ABSTRACT
Survival of yolk-sac larvae and gonad development of Oreochromis niloticus in serially diluted solutions of layer (chicken) manure were evaluated. The experiment was a complete randomised design with five treatments and three replicates. Levels of layer manure concentrations were introduced to 70 litre containers at the concentration of 8.4mg/l, 19.6mg/l, 28mg/l, 42mg/l and 84mg/l and the control devoid of any toxicant. The acute toxicity lasted for 4 days (96hrs LC50). The survival larvae were reared for three months with the larvae being fed twice a day to satiation at a stocking density of 10 fish per treatment. From the toxicity result the median lethal concentration (LC50) value of layer (chicken) manure for O. niloticus larvae was 30.90mg/l and the threshold is 1.49mg/l. The pH and temperature varied from control (p<0.05) while the dissolved oxygen decreased as the concentration increased. At the end of the rearing period, fish were dissected and gonad obtained for histological analysis. From the result, it could be attributed histologically that layer manure reduced the maturity of the gonads. The highest concentration (84mg/l) had more immature ovaries with mean value of 98.21±0.50, while control had the least (30.89±1.38). Maturing ovaries were highest in the control with mean value of 69.11±1.39 as compared to 84mg/l concentrations (1.75±0.52). There was significant difference between the means of dissolved oxygen, pH and temperatures (p<0.05).
TABLE
OF CONTENTS
Title
Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table
of Contents vi
Lists
of Tables ix
List
of Figures x
List
of Plates xi
Abstract xii
CHAPTER 1: Introduction
1.1 Background
of the Study 1
1.2 Toxicants 2
1.3 Statement
of Problem 3
1.4 Justification 3
1.5 Objectives
of the Study 3
Chapter
2: review OF RELATED LITERATURE
2.1 Aquatic Environment 4
2.2 Fertilizer 8
2.3 The Chemical Composition of Layer Manure 10
2.4 Nile Tilapia (Oreochromis niloticus) 10
2.4.1 Natural distribution and habitant 11
2.4.2 Diet and mode of feeding 11
2.4.3
Growth 12
2.4.4 Reproduction 12
2.4.5 Environmental tolerance ranges 13
2.4.6 History of domestication 13
2.5 Patterns of Ovarian Development in Teleosts 14
2.6 Reproductive Physiology 15
2.6.1 Size
at sexual maturation 17
2.6.2 Egg
size and fecundity 17
2.7 External Factors Affecting Reproduction in Tilapia 18
2.7.1 Water
temperature and dissolved oxygen 18
2.7.2. Photoperiod 19
2.7.3 Rainfall 20
2.7.4 pH 20
2.7.5. Stocking density 20
2.7.6 Diet 21
2.8 Methods
to Control Indiscriminate Spawning in Tilapia Farming 21
2.8.1 Polyploidy 21
2.8.2 Sex
reversal in fish (monosex male or female population) 22
2.8.3 Temperature 23
2.8.4 Manual
sexing 23
2.9. Female Gonadal Development in Tilapia (Oogenesis) 24
2.10. Ovarian
Development 26
2.10.1 Histological staging 27
2.11 Stages of Oocytes
Development 28
2.11.1 Chromatin nucleolar 28
2.11.2 Perinucleolar stage 28
2.11.3 Yolk vesicle (cortical alveoli) formation 29
2.11.4 Vitellogenic (yolk) stage 30
2.11.5 Ripe (mature) stage 30
2.12 Heavy
Metal 31
CHAPTER 3:
METHODOLOGY
3.1
Experimental Location 34
3.2 Experimental Procedure 34
3.3 Test Concentration Media 35
3.4 Procurement
of Larvae 35
3.5 Water Quality Parameters 35
3.6 Gonads Sample Collection and Histological
Examination 38
3.7 Heavy Metal Analysis 39
3.8 Data Collection 42
chapter 4: RESULTS AND discussion
4.1 Survival,
Mortality Rate and General Responses of the Fish to Toxicant 44
4.2 Survival Rate
of Test Organism 49
4.3 Effect of Heavy
Metal on Test Organism 52
4.4 Effect of Toxicant on the Gonads 55
4.5 Effects of Layer Manure on the Weight
and Feed Conversion Ratio 62
CHAPTER
5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 66
5.2 Recommendations 66
References 67
LIST OF TABLES
TABLE PAGE
2.1 Fresh
Layer Manure Concentration 10
4.1 pH variations in serially diluted layer
manure solutions containing
8.4mg/l
(T2), 19.6mg/l (T3), 28mg/l (T4), 42mg/l (T5), 84mg/l (T6)
of
fertilizer 41
4.2 Temperature
variations in serially diluted layer manure solutions
containing 8.4mg/l(T2), 19.6mg/l
(T3), 28mg/l (T4), 42mg/l (T5),
84mg/l (T6) of fertilizer 42
4.3 Oxygen variations in serially diluted
layer manure solutions containing
8.4mg/l
(T2), 19.6mg/l (T3), 28mg/l (T4), 42mg/l (T5), 84mg/l (T6) of
fertilizer 43
4.4 Mortality record (96 hrs LC50) of O. niloticus exposed to different
concentrations
of serially diluted layer manure , containing 8.4mg/l,
19.6mg/l,
28mg/l, 42mg/l and 84mg/l of fertilizer 50
4.5 Heavy
metal analysis on layer manure 53
4.6 Quantity
of heavy metal introduced into a serially diluted solution of
layer
manure 54
4.7 Gonad development of O. niloticus reared for three months in serially
diluted
layer manure solutions containing 8.4mg/l, 19.6mg/l, 28mg/l,
42mg/l,
and 84mg/l of fertilizer 63
4.8 Weight and feed conversion ratio of O. niloticus reared for three months
in
serially diluted layer manure solutions containing 8.4mg/l, 19.6mg/l,
28mg/l,
42mg/l, and 84mg/l of fertilizer 64
4.9 Mean Weight and Feed Conversion Ratio of O. niloticus 53
LIST OF FIGURES
FIGURE PAGE
4.1 96hr LC50
of the Layer Manure for O. niloticus larvae 51
4.2 Percentage Immature and Mature Ovaries 65
4.3 Bar chart showing the effect of layer
manure on the GSI 65
LIST
OF PLATES
PLATE PAGE
1:
Experimental Set-up and Units in Progress 36
2: Larvae of O.
niloticus 36
3: Histological
Analysis on Gonads of O. niloticus Treated
with
Layer Manure 56
3.1: Atretic Oocytes, Decreased in
Perinucleolar Stage 57
3.2:
Atretic Oocytes and Altered Chromatin Nucleolar Stage of Oocyte
Development 58
3.3:
Atretic Oocytes in Ovary of Fish 59
3.4: Vacuolation and Broken wall in
Vitellogenic Oocytes of Fish 60
3.5: Dissolution of Yolk globles and
Vacuolation in Vitellogenic Oocytes 61
CHAPTER 1
INTRODUCTION
1.1 Background
of THE study
Aquaculture has advanced considerably
to the level of intensive and extensive rearing of fish in flow-through and
recirculatory systems. Fish farming is integrated with livestock i.e. savings
for feeds, labour etc or gains to livestock or crops by introducing fish (Ahmed
and Bimbao, 2001). Pond preparation involves amongst other things organic and
inorganic fertilization (Omole et al.,
2006). Fish farmers are usually confronted with the problem of choice of
fertilizer (organic) for treatment of their pond water before stocking of
fingerlings. The life of fish is dependent on the water medium in which it
lives. The environmental factors affecting the development and practice of
aquaculture include the parameters of water quality such as temperature, dissolved
oxygen, turbidity, pH, nitrate-nitrogen and phosphate-phosphorous (Aguigwo,
1998).
Temperature affects a lot of vital
activities in the aquatic system particularly plankton and fish life (Balanin
and Hatton, 1979). In ponds, turbidity and colour matter originating from
colloidal clay particles entering with run-offs, colloidal organic matter
originating from the decay of vegetation or from abundance of plankton
(Nwadukwe and Onuoha, 1987). Fertilizers are organic or inorganic substances
that are used in ponds to increase the production of the natural food organisms
to be eaten by the fish. These organisms include phytoplankton, zooplankton and
insects. They are all part of a complex food web converging towards fish
production. By increasing the availability of major nutrients, fertilizer
promotes the development of plankton algae, which provide food for many fish.
Fertilization leads to the development of animals which feed on algae,
including some fish such as the Chinese silver carp and the tilapia. When a
fertilizer is added to a fish pond, the chemical it contains dissolve in water,
where; a portion is usually rapidly taken up by the phytoplankton present,
either to be stored, sometimes in quite large proportions, or assimilated and
used for growth. Chemicals cannot be used directly in fresh water bodies unless
their toxicity and sublethal long-term effect have been studied on non-target
animals like fish, sharing the same habitat. (Kabir and Ovie, 2011). Longer
studies need to be conducted to determine the long-term effect of fertilizers
on water quality (Zachary and Martin Petrovi, 2004). In many regions of the
world, nitrogen pollution from agricultural sources is a major problem (Vidal et al., 2000; Haygarth and Jarvis,
2002). This has originated from human habitation, agriculture and large number
of farm animals such as pigs, cows and poultry (Randall and Tsui, 2002).
Ammonia makes their presence in water
owing to fish excretion, untreated sewage effluent or seepage from agricultural
operations like the application of fertilizers contribute to the nitrogen
pollution. Clarkson et al., (1986)
has reported that ammonium is the main inorganic form of nitrogen. Accumulation
of ammonium in water may lead to decreased growth (Thurston and Russo, 1963;
Palanichamy et al., 1985); changes
fish behaviour (Rani et al., 1997;
Wicks and Randall, 2002) and increased vulnerability to disease (Thurston and
Russo, 1983).
Furthermore, sub lethal ammonium
concentrations in water showed inhibitory effects on the enzyme activities of
fish (Hisar et al., 2004) and caused
degeneration on different tissues (Erdogan et
al., 2005). They exhibit different degree of charges in the behavioural
pattern when their habitat is polluted.
1.2 Toxicants
Toxicants produce many physiological
and biochemical changes in fresh water organisms by influencing their
activities. Alterations in the chemical composition of the natural aquatic
environment usually affect behavioural and physiological systems of the
inhabitants, particularly those of the fish (Radhaiah et al., 1987). Fish mortality due to toxicant exposure mainly
depends upon its sensitivity to the toxicant, its concentration and duration of
exposure (Ram et al., 2009). Observations
of fish under a control treatment are based on comparison of the responses of
exposed fish which is a way of detecting abnormality (Richmond and Dutta,
1992).
Fertilizer might positively or
negatively affect the lives of aquatic animals (Yaro et al., 2005). These effects for aquatic organisms might be toxic
effects of pollutant which may be deadly (Kumar and Krishnamoorthic, 1983; Yaro
et al., 2005).
1.3. Statement
of Problem
Tilapia matures early and reproduces
frequently and this leads to stunting in the ponds. Up till now research on how
to deal with this situation has focused on genetic modification that would
produce sterile offspring. Tilapia and fertilizer co-exist in the pond when
fertilizer is applied and in natural water body from agricultural lands
runoffs.
1.4. Justification
This study will attempt to find a
solution based on low technology of old age problem of tilapia over population
and stunting in ponds.
1.5. Objectives
OF THE STUDY
i. To
monitor growth and survival of yolk-sac larvae of O. niloticus.
ii. To monitor the development of gonad of O. niloticus grown out in serially diluted
layer (chicken) manure solution.
(iia) To monitor the weight development or
gonadosomatic index.
(iib) To monitor histological development of the
gonads.
iii. To
monitor the growth and survival of sub-adult stages of O. niloticus.
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