MONITORING WATER QUALITIES [FISHERY]
CHAPTER SEVEN
MONITORING WATER QUALITIES
WATER QUALITY
7.1 MEANING
OF WATER QUALITY.
Water quality refers to the chemical, physical and biological
and aesthetic (appearance and smell) characteristic of water. It is a measure
of the condition of water relative to the requirement of one or more biotic
species and or to any human need purpose. The most common standards used to
assess water quality relate to health of ecosystems, safety of human contact
and drinking water
HOW IS WATER QUALLITY
MEASURED?
The presence of
contaminants and the characteristics of water are used to indicate the quality
of water. These water quality indicators can be categorized as:
a)
Biological: bacteria algae
b)
Physical: temperature turbidity and clarity colour,
salinity, suspended, solids, and dissolves, solid.
c)
Chemical: PH, dissolves oxygen,
biological, demand, nutrients(including nitrogen and phosphorous),organic and
inorganic compounds (including toxicants)
d)
Aesthetic: odours, taints, colours, floating matter
e)
Radioactive: alpha, beta, and gamma radiation emitter
Measurements of these indicators can be use to
determine and monitor changes in, water quality and determine whether it is
suitable for the health of natural environment and the uses for which the water
is required.
CONDITIONS OF WATER THAT PROMOTE GOD HEALTH OF FISH.
Fish need quality water to survive, grow, and
reproduce. Quality water has no pollutants, is high in dissolved oxygen and
does not have excessive organic matter or silt.
Fencing
pond to prevent access by livestock is extremely important for maintain good
water quality. Livestock trampling erodes pond banks which causes pond
swallowing, muddy water and loss of fish habitat. Livestock waste promotes
algae and other plant growth, increase organic content, and increase the
chances for fish kills. Livestock fences should be 50 to 100 feet from the pond
bank and completely enclose the pond including the dawn and spillway.
Every pond should have a vegetated
border. Forested or grassy areas at least 50 feet wide will reduce soil erosion
and reduce the amount of fertilizer and pesticides entering the pond with run
off. Trees along the shoreline are desirable for shading nutrient uptake.
Oxygen in water is produce by
microscopic plants (phytoplankton) and other larger plants during
photosynthesis and by wind and wave action mixing the air and water. Most fish
need attract 5parts per million (ppm) of dissolved oxygen for good health
oxygen levels below 3ppm stress fish, and most will die when dissolved oxygen
levels in ponds with poor water quality. Some fish have strict habitat
requirements. For example trout are very sensitive to temperature and dissolved
oxygen levels. To survive, trout typically need water less than 700
F, and dissolved oxygen levels greater than 5ppm.
Muddy water directly influences the
health of a pond. Sight feeding fish like largemouth bass and bluegill need
reasonable clear water to find their food. Water clarity is necessary for
plankton production the basic component of the food chain. Water clarity should
be at least 18 inches throughout the year clarity can be measured using a
secchi disk, which is an 8 inch disk made of wood, metal, or plastic. The disk
is marked into quarter alternately painted black and white attach the disk to
the end of a yard stick or pole (right). Ponds that receive excessive sediments
from heavy rains may need a diversion ditch to channel water away from the pond
that stay muddy may need lime to reduce acidity and to settle suspended clay
7.2 WATER QUALITY PARAMETER
The
water quality parameters to be considered in an aquaculture are as follow
1.
Dissolves oxygen (DO)
2.
PH
3.
Temperature
4.
Turbidity
5.
Conductivity
1.
DISSOLVES OXYGEN (DO) :-This is the
most important chemical parameter in aquaculture. Low dissolved oxygen levels
are responsible for more fish kill, like human, fish require oxygen for respiration the amount of oxygen
consumed by fish is a function of its size feeling rate, activity levels and
temperature small fish consume more oxygen than do large fish because of their
higher metabolic rate. The amount of oxygen that can be dissolved in water
decreases at higher temperatures and decreases with increase in altitudes and
salinities.
Oxygen
enters the water primary through direct diffusion at the air-water interface
and through plant photosynthesis. Direct diffusion is relatively insignificant
unless there is considerable wind and wave action several forms of mechanical
aeration are available into the fish farmer.
Ways of achieving aerator in a fish
pond.
I.
Paddling II. Beating of water. III. Walking/ wadding through water
IV.
Reduce water level and refill with water from shower.
Dissolve oxygen can be
measured through dissolve oxygen meter
Dissolved
oxygen meter
CONDITIONS THAT
REDUCE THE LEVEL OF OXYGEN IN FISH PONDS.
·
Overfeeding
·
Present
of zooplankton
·
High
stocking density / overstocking / overcrowding
·
Reduced
phytoplankton population/ high transparency in water
·
Long
period of hot weather
·
Oxidation
process of decay
·
High
temperature
·
High
load of organic matter
·
Over
fertilization
2.
PH:- The quality
of hydrogen ions (H+) In water will determine if it is acidic or
basic. To measure the PH meter and pH paper test strip
can be used. The pH paper strip is a scale for measuring the degree
of acidity, which ranges from 1-14. A value of 7 is considered neutral neither
acidic nor basic, value below 7 are considered acidic, above 7 basic. The
acceptable range for fish culture is normally between pH 6.5-90.
PH meter
3.
TEMPERATURE:-After
oxygen, water temperature may be the single most important factor affecting the
welfare of fish. Fish are cold-blooded organisms and assume approximately the
same temperature as their surrounding. The temperature of the water affects the
activity , behaviors, feeding growth and reproduction of all fishes.
Warm water species like catfish and tilapia a temperature of
850 F and 870F respectively is considered optimum while
in cold water species like trout salmon is at the optimum range 48-650F
for growth
4. TURBIDTY:- The turbidity
are caused by phytoplankton and zooplankton is not directly harmful to fish
phytoplankton(green algea) not only produces oxygen but also provide a food
source for zooplankton and filter feeding fish/shellfish. Phytoplankton also
uses ammonia produced by fish as a
nutrient source. Zooplankton is a very important food source for fry and
fingerlings such as yellow perch and striped bass. However excessive amount of
algae can lead to increased rates of respiration during the night thereby
consuming extra oxygen. Excessive phytoplankton buildups or “bloom” which
subsequently die will also consumes extra oxygen. Any wide swings between day
and night oxygen levels can lead to dangerously low oxygen concentration . Most clay turbidity problems are the result
of exposed soil on the pond levee, exposed watershed, crayfish activity or
feeding of bottom dwelling species such as carp and catfish. Turbidity value
levels exceeding20,000ppm can cause behavioral changes in fish. In natural
bodies of water, turbidity value seldom exceed these critical level. Turbidity
caused by clay or soil particles however can restrict light penetration and
limit photosynthesis . Removal of clay turbidity can be accomplished by adding
materials that attach to the negative charges of the clay particles, forming
particle heavy enough to settle to the bottom.
Common remedies
for day turbidity are 7-10 square bales of hay per surface acre or 300-500
pounds gypsum per surface acre. Gypsum application may be repeated at two week
intervals if pond does not clear.
Secchi disc
WATER QUALITY TOLERANCE BY SOME FISHES
|
SPECIES |
TEMP(OF) |
D.O(MGLL) |
PH |
ALKALINITY |
NH3(%) |
|
Catfish |
65-80 |
3-10 |
6-8 |
50-250 |
o-o.03 |
|
Bait fish |
60-75 |
4-10 |
6-8 |
50-250 |
0-0.03 |
|
Salmon/trout |
45-68 |
5-12 |
6-8 |
50-250 |
0-0.03 |
|
Tilapia |
75-94 |
3-10 |
6-8 |
50-250 |
0-0.03 |
7.3 AQUATIC PLANTS
Aquatic plants are plants
that grow in water, they can be found in any water bodies.
TYPES OF AQUATIC PLANTS
I. FLOATING PLANT: These are aquatic plants that float in water. They
have special types of leaves that help them to stay afloat. They use sunlight
and air to make their food e.g water hycinthes
II. SUBMERGED PLANT: These are aquatic plant that grow under water.
These plants take carbondioxide from the water around them and give out oxygen.
Their leaves have no pores or stomata and they breathe through their surface.
These plants are flexible and can bend easily with the flow of water. e.g pond
weed, hydrilla
III. ROOTED PLANT: These are aquatic plants have their root fixed in
the waterbed. Their stems are hollow and light so that the flower and the
leaves can float on water. They breathe through the pores or stomata on their
broad leaves e.g water lily, lotus
IMPORTANCE OR BENEFITS OF AQUATIC PLANTS
1. Provides protection to fish.
2. It increase oxygen levels in water.
3. It serves as food to some aquatic organisms.
4. It filter water.
5. It prevent undesirable plants from growing.
6. In large water bodies,
they also help our shores fight against aggressive currents and erosions.
7.4 WATER POLLUTION
Water pollution is the contamination
of water bodies. It occurs when pollutants are directly or indirectly
introduced into water bodies without adequate treatment to remove harmful
compounds.
7.41 CAUSES OF WATER POLLUTION AND THEIR CONTROL
1. Sewage or human waste
Control: - Sewage should be properly
disposed in dug pit.
- Sewage should be treated and free of
impurities before disposing in water.
- Proper education on sewage disposal.
2. Debris
Control: - Should be properly disposed
at dump site not water.
3. House refuse
Control:
Avoid disposing in water.
4. Poisons or agrochemical
Control: - Avoid use of poison in fishing or disposing poison or chemical
into waste sewage.
5. Oil
spillage
Control: - Dispose at proper site.
-
Properly maintain oil pipeline to prevent leakage.
- Provide security against oil pipeline.
6. Sand mining
Control: - Adhering to government
policy on sand mining.
- Sand mining should be
discouraged and prevented especially near fish breeding ground.
7. Industrial waste / industrial effluents
Control: - The waste should be treated
before disposal.
- Adherent to government policy on
waste disposal.
7.42 EFFECTS
OF POLLUTION ON AN AQUATIC ORGANISMS
1. Death of
aquatic organism: The main problem caused by water pollution is that it
kills life that depends on water bodies. Death fish, crabs, tortoise and many
other animals often wind up on water bodies, killed by pollutants in their
habitat.
2. Destruction
of ecosystems: Many areas are now being affected by careless human
pollution, and this pollution is coming back to hurt humans in many ways.
3. Destruction
of food chains: Pollution affect natural food chain. Pollution such as lead
and cadmium are eaten by tiny animals. Later, these animals are eaten by fish
and shellfish, and the food chain continues to be disrupted at all higher
levels.
4. Diseases:
People can get diseases such as hepatitis by eating seafood that has been
poisoned.
IMPORTANCE OF WATER TO FISH
1. It is a source of habitat for fish.
2. Water help in fish locomotion.
3. Plays important role in fish metabolism.
4. It regulate or stabilize their body temperature.
5. It aids digestion of food in fish.
7.5 WATER
QUALITY MONITORING
Clean water is
colorless, odorless and tasteless and has a pH of 7, but in fisheries suitable water can
have color, taste and odour but the degree and type of colour taste and odour
determine water suitability for fish. Fish unlike other animals feed and
defecate inside the same water where they live and the quality of the water
inside which they live directly affects feed efficiency, rate of growth
,survival and the state of health of the fish. When water quality depreciates,
consumed feed is not properly converted into body flesh. Poor growth is
recorded, fish survival is affected and ultimately massive fish kill may occur.
In fish production, the following water parameter should be continually
monitored are dissolve oxygen, temperature,
pH and ammonia. Water quality parameter standard for
fisheries are:
- Dissolved
oxygen (DO):- 5.0-8.0mg/l
- PH:- 6.5-8.0
- Turbidity/
Transparency: - less than 30cm secchi disc measurement.
- Temperature:
20-30oC.
- Nitrite: <
0.25 ppm
- Ammonia: <
0.05 ppm
- Alkalinity:
< 50- 200 ppm(m/l)
Water quality parameter and instrument of measurement
|
Water quality parameter |
Instrument /kit |
|
1.
Dissolved oxygen |
Dissolved oxygen meter. |
|
2.
pH |
pH meter, litmus
paper, field kit. |
|
3.
turbidity |
Secchi disk, nephelometer. |
|
4.
conductivity |
Electrical conductivity
meter. |
|
5.
Temperature |
Thermometer, deptherm. |
|
6.
salinity |
Hydrometer refractometer . |
7.6 WATER TREATMENT
OF POLLUTION AND INFECTION.
Aquarium were polluted done to the buildup of organic waste
due to over feeding fish or plant death and decay, improper cycling or toxic
gases from rotten debris and waste in the gravel of the tank. The pollution of
the water can also be caused by free chlorine present in most tap water and
heavy metals poisoning from old pipes and deposition of metal in the fish
tanks. Fish also susceptible to unless due to stressor and crowding condition
of fish.
TYPES OF POLLUTANTS AND
TREATMENTS
1.
AMMONIA POISONING:- Aquarium
pharmaceuticals melafix heals open wounds and abrasion, treats fin and tail
rot, eye, cloud, mouth fungus and promotes regrowth of damaged fin rays and tissue. Do daily water change to reduce
ammonia levels to1-2ppm for freshwater or below 1ppm for salt water, aerate, and make sure pH at or below 7.0 for freshwater tanks.
2.
CARBON (ii) OXIDE POISONING:- Strong
aeration water change and never fertilize with co2 at night.
3.
NITRATE /NITRATE POISONING:- Find
cause of organic pollution and change water to bring down level.
4.
POISONING FROM TAP WATER:- Test the
water before using and filter with tap water purifier or use water run through
an reverse osmosis filter.
5.
HEAVY METAL POISONING:- This
poisoning is remove by utilizing a reverse osmosis system or filtering the
water through activated carbon and using water conditioners.
6.
HYDROGEN SULPHIDE POISONING:- Using a
siphon to remove waste from the gravel or a water change.
TYPES OF INFECTION AND TREATMENT
1.
BACTERIA FIN ROT:-Using
antibiotic (tetracycline) check for water condition bath in trypaflavine.
2.
DROPSY:- At early detection use
peniciline, tetracycline and neladixic acid and late stage treat with
medication for internal infections.
3.
HEXAMITA (HOLE IN THE HEAD DISEASE) :-Early
stage with only small holes can be helped with the addition of vitamins A and C
.Treatment can also include dosage of antibiotics, metronidazole and flagyl
4.
GILL AND SKIN FLUKES:- Formalin
bath outside of aquarium or consecutive salt bath over 2-3 days or using
ammonium hydroxide baths.
5.
WHITE SPOT OR ICH:-( a) using
hypo-salinity (b) copper treatment (c) using melachite green (d) tank transfer
methods.
6.
VELVET:- Copper sulphate solution
at a concentration of 0.2ppm. This should be repeated after 3days to ensure
eradication. Treat with methylene blue or quinine hydrochloride.
7.
HEMMORAHGIC SEPTICEMIA:- use of
tetracycline
8.
FISH LICE (ANGULUS):- The
treatment is careful, manual removed with a pair of tweezer and siphon the
gravel daily to remove eggs. Heavy infectation can be treated by dylox, masoten
or trichlorofon, be sure to remove all invertabrates from the aquarium as they
may be harmfully affected by the treatment .
9.
SAPROLEGNIA AND ACHLYA:- 3ominutes
bath In 1ppm sodium permanganate, the addition of malachite green.
MONITORING
WATER QUALITIES
1. Heavy
plankton bloom in pond water could (a) Make the water clean (b) Cause depletion
of oxygen in the water (c) Increase nutrient content of the water (d) Improve
the oxygen content of the water.
2. Fishes
cultured in water with pH ranges 1-14 are most likely to (a) Eat
more (b) Be more active (c) Die (d) Reproduce.
3. In which
pH range(s) are fishes likely to stop reproduction? (a) 4-6 (b) 6-9
(c) 4-6 and 6-9 (d) 4-6 and 9-11
4. Which of
the following statements about water quality in a fish pond is correct? (a)
Addition of lime increase pH (b) Stirring of water reduces dissolved
oxygen (c) Addition of cold water increases temperature (d) Excessive feeding
of fish reduce turbidity.
5. The
desirable pH range for fish culture is (a) 1-4 (b) 4-6 (c) 6-9 (d) 9-11
.
6. Dissolved
oxygen in pond water is obtained from (a) Runoff from land (b) Photosynthesis
of aquatic plants (c) Photosynthesis of terrestrial plant (d) Absorption of
carbondioxide from water.
7. The optimum range of dissolved oxygen
recommendation for fish pond is (a) Below 2.0mg/L (b) 2.0-3.5mg/L (c) 3.6-4.9mg
/L (d) 5.0-8.0
8. The water
quality of a fish pond could be improved by (a) Stirring the pond water (b)
Introducing different fish species (c) Changing the feeding time of fish (d)
Continuous feeding of fish.
9. Which of
the following is not a way of improving dissolved oxygen in a fish pond? (a)
Correct stocking (b) High feeding rate (c) Photosynthesis by aquatic plants (d)
Increase water flow.
10. Which of
the following is not a water quality parameter in fish culture? (a)
Conductivity (b) Dissolved oxygen (c) pH (d) Phosphate.
11. The
following are ways of Improving dissolved oxygen in a fish pond except (a)
Aeration (b) Paddling (c) Splashing (d)
Stocking.
12. The
following are live phytoplankton except (a) Chlorella (b) Closterium (c)
Thalassiosira (d) Copepod.
13. Which of
the following causes water pollution? (a) Fish stocking (b) Industrial effluent
(c) Liming of pond (d) Stirring pond bottom.
14. An
instrument used for measuring temperature in a fish pond is called (a)
Conductivity meter (b) Dissolved oxygen meter (c) pH meter (d)
Thermometer.
15. The
instrument used for monitoring turbidity in a fish pond is called (a)
Conductivity meter (b) Secchi disc (c) Dissolved oxygen meter (d) pH
meter.
16. What are
the small floating zooplankton in pond called (a) Bloom (b) Alkaloids (c)
Flukes (d) Gall.
17. What is
the most critical water quality for fish ? (a) PH (b) Nitrite (c)
Oxygen (d) Temperature.
18. The
following method improves dissolved oxygen in water except (a) Add fresh water
into the pond (b) Increase manure loading (c) stir the pond (d) Provision of
flow through system.
19. Heavy
plankton bloom in a water body may lead to (a) High temperature (b) Low
dissolved oxygen (c) Low carbon dioxide (d) High pH.
20. The lowest
concentration of dissolved oxygen in a pond occur (a) Midday (b) Mid –morning
(c)Just before dawn (d)Mid night.
21 The
recommended temperature range at which fish perform well in a pond is (a) 15-22oC
(b) 25-32oC (c) 35-42oC (d) 45-52oC .
22. The degree
of hotness or coldness of an aquatic environment is called (a) alkalinity (b)
conductivity (c) hardness (d) temperature.
23. The
physical, chemical and biological characteristics of water constitute (a) post
stocking (b) pre-stocking (c) water management (d) water quality.
24. Which of
the following is not a way of improving dissolved oxygen in a fish pond? (a)
Aeration (b)overstocking(c) Padding (d) Splashing.
25. The following are methods of controlling
aquatic vegetation except (a) biological (b) cultural (c) economical (d)
integrated.
26. The cloud
appearance of water due to suspended particles causes (a) acidity (b)
conductivity (c) hardness (d) turbidity.
27. Microscopic
plants that grow in water are called (a) blue-green algae (b) parasite (c) phytoplankton
(c) spirogyria
THEORY
1. Enumerate five
importance of water to fish.
__________________________________________________________
__________________________________________________________
___________________________________________________________
___________________________________________________________
___________________________________________________________
2a. Mention
five water quality parameter.
_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
(b) State one method used in
measuring each of the water quality parameter mentioned in 2 (a) above.
_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
3. Mention three
sources of water for fish farming.
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
4.
State two disadvantages of algal bloom in a fish pond.
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5(a) What is water
pollution.
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
(b) Name three water pollutants.
_________________________________________________________________________________________________________________________________________________________________________________
6. List four ways of
improving dissolved oxygen in a fish pond.
_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
7. List five effects of pollution on aquatic
organisms.
_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
8(a). List four causes of
water pollution.
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
(b)State one way of controlling each of the
causes listed in 8(a) above.
_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
9. Complete
the table below.
|
Water quality
parameter |
Recommended value
for fish culture |
Monitoring
instrument |
|
pH |
|
|
|
Temperature |
|
|
|
Dissolved oxygen |
|
|
|
Conductivity |
|
|
|
Turbidity |
|
|
10. State
five ways of preventing pesticides from contaminating fish pond water.
_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
11. State
two other ways of achieving the purpose for which aquarium aerator is used in a
fish pond.
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