Aquaculture has been responsible for increasing global fish supplies and providing an essential protein source for human consumption. Climate change identified as a major threat to the aquaculture sector’s sustainability. Because of the elevated temperature, fish larvae may expend excessive metabolic rate. It will lead to malfunctioned of sensory organs and maladaptive behavioural changes. Impact of elevated temperature on Asian seabass juvenile has not been documented and its consequences is unknown in aquaculture industry.
The effect of elevated temperature on the nutritional condition of Asian seabass, Lates calcarifer larvae were examined under controlled conditions. From 1dAH to 15dAH, the survival, average number of rotifers in the larval gut, and morphometric changes of larvae reared at five different temperatures (28,29,30,32, and 34°C) were compared. 25 of 7L sampling tanks were designed to resemble five different temperature treatments, and 180 tails were stocked per tank. Rotifer, Brachionus plicatilis sp., and cultivated Nannochloropsis oculata were fed at densities of 30 individual L and 0.5 x 10 cells ml, respectively, for the initial feeding. Statistical analysis was performed using SPSS 27.0 software (SPSS incorportion, Chicago, IL, USA) and a significance level of P<0.05 was applied. One-way-ANNOVA was performed to compare average rotifer number in gut and each body proportion examined. When a significant difference was found, a post hoc test using Duncen was performed to ascertain any significant differences between treatment means.
The survival percentage of larvae reared in 28, 29 and 32°C (78.70±4.79,76.85±3.94 and 73.70±4.63%) was significantly higher than (P<0.05) compared to 32 and 34°C (58.33±5.00 and 0%). Different number of rotifer intake was observed as early at 3dAH which show higher temperature 32°C(8.0±0.8) and 34°C(10.0±2.2) treatments was significantly higher compared to lower temperature treatments 28°C(3.0±0.8), 29°C (4.0±1.4) and 30°C (4.0±1.6). However no significant difference was detected (P<0.05) between all treatment on 11 and 13 dAH.
All morphometric measurements, body length (BL), body height (BH), pectoral height (PH), gut height (GH), eye height (EH) and head height (HH) on each body proportion of larvae reared in 28°C, 29°C, 30°C had increased gradually as they developed, while larvae reared in 32°C and 34°C experienced rapid growth in early larval stage and has slower development upon 10 dAH.
This study concludes water temperature can affects the larval nutritional condition that is important to maximize the larval survival and early stage of larvae growth.