Effects of water quality parameters on susceptibility of marine fishes to vibriosis and treatment options

Veronica Albert Jiran (2013) Effects of water quality parameters on susceptibility of marine fishes to vibriosis and treatment options. Masters thesis, Universiti Malaysia Sabah.

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Abstract

A long-term environmental study was conducted to evaluate the correlation of four basic physical water parameters (temperature, pH, dissolved oxygen and salinity) to the occurrence of vibriosis in netcage facilities in Serusup, Tuaran. Weekly recording of mortalities and water parameters from net cages was done, averaged each month and plotted to determine the relationship between parameters and vibriosis outbreak. Water samples, diseased fish and net biofilm were also collected and analyzed for Vibrio bacteria on the TCBS agar plates. Our findings showed that the cultured fish were constantly exposed to fluctuating salinities (24 to 31 ppt), water temperatures (27˚to 32˚C) and dissolved oxygen (5 to 7mg/l). However, the pH of the water was relatively constant at 7.8. During the study period, two major disease outbreaks were recorded; April 2010 (165 fish died) and September 2010 (78 fish died). Weekly bacterial isolation from the water and bio-film samples showed a relationship between the presence of Vibrio in the culture system and the prevalence of disease outbreak. It was found that Vibrio count in biofilm and fish mortality positively correlated with temperature (˚C). However, there was no significant (p>0.05) correlation between pH, dissolved oxygen and salinity to Vibrio count. The finding suggests that the environmental water parameter especially temperature do have a positive correlation with the presence of bacteria in the net cages which cause disease outbreak and fish mortality. This study also conducted to characterize Vibrios isolated from the sea cage facility using phenotypic and genotypic methods. A total of 51 Vibrio colonies from all biofilm and water samples were phenotypically characterized using 45 biochemical tests and all screened using PCR. V. parahaemolyticus was detected in bio-film (28%) and water (20%), V. alginolyticus in biofilm (19.2%) and water (4%), V. communis in biofilm (19.2%) and water (4%), V. harveyi in biofilm (12%) and water (4%), V. owensii in biofilm (12%), V. ponticus in biofilm (3.8%), P. damselae (3.8%) and P. rosenbergii (3.8%) in biofilm, P. damselae subsp. piscicida (4%), V. brasiliensis (12%), V. campbellii (24%), V. fortis (8%), V. rotiferianus (8%), V. tubiashii (4%), V. natriegens (4%) and V. coralliilyticus (4%) in water. Vibrios were present in most of the biofilm and water samples which may reflect that the bacteria responsible for the vibriosis outbreak. This study was also focused in finding alternative treatments for fish diseases by using plants that known to have medical potentials. In this study, 52 plant species were screened against 12 bacterial strains. The diameter of the inhibition zone produced by the plants was recorded in millimetre (mm). Results recorded that 20 of them showed positive results. However, only three have the highest and broader spectrum of inhibition (Dukung anak (Phyllanthus ninuri), Sireh (Piper betle), and Cengkih (Syzygium aromaticum)). This suggests that crude extract of herbs and spices can substitute the usage of antibiotics in inhibiting the bacterial activity. The data presented herein can be useful for controlling fish vibriosis.

Item Type:	Thesis (Masters)
Keyword:	Vibriosis, Netcage facilities, Vibrio bacteria, Environmental water parameters, Fish mortality, Temperature, Phytochemicals, Alternative treatments, Plant extracts, Fish diseases, Biochemical characterization
Subjects:	Q Science > QL Zoology > QL1-991 Zoology > QL605-739.8 Chordates. Vertebrates > QL614-639.8 Fishes
Department:	INSTITUTE > Borneo Marine Research Institute
Depositing User:	DG MASNIAH AHMAD -
Date Deposited:	24 Feb 2025 09:30
Last Modified:	24 Feb 2025 09:30
URI:	https://eprints.ums.edu.my/id/eprint/42826

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