Thesis (Ph.D)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Copper oxychloride is a fungicide that is extensively used in vineyards in the Western
Cape to treat and prevent fungal diseases. It is however not clear what the effects are
on soil organisms, which play an important role in soil fertility, in South African soils.
There is paucity of data linking results obtained in the laboratory to effects observed
in the field, which will only become useful if a clear relation can be demonstrated.
The aims of this study were to:
~ Determine the effects of copper oxychloride on field populations of earthworms
and simultaneously monitor lysosomal membrane stability, measured as neutral
red retention time (NRRT).
~ Validate experimental field studies by doing inventories of earthworm populations
in long-term sprayed vineyards.
~ Determine the LC50 of copper oxychloride and simultaneously measuring NRRT,
and linking them to the experimental field studies.
~ Conduct bioassays, burrowing activity- and soil-avoidance experiments to
investigate their relations to earthworm population responses in the experimental
field studies.
Earthworms were sampled by hand-sorting in the field tests on treated and untreated
field plots in the Western- (October 1998 - July 1999) and Northern Cape (April 1998
- October 1999). Soil samples and worms were analysed for copper contents and
coelomocytes of live earthworms were used to conduct the neutral red retention
assays.
Acute toxicity tests were conducted over a period of 28 days during which the
earthworms (Eisenia fetiday were exposed to different concentrations of copper
oxychloride. Change in biomass and mortality were measured as endpoints, as well as
NRRT.
Bioassays, burrowing activity and soil-avoidance were conducted by exposing
Aporrectodea caliginosa to grassland- and vineyard soil as well as grassland soil
spiked with 60 J.1g.g-1copper in the form of copper oxychloride. Growth and
mortality were recorded in the bioassays as well as copper concentrations In
earthworm body tissues and substrates used over a period of28 days. Burrowing activity and soil-avoidance were determined by measuring the length of
tunnels burrowed by A. caliginosa in soil profiles over a period of 4 days under
different exposure regimes.
Results from the field tests showed that spraying of copper oxychloride had a negative
effect on earthworm populations at the prescribed application rates. NRR T in
earthworms from the exposure plots was significantly (p<0.05) lower after just one
spraying application. It was concluded that spraying copper oxychloride at prescribed
application rates caused a decrease in field populations of earthworms and that NRRT
was an early and reliable biomarker since it was indicative of later effects observed at
the population level. Results obtained from the field inventory of earthworms in
vineyards at Nietvoorbij, Robertson end Worcester confirmed data from the two field
studies.
The calculated LC50 of 882.78 I1g.g-1 for copper oxychloride and 519.40 I1g.g-1 for
copper was ecologically relevant if a safety factor of 10 was applied. NRRT which
manifested earlier than effects on biomass change in the acute toxicity tests, were
significant when viewed against the background of responses of field populations of
earthworms.
From the bioassay experiments it was found that A. caliginosa exposed to copper
oxychloride spiked soil had significantly (p<0.05) higher weight loss and mortality
than those in grassland- and vineyard soil. This indicated that changes in biomass and
mortality were indicative of population responses in the field and can be considered as
ecologically relevant.
Burrowing activity of A. caliginosa was significantly (p<0.05) lower in vineyard and
copper oxychloride spiked soil than in grassland soil. Similarly in the soil avoidance
experiments it was found that A. caliginosa avoided vineyard- and copper oxychloride
contaminated soil. It is therefore concluded that burrowing activity and soil
avoidance were ecologically relevant endpoints since they corresponded with
population responses in the field.
The study thus revealed that the long-term usage of copper oxychloride could have
negative effects on earthworm populations. The spraying of copper oxychloride can
have important implications on the sustainable use of agricultural soils since
earthworms and other soil organisms play such an important role in soil fertility. The
use of biomarkers and other ecotoxicological indicators can provide an early warning
that soil organisms are under environmental stress. / AFRIKAANSE OPSOMMING: Die fungisied koperoksichloried word wyd gebruik in die Wes-Kaap om swamsiektes
in wingerde te beheer en te voorkom. Dit is egter nie bekend wat die effek daarvan op
Suid Afrikaanse grondbiota, wat 'n belangrike rol speel in grondvrugbaarheid, is nie.
Daar is ook 'n tekort aan inligting wat die resultate van laboratoriumondersoeke in
verband bring met veldstudies.
Die doelstellings van die studie was om:
~ Die effek van koperoksichloried op erdwurmpopulasies in die veld te ondersoek
en terselfdertyd membraanstabiliteit, as moontlike biomerker, gemeet as neutraal
rooi retensietye (NRRT), te monitor.
~ Die geldigheid van eksperimentele veldstudies te toets deur ook grondanalises te
doen in wingerde wat oor langtermyn met koperoksichloried bespuit is.
~ Die LC50 van koperoksichloried vir erdwurms te bepaal en terselfdertyd NRR T te
meet asook om dié gegewens in verband te bring met die resultate van seisoenale
veldstudies oor die uitwerking op erdwurmpopulasies.
~ Bio-evaluerings ("bioassays"), tonnelaktiwiteit- en vermydingseksperimente te
onderneem en die verband tussen die toksiteitstoetse en populasieresponse, soos
waargeneem in die veld, te ondersoek.
Erdwurms is versamel deur handsortering tydens die veldtoetse in die Wes- (Oktober
1998 - Julie 1999) en Noord-Kaap (April 1998 - Oktober 1999) op kontrole en
bespuite persele. Grondmonsters en erdwurms is spektrofotometries geanaliseer om
koperinhoude te bepaal. Die selomosiete van lewende wurms is gebruik om NRR T te
bepaal. Akute toksisiteitstoetse is uitgevoer oor 'n tydperk van 28 dae waartydens
Eisenia fetida blootgestel is aan verskillende koperoksichloried konsentrasies.
Veranderinge in biomassa en mortaliteit is bepaal asook NRRT.
Bioevaluerings ("bioassays"), tonnelaktiwiteit- en vermydingseksperimente IS
uitgevoer deur Aporrectodea caliginosa bloot te stel aan grasveld- en wingerdgrond
asook grasveldgrond wat met koperoksichloried gekontamineer is. Groei en
mortalitiet is bepaal in die "bioassays" asook koperkonsentrasies in die grond en
erdwurm liggaamsweefsels oor 'n tydperk van 28 dae. Tonnelaktiwiteit en
grondvermyding is bepaal deur die lengte van tonnels wat deur A. caliginosa gegrawe
is te meet oor 'n tydperk van vier dae vir die verskillende blootgestelde groepe.
Die resultate het aangedui dat koperoksichloriedbespuiting 'n negatiewe invloed het
op erdwurmpopulasies teen die voorgeskrewe toedieningsprogram. NRRT in
erdwurms van die blootstellingperseel, was beduidend (p<0.05) laer na 'n enkele
bespuiting. Daar is verder bevind dat NRR T 'n betroubare en vroeë biomerker is,
aangesien dit 'n aanduiding gegee het van latere effekte wat op populasievlak na vore
getree het. Veldopnames in Nietvoorbij, Robertson en Worcester het die geldigheid
van data verkry uit die veldstudies ondersteun.
Die berekende LC50 van 882.78 ug.g" vir koperoksichloried en 519.40 ug.g" VIr
koper was ekologies relevant indien 'n veiligheidsfaktor van 10 toegepas is. NRRT se
ekologiese relevansie is bevestig deur dit te vergelyk met response wat in die
veldtoetse waargeneem is.
Deur bioevalueringseksperimente is bevind dat gewigsverlies en mortaliteit van A.
caliginosa beduidend hoër was in koperoksichloried gekontamineerde grond as in die
grasveld- (kontrole) en wingerdgronde. Veranderinge in biomassa en mortalitiet was
aanduidend van populasieresponse soos waargeneem in die veldstudies en kan dus as
ekologies relevante eindpunte beskou word.
Tonnelaktiwiteit van A. caliginosa was beduidend (p<0.05) laer in wingerd- en
koperoksichloried gekontamineerde grond as in grasveldgrond. Dieselfde is gevind in
die grondvermydingstoetse waar A. caliginosa wingerd- en koperoksichloried
gekontamineerde grond vermy het. Dit kan dus afgelei dat tonnelaktiwiteit en
grondvermyding ook ekologies bruikbare eindpunte is aangesien dit verband hou met
populasieresponse soos waargeneem in die veldstudies.
Hierdie studie het getoon dat die herhaalde gebruik van koperoksichloried 'n nadelige
invloed kan hê op erdwurmbevolkings. In die lig van die belangrike rol wat
erdwurms en ander grondorganismes speel in grondvrugbaarheid kan die oormatige
gebruik van hierdie fungisied ernstige implikasies inhou vir volhoubare benutting van
landbougronde. Die gebruik van biomerkers en ander ekotoksikologiese eindpunte
kan egter as vroeë waarskuwingsmetode dien dat die grondorganismes onder
omgewingstres verkeer.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51734 |
| Date | 12 1900 |
| Creators | Maboeta, Mark Steve |
| Contributors | Reinecke, A. J., Reinecke, S. A., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 88 p. : ill. |
| Rights | Stellenbosch University |
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