Bioassays were carried out to determine the toxicity of two pesticides, Roundup and Gramoxone on Clarias gariepinus. The acute toxicity of both pesticides decreased towards the end of the bioassay period. The calculated safe concentrations for Roundup and Gramoxone are 0.99 ppm - 0.99 ppm and 0.09 ppm - 0.9 ppm respectively. Histological examination revealed that there were pathological changes in the gills and liver even when the fish were subjected to sub-lethal level

Mulero, O.

Odukale, B.

Oloruntuyi, O.O.

English

Aquatic Commons

TBy
UNTUYI, O., MULERO, O.
rfF and zooioTy rinculty a science
Lagos State University, Ojo
P. M. B. 1087 Apapa, Lagos.
96 - hour Bioassays were carried out to determine the toxicity of two pesticides, Round
up and Gramoxone on Claries gariepinus. The acute toxicity of both pesticides decreased
towards the end of the Bioassay period.
The calculated safe concentrations for Round up and Gramoxone are 0.99 ppm -0.99 pprn
and 0.09 ppm - 0.9 ppm respectively. Histological examination revealed that there were
pathological changes in the gills and liver even when the fish were subjected to sub-lethal levels.
INEIRf)DITICTION
As serious efforts are being made to increase fish production, many attempts are also being
made to increase crop production through intensive agricultural practices. This has resulted
in a large scale use of pesticides which is on the increase daily.
Although there are definite advantages in the use of pesticides particularly in the area of
crop production. The extensive use of these materials has resulted in a large reduction in fish
production, not only in capture fisheries sector but also in aquaculture. The indiscriminate use
of pesticides has been identified as a cause for many previously unexplained fish kills in fish
farms in other parts of the world
Pesticides usually get into the aquatic environment through accidents or through run offs
fi-om surrounding farmlands. This later results in fish mortality and morbidity.
The effect of these pesticides may be less pronounced if effective screening is made of
various pesticides in use and ifpesticides with low toxicity to fish are used, particularly in areas
where fish farming is being practiced.
Various pesticides are in uss) in the country and while some information is available on their
impact on vertebrates such e ?Id rnan, very little information is available as to the effect
Ofthese pesticides on fishes. is thus a need to evaluate the significance of such pesticides
in order to understand the poteniial harm of these pesticides if persistent use is made Of them.
Herbicides are of particular importance, because of their use in aquatic systems. 1
herbicides are being used to control aquatic pests. It has often been recommended as CJAk,
the easiest method of controlling the mence of water hyacinth in Nigerian waters.
It is against this background that this study was carried out
173
Round up and Gramoxone are two herbicides commonly used on land. But they have also
been used for aquatic weeds ( larias,eariepimis is a finfish which is of economic importance
in Nigeria. it is cultured extensively and is at a risk from pollutants such as herbicides frceo
surrounding farms.
The study was carried out to determine the toxicity ofRound up and Gramoxone to c. I."
gariepinus and to evaluate the effect on fish histopat hology Thus adding to documental,
and intbrmation on the effect of these two herbicides on fishes.
WilATERAAL AND METH
Clarias gariepinus with an averge wei.ght of 30g were obtained from fishermen,
transported to the laboratory and acclimatized to laboratory conditions for one week
Static bioassay tests were conducted for 96 hours, with 10 fish per tank. 1 he tanks
asure,cl 90.0cm by 35.0cm. Gramoxone and Round up were obtained from local sources
The concentrations used for Gramoxone were 500.0ppm, 350.0ppm, 250 Oppm, 150.0ppm,
50.0ppin, 10.0ppm, 1.0ppm and control. While for Round up 500.0ppm, 100.0ppm, 50.00 pin,
10,Oppin, 1.0pprn, and control were used. The media was aerated foi the duration of the:
experiment. Water analyses vvere carried out using standard methods of analysis for
determination of oxygen and pH (Boyd, 1979).
In another experiment, ('lar/as gariepinus was exposed to sublethal concentration
(1.0ppin) of each of the pesticides. After two weeks, fish were sampled fbr hiStological
analyses ofgills and liver. The gills and liver were pr eserved in 10% fi)rmalin. They were fixed
in wax sectioned and later stained with hernatoxOn and eosin, using standard histological
techniques.
RES U LTS
Water quality parameters were normal for survival of (.:larias gariepinus. Temperature
ranged from 24.5°C to 26.5°C. Average oxygen content was 7.4mg/L and average pi-I value
was 7.3. These values ranged within the tolerance limits of vvarm water fish species (Boyd,
1979). Some behavioural clia.nges were observed in the exposed fish. The fish exhibited erratic
swimming movements, arid surfaced fairly frequently. The skin took on a mottled appearance
and mucus Secretion appeared to increa.se.
Table 1 shows the LC50 values obtained at yarious periods for fish exposed to the two
pesticides. These values are the concentrations of each pesticide required to bring about 50%
mortality of C. gariepinus in the stipulated time period.
Thc,- acute toxicity of Round up and Gramoxone decreased with an increase in time. Round
up is apparently more toxic, as it requires a lesser concentration to bring about mortality in
relation to Grw,ioxone.
Figure 1 shows the comparison between the cOncentration of both pesticides arid their
effect on the mortality rate of C. gariepinus for a period 496 hours. It is observed that at
a concentration Of 5-00ppm both pesticides resultecLin a 100% mortality for C. gariepinus.
*WHY
174
The gill of cinificgs ga-piepjrafs exposc,,,,z1 to the various ife9irriliS Showy.) pa-,PiThoilogical
changes. These were extensive byperplasia among the gili fillaTinnt3 mî epHigleAai
IE1 ale link"-, fishes exposed to Curainoxone ha d E rophifs d whit?. Va-»se Tz:poz?,,,-;!jç
Round up revegled fibrosis and hyperp/asia of liver hopatocyt,;,,:o
T1 LETHAL CO1ICN
CLAMzi.' GARITEPDTZI3 EXTPO 2E(71`70
iiÍ ISTC 'GES
175
Pesticide 24 hr. LC50 . LC50 72 hr. LC50 965117.11-05o
Round up (pprn)
Gramox*ne (pp,i)
170.0
320.0
95.0
300.0
85.0
290.0
99.0
90.0
-to
300 400 500
Concentration (pprn)
176
KEY -
e GR A MO X0 NE
1 . Y:72'4q f'°7-7ïL1T1 AcI)57P C3CEÑrTIO N
::" ITO G X0 ?V ROUND UP
The results of the present study have showr Claria7 -ariepinus is more tolerant to
Grramoxone than Round up. The safe level o-7-- fAatliiiplyL19;
96 - hours LC50 id-Ail an applicaiioil factor of between 0.1 io 0.01 depending on 1110 "p,A.3?..;itVif.','S''
ofThe pollutant (Koesoemadinate, 1980). This gives an estirm-kte of concenti-ations ihan can
be considered sale for along time e;,;posure of the organisms. This would thei7.-,-FoFe give
leve of between 0 99ppm and O 999prn for Round up and between 0.09pprn and 0.90pprn fOT
Gramoxone ahhough the e,;;act Ic-vel of iivDse chemi-,als ill our 7;V9,,ei" ").06.Aes 1119-Ve
determined, the LC50 values siNves as a guide, for futuna -,-vork 911(1
The pathological changes observed revealed that nr3ortaiiiy was caused
&the gill system and probably disorders ofthe liver. Changes in the gill structure, -would ,-,31.11.1:
in asphyxiation and also interfere with excretory functions (Eller, 1975; Gardner 1975). These
factors are quite likely to have caused death in Clanas gariepinus exposed to the various
treatments. The changes observed in the liver calls have also been observed by other
and appears to be typical in fish exposed to peticides (Crz el al.:1988; Walsh et al. 197:).
The result show that both Round up and Gramoxone are toxic to Clarias gariepinus and
more control on their use is advocated, particularly on water bodies and farmlands based near
aquatic sources or where intensive irrigation is practiced.
REFERENCES
Boyd, C. E. (1979) Water quality in warm water fish ponds Auburn University
Agricultural Experiment station 359ppm.
Cruz, E. R, Cruz M. C. D., __, N. A.(1988)
Hematological and histopathological changes in Oreochromis
mossambicus after exposure to the moo luscicides Aquatin and
Brestan PP 99 - 110. IrrPullin et al (eds) The 2nd Int. symp.
on Tilapia in Aq. ICHAf Conf. proc. 15 623p.
Eller, L. L. (1971) Histopathological lesions in cuthroat trait (Salmo Clark),
exposed chronically to the ins ectifide endin. Am. J. Paihol. 64:
321 336.
Gardner, G. R. (1975) Chemically induced lesions in estuaries on marine teleosts. P.
657 - 693. In WI .E. Ribelin and G. Migaki (eds) The Pathology
of fish Univ of Wisconsin Press.
Koeso ite S. (1980) Pesticides as a major constraint to integrated e° hum -
aquaculture farming systems P. 45 - 51 In Puilin et al (es)
Integrated agriculture - aquaculture farming systmes. 1
CL I conference proceedings.
A. H. and IM).?.FIEH W. S. (1375)
The pathology of pesticide poisoning. P. 515 - 541. In W. E.
'belin ei al (eds) The pathology of fishes. Univ. of Wisconsin
Press.
177


The effects of two pesticides on Clarias gariepinus

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