Browsing by Author "Reinecke, A. J."

Now showing 1 - 11 of 11
  • Thumbnail Image
    Item
    Die beskerming van biologiese diversiteit deur gebruik te maak van die gevoeligheidsvariasie van spesies vir toksiese stowwe
    (AOSIS, 2004) Reinecke, A. J.; Reinecke, S. A.
    ENGLISH ABSTRACT: Efforts to develop generally applicable criteria or standards for environmental quality for the purpose of protecting South Africa’s rich biodiversity are normally hampered by the fact that species can differ considerably in their sensitivity to toxic substances. Direct extrapolation from one species to another is therefore not possible. By actually using this variation in sensitivity of species, the assessment of risk posed by contaminants may be placed on a more rigorous scientific footing. This concept holds that if quality criteria are accepted which would protect the most sensitive species, all other species are automatically protected. This article focuses on the use of sensitivity distributions of species as method and critically reviews the nature and applications of extrapolation models which are based on these distributions. Their possible use and arguments for and against such use are discussed. The conclusion is drawn that species sensitivity distributions have useful applications but data on the sensitivities of local species are scarce. Although already useful, this methodology can find more general application in South Africa if more research is undertaken to obtain reliable toxicity data for different species. In order to do that standardized toxicity tests for local species will have to be developed.
  • Thumbnail Image
    Item
    Eienskappe van betroubare wetenskaplike inligting
    (AOSIS, 2002) Reinecke, A. J.
    In die lig van die onlangse kontroversiële berigte en uitsprake in Suid-Afrika oor die MI-virus en die aansprake oor die wetenskaplike “bewyse” van die oorsake, kan dit baat om opnuut te kyk na maniere waarop die kwalitiet van wetenskaplike kennis beoordeel kan word.
  • Thumbnail Image
    Item
    Die inkorporering van biomerkers in die assessering van die ekologiese risiko van chemiese bodemkontaminante
    (AOSIS Publishing, 2007) Reinecke, A. J.; Reinecke, S. A.; Maboeta, M. S.; Odendaal, J. P.; Snyman, R.
    Soil is an important but complex natural resource which is increasingly used as sink for chemicals. The monitoring of soil quality and the assessment of risks posed by contaminants have become crucial. This study deals with the potential use of biomarkers in the monitoring of soils and the assessment of risk resulting from contamination. Apart from an overview of the existing literature on biomarkers, the results of various of our field experiments in South African soils are discussed. Biomarkers may have potential in the assessment of risk because they can indicate at an early stage that exposure has taken place and that a toxic response has been initiated. It is therefore expected that early biomarkers will play an increasing role as diagnostic tools for determining exposure to chemicals and the resulting effects. They may have predictive value that can assist in the prevention or minimising of risks. The aim of this study was to investigate the possibilities of using our results on biomarker responses of soil dwelling organisms to predict changes at higher organisational levels (which may have ecological implications). Our recent experimental results on the evaluation of various biomarkers in both the laboratory and the field are interpreted and placed in perspective within the broader framework of response biology. The aim was further to contribute to the development and application of biomarkers in regulatory risk assessment schemes of soils. This critical review of our own and recent literature on biomarkers in ecotoxicology leads to the conclusion that biomarkers can, under certain conditions, be useful tools in risk assessment. Clear relationships between contamination loads in soil organisms and certain biomarker responses were determined in woodlice, earthworms and terrestrial snails. Clear correlations were also established in field experiments between biomarker responses and changes at the population level. This indicated that, in spite of the fact that direct mechanistic links are still not clarified, biomarkers may have the potential to provide early indications of forthcoming changes at higher organisational levels. Ways are proposed in which biomarkers could be used in the future in risk assessment schemes of soils and future research directions are suggested.
  • Thumbnail Image
    Item
    Kadmium in Valsbaai : moniteringspotensiaal van die mariene slak, Oxystele tigrina (Mollusca)
    (AOSIS, 2009-06) Reinecke, A. J.; Mdzeke, N. P.; Reinecke, S. A.
    ’n Opname is onderneem van die kadmiumvlakke in die tussengetygebied van Valsbaai, Suid- Afrika. Kadmiumkonsentrasies is seisoenaal bepaal in die water en sediment in verskillende lokaliteite. Die metings is oor ’n periode van een jaar gedoen deur seisoenaal monsters te versamel by ses verskillende versamelpunte in en een buite die baai. Dit is met behulp van atoomabsorpsiespektrofotometrie ontleed vir kadmium en die hoogste kontaminasievlakke is by die noordelike kusstreek gevind tussen Strand en Muizenberg waar die digsbevolkte gebiede en die meeste industriële aktiwiteit voorkom. Betekenisvolle variasie in konsentrasies van kadmium het seisoenaal en ruimtelik voorgekom. Die gemiddelde konsentrasies in die water en sediment was in sommige gevalle effens hoër as die vlakke wat deur die Suid-Afrikaanse waterkwalitetisriglyne aanbeveel is. Kadmiumkonsentrasies is ook in versamelde eksemplare van die mariene slak Oxystele tigrina vir verskillende seisoene vir drie lokaliteite bepaal. Laboratoriumeksperimente is uitgevoer om die opname, akkumulasie en verlies van kadmium in verskillende organe van die tussengetyslak, Oxystele tigrina te ondersoek. Weefselspesifi eke kadmiumkonsentrasies in kontrolesowel as blootgestelde lewende eksemplare is vergelyk oor ’n blootstellingsperiode van veertien dae. Die eksperimentele slakke is aan twee subletale konsentrasies van onderskeidelik 0.20 en 0.40 μg/ml watergedraagde kadmium in die vorm van CdCl2 blootgestel. Die proefdiere is gereeld gemonitor en kadmiumkonsentrasies is in verskillende organe, na suurvertering, atoomabsorpsiespektrofotometries bepaal. Die resultate het ’n algemene toename van kadmium in die liggame van die slakke uitgewys. Kadmium is in variërende konsentrasies in alle weefsel gevind. ’n Ongeveer liniêre patroon van akkumulasie het aangetoon dat die metaal waarskynlik nie deur O. tigrina gereguleer is nie. Die metaal se teenwoordigheid het verskil tussen die sagteweefsel en skulp op so ’n wyse dat die sagteweefsel normaalweg ’n hoër opnamekoers van die kadmium weerspieël het. Nadat die blootgestelde organismes in kadmiumvrye seewater oorgeplaas is, het gedeeltelike kadmiumverlies wel plaasgevind. Die variasie in kadmiumverlies van die verskillende organe dui moontlik daarop dat slegs ’n gedeelte van die geakkumuleerde kadmium sterk gebind was in sekere weefsels of organe. Die behoud van kadmium in beide sediment en diereliggame was sodanig dat afgelei kan word dat kadmium teen huidige omgewingskonsentrasies in sekere dele van Valsbaai, wat algemeen as laag beskou word, steeds met verloop van tyd in hierdie tussengetydiere kan akkumuleer tot vlakke wat nadelig is vir die spesies self, maar ook vir hulle predatore. Dit sal veral kan gebeur indien fi siese toestande verander om die biobeskikbaarheid te verhoog.
  • Thumbnail Image
    Item
    Die konsep van biobeskikbaarheid en die neerlê van eenvormige standaarde vir toelaatbare chemiese kontaminante in die grond
    (AOSIS OpenJournal, 2006) Reinecke, A. J.; Reinecke, S. A.
    Soils are very heterogeneous substrates providing an environmental matrix with varying spatial and temporal gradients of pH, organic carbon, particle size distribution, moisture content as well as biological factors associated with soil organisms. These chemical, physical as well as biological factors determine the bioavailability of chemicals to soil-dwelling invertebrates. This review of recent literature on the use of the bioavailability concept in soil ecotoxicology indicates that the concept is often used unqualified and indiscriminately to mean different things to different authors. A clear understanding of the concept is crucial for toxicity testing, environmental monitoring, risk assessment and the setting of soil quality criteria since knowledge of the actual exposure of organisms, and not merely the total amount of the chemical, is required. The aim of this paper is to contribute towards a clarification of the concept. Apart from defining or describing bioavailability, the problems related to the comparability of toxicity data between soils and species, inter-soil and inter-species comparisons of toxicity data are discussed. The potential role that biomarkers can play in assessing bioavailability, is touched upon. In an effort to prescribe uniform criteria or standards for environmental quality, both biotic and abiotic characteristics, which determine the bioavailablity of contaminants, should be considered. This requires a dynamic approach which takes both uptake processes as well as a variety of other biological factors into consideration. It is concluded that bioavialiblity should be interpreted qualitatively and that the rate of uptake of a contaminant could possibly serve as a measure of bioavailability. The development of standardised protocols for exposure of selected species and the measurement of biological responses with the aid of biomarkers could serve to refine and take risk assessment a step further.
  • Thumbnail Image
    Item
    Die konsep van biobeskikbaarheid en die neerlê van eenvormige standaarde vir toelaatbare chemiese kontaminante in die grond
    (AOSIS, 2006) Reinecke, A. J.; Reinecke, S. A.
    ENGLISH ABSTRACT: Soils are very heterogeneous substrates providing an environmental matrix with varying spatial and temporal gradients of pH, organic carbon, particle size distribution, moisture content as well as biological factors associated with soil organisms. These chemical, physical as well as biological factors determine the bioavailability of chemicals to soil-dwelling invertebrates. This review of recent literature on the use of the bioavailability concept in soil ecotoxicology indicates that the concept is often used unqualified and indiscriminately to mean different things to different authors. A clear understanding of the concept is crucial for toxicity testing, environmental monitoring, risk assessment and the setting of soil quality criteria since knowledge of the actual exposure of organisms, and not merely the total amount of the chemical, is required. The aim of this paper is to contribute towards a clarification of the concept. Apart from defining or describing bioavailability, the problems related to the comparability of toxicity data between soils and species, inter-soil and inter-species comparisons of toxicity data are discussed. The potential role that biomarkers can play in assessing bioavailability, is touched upon. In an effort to prescribe uniform criteria or standards for environmental quality, both biotic and abiotic characteristics, which determine the bioavailablity of contaminants should be considered. This requires a dynamic approach which takes both uptake processes as well as a variety of other biological factors into consideration. It is concluded that bioavialiblity should be interpreted qualitatively and that the rate of uptake of a contaminant could possibly serve as a measure of bioavailability. The development of standardised protocols for exposure of selected species and the measurement of biological responses with the aid of biomarkers could serve to refine and take risk assessment a step further.
  • Thumbnail Image
    Item
    Sellulere biomerkerresponse as maatstaf van gevoeligheid van klipmossels (Mollusca) vir kadmiumbesoedeling
    (AOSIS, 2008) Reinecke, A. J.; Schoeman, W.; Reinecke, S. A.
    ENGLISH ABSTRACT: Due to the availability and chemical nature of some heavy metals, sub-lethal toxicant levels may persist in the ocean waters and may cause physiological problems and toxicity in invertebrates and other marine organisms. Although studies of metal concentrations in False Bay showed relatively low mean concentrations of Cd, invertebrates such as molluscs, crustaceans and many other groups are able to accumulate high levels of heavy metals in their tissues and still survive in the heaviest polluted areas. They can accumulate numerous pollutants from natural waters in quantities that are many orders of magnitude higher than background levels. Bioaccumulation ofcadmium in intertidal species could cause stress which may be measurable at the cellular level. A variety of limpet species that may serve as suitable ecotoxicological monitoring species occur in abundance on rocky shores along the South African coastline. The aim of this study was to obtain sensitivity data which could contribute to the selection of a suitable monitoring species and the eventual establishment of a species sensitivity distribution model (SSD) with a biomarker responseas endpoint. The limpets Cymbula oculus, Scutellastra longicosta, Cymbula granatina and Scutellastragranularis as well as water samples were collected at two localities in False Bay, South Africa. Analysis of water and biological samples were done by atomic absorption spectrometry. Exposures were done to three different sublethal concentrations of cadmium in the laboratory in static flow tanks over three days. There was a moderate increase in cadmium body concentrations over time. Results obtained at three exposure concentrations showed no significant differences in metal concentrations between the different C. oculus samples. Significant differences were obtained between the control and the exposure groups for each exposure time except between the control and the 1mg/L CdCl2 exposure group after 24 and 72 hours of exposure. Cd body concentrations(soft tissue) varied between 4.56 and 21.41µg/g (wet mass).Mean Cd concentrations in soft tissue of S. longicosta was considerably lower (varying between 1.18 and 19.58 µg/g Cd ) than in the tissues of C. oculus. The control group differed significantly from the 0.8 and 1 mg/L CdCl2 exposures after 48 and 72 hours. Mean Cd body concentrations in S. granular is were the highest of all exposed species, reaching a level of 148 µg/g Cd at the highest exposure concentration and differed significantly from the means of the other samples of the 0.8 mg/L CdCl2 exposure group after 72 hours and from the 1 mg/L CdCl2 group after 24 hours. Significant differences were also obtained between theCd body concentrations of C. granatina for the three exposure concentrations and three exposure times. Lysosomal membrane integrity was determined for both exposed and control animals, using the neutral red retention assay. Three of the four species showed a significant decrease in retention times with an increase in Cd concentration. Inter-species differences in sensitivity to environmentally relevant cadmium concentrations were reflected in the biomarker responses. Based on reduction of NRR times, the order of relative sensitivity to cadmium was S. granularis >C. oculus> S. longicosta.> C.granatina.
  • No Thumbnail Available
    Item
    Sperm abnormalities associated with high copper levels in impala (Aepyceros melampus) in the Kruger National Park, South Africa
    (1999) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.; Grobler, D. G.; Reinecke, S. A.
    The morphology of spermatozoa may be affected by very low concentrations of pollutants in the environment, and sublethal effects of toxic substances can be detected by studying the sperm of an animal. Sperm were collected from 50 impala (Aepyceros melampus) from a conservation area in South Africa and studied ultramicroscopically. Thirty-two samples were obtained from animals close to a copper mine, while 18 represented animals from an unpolluted area and held in captivity. Liver samples from all these animals were analyzed for their copper content. The findings from 12 animals kept in captivity and fed on a diet to which copper was added correlated with the findings from the field study. The general condition of the animals as expressed by the fat content of the bone marrow from the area exposed to copper contamination was affected detrimentally in comparison to the animals from the uncontaminated area. High percentages of sperm with neck vacuoles were found in all animals with high liver copper levels. A statistically significant correlation is demonstrated between the percentage of impala sperm with vacuoles in the neck region and the copper concentrations in this group of animals.
  • Thumbnail Image
    Item
    Transmission electron microscopic observations of acrosome and head abnormalities in impala (Aepyceros melampus) sperm from the Kruger National Park
    (AOSIS, 1997) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.
    Sperm morphological features play an important role in semen evaluation. Exposure to a variety of chemical compounds, especially environmental endocrine disrupters, elicit abnormalities in sperm of certain species. Baseline data on ultrastructure of normal sperm as well as abnormalities observed concomitantly, are required before causal links between such substances and abnormalities can be established. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in the Kruger National Park and studied by transmission electron microscopy to document normal sperm features and abnormalities. The following abnormalities of the acrosome and sperm head were documented from micrographs: Loose acrosome in various stages of disintegration, lip forming of the acrosome; bizarre head, crater defect, poor condensation of the nucleus and the Dag defect. The observed abnormalities were very similar to those reported for other members of the Bovidae. Different forms of a hollow sphere, formed by the nucleus and covered by an abnormal acrosome have not previously been described for other species.
  • Thumbnail Image
    Item
    Transmission electron microscopic observations of flagellum abnormalities in impala (Aepyceros melampus) sperm from the Kruger National Park
    (AOSIS, 1997) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.
    Sperm must remain motile in order to reach and penetrate the ovum and defects in the ultrastructure of the tail can have an adverse influence on motility. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in. the Kruger National Park and studied by transmission electron microscopy to document sperm abnormalities. The following abnormalities of the flagellum were documented from micrographs: abnormal baseplate and neck attachments; neck vacuoles and displaced organelles; double or short flagella; bent flagella; principal-piece vacuoles; displaced axoneme and the Dag defect. The implications of these abnormalities for sperm motility are discussed.
  • Thumbnail Image
    Item
    A transmission electron microscopic study of impala (Aepyceros melampus) sperm from the Kruger National Park
    (AOSIS, 1996) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.
    Since knowledge of sperm morphology can play an important role in semen evaluation and fertilisation, baseline data are required. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in the Kruger National Park and studied by transmission electron microscopy. The morphology of normal sperm was documented. The impala sperm shares characteristics with other members of the Bovidae. The occurrence of appendages on the cytoplasmic droplet of the flagellum of impala sperm is described for the first time. A total of 31 micrographs, showing typical features of impala sperm, in sections through various planes of the sperm, are presented.