A method to prioritize and monitor wetland restoration for water-quality improvement

Wetland restoration can improve water quality by reducing concentrations of sediment, total phosphorus, and nitrate in runoff. Managers need a simple method to choose among many possible restoration sites, particularly in large agricultural basins covering thousands of square kilometers. The purpose of this paper is to outline a method for prioritizing and monitoring wetland restoration sites in light of the factors that affect water-quality improvement by wetlands. These factors are categorized as loading factors, path factors, and process factors. The method for prioritizing wetland restoration sites depends primarily on assessing the potential effectiveness of the wetland for improving water quality. Three types of effectiveness are considered: problem effectiveness (is the site in an area with known water-quality problems?), function effectiveness (is the site likely to improve water quality more or less than other sites?), and information effectiveness (does the site fit within an overall research plan to gain information on how wetlands improve water quality?). The variables of hydraulic residence time, hydraulic flux, and wetland area, volume, and average depth are combined into a single variable termed and used as a proxy for estimating the relative function effectiveness of potential restoration sites. Monitoring restoration sites is targeted at establishing a minimum data set that can be collected consistently at different sites over time, and that can be used for inter-site comparison with simple statistical techniques. The Minnesota River Basin is used as an example throughout to demonstrate the types of data that are available to plan wetland restoration. While this paper focuses on the water-quality benefits, wetland restoration should be a multi-disciplinary effort to integrate other benefits of restoration, such as improvement of wildlife habitat and flood abatement.     

A method to prioritize and monitor wetland restoration for water-quality improvement

Wetlands Ecology and Management - Wetland restoration can improve water quality by reducing concentrations of sediment, total phosphorus, and nitrate in runoff. Managers need a simple method to...     

Plant invasions in arid areas: special problems and solutions: a South African perspective

Management of invasive alien plants in arid areas is complicated by the cryptic and stochastic nature of the invasion process, the low density of researchers, extension officers and farmers in these areas, the complex, delayed and sometimes, indirect, effects of alien invasive plants on these ecosystems, and by high and shifting values placed on goods and services derived from invasive alien plant species. Fluctuating vegetation cover together with convergent adaptations for dispersal and facilitation enables some desert aliens to invade intact vegetation. Invasive plants in arid areas are not all arid-adapted: the most problematic species globally are phreatic, wetland or oasis specialists that can colonise remote wetlands and springs through a combination of wind-dispersed seeds and vegetative reproduction. Their success is often linked to disturbance and facilitated by agricultural activities including water extraction, cropping and livestock management. Invasive alien plants in arid region wetlands have an impact on forage, water resources and biodiversity in these key resource areas, that is disproportionately great relative to the area they occupy. Management of arid region aliens could include pre-introduction biocontrol planning that makes it possible to use aliens while reducing invasion risks. An alternative is to replace the aliens with extralimital indigenous plants that can supply the rangeland services perceived to be absent from arid environments—but such interventions may carry even greater risks.     

How to tell a shrub from a tree: A life‐history perspective from a South African savanna

The ecological differences between ‘shrubs’ and ‘trees’ are surprisingly poorly understood and clear ecological definitions of these two constructs do not exist. It is not clear whether a shrub is simply a small tree or whether shrubs represent a distinct life‐history strategy. This question is of special interest in African savannas, where shrubs and trees often co‐dominate, but are often treated uniformly as ‘woody plants’ even though the tree to shrub ratio is an important determinant of ecosystem functioning. In this study we use data from a long‐term fire experiment, together with a trait‐based approach to test (i) if woody species usually classified as shrubs or trees in African savanna differ in key traits related to disturbance and resource use; and (ii) if these differences justify the interpretation of the two growth forms as distinct life‐history strategies. We measured for 22 of the most common woody plant species of a South African savanna 27 plant traits related to plant architecture, life‐history, leaf characteristics, photosynthesis and resprouting capacity. Furthermore we evaluated their performance during a long‐term fire experiment. We found that woody plants authors call (i) shrubs; (ii) shrubs sometimes small trees; and (3) trees responded differently to long‐term fire treatments. We additionally found significant differences in architecture, diameter‐height‐allometry, foliage density, resprouting vigour after fire, minimum fruiting height and foliar δ¹³C between these three woody plant types. We interpret these findings as evidence for at least two different life‐history‐strategies: an avoidance/adaptation strategy for shrubs (early reproduction + adaptation to minor disturbance) and an escape strategy for trees (promoted investment in height growth + delayed reproduction).     

Fish species diversity in southern African estuarine systems: an evolutionary perspective

Synopsis The ichthyofauna of southern African estuaries consists primarily of juvenile marine species that use these habitats as nursery areas. The abundance and biomass of fishes in estuarine systems are typically high but species diversity is generally low, with only a few taxa dominating the community. This relatively low species diversity is attributed to the fact that estuaries in the region are unpredictable environments which lack any degree of permanence and are dominated by mobile marine eurytopes. Although stenotopes, represented mainly by small resident species from the families Gobiidae, Clinidae and Syngnathidae, are present in southern African estuaries, little speciation appears to have occurred. A possible reason for this lack of speciation, apart from the seasonal and annual variability of the abiotic environment, is that the lifetime of individual systems is usually limited to a few thousand years. In addition, fishes utilising southern African estuaries need to remain flexible (eurytopic) in their responses to an external environment which is unlikely to become more stable in the future. Thus the lack of permanence and fluctuating nature of southern African estuaries on both a spatial and temporal scale, together with the dominance of eurytopes in these systems, does not favour the evolution of new species. A preliminary examination of the available literature indicates that a detailed review of estuarine ichthyofaunal communities on a global basis will probably mirror the trends outlined above, and reveal a domination of these dynamic ecosystems by eurytopic taxa with low speciation potential.     

Using nanovibrations to monitor biofouling

The article proposes the use of the mechatronic surface sensor (MSS) to detect surface contamination. This methodology is based on the analysis of the vibration response of the monitored surface. In the present work a comparison between the responses of the MSS to different structural deposits build-up (Pseudomonas fluorescens biofilm--formed under turbulent and laminar flow and a silica deposit) were made. The results showed that the MSS response depends not only on the amount but also on the viscoelasticity of the attached deposit--different responses were obtained for the deposits according to their viscoelasticity. Another important conclusion is that the MSS response is not highly affected by solids that are not really attached to its surface.     

Bioethics: an African perspective

In this paper I have attempted to open a window on an African approach to Bioethics — that of the Nso' of the Bamenda Highlands of Kamerun — from the vantage position of someone who has familiarity with both African and Western cultures. Because of its scientific-cum-technological sophistication and its proselytising character, Western culture, as well as Western systems of thought and practice, have greatly affected and influenced other cultures, particularly African culture. But Western culture, systems of thought and practice, have been highly impervious and immune to influences from other cultures, philosophies, systems of thought and practice, even where these might have been salutary and enriching to Western culture and systems. What I have here termed Nso' eco-bio-cummunitarianism clearly indicates a viable alternative world-view within which some of the bioethical perplexities and controversies of today might be more satisfactorily resolved than within a Western framework. I have further attempted to show, by way of example, how within such a world-view, abortion and suicide, for instance, would be disapproved of while euthanasia, in its etymological purity, is approved of.     

Using bird species community occurrence to prioritize forests for old growth restoration

Conservation often focuses on ‘ecologically intact’ habitats with little human influence. But where all such habitats have been lost or modified, identifying promising restoration targets is a key goal. We describe a direct approach to identify high conservation value targets using predictive distribution maps of taxa that, based on habitat affinity, ease of detection and abundance can be used to infer native species richness and prioritize conservation investment. We used 1169 avian point counts in a 1560 km2 study area, remote‐sensed data and models incorporating imperfect detectability to predict habitat occupancy in 18 widely‐distributed native birds; 12 of which were determined by experts to be positive indicators of old‐forest conditions. Forest‐association scores for these 12 species where then used as weights in a composite distribution map of the probability of community occurrence, which corresponded well with the occurrence of old forest stands mapped by aerial photography. Our results indicate that composite maps of widespread indicators improve site prioritization by incorporating the behavioural and demographic responses of a diverse range of indicators to variation in patch size, configuration and adjacent human land use.     

Bioethics and culture: an African perspective

The project of Bioethics seems to me to require paying attention to the cultural realities and assumptive frame of reference of different peoples. I assume that this must be one of the views of the organizers of this conference too and that this is why the idea of country reports is taken seriously. If I am right about this, then it makes sense for me to start my discussion with a very brief discussion of some aspects of the cultural realities of Africa with particular reference to the Yoruba of Nigeria. Then I will discuss how this world view raises issues for bioethics. Two aspects of people's worldview relevant to bioethical issues are their conception of the human person and their conception of cause. What they consider themselves to be, and what they consider to be the principles of causation will normally influence their attitudes to health and illness and their choices regarding health care. I will briefly discuss these issues with regard to the Yoruba worldview.     

Sleep and physiological systems: a functional perspective

The knowledge of sleep evaluation and its regulation processes has evolved dramatically over the last half-century. Sleep state and the preoccupied view of its obligation to perform positive function for the organism have kept enthusiastic research flourishing. The restoration of macromolecular synthesis and repair players, energy conservation, neural plasticity and synaptogenesis are cellular and biochemical-level functional implications of sleep. The demarcation between molecular, cellular and systemic strata is not mutually exclusive at organism level. Sleep functions have been researched with their focus at each of these strata. The review discusses the systemic-level functions of sleep in brief with special reference to respiration, reproduction, digestion, cardiovascular, endocrine, immune and integumentary systems. Sleep and physiological system relations are usually bidirectional and are operationally mediated by intercellular message transmitters like hormones, cytokines and/or continuum of direct anatomical connections with the neuroanatomy of sleep management.     

Cardiac allografts: a 24-year South African experience

The history of using homologous cardiac valves dates back more than 30 years. Through the years emphasis was placed on the optimization of graft retrieval, preservation techniques and clinical application. A cardiac homograft valve bank was established at the Department of Cardiothoracic Surgery, University of the Free State, Bloemfontein in 1982. A retrospective analysis was performed on all allograft data since 1984. Since the first valve was successfully procured and transplanted in 1984, 2,540 aortic and pulmonary homografts were harvested from 1,792 donors, of which 1,545 [989 (64%) aortic and 556 (36%) pulmonary] were released for clinical use. Valves were discarded for various reasons, the main reasons being Human Immunodeficiency Virus (32.4%), Hepatitis B (9.6%) and venereal diseases (8.9%). The mean donor age was 26.98 years with a male predominance of 1,368 males versus 424 females. The average ischemic time was 33 h mainly due to medico-legal autopsies exceeding the desired 24 h time limit. The valves were disinfected in an antibiotic cocktail of Mefoxin, Piperacillin, Amikacin and Amphotericin B prior to cryopreservation. The surgical procedures utilizing the majority of homografts were aortic valve replacements (42.9%), aortic root replacements (19.3%) and right ventricular-pulmonary artery conduits (33.3%). The bank also supplied 23 other centers with homografts (402 aortic and 301 pulmonary). The Bloemfontein bank has established itself over the years as a viable and functional cardiac homograft bank. However, with increasing activity in the procurement arena and widened applications in the operating room the role of the homograft seems assured but availability still remains a major concern.     

Using multi-way admixture mapping to elucidate TB susceptibility in the South African Coloured population

Background

The admixed South African Coloured population is ideally suited to the discovery of tuberculosis susceptibility genetic variants and their probable ethnic origins, but previous attempts at finding such variants using genome-wide admixture mapping were hampered by the inaccuracy of local ancestry inference. In this study, we infer local ancestry using the novel algorithm implemented in RFMix, with the emphasis on identifying regions of excess San or Bantu ancestry, which we hypothesize may harbour TB susceptibility genes.

Results

Using simulated data, we demonstrate reasonable accuracy of local ancestry inference by RFMix, with a tendency towards miss-calling San ancestry as Bantu. Regions with either excess San ancestry or excess African (San or Bantu) ancestry are less likely to be affected by this bias, and we therefore proceeded to identify such regions, found in cases but not in controls (642 cases and 91 controls). A number of promising regions were found (overall p-values of 7.19×10^-5 for San ancestry and <2.00×10^-16 for African ancestry), including chromosomes 15q15 and 17q22, which are close to genomic regions previously implicated in TB. Promising immune-related susceptibility genes such as the GADD45A, OSM and B7-H5 genes are also harboured in the identified regions.

Conclusion

Admixture mapping is feasible in the South African Coloured population and a number of novel TB susceptibility genomic regions were uncovered.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1021) contains supplementary material, which is available to authorized users.