The effects of pH on survival, growth performance and chemoreception of Macrobrachium rosenbergii postlarvae

• Main Author: Chen, Chiau Yu
• Format: Academic Exercise
• Language: English; English
• Published: 2014
• Subjects: QL614-639.8 Fishes
• Online Access: https://eprints.ums.edu.my/id/eprint/38225/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/38225/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/38225/

Acid rain causes acidification of freshwater resources which can be harmful to all aquatic organisms. Water acidification is difficult to reverse due to continuous development and emission of anthropogenic carbon dioxide. This will lead to ecosystem damage and unsustainable aquaculture especially crustaceans production. It is hypothesized that acidic water might damage the chemoreception of giant freshwater prawn ( Macrobrachium rosenbergi1) subsequently lead to poor growth performance and survival. The survival, growth performance and chemoreception of the postlarvae (PL) were examined in water with pH 6, 5, 4 and control (pH 7.5) in laboratory. All treatment groups which contained 250 PL per treatment were slowly acclimatized to respective pH. Mortality was monitored throughout 27 days of rearing. Feeding trials were conducted every evening using agar pellets containing different concentration of chemo-attractants. The touch frequency and duration of contact the PL made with the pellet were recorded. Body weight and total length were measured after 27 days of rearing. From the results obtained, touch frequency and duration of contacts show no tendency of decreasing or increasing with reducing water pH. It was also found that vision is one factor that affecting the feeding trial. Thus further analysis could not be completed. Even with poor chemoreception, the PL were able to locate the agar and make contact. However, it was known that the PL at pH 4 have damaged chemoreception based on duration of contact the PL make with control agar pellets which did not contain chemo-attractant. The PL from pH 4 took extra one second to release the control agar compare to control, pH 6 and 5. The slow response could indicate damaged chemical sensitivity. Based on survival and growth performance, pH 6 is the best for rearing of giant freshwater prawn PL since the survival was highest (83.6 %) and the size variation was homogenous. Based on length-weight relationship analysis, the PL growth at pH 6, 5 and control have similar growth pattern and were metamorphosed into early juveniles after 27 days. Lengthweight relationship of PL at pH 4 shows that they were split into two groups with different body ratios and could not turn into early juveniles after 27-day rearing. It can be concluded that pH 4 is extremely harmful to PL of giant freshwater prawn and pH 6 is recommended for PL production.