’n Vergelykende ondersoek na die akkumulering van metale in die mosselkrewel (Tetraclita serrata) en die swartmossel (Choromytilis meridionalis) in Valsbaai, Suid-Afrika

Reinecke, Adriaan J. ; Reinecke, Sophia A. ; Mdzeke, Naomi P. (2014)

CITATION: Reinecke, A. J., Reinecke, S. A. & Mdzeke, N. P. 2014. ’n Vergelykende ondersoek na die akkumulering van metale in die mosselkrewel (Tetraclita serrata) en die swartmossel (Choromytilis meridionalis) in Valsbaai, Suid-Afrika. Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie, 33(1), Art. #1181, doi:10.4102/satnt.v33i1.1181.

The original publication is available at http://www.satnt.ac.za

Article

Die ontwikkeling van metodes om die Suid-Afrikaanse kuswaters te moniteer, bied geweldige uitdagings. Kennis en die beskikbaarheid van geskikte spesies wat as biomoniteerders kan optree, kan nuttig wees om inligting te bekom wat goeie besluitneming kan bevorder. Dit is gevolglik van nut om plaaslike spesies te identifiseer wat as biomoniteerders gebruik kan word. Die doel van hierdie studie was om as deel van ’n seisoenale veldstudie van metale in die tussengetygebied van Valsbaai, Suid-Afrika, ’n vergelyking te tref tussen die liggaamsladings van koper (Cu), nikkel (Ni), lood (Pb), kadmium (Cd) en sink (Zn) in die swartmossel (Choromytilis meridionalis) en die mosselkrewel (Tetraclita serrata), en om dit met omgewingskonsentrasies te vergelyk. Die oogmerk is om afleidings te maak oor die diere se relatiewe vermoëns om die prioriteitsmetale te akkumuleer. Eksemplare van beide spesies is oor verskeie seisoene gedurende 2000 en 2001 by verskillende punte langs die kus versamel en chemies ontleed. Die gemiddelde liggaamsladings (skulp en sagte weefsel) van metale in die swartmossel was vir alle metale hoër as dié van die mosselkrewel gedurende alle seisoene. Vergelykings tussen die liggaamsladings en omgewingskonsentrasies in water en sediment het getoon dat die prioriteitsmetale Cd, Pb en Ni sterk deur beide C. meridionalis en T. serrata uit die omgewing geakkumuleer word. Die gemiddelde liggaamsladings van Cd vir die verskillende seisoene het gevarieer tussen 6.43 μg/g en 14.73 μg/g maar geen statisties betekenisvolle verskille is gevind nie. In die meeste gevalle was die metaalkonsentrasies in alle seisoene die hoogste gedurende die winter. Die konsep van biomonitering het meriete omdat dit langtermyntendense uitwys, maar dit bied nie ’n absolute maatstaf van oombliklike, wisselende besoedelingvlakke nie. Dit kan as bykomende bestuurshulpmiddel in ’n nasionale mariene program dien vir die beskerming van die biodiversiteit van die tussengetygebied.

The development of methods to monitor the South African coastal waters offer major challenges. Knowledge and availability of suitable species that may serve as biomonitors will be valuable to obtain information to support good management decisions. It is therefore important to identify local species that show the basic characteristics required for biomonitoring. The aim of this study was to compare, as part of a wider seasonal field study of metals in the intertidal zone of False Bay, South Africa, the body loads of copper (Cu), nickel (Ni), lead (Pb), cadmium (Cd) and zinc (Zn) in the black mussel (C. meridionalis) and the barnacle (T. serrata), and to compare these with environmental concentrations. Also to draw conclusions about the animals’ relative abilities to accumulate priority metals. Specimens of both species were collected over several seasons at different points in False Bay and analysed chemically. The mean body load (soft tissue and shell) of metals was higher in the black mussel than in the barnacle during all seasons. A comparison between the body loads and environmental concentrations in water and sediment showed that the priority metals Cd, Ni and Pb are accumulated strongly by both C. meridionalis and T. serrata. The mean Cd body loads varied between 6.43 µg/g and 14.73 µg/g for the various seasons but was not statistically significantly different between seasons. Metal concentrations were in most cases highest during winter. Multiple regression analysis showed a strong correlation between body load of metals in the black mussel and the environmental concentration for most seasons, which indicates that the black mussel can be useful as an active rather than a passive biomonitor. The concept of biomonitoring has merit because it may show long-term tendencies, but it does not offer an absolute measure of immediate, varying pollution levels. It could serve as an additional management tool in a national marine programme for the protection of the intertidal zone’s biodiversity.

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