A comparison of mollusc diversity between the relatively pristine Marico River and the impacted Crocodile River, two major tributaries of the Limpopo River, South Africa

A study of the freshwater mollusc diversity was conducted at selected sites in the relatively pristine  Marico River and the impacted Crocodile River, the major tributaries of the Limpopo River. Four  surveys were conducted, two in an early (May 2013 and 2014) and two in a late (November 2013 and 2014) low-flow period. Semi-quantitative surveys were done by sampling the vegetation, as well as the substratum, with a standard SASS net for approximately 15 min each. Environmental parameters including water temperature, electrical conductivity (EC) and pH were measured at each site. Molluscs were identified up to species level, sorted, counted, and the presence of juvenile specimens recorded. Historical data for the 1/16th degree square grids (loci), in which each of the sampling sites of the current study was located, were extracted from the National Freshwater Snail Collection at the Unit for Environmental Sciences and Management, Potchefstroom Campus of the North-West University. During this study, 20 and 9 species were recovered from the Marico and Crocodile Rivers, respectively, as compared to 13 and 12 species on record for these loci, respectively. Juvenile specimens were present during the four surveys at most of the sites. Canonical correspondence analyses were applied which revealed that biotopes, water temperature and EC played the most significant role in the distribution and abundance of species. The relatively high mollusc diversity and the fact that juveniles were present throughout the study, demonstrated that current habitat and environmental conditions were suitable to promote recruitment and the sustainability of diverse mollusc populations in the Marico River and its tributaries. However, in contrast to this, the exploitation of and habitat transformation in the Crocodile River has resulted in the decrease of biotopes which eventually could have led to the  decrease in diversity and the establishment of P. acuta, an exotic invader species.Keywords: freshwater molluscs, biodiversity, Marico River, Crocodile River, environmental variable

The influence of health education on the prevalence, intensity and morbidity of Schistosoma haematobium infections in children over a two-year period in the Limpopo Province, South Africa

The influence of health education on the prevalence and intensity of Schistosoma haematobium infections, as well as on the related morbidity, was studied in schoolchildren between the ages of 4 and 14. Three groups of children were selected for this investigation. The 67 children in the experimental group received chemotherapy before health education was implemented, as well as when they got re-infected during the study. Health education was presented in mother tongue by means of a puppet show. The 99 children in one of the control groups received treatment only after the study while the 80 children in the remaining control group were treated as those in the experimental group, except that no intervention by means of education was applied. Health education, parasitological screens and snail surveys were done during the rainy, cold-dry and hot-dry seasons between 2004 and 2006. The prevalence and intensity of infection, as well as the morbidity (degree of haematuria) due to the infections, were determined after the urine samples, collected from each child, were screened. Significant differences (p<0.05) were found between the initial prevalence of infection (100%) and all the values recorded from survey 2 to survey 7. With regard to the intensity of infection, significant differences were found in all cases between the experimental and the treated control groups except in the heavy category (p=0.84). Statistical comparisons between the mean percentages calculated for corresponding categories of haematuria between the different groups revealed significant differences in all cases except between the experimental and treated control groups in the heavy category (3+) of haematuri

Die invloed van gesondheidsopvoeding op die prevalensie van skistosoombesmettings by leerders in 'n skistosoomendemiese gebied in die Limpopoprovinsie

http://search.sabinet.co.za/WebZ/Authorize?sessionid=0&next=ej/ej_content_aknat.html&bad=error/authofail.htm

Korttermynbedreigings vir varswater–Mollusca in die Olifantsrivier en enkele sytakke

Short-term threats for the sustained survival of freshwater Mollusca in the Olifants River and selected tributaries. The conservation status of less than 2% of the more or less 7000 mollusk species known worldwide have been properly assessed. Consequently the general level of imperilment is poorly documented and almost certainly underestimated. Freshwater mollusks live permanently in water, have limited means of movement and are exposed to a variety of anthropogenic waste products due to the fact that waterbodies often act as sinks for a large array of harmful pollutants. The Olifants River is often described as one of the most polluted rivers in Southern Africa and is progressively subjected to extremely high pressure with regard to natural resources and associated rural transformation and pollution. Little is on record regarding the diversity of the Mollusca in the Olifants River; therefore, in the present study, four surveys of the molluscs were conducted in this river and selected tributaries during two consecutive years at three localities situated on the Highveld and four localities situated in the Lowveld respectively. The pH and electric conductivity of the water were determined during each survey at each one of the localities and values ranged from 6.93 to 9.50, and 110 μS to 1336 μS, for pH and conductivity respectively. A total of 25 mollusk species were collected during the four surveys which included the exotic invader species Lymnaea columella, Physa acuta, Aplexa marmorata and Tarebia granifera. The latter species yielded the highest number of specimens by far, mainly at a locality which could be described as largely transformed. The results of this investigation can serve as a point of departure for future surveys to evaluate the impact of anthropogenic disturbances on the mollusc diversity in the Olifants River and catchmenthttp://www.satnt.ac.za/index.php/satnt/issue/archivehttp://www.satnt.ac.za/index.php/satnt/article/view/39

’n Vergelyking van die Mollusca-diversiteit in die Mooirivier (Noordwes-Provinsie) soos gevind met opnames wat gemaak is in 1963 en weer 50 jaar later

Die hoogste getal gedokumenteerde uitsterwings van enige belangrike taksonomiese groepword aan die Mollusca toegedig. Faktore wat hoofsaaklik hiervoor verantwoordelik is, sluitonder meer omgewingsveranderinge en antropogeniese impakte in wat tot die tot niet gaanvan die habitat aanleiding gee. Daarbenewens is die bewaringstatus van minder as 2% van dieongeveer 7000 molluskspesies wêreldwyd bekend tot dusver nog nie behoorlik geassesseernie. Die doel van die huidige ondersoek wat in 2014 uitgevoer is, was om die molluskdiversiteitvan die Mooirivier met die resultate van 1963 te vergelyk. Dit is gedoen deur ’n opnameuit te voer van die molluskdiversiteit by dieselfde lokaliteite as in 1963. Twee opnames isgemaak tydens ’n vroeë- en laatlaagvloeiperiode in 2014 by agt lokaliteite wat met dié vandie 1963-opnames ooreenstem. Die pH, elektriese geleiding (EG) en temperatuur is ook byelk van die lokaliteite gemeet. Die identiteit van die 14 slakspesies wat in 1963 gevind is, hetooreengestem met 14 van die 15 in 2014. Die uitheemse indringerspesie Physa acuta is tydensdie 2014-opname vir die eerste keer in hierdie rivier gevind, waarskynlik weens ’n toename inorganiese verryking. In die 1963-opname is <em>Burnupia mooiensis</em> en<em> Pisidium langlyanum</em> by diemeeste lokaliteite gevind, en in 2014 <em>Gyraulus connollyi</em> en F<em>errissia cawstoni</em>. Die meeste van diemolluske uit hierdie gebied wat voorheen op rekord gestel is, is in 2014 gevind. Die pH watin 2014 ’n geringe tot aansienlike verlaging getoon het, word aan mynversuring toegeskryfen het nie ’n merkbare invloed op die molluskdiversiteit gehad nie. Die hoër elektriesegeleiding wat tydens die 2014-opname gemeet is, het vanweë die verdraagsaamheid vanvarswatermolluske in hierdie verband, ook geen verandering in die molluskdiversiteit teweeggebring nie. Die temperatuur was in die laatlaagvloei deurgaans hoër. Ondanks die feit dathierdie studies vyf dekades uitmekaar gedoen is en antropogeniese impakte toegeneem het, isgeen noemenswaardige verandering in die molluskdiversiteit waargeneem nie