LETHAL DISSOLVED OXYGEN AND BLOOD PROPERTIES OF GREY MULLETS Mugil cephalus IN SEAWATER AND FRESHWATER
ABSTRACT: Grey mullets Mugil
cephalus is one of euryhaline and economically important species widely
distributed in the world. However, studies on the effects of environmental
factors related to fish metabolism is still less investigated even though it
was important to optimize aquaculture. Therefore, present study was conducted
to understand the lethal dissolved oxygen (DO) and blood properties of grey
mullets under different salinity rearing condition. Two experimental groups
were conducted to measure the lethal DO and blood properties of grey mullets in
seawater (LOS) and freshwater (LOF). Observation was conducted using closed
rectangular chamber and blood samples. The results showed that grey mullets
became unstable after DO levels were below 2 mg/L (1.3 mg/L on LOS, 1.6 mg/L on
LOF). As the DO levels declined to 1 mg/L, their activities became lower and
totally died at 0.3 mg/L. No significant difference found on these lethal DO
experiments (P>0.05). The blood factors including Ht, Hb, osmolality,
cortisol, and glucose in LOS were totally higher than those in LOF. Both
experiments showed grey mullets’ stress response indicator getting increased by
oxygen depletion. The cortisol level was at 90.7 ng/ml in LOS and 56.4 ng/ml in
LOF, while glucose level was at 169.0 ng/ml in LOS and 71.5 ng/ml in LOF. In
conclusion, DO level of grey mullets Mugil cephalus should be maintained not
lower than 2 mg/L whether in seawater or freshwater rearing condition to avoid
fish mortality.
Penulis: Vitas Atmadi Prakoso
Kode Jurnal: jpbiologidd160602
