’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
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie/South African Journal of Science and Technology
| Field | Value | |
| Title | ’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 A comparison of the Mollusca diversity in the Mooi River (North-West Province) as found during surveys conducted in 1963 and again 50 years later | |
| Creator | Wolmarans, Cornelius T. Wepener, Victor Pretorius, Uané Erasmus, Johannes H. de Kock, Kenné N. | |
| Description | 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 Burnupia mooiensis en Pisidium langlyanum by diemeeste lokaliteite gevind, en in 2014 Gyraulus connollyi en Ferrissia cawstoni. 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. The highest number ofdocumented extinctions of any major taxonomic group is ascribed to the Mollusca. Factorsmainly responsible for this include environmental changes and anthropogenic impacts whichresult in habitat destruction. Furthermore, the conservation status of less than 2% of the moreor less 7000 mollusc species, known worldwide, is still not properly assessed. The aim ofthe study done in 2014 was to assess the current status of the mollusc diversity in the MooiRiver and to compare the results to the study done in 1963. The eight sites selected for thissurvey correspond with sites surveyed during the 1963 study, with surveys conducted duringboth an early and late low-flow period. The pH, electrical conductivity (EC) and temperaturewere also measured at each locality. Of the 15 mollusc species collected in 2014, altogether14 were the same as in the 1963 survey. However, an alien invasive species Physa acuta wasadditionally collected during the current survey, which is probably due to an increase inorganic enrichment. During the 1963 survey Burnupia mooiensis and Pisidium langlyanum werepresent at most of the sites, while Gyraulus connollyi and Ferrissia cawstoni were found at sixof the eight sites during the 2014 survey. Most of the molluscs previously recorded, were stillpresent in 2014. With regard to the abiotic factors, the pH values recorded in 2014 showed amoderate to large decrease as compared to the 1963 survey. This acidification is ascribed tothe development of gold mines in the adjacent area and apparently had little influence on themollusc diversity. The increase in EC measured in 2014 did not have any influence on thediversity of the molluscs, probably due to their wide tolerance for this factor. As expected,the temperature measured in 2014 was markedly higher during the late low-flow period ascompared to the early low-flow period. In conclusion, the differences discussed above revealedno obvious influence on the diversity of the freshwater molluscs over a 50 year period, despiteincreased anthropogenic impacts. | |
| Publisher | AOSIS | |
| Date | 2015-06-25 | |
| Identifier | 10.4102/satnt.v34i1.1294 | |
| Source | Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie; Vol 34, No 1 (2015); 7 bladsye Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie; Vol 34, No 1 (2015); 7 bladsye 2222-4173 0254-3486 | |
| Language | eng | |
| Relation |
The following web links (URLs) may trigger a file download or direct you to an alternative webpage to gain access to a publication file format of the published article:
https://journals.satnt.aosis.co.za/index.php/satnt/article/view/1294/2900
https://journals.satnt.aosis.co.za/index.php/satnt/article/view/1294/2901
https://journals.satnt.aosis.co.za/index.php/satnt/article/view/1294/2902
https://journals.satnt.aosis.co.za/index.php/satnt/article/view/1294/2865
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