A study was conducted to determine the relationships between secchi disk variability, water temperature and dissolved oxygen in fish ponds. Multiple regression correlation analysis was done to evaluate the relationships between the variables. Results indicated that the ranges of secchi disk visibility, water temperature and dissolved oxygen in the study ponds were just within the ranges of the variables for tilapia culture. Multiple regression correlation showed no (or insignificant) relationships with dissolved oxygen and water temperature, dissolved oxygen with secchi disk visibility and water temperature with secchi disk visibility

Ali, M.H.

Cagauan, A.G.

Aquatic Commons

Bangladesh'. Fish. Res., 11(1), 2007: 45-50 
	 ©BFRI 
Relationships between secchi disk visibility, water 
temperature and dissolved oxygen in freshwater fishpond 
M. Hazrat Ali * and Arsenia G. Cagauan 
Central Luzon State University, Science City of Munoz, Nueva Ecija, Philippines 
*Present and corresponding address: Rice Farming Systems Division, 
Bangladesh Rice Research Institute, Gazipur, Bangladesh 
Abstract 
A study was conducted to determine the relationships between secchi disk variability, 
water temperature and dissolved oxygen in fish ponds. Multiple regression correlation 
analysis was done to evaluate the relationships between the variables. Results indicated 
that the ranges of secchi disk visibility, water temperature and dissolved oxygen in the 
study ponds were just within the ranges of the variables for tilapia culture. Multiple 
regression correlation showed no (or insignificant) relationships with dissolved oxygen 
and water temperature, dissolved oxygen with secchi disk visibility and water 
temperature with secchi disk visibility. 
Key words: Secchi disk, Water temperature, Dissolved oxygen 
Introduction 
Fish production is usually closely related to phytoplankton abundance (Boyd 1982) and 
phytoplankton is in turn the main nutritional component for tilapia (Harbott 1982). 
Fish perform best and healthiest when dissolve oxygen (DO) concentrations are near 
saturation. However, DO is directly controlled by the amount of phytoplankton in the 
ponds (Boyd 1982) but oxygen depletions resulting from massive plankton blooms can 
results in fish kills. 
In fish ponds, plankton is usually the primary source of turbidity which is generally 
desirable for fish culture but the turbidity resulting from high concentrations of humic 
substances is not desirable because of acidity, low nutrient levels and limited light 
penetration for photosynthesis. Secchi disk visibility (SDV) however, provides an 
estimate of water transparency (turbidity) that is generally related to plankton 
abundance (Barica 1975). At lower SDV plankton blooms are so dense that there is high 
probability of problems with DO. Higher SDV indicates insufficient phytoplankton 
productivity to support enough fish food organisms for fish production. 
Temperature is among the most important environmental variable that influence 
behavior of aquatic poikilotherms (Gunter 1957, Kinne 1963). The rates of biochemical 
M. H. All az A.G. Cagauan 
processes of organisms are temperature dependent (Boyd 1990) and increasing water 
temperature enhancing fish metabolism and synthesis of body tissues (Perin 1993). 
As of Moncrief and Jones (1977) a 10°C increase of temperature roughly doubles 
biochemical rate. They also suggested that oxygen consumption increase with 
temperature increase until a maximum value is achieved and then oxygen consumption 
decreased relatively rapidly as temperature continuous to increase. However, to obtain 
optimum fish growth, temperature, SDV and DO are important. Therefore, this study 
aimed to evaluate the relationship between secchi disk visibility, water temperature and 
dissolved oxygen using multiple regression and correlation. 
Materials and methods 
A case study was conducted in fishponds at the University Agribusiness Program 
Fish Farm of Central Luzon State University, Science City of Munoz,
. Nueva Ecija, 
Philippines. Eight ponds were selected where tilapia (Oreochromis niloticus) was cultured. 
Each of the ponds consisted 3000 m 2 area. Average water depth ranged from 0.90-1.0 m. 
Fingerlings of tilapia were released with stocking density of 4/m 2. Chicken manure at 
the rate of 2000 kg/ha/week was applied twice a day at 9 am and 1 pm. Each of the 
selected pond was divided into three locations from where SDV, water temperature and 
DO were determined three times in a week at 9-10 am and which was continued for a 
month. Measurements of these variables were taken 1 m away from the dike. 
Measurement of SDV 
A Secchi disk, made of wood consisted of a weighted circular plate, 20-cm in 
diameter with the surface, pointed with opposing black and white was used to determine 
the SDV depth. The secchi disk was attached to a calibrated line a ring at the center so 
that when hold by line, it hanged horizontally. To determine the SDV, the secchi disk 
was lowered into the water until it was disappeared and noted the depth. Lowered the 
disk a few more cms and then slowly raised until it was appeared and also recorded the 
depth. The average of the two reading considered for the final secchi disk variability 
depth. Clearness of the day, lee side of the sun and without sunglass of the observer was 
taken into consideration during the period of observation. 
Measurements of DO and water temperature 
Dissolved oxygen and water temperature were measured by using Polarograhhic 
digital oxygen meter. The electrode of the digital DO meter was submerged under water 
at about 10-15 cm. The meter automatically gave the reading of DO and temperature. 
The reading of DO and temperature are usually blinking. However, DO and 
temperature were recorded when the reading of the variables were stable. 
All the collected data were computed as multiple regression and correlation analysis 
using Microsoft Excel program by computer. 
46 
Relationships between secchi disk visibility, water temp. & DO 
Results and discussion 
Secchi disk visibility provides an estimate of phonic zone where most of the natural 
food (plankton) for fish being grown. Results of SDV monitoring exhibits the overall 
ranged from 9.90-36.38 cm. Highest SDV observed in pond number 1 & 6 ranged from 
20.72 - 32.66 and 19.95 - 36.38 cm, respectively (Table 1). These results just within the 
range (15-40 cm) for tilapia culture as suggested by Boyd (1982). Rest of the ponds 
showed lower SDV than the recommended for tilapia culture. 
Table 1. Ranges of secchi disk visibility, temperature and 
dissolved oxygen of the study ponds 
Pond 
No. 
Ranges 
Secchi disk 
visibility (cm) 
Temperature 
(0C) 
Dissolved oxygen 
(mg/1) 
1 20.72 - 32.66 24.53 - 28.63 5.45 -19.15 
2 13.21 - 26.87 24.87 - 28.90 3.47 - 9.04 
3 12.32 - 32.54 24.93 - 28.50 3.89 - 8.97 
4 16.27 - 27.85 25.23 - 28.97 3.70 - 6.54 
5 9.90 - 20.25 24.52 - 29.40 3.12 - 5.41 
6 19.95 - 36.38 24.73 - 29.50 4.07 - -8.46 
7 13.88 - 23.40 24.50 - 29.53 4.42 - 8.34 
8 15.52 - 26.43 25.00 - 29.20 3.97 - 7.97 
As the SDV provides the estimate of water transparency (turbidity) which is 
generally related to plankton abundance (Barica 1975, Almazan and Boyd 1978), 
planktons provides oxygen ranges from 20-25 mg/I, about 80% of the total source 
through photosynthesis in a sunny day (Zhu and Tang 1996) and DO is directly 
controlled by the amount of phytoplanktons in the pond, besides other factors (Boyd 
1982), hence DO might have some influence in relationship with SDV. However, 
multiple regression (r =0.102 ", Y = 5.466 + 0.0287 X) of SDV and DO showed no (or 
insignificant) relationship in the study (Fig. 1). Perhaps, turbidity produced by dirt and 
other suspended particles prevented sunlight from reaching the plankton which 
contributed not to produce enough oxygen, resulted in insignificant relationship 
between SDV and DO. 
Temperature is among the most important environmental variable that influence 
biological process, survivability, growth and reproduction and susceptibility to diseases 
of organisms (Boyd 1990). However, temperature ranged from 24.50 to 29.53 °C (Table 
1) which found ideal for tilapia culture. Generally, tilapia able to live over a wide ranges 
of water temperatures from 8-42 °C (Balarin and Haller 1982 as cited by Mair and Abella 
1997). It has also been observed that when rain occurred at night followed by wind at the 
time of monitoring, comparatively lower temperature was measured at the following 
day. Prein (1993) suggested that water temperature increased with solar radiation but 
47 
M. H. Ali & A.G. Cagauan 
decreased by wind-driven evaporation cooling. He also reported that variation of water 
temperature is responsible for 38% by solar radiation and wind of which wind 
responsible for 36% alone. The results of the study, to some extent again confirmed the 
findings of Prein (1993). 
10 
9 
7 
U 
* * 
40.* 
	 * 
* 
*+ 
* 
* 
• ** 	 * 
* t * • 
• + '14 ,1; 
5 
4 * * * 
3 4 y = 5.466 +0.0287x 
2 r = 0.102ns 
1 ri= 120 
0 
8 	 13 	 18 	 23 	 28 	 33 	 38 Secchi disk visiblity (cm) 
Fig.1. Relationship between Secchi disk visibility and 
dissolved oxygen 
10 - 
** 	
.0.4. 
• . 
* 
.ft * 	 4 CI 8 - 
7 - 
	 + 
+ *4, 
* 	 ,----. 6 - 	 * 
5 	
* 
...'c' 	 ** 4**. 
- + *
* 
 
4 - 	 • • 	 * ..0. 
.. 	
-7,. 	 4. 	 y = 1.946 + 0.1502x44 t 4. 4 
_. - 
-) _ 	 r = 0.125ns ii1 
	 n=120 
0 
24 	 26 	 22 
	 30 
Temperature (oC) 
Fig. 2. Relationship between temperature and 
dissolved oxygen 
Dissolved oxygen is the most limiting water quality parameters to fish life and 
commonly managed in fishponds particularly in intensive culture systems. Dissolved 
oxygen in the study ponds recorded ranged from 3,12 — 12.96 mg/1 (Table 1). Highest 
DO measured from the pond number 1, ranged from 5.45 — 12.95 mg/1 followed by pond 
number 7, ranged from 4.42 — 8.34 mg/1 and pond number 6, ranged from 4.07 — 8.46 
mg/l. In the other ponds DO observed just above the critical level (0.1 — 3.0 mg/1) as 
cited by Mair and Abella (1997). Dissolved oxygen below 5 mg/1 is undesirable in ponds 
(Swingle 1969, Boyd 1990). Prein (1993) reported that water temperature has a relatively 
strong influence on DO. Multiple regression correlation of DO versus temperature 
showed that DO had no (or insignificant) relationship (r = 0.125", Y= 1.946+ 0.150X) 
Di
sso
lv
ed
 ox
yg
en
  (In
g/L
)  
48 
Relationships between secchi disk visibility, water temp. & DO 
with temperature (Fig. 2). Similar results have also been observed in relationship 
between secchi disk visibility and temperature (Fig. 3). 
35 
30 - 
y = 28.26 - 0.045x 
r = 0.196ns 
n=120 
0 25 
20 
I 15 
E 
H 10 
5 
0 
0 	 10 	 . . 	 20 S ec chi disk visibility (cm) 30 
Fig. 3. Relationship between Secchi disk visbility 
and temperature 
References 
Almazan, G. and C.E. Boyd, 1978. Water quality management for pond fish culture. Department 
of fisheries and allied aquaculture. Agricultural Experiment Station, Auburn, Alabama, 
Birmingham Publishing Company, New York. 
Balarin, C. and D. Haller, 1982. Techno guide on the production of genetically male tilapia (eds. 
G. Mair and T.A. Abella). Freshwater Aquaculture Center, Central Luzon State University, 
Philippines. 
Barica, J., 1975. Summer kill risk in prairi ponds in possibilities of its production. 1. Fish Res. 
Bd. Canada, 32(1): 283-288. 
Boyd, C.E., 1982. Water quality management for pond fish culture. Department of Fisheries and 
Allied Aquaculture. Agricultural Experiment Station, Auburn, Alabama, Birmingham 
Publishing Company, New York. 
Boyd, C.E., 1990. Water quality management for pond fish culture. Department of Fisheries and 
Allied Aquaculture. Agricultural Experiment Station, Auburn, Alabama, Birmingham 
Publishing Company, New York. 
Gunter, G., 1947. Differential rate of death for large and small fishes caused by hard cold waves. 
Science, 106: 472-479. 
Harbott, D.E., 1982. Multiple regression and path analysis of Nile tilapia growth in integrated 
livestock-fish in the Philippines. In: Multivariate methods in aquaculture research: Case 
studies of tilapia in experimental and commercial systems (eds. M. Prein, G. Hulata and D. 
Pauly). International Center for Living Aquatic Research Management. Metro Manila, 
Philippines. 
Kinne, 0., 1963. The effects of temperature and salinity on marine and brackish water animals. I. 
Temperature. Oceanogr. Mar. Biol. Ann. Rev. 1: 301-340. 
49 
M. H. Ali & A.G. Cagauan 
Moncrief, J.W. and W.H. Jones, 1977. Water quality management for pond fish culture. 
Department of Fisheries and Allied Aquaculture (ed. C.E. Boyd). Agricultural Experiment 
Station, Auburn, Alabama, Birmingham Publishing Company, New York. 
Prein, M., 1993. Multiple regression and path analysis of Nile tilapia growth in integrated 
livestock-fish in the Philippines. In: Multivariate methods in aquaculture research: Case 
studies of tilapia in experimental and commercial systems (eds. M. Prein, G. Hulata and D. 
Pauly). International Center for Living Aquatic Research Management. Metro Manila, 
Philippines. 
Swingle, H.S., 1969. Water quality management for pond fish culture. Department of Fisheries 
and Allied Aquaculture (ed. C.E. Boyd). Agricultural Experiment Station, Auburn, Alabama, 
Birmingham Publishing Company, New York. 
Zhun, S. and S. Tang, 1996. Water quality management for pond fish culture. Department of 
Fisheries and Allied Aquaculture, Bangkok, Thailand. Jan. 29-Feb. 2, 1996. 
(Manuscript received 11 June 2007) 
50 


Relationships between secchi disk visibility, water temperature and dissolved oxygen in freshwater fishpond

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Relationships between secchi disk visibility, water temperature and dissolved oxygen in freshwater fishpond

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