Effects of salinity on the survival, growth and development of sensory organs, and gill chloride cells of marble goby, Oxyeleotris marmoratus larvae

Sow , Sok Hui (2007) Effects of salinity on the survival, growth and development of sensory organs, and gill chloride cells of marble goby, Oxyeleotris marmoratus larvae. Masters thesis, Universiti Malaysia Sabah.

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Abstract

Marble goby, Oxyeleotris marmoratus is one of the most important freshwater fish in the aquaculture industry because it has high market demand and value. The main constraint in O. marmoratus farming is insufficient seed supply due to overfishing. Another constraint is high mortality during the early larval stage under artificial rearing conditions. The experiments were conducted to obtain the optimum salinity for larval rearing and to study of the development of sensory organs and gill chloride cells of O. marmoratus larvae reared in 0 and 10 ppt. Experiment 1 was conducted to determine the optimum salinity level for larval stage from 1-40 days after hatching (dAH) with different salinity (0, 5, 10, 15, 20, and 30 ppt). The results showed that 10 ppt is the optimum salinity for survival rate and growth for O. marmoratus larval stage from 1-40 dAH. The results also revealed that the larvae can feed on the seawater rotifer, Brachionus sp. and this has solved the problem of first feeding. With these findings, the high mortality during early larval stage can be overcome and larval rearing technique can also be developed. Experiment 2 was conducted to determine the optimum salinity for the larvae reared in four shorter periods (1-10, 11-20, 21-30, and 31-40 dAH) by testing the same salinity used in Experiment 1. The rearing period 1- 10 dAH was shown as the most critical period for larval survival. The results revealed that the larvae in the rearing period from 1-10 dAH must be reared in 10 ppt. The results also revealed that 11-40 dAH larvae can be reared in the salinity range of 0-30 ppt depending on available water sources. In Experiment 3, the developments of sensory organs were observed histologically for the larvae reared in 0 and 10 ppt. The development of eyes, inner ears, olfactory organs, taste buds and free neuromasts of O. marmoratus larvae were similar in larvae reared in 0 and 10 ppt. The results indicated that the development of sensory organs does not affect the high survival rate in 10 ppt. In Experiment 4, the developments of the gill chloride cells were identified immunocytochemically for the larvae in 0 and 10 ppt. The results showed that the larvae reared in 0 and 10 ppt have different distribution and sizes of the gill chloride cells. This suggested that the larvae have the ability to adapt and survive in 10 ppt with the help of their gill chloride cells that can deal with the osmotic pressure despite it being a freshwater fish. As a conclusion, 10 ppt is the optimum salinity that can overcome the high mortality of O. marmoratus during early larval stage. Results from these experiments can contribute to improve the larval rearing techniques for the mass seed production of O. marmoratus.

Item Type:Thesis (Masters)
Uncontrolled Keywords:Oxyleotris marmoratus, freshwater fish, seed supply, salinity for larval, seed production
Subjects:Q Science > QH Natural history > QH301 Biology
Divisions:SCHOOL > Borneo Marine Research Institute
ID Code:10290
Deposited By:IR Admin
Deposited On:13 Jan 2015 11:32
Last Modified:13 Jan 2015 11:32

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