LOW WATER TEMPERATURE AND ITS EFFECTS ON STRESS RESPONSE OF GREY MULLETS Mugil cephalus ACCLIMATED IN FRESHWATER
Abstract: Grey mullet (Mugil
cephalus) can adapt to saline and freshwater. Although belonged to euryhaline
species, but information regarding their stress response on low temperature.
Environmental disturbance such as low water temperature may effect their
physiological condition. These information can be useful for aquaculture
development of this species in freshwater. Therefore, the purpose of study was
to investigate the effects of low water temperature on the stress response of grey
mullets Mugil cephalus acclimated in freshwater. The blood samples of
experimental fish (TL: 28.2±1.1 cm, BW: 198.6±25.9 g) were collected during
winter season when the water temperature of controlled rearing system was
stable at 25°C and uncontrolled rearing system slowly dropped until 12°C. Their
stress response on both rearing systems was observed. The results showed that
low temperature affected to lower the behavior activity and increase the stress
response of grey mullets. The breath frequency of grey mullet regarding their
opercular movement at 12°C was 74-97 breath/min., while at 25°C it was 95-114
breath/min. Hematocrit (Ht) and hemoglobin (Hb) were shown higher values of
43.5% and 9.5 g/dL, respectively at 25°C than 12°C (28.0% and 7.1 g/dL, respectively).
The tendencies of cortisol and glucose level increased with the lowering
temperature, showing higher value of 264.8 ng/mL and 35.5 mg/dL in 12°C than
5.5 ng/mL and 32.7 mg/dL in 25°C. The chemical properties of blood in grey
mullets showed same tendency comparing between 12°C and 25°C, there was no
significant different between each temperature, except for chloride
(P<0.05). Chloride value was higher at 25°C, while other blood components
such as osmolality, sodium, potassium, and magnesium were showing no
significant differences. However, the results showed lower values at 12°C in
every blood components, except for chloride. In conclusion, lowering water
temperature to 12°C had impact as stressor to the behavior and stress response
of grey mullets acclimated in freshwater.
Keywords: temperature; stress
response; grey mullet; Mugil cephalus; freshwater
Author: Vitas Atmadi Prakoso,
Jojo Subagja, Young Jin Chang
Journal Code: jpperikanangg150041
