Bio-accumulation of selected metals in the organs and tissues of the redknobbed coot, Fulica

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by  Van Eeden

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Bio-accumulation of selected metals in the organs
and tissues of the redknobbed coot, Fulica cristata,
reed cormorant, Phalacrocorax africanus and
sacred ibis, Threskiornis aethiopicus, in mine and
industrial polluted freshwater ecosystems.
By
PIETER HERMANUS VAN EEDEN·
Thesis presented
in fulfilment ofthe requirements
for the degree
PHILOSOPHIAE DOCTOR
.
In
ZOOLOGY
in the
FACULTY OF NATURAL SCIENCES
at the
RAND AFRIKAANS UNIVERSITY
SUPERVISOR: Prof. H.J. Schoonbee
CO-SUPERVISOR: Prof. H.H. du Preez
NOVEMBER 1994
SUMMARY
The present study deals withthe effects ofmetal-polluted aquatic habitats at five different localities
on the Witwatersrand and the Orange Free State on the concentrations oflead, nickel, copper and
cadmium in the organs and tissues of the Redknobbed Coot, Fulica cristata, the Sacred Ibis,
Threskiomisaethiopicus, andthe Reed Cormorant,Phalacrocoraxafricanus.
The physical and chemical conditions of the water and the sediments which prevailed during the
period of survey at the various sampling sites suggest that concentrations of parameters such as
phosphates, nickel and lead in a number ofcases exceeded the limitslaid down by Kempster et at.
(1980) for acceptable river water quality standards in South Africa. The major sources ofpollution
responsible for these conditions can primarily be related to sewage, mine and industrial effiuents
(urban) as well as agricultural practices (rural), respectively. Mining activities were largely
responsible for the acidification and miniralization as well as metal pollution of the water and
sediments, especially so at the Marievale Bird Sanctuary in the Blesbokspruit catchment area.
However, automobiles are suspected to contribute much towards the lead concentrations in the
water andsedimentsat allthe samplingsites. Levels ofcadmiumwere generallylow and maybe the
onlyone ofthe four metals analysed which truly reflected unpolluted, environmentalconditions for
thismetal inthe water and sedimentsofallthe samplingsites. The nutrient loads which suggest mild
to moderate eutrophication of the water at all the localities can largely be attributed to sewage
effiuentsand surface runoffwaters from the surrounding townships on the Witwatersrand as well as
from inorganicfertilizers from farm lands inthe vicinityofthe Steynsrus and Senekalfarm dams in
the Orange Free State. These conditions resulted in the overall increase in primary and secondary
production of the affected waters which also coincided with the development of submerged and
floating water weeds such as Potamogeton pectinatus and Azolla filliculoides, respectively. The
herbivorous Redknobbed Coot and to a lesser extent the piscivorous Reed Cormorant, benefitted
directlyor indirectlyfrom these conditions.
Data obtained duringthe investigationpresent a complex situation in terms ofthe environment and
thebiologicalavailabilityofthe four metalsunder discussion. Anumber offactors inboth the abiotic
and biotic components may have had an effect on fluctuations in metal concentrations. These may
have acted individually and/or synergistically, making the interpretation of the data difficult.
Cadmiumoccurred inthe lowest concentrations ofall four metals in all four the organs and tissues
during allfour seasonsofinvestigation.In the case ofthe rest ofthe metals as wellas the organs and
tissues no specific, clear seasonal trend or sequence in the concentrations of the metals was
discernible. Copper in the kidney and liver and lead in the bone and blood tissues had the highest
mean concentrations over the four seasons of investigation. As far as the winter and summer
seasonaltendencies are concerned, statisticallysignificantdifferencesoccurred in the concentrations
ofsome metalsin specificorgans and tissues between the winter and summer seasons, respectively.
However, values recorded were not necessarily higher during a particular season. Lead (liver) and
cadmium (kidney) concentrations were found to be significantly higher in winter 1991 whilst
cadmiumand copper (both inthe blood) were significantly lower duringthis same season, compared
to winter 1992. Concentrations ofnickeldid not differsignificantly between organs and tissues such
as the liverand blood for particular seasons. It was only nickel in the kidney and cadmium in the
bonetissuewhichreflecteddefiniteseasonaltrends for the four successiveseasons ofinvestigation.
The Germiston lake sediments contained relatively high concentrations of metals such as nickel
(industrial pollution) and lead (mainlyfrom street surface runoff which enters the lake via storm
water drains). Recently, anaccidental spillofcadmium-containing effiuentinto the lake occurred via
a stormwater drain along the south-eastern perimeter of the lake (Schoonbee, personal
11
communication). It is therefore not surprising that the liver and kidney, but not the bone tissue of
coot caught at this locality contained the highest concentrations ofthis metal. The absence ofmetal
processing industriesinthe catchment ofthe Florida lake and ofthe Steynsrus farm dams reflect the
low liver and kidney concentrations of cadmium, nickel and copper, respectively. The highest
concentrations of nickel, cadmium, copper and lead (Natalspruit wetland) in the blood ofthe coot
may be related to its dietary preferences which include P. pectinatus, A. filliculoides and Lemna
sp. These aquatic weeds are known to beefficient bio-accumulators ofmetals from metal-polluted
aquatic environments. The statistical evaluation ofthe data point towards geographical differences in
the concentrations ofthe metals inthe organs and tissues ofthe coot from the five different localities.
However, in terms ofactual metal concentrations recorded, significant differences existed between
coots ofthe reference site (Steynsrus farm dams) and those from the other four localities (East
Rand).
It can be accepted that the dietary preferences ofthe herbivorous Redknobbed Coot, the omnivorous
Sacred Ibis and the piscivorous Reed Cormorant as well as the metal content inthe food items all
play an important role in the actual uptake and bio-accumulation of lead, nickel, copper and
cadmium in the organs and tissue ofthese bird species. This particularly applies to birds collected
from the Natalspruit wetlands known to be seriously polluted by effiuents from metal-processing
industries and mines. In the case ofall three species the cadmium levels were consistently lowest in
all four the organs and tissues. Highest concentrations of this metal occurred in the kidneys,
especially inthe case ofthe Sacred Ibis andinterestinglyin the bone tissue ofthe Redknobbed Coot.
The maximum blood cadmium concentrations were recorded for the Reed Cormorant. Copper,
nickel and lead were found in much higher concentrations in the various organs and tissues than
cadmium, with copper clearly being the dominant metal by weight in the liver ofall three species of
birds. Nickel and lead occurred in the highest concentrations in the bone tissue ofall three species
with concentrationsbeing as much as sixtimes higher than those ofcadmium or copper. Ofthe three
species, the Reed Cormorants generally exhibited the highest bone lead concentrations. Nickel and
lead values for the blood and kidneys were approximately 1-3 times higher than the concentrations of
those metals inthe bone tissues. With the exception ofthe liver, significant differences were recorded
for cadmium in all the other organs and tissues among the three species. In the case ofthe other
metals, significantdifferences were recorded betweenat least two ofthe three species.
The three bird species under investigation have distinctive different dietary habits with all three
species feeding actively on metal-polluted food items at the localities where they were collected
from. It can therefore be assumed that the metal concentrations found in their tissues and organs
must largely originate from these food items. Metal concentrations in the Kikuyu grass Pennisetum
clandestinum which is actively eaten by the coot, vary considerably in its metal contents from one
locality to another and also during the different seasons of the year. The Sago Pondweed P.
pectinatus as well as the Red Water Fern A. filliculoides, which are favoured by the Redknobbed
Coot, are both knownto accumulate substantial quantities ofmetals from the sediments and water of
metal-polluted habitats. A similar picture evolved when looking at dietary habits and the possible
uptake ofmetals from theirfood bythe Sacred Ibis (scavengers) andtheReed Cormorant (predator),
respectively. The ibis obtain its food and consequently its metal loads from a variety offood items in
the areas where this bird occurs whilst the Reed Cormorant may obtain metal loads by feeding on
fishand largemacro-invertebrates from these metal-polluted waterbodies.
It is clear from the results ofthe present investigation that the water and sediment concentrations of
lead, copper and nickel in most ofthe different localities were usually higher than the recommended
water quality guideline values while cadmium was well within the set limits for the protection of
aquatic life.It is also apparent that the coots from the five geographically different populations as
III
well asthe Sacred Ibisand ReedCormorant from theNatalspruit wetlands were clearly ableto bio
accumulateallfourmetals.
Bottom sediments may play a very important role in the retention and distribution of cadmium,
copper, nickel and lead in the various aquatic environments. They act as reservoirs for metals,
releasingandadsorbingmetalsto and fromthe water columnthrough various processes. The results
indicated that the Redknobbed Coot, Sacred Ibis and Reed Cormorant were all three exposed to
chronicallyhigh levelsofnickel, lead, copperand cadmiumfor prolonged periods oftime.
Emerging from this investigation is a picture which suggests that the levels of copper, cadmium,
nickel andlead inthetissues andorgans ofthe Redknobbed Coot, Sacred Ibis and Reed Cormorant
reflectthenatureoftheir dietaryintake ratherthan the specificgeographicaland/or seasonalpatterns
ofmetal accumulation. It mustbe borne in mind that, besides the concentrations of metals in the
abiotic environment and in the diet of these particular bird species, various other factors can
contribute to the observed geographical variations in metal concentrations recorded during this
investigation. The metal-polluted streams, lakes and wetlands on the Witwatersrand and even
elsewherein SouthAfrica,canserve asidealfield laboratoriesinassessingthis specificsituation.
IV
QpSOMMING
Die huidige ondersoek handel oor die effek van metaalbesoedelde akwatiese habitatte by vyf
verskillende lokaliteite aandie Witwatersrand en die Oranje Vrystaat op die konsentrasies van lood,
nikkel, koper en kadmium in die organe en weefsels van die Bleshoender Fulica cristata, die
Skoorsteenveer Threskiornis aethiopicus en dieRietduikerPhalaeroeorax africanus.
Die heersende fisiese en chemiese toestande van die water en sedimente gedurende die
opnameperiode soos aangetrefby dieverskillende lokalitiete, dui daarop dat die konsentrasies van
parameters soos fosfate, nikkel en lood in 'n hele aantal gevalle die perke soos neergele deur
Kempster et al. (1980) vir aanvaarbare rivierwater- kwaliteitstandaarde oorskrei het. Die
belangrikste bronne van besoedeling verantwoordelik vir hierdie toestande, kan hoofsaaklik
toegeskryfword aan riool-, rnyn- en industriele afloopwaters (stedelik) sowel as landbougebruike
(landelik), onderskeidelik. Mynbouaktiwiteite is grootliks verantwoordelik vir die versuring en
mineralisering sowel as metaalbesoedeling van die water en sedimente. Dit geld veral vir die
Marievale Voelreservaat in die Blesbokspruitopvanggebied. Dit word egter vermoed dat
motorvoertuie heelwatbydratot dieloodkonsentrasie indiewaterendie sedimente soos gevind by al
die lokaliteite. Vlakke van kadmium was oor die algemeen laag en is dit die enigste van die vier
metale wat algerneen onbesoedelde toestande vir hierdie element in die water en sedimente
verteenwoordig. Die nutrientladingswat dui op ligte tot matige eutrofikasie van die wateromgewing
by al die lokaliteite kan grootliks toegeskryf word aan rioolafloop- en stormwaters vanaf die
omliggende stedelike gebiede aan die Witwatersrand asook van organiese kunsmisstowwe vanaf
landeryein dieomgewingvan die damrneby Steynsrus enSenekal. Hierdie toestande het geleitot die
algemene toename in die primere en sekondere produktiwiteit van die geaffekteerde waters wat
terselfdertyd saarngeval het met die oormatige ontwikkeling van onderwater- en drywende
waterplante soosPotamogetonpeetinatus enAzollafilliculoides, onderskeidelik. Die plantvretende
Bleshoender en tot 'n mindere mate die predatoriese Rietduiker het direk of indirek by hierdie
toestande gebaat.
Dataverkrygedurendedieondersoekbied 'n komplekse toestand interme van die omgewing en die
biologiese beskikbaarheidvan die vierrnetale onder bespreking aan.'n Aantal faktore rakende beide
die biotiese en abiotiese kornponente kon 'n effek gehad het op die skommelinge gevind in
metaalkonsentrasies. Hierdie faktore kon individueel en/of sinergisties opgetree het, wat die
vertolking vandie data uiters bemoeilik het. Kadmium het voorgekom in die laagste konsentrasies
vanalvier metale in dievierorgane enweefsels van die drie voelsoorte. In diegeval van die res van
diemetale sowel as die organe en weefsels isgeen spesifieke, duidelikeseisoenstendense ofvolgorde
in die konsentrasies van die rnetale waargeneem nie. Koper in die nier en lewer en lood in die
beenweefselsenbloed hetdie hoogste gemiddelde konsentrasies oor die vier seisoene van ondersoek
opgelewer. In soverre dit die winter- en somerseisoenstendense betref, is statisties-beduidende
verskille gevind in die konsentrasies van sommige metale en weefsels tussen die winter- en
somerseisoene, onderskeidelik. Waardes aangetref was nie noodwendig hoer gedurende bepaalde
seisoene nie. Lood- (Iewer) en kadmium- (nier) konsentrasies is gevind om betekenisvol hoer
gedurende die winter van 1991 te wees terwyl kadmium en koper (beide in die bloed) weer
betekenisvol laer gedurende dieselfde seisoen was vergeleke met die winter van 1992 was.
Konsentrasies van nikkel hetniebetekenisvol verskil tussenorgane enweefsels soos dit weIdie geval
wasvir die leweren bloedtydens bepaalde seisoene nie.Dit was slegsnikkel indie nier en kadmium
in die beenweefsel wat definitiewe seisoenstendense weerspieel het vir die vier opeenvolgende
seisoenevan ondersoek.
v
Die Germistonmeer sedimente bevat relatief hoe konsentrasies van metale soos nikkel
(nywerheidsbesoedeling) en lood (hoofsaaklik van stormwaters wat die meer op verskeie plekke
bereik). Onlangs was daar 'ntoevallige stortingvan kadmiumbevattende afloopwatersin die meer via
'n stormwaterkanaal aan die suid-oostelike oewer van die meer (Schoonbee, persoonlike
mededeling). Dit is dus nie verbasend dat die lewer en nier, maar nie die beenweefsel van die
Bleshoenderwat by hierdie lokaliteit versamel is, die hoogste konsentrasies van hierdie metaal vir al
die lokaliteite opgelewer het nie. Die afwesigheid van metaalverwerkingsnywerhede in die
opvanggebied van die Floridameer en in die omgewing van die Steynsrus plaasdamme word
weerspieel deur die lae lewer- en nierkonsentrasies van kadmium, nikkel en koper, onderskeidelik.
Die hoogste konsentrasies van nikkel, kadmium, koper en lood (Natalspruit vleiland) in die bloed van
die Bleshoender mag "n verband hou met sy voedselvoorkeure wat P. peetinatus, A. fillieuloides
en Lemna sp. insluit. Hierdie akwatiese makrofiete is bekend vanwe hulle doeltreffende bio
akkumulering van metale in metaalbesoedelde wateromgewings. Die statistiese evaluering van die
data duiop geografieseverskille in die konsentrasiesvan die metale in die organe enweefsels van die
Bleshoendervir dievyfverskillende lokaliteite. Interme van diewerklike metaalkonsentrasies gevind
kom daar egter betekenisvolle verskille voor tussen die Bleshoenderbevolkings van die kontrole
lokaliteit (Steynsrus plaasdamme) en dievan die andervier lokaliteite (Oos-Rand).
Dit kan aanvaar word dat die dieetsvoorkeure van die plantvretende Bleshoender, die omnivore
Skoorsteenveer en die visvretende Rietduiker sowel as die onderskeie metaalinhoude van die
voedselitems, gesamentlik 'n belangrike rol speel in die werklike opname in bio-akkumulering van
die vier metale in die organe en weefsels van hierdie voelsoorte. Dit geld veral vir voels wat in die
Natalspruit vleilande voorkom wat bekend is vir die emstige besoedeling van afloopwaters vanaf
metaal-verwerkingsindustriee en myne. In die geval van al drie spesies was die kadmiumvlakke
deurgaans die laagste in al vier die organe en weefsels. Hoogste konsentrasie vir hierdie metaal het
voorgekom in die niere, veral in die geval van die Skoorsteenveer en interessant genoeg, in die
beenweefsel van die Bleshoender. Die maksimum bloedkadmiumkonsentrasies is gevind vir die
Rietduiker. Koper, nikkel en lood is inveel hoer konsentrasies in die verskillende organe en weefsels
aangetrefas wat dit die geval was vir kadmium met koper duidelik die dominante metaal per massa
in die lewer van al drie voelsoorte. Nikkel en lood kom in die hoogste konsentrasies in die
beenweefsel van al drie voelsoorte voor met waardes wat tot ses keer hoer was as die vir kadmium
of koper. Van die drie voelsoorte vertoon die Rietduiker oor die algemeen die hoogste
beenloodkonsentrasies. Nikkel- en loodwaardes vir diebloed en niere was ongeveer een tot drie keer
hoer as die konsentrasies hiervan in die beenweefseI. Met die uitsondering van die lewer, is
betekenisvolle verskille gevind vir kadmium in al die ander organe en weefsels tussen die drie
voelsoorte. In die geval van die ander metale is beduidende verskille gevind tussen minstens twee
van die drievoelsoorte,
Die drie spesies van voels wat ondersoek is vertoon opvallende dieetsverskille maar met aldrie wat
aktiefvoed metaalbesoedelde voedselitemsby die onderskeie lokaliteite waar hulle aangetrefword.
Dit kan dus aanvaar word dat die metaalkonsentrasies in hulle weefsels en organe grootliks verband
moes hou met hierdie betrokke voedselitems. Metaalkonsentrasies in die Kikuyugras Pennisetum
clandestinum wat aktief benut word as voedsel deur die Bleshoender, wissel aansienlik van een
lokaliteit na die ander en ook tussen die verskillende seisoene van die jaar. Die watergras P.
pectinatus sowel as die Rooiwatervaring A. filliculoides wat voorkeurvoedsel is vir die
Bleshoender, is beide bekend daarvoor vir hul vermoeens om aansienlike hoeveelhede van metale
vanuit die sedimente en waterkolom van metaalbesoedelde wateromgewings te akkumuleer. 'n
Soortgelyke patroon word gevind wanneer daar gekyk word na die voedingsgewoontes en die
moontlike opname van metale vanuit hulle voedsel,deur die Skoorsteenveer (aasdier) en die
Rietduiker (predator), onderskeidelik. Die Skoorsteenveer verkry sy voedsel, en ook die metale
VI
vanaf'n verskeidenheid vanvoedselitems in die omgewings waar hierdie voel voorkom terwyl die
Rietduiker metale opneem deur te voed op vis en groter makro-invertebraatorganismes van hierdie
metaalbesoedelde wateromgewings.
Uit die resultate verkry tydens die huidige ondersoek is dit duidelik dat die water- en
sedimentkonsentrasies vir lood,koper ennikkel in diemeeste van die lokaliteite gewoonlik hoerwas
as die aanbevole waterkwaliteitsriglyne vir die beskerming van akwatiese lewe terwyl
kadmiumkonsentrasies in aldie gevalle binne hierdie standaarde voorgekom het. Dit is ook duidelik
dat dieBleshoendervan alvyf geografies- verski1lende bevolkings sowel as die Skoorsteenveer en
Rietduiker van die Natalspruitvleilande onteenseglik in staat was omal vier metale te bio
akkumuleer.
Bodemsedimente spee1 waarskynlik 'n belangrike rol in die retensie en verspreiding van kadmium,
koper, nikkel en lood in die verskillende akwatiese omgewings. Dit kan optree as stoorplek vir
metale en die vrystelling en adsorpsie van metale na en vanaf die waterkolom deur midde1 van
verskeie prosesse. Die resultate toon aan dat die Bleshoender, die Skoorsteenveer en Rietduiker al
drie blootgeste1 was aan chronies-hoe vlakke van nikkel, lood, koper en selfs ook kadmium vir
langdurigetydperke.
Voortvloeiend uit die huidigeondersoek kom 'n bee1d na yore wat daarop dui dat die vlakke van
koper, kadmium,nikkel enlood in dieweefsels en organe van al drie voelsoorte 'n weerspieeling is
van die tipes voedsel wat hulle ingeneem het, eerder as die spesifieke geografiese en/of
seisoenspatrone van metaalakkumulering. Dit moet egter in gedagte gehou word dat naas die
konsentrasies van metale in die abiotiese omgewing asook in die onderskeie diete van die betrokke
voelsoorte, daarverskeie anderfaktore iswat kon bydratot diewaargenome geografiese variasiesin
metaalkonsentrasies wat gevindis tydens hierdie ondersoek. Die metaalbesoedelde strome, mere en
vleilande aan die Witwatersrand en selfs elders in Suid-Afrika, kan sonder twyfel dien as ideale
veldlaboratoriaindieevalueringvan hierdiespesifiekesituasie.
VII
ACKNOWLEDGEMENTS
I herebywishto expressmysincerest thanks to:
• JesusChrist, myLord andSaviour, for providing me with the strenght and courage over the years
ofstudy.
• Prof H.I. Schoonbee forhis constant support, encouragement andmuch appreciated criticismand
adviceduringthe course ofmy studies.
• Prof H.H. duPreezfor hismany usefullcomments and advice duringthe writing ofmythesis.
• Mywife Karen-Usefor her constant love, support and for the proofreading ofthe manuscript.
• My parents, Mr. and Mrs. I.A. VanEeden, for their moraland financial assistance over the years
duringmystudies at RandAfrikaansUniversity.
• Louis and Louise de Wet,Louise Fleischer, AminaAdendorff, Veronica Steenkamp, Paul Grobler
and Gerhard lanse van Rensburg for all their friendship, encouragement and help during the
various fieldsurveys andlaboratoryanalysisofthe data over the years.
• Juan Viljoen and Rene Bredenkamp as well as her parents for much appreciated assistence and
accommodation during fieldcollections ofbirdsat Steynsrus.
• DirkErIank forthe equipment andtransport provided for myfieldexcursions.
• The teaching, technical and secretarial staff ofthe Department of Zoology for their respective
assistance duringmy studies.
• The Rand Afrikaans University for facilities and equipment provided which made this study
possible.
• The Water Research Commission and the City of Germiston for financial support which made
thisstudy possible.
• The Cities ofRoodepoort and Germiston for permission to collect material at the Florida and
Germiston Lake areas.
• DriesLouwaswell asHennie Basson Snr. andJnr. for their constant support and help during the
periods ofcollection ofsamples atthe Vlakplaats WaterPollution Control Works.
• The Transvaal and Orange Free State Provincial Administrations for permits granted for the
collection ofthe various bird speciesinthese two provinces.
• Marius de Jager from Wirsam Scientific Instruments for his much appreciated advice in the
operation ofthe atomic absorption spectrometer.
• Wynand Schoonbee for hismuch appreciated technical assistance during the computer processing
ofthe manuscript.
YI11
CONTENTS
Chapter 1
Introduction 1
Chapter2
The avifauna ofmetal-pollutedwetlandsinthe Transvaalwith referenceto the selection ofbirds
as bio-indicatorsofmetal pollution 12
Chapter 3
Description ofthe various sampling localities 27
Chapter4
Noteson the geographical distributionand general ecologyofthe Sacred Ibis, Redknobbed Coot
and Reed Cormorant 34
Chapter 5
Materials and methods 44
Chapter6
The physico-chemical qualityand metal concentrations inthe water and sediment at the different
samplinglocalities 56
Chapter7
Seasonal variations ofmetalconcentrations in selected organs and tissues ofthe Redknobbed Coot
from ametal polluted wetland 76
Chapter8
Metal concentrations in selected organs and tissues offivegeographically distinct Redknobbed
Coot populations 94
Chapter9
Comparative metalconcentrations inorgans and tissues ofthree species ofbirdsfrom a polluted
wetland 112
Chapter 10
Metal concentrations in somefood itemsconsumed by the Redknobbed Coot, Reed Cormorant
and Sacred Ibis 131
Chapter 11
General discussion 141
Chapter 12
Concluding remarks and recommendations 157
IX