Relationships between gonad maturity and selected physico-chemical characteristics of water in female air-breathing fishes of the Klias blackwater

• मुख्य लेखक: Vainsylyen Majelim
• स्वरूप: थीसिस
• भाषा: अंग्रेज़ी; अंग्रेज़ी
• प्रकाशित: 2015
• विषय: QL614-639.8 Fishes
• ऑनलाइन पहुंच: https://eprints.ums.edu.my/id/eprint/40663/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/40663/2/FULLTEXT.pdf

Less is known about the reproduction of fish that inhabited the blackwater of the peat swamp forest. It was found that most of the fishes living in that area occupied with air-breathing organ to survive in acidic water with low oxygen levels. The main objective of this study was to determine the relationship between rainfall and physico-chemical characteristics of water (water depth, water temperature, pH, DO and conductivity) on the GSI of female air-breathing fishes in the blackwater of Klias Forest Reserve (Site 1) and Bukau Api-Api Forest Reserve (Site 2), in the Klias Peninsula of Sabah. The subsequent objective was to compare the composition, occurrence and similarity of fish fauna between blackwater (Site 1 and 2) and brownwater (Site 3) of the Klias Peninsula. The fishes were collected mainly with gill nets for one-year study period. Rainfall data was obtained from the nearest Meteorological Department and water physico-chemical characteristics were measured in situ every month. The frequency occurrence of gonad maturity stages and the GSI of the female air-breathing species were determined and the GSI were correlated with rainfall and water physico-chemical characteristics. Species composition, occurrence and similarity were compared between sites. There were 29 species, distributed in 17 genera and thirteen families recorded in blackwater and brownwater sites of the Klias Peninsula with Cyprinidae being the most dominant family with 9 species. Fish composition was found to be higher in blackwater compared to brownwater with 21 species and 17 species, respectively. There were eight species found exclusively in Site 1 compared with only seven species in Site 3, while only one species found exclusively in Site 2. Site 2 and Site 3 has the highest species similarity (0.6) whereas Site 1 and Site 3 has the lowest species similarity (0.3). The changes in water depth found to be closely associated with rainfall (p<0.05). The frequency occurrence of female air-breathing fishes in mature stage showed that Anabas testudineus and Channa lucius has single and two reproductive peaks, respectively, while Channa cf. melasoma and Clarias sp. 1 have more than two reproductive peaks. When GSI correlated with rainfall, significant relationship only found for Channa lucius (p<0.05). The correlation between water depth and GSI showed significant result for Anabas testudineus and Channa lucius. These results indicated that Anabas testudineus and Channa lucius might have periodic reproduction while rest of the female air-breathing fishes reproduce all year round. Water temperature, pH and DO showed no significant effect towards the GSI of all of the female air-breathing fishes (p>0.05) except conductivity that showed significant (p<0.05) effect on the GSI of Channa lucius. Further study is suggested to enable a refinement about the effect of water physico-chemical characteristics on the reproduction of air-breathing fishes in the Klias Peninsula blackwater.