface-sculpturing, its endocarps resemble those of the fossil assemblage more than those of the other living species. The occurrence of this distinctive new member of a definitely Laurasian family, in association with other endemic or nearly endemic Laurasian taxa, at wet mid-elevations lends credence to the idea that these forests harbor remnants of the really ancient flora of southern Central America.     

Adaptation of the cholinergic system of <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> (Bivalvia,Mytilidae) to the impact of natural and anthropogenic conditions

The effects of environmental conditions on cholinesterase activity and kinetic parameters of substrate hydrolysis in the hemolymph of the mussel Crenomytilus grayanus were studied. Under seasonal upwellings, the cholinergic system efficiency is provided for by a wide range of efficient concentrations of the substrate, i.e., under such conditions the mussels at the molecular level have a quantitative adaptation strategy of the enzyme. In mussels from the stationary upwelling zone (at a steady low temperature of water) for efficiency of the cholinergic system, the quantitative strategy of enzyme adaptation is realized. In mussels from a highly contaminated site, irreversible damages to the cholinergic process were observed. The affinity of the substrate to the enzyme is highly informative and an appropriate biomarker for the load level and the adaptation capacity of the organism. The affinity of the substrate to the enzyme is recommended as a new biomarker.     

The pollination niche and its role in the diversification and maintenance of the southern African flora

The flora of southern Africa has exceptional species richness and endemism, making it an ideal system for studying the patterns and processes of evolutionary diversification. Using a wealth of recent case studies, I examine the evidence for pollinator-driven diversification in this flora. Pollination systems, which represent available niches for ecological diversification, are characterized in southern Africa by a high level of ecological and evolutionary specialization on the part of plants, and, in some cases, by pollinators as well. These systems are asymmetric, with entire plant guilds commonly specialized for a particular pollinator species or functional type, resulting in obvious convergent floral evolution among guild members. Identified modes of plant lineage diversification involving adaptation to pollinators in these guilds include (i) shifts between pollination systems, (ii) divergent use of the same pollinator, (iii) coevolution, (iv) trait tracking, and (v) floral mimicry of different model species. Microevolutionary studies confirm that pollinator shifts can be precipitated when a plant species encounters a novel pollinator fauna on its range margin, and macroevolutionary studies confirm frequent pollinator shifts associated with lineage diversification. As Darwin first noted, evolutionary specialization for particular pollinators, when resulting in ecological dependency, may increase the risk of plant extinction. I thus also consider the evidence that disturbance provokes pollination failure in some southern African plants with specialized pollination systems.     

The isotopic composition of anthropogenic boron and its potential impact on the environment

The present study investigates the isotopic composition of anthropogenic boron (B) and its potential affects on the environment. The isotopic ratios of B in synthetic products from the main ores in the world have been measured by negative thermal ionization mass spectrometry. The data show that the isotopic compositions of Na-borate products and washing powders overlap with those of natural Na-borate minerals. In contrast, the¹¹B/¹⁰B ratios of synthetic Ca-borate and Na/Ca borate products are significantly lower (by 15 permil) and overlap with those of the natural Ca-borate minerals. Consequently, the original isotopic signature of natural borate minerals is not modified during the manufacturing process of synthetic products. The B isotopic composition of domestic wastewater from Israel and Riverside, California suggests that B in sewage is derived from Na-borate components used in detergents. Since B, like other inorganic ions, is not removed during conventional sewage treatment, it accumulates in domestic wastewater. Although the B concentration in pristine groundwaters is generally low (<0.05 mg/L), contaminant sources (e.g., wastewater) are relatively enriched in B (0.5–1 mg/L). The isotopically distinguished signature of borate compounds is used to trace groundwater contamination.