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Öğe Combined effects of temperature and salinity on egg hatching rate and incubation time of Penaeus semisulcatus (Decapoda: Penaeidae)(Lab Research Fish Diseases, 2004) Aktas, M; Eroldogan, OT; Kumlu, MThis study was undertaken to determine the combined effects of temperature and salinity on the incubation time and hatching rate of Penaeus semisulcatus eggs in controlled laboratory conditions. Fertilized eggs, from a female caught in nature and spawned in our laboratory, were stocked in 2-1 round bottom glass flasks and received one of nine temperature (24, 28 and 32degreesC) and salinity (30, 35 and 40 ppt) combinations. The eggs hatched in all treatments. The hatching rate increased as salinity increased and was highest at 24degreesC. In terms of hatching rate, the best combinations in descending order were 24degreesC at 40 ppt, 32degreesC at 40 ppt and 28degreesC at 40 ppt. However, the incubation time was longer at 24degreesC (17.5 h) than at 28degreesC (14.5 h) or 32degreesC (11.5 h).Öğe The effect of salinity on larval growth, survival and development of Penaeus semisulcatus (Decapoda: Penaeidae)(Lab Research Fish Diseases, 1999) Kumlu, M; Eroldogan, OT; Aktas, MThis study determined the optimal salinity for larval growth, survival and development of Penaeus semisulcatus. Protozoea 1 (PZ1) larvae were slacked in 2 l glass round bottom flasks in two replicates at 25, 30, 35, 40, 45, 50 and 55 ppt salinities and were fed live diets until the postlarval (PL) stages. The PZ larvae required an acclimation rate of 1 ppt per 15 min when exposed to a salinity change of over 5 ppt. The larvae displayed better tolerance to high rather than low salinities. The lowest and highest critical salinities appeared to be 23 ppt and 55 ppt, respectively. Early PZ larvae showed a high tolerance to hypersalinities but only for a few days. Although higher survival rates were obtained at high salinity levels (45-55 ppt), larval growth and development were better in lower salinities (25-40 ppt). Taking into account both survival and growth results, the optimal salinity level for larval culture of P. semisulcatus inhabiting the eastern Mediterranean has been estimated to lie between 30 and 35 ppt, The present results demonstrate that P. semisulcatus larvae obtained from broodstock from the eastern Mediterranean can be successfully reared at 30-35 opt until PL1/2 stages within on ly 6-7 days with a feeding regime of Tetraselmis chuii (20 cells/mu l), Chaetoceros calcitrans (50 cells/mu l) and Isochrysis galbana (30 cells/mu l), plus 5 newly hatched Artemia nauplii/ml from M1 onwards, at 28 degrees C.Öğe Effects of temperature and salinity on larval growth, survival and development of Penaeus semisulcatus(Elsevier Science Bv, 2000) Kumlu, M; Eroldogan, OT; Aktas, MFour temperatures (22 degrees C, 26 degrees C, 30 degrees C and 34 degrees C), and the combined effects of three salinity (25, 30 and 35 ppt) and three temperature (26 degrees C, 30 degrees C and 34 degrees C) levels from protozoea 1 (PZ1) to postlarvae 1 (PL1) stages of Penaeus semisulcatus were studied in two separate experiments. In the first experiment, the PZ1 larvae at the lowest temperature of 22 degrees C showed the highest survival (69%) to PL1 compared to 61% at 26 degrees C, 44% at 30 degrees C and 12% at 34 degrees C. However, 22 degrees C slowed the growth and delayed the larval development by about 2-4 days. Growth rate at 30 degrees C (0.44-0.48 mm day(-1)) was double of that (0.22-0.25 mm day(-1)) at 22 degrees C. The results showed that P. semisulcatus is tolerant to low, rather than to high temperatures during the larval development. Hence, a water temperature; level of about 30 degrees C is optimal for the larval culture of this species. The second experiment showed that temperature exerted a greater influence than the salinity on the growth and survival during the larval development. The range of temperature in which the larvae showed high survival and growth is relatively narrow as compared to that of salinity. At all salinity levels, survival to PL1 (69-77%) was higher at 26 degrees C as compared to 30 degrees C (44-73%) and 34 degrees C (14-21 degrees), However, daily growth rate at 30 degrees C and 34 degrees C was about 60% higher than at 26 degrees C. Larval development was also 3-4 days faster at 30 degrees C and 34 degrees C. Based on the survival and growth results, the best salinity and temperature combination for the culture of P. semisulcatus was 30 Dpt and 30 degrees C. (C) 2000 Elsevier Science B.V. All rights reserved.Öğe Larval growth, survival and development of Metapenaeus monoceros (Fabricius) cultured in different salinities(Blackwell Science Ltd, 2001) Kumlu, M; Eroldogan, OT; Aktas, M; Saglamtimur, BLarvae of Metapenaeus monoceros (Fabricius) at protozoea 1 (PZ1) stage were stocked in 2-L glass flasks to investigate the effects of various salinities (25, 30, 35, 40, 45, 50 and 55 ppt) on growth and survival until the post-larval (PL) stages. The PZ larvae were not able to tolerate a sudden salinity drop of over 10 ppt. Yet, an abrupt salinity increase of over 10 or even 15 ppt did not cause mortality. The PZ larvae were successfully acclimated to different test salinities at a rate of 4 ppt h(-1). The larvae displayed better tolerance to high rather than low salinities. The lowest and highest critical salinities appeared to be 22 and 55 ppt respectively. Taking into account survival, growth and development results, the optimal salinity for the larval culture of M. monoceros inhabiting the Eastern Mediterranean was 40 ppt. At this salinity, the PZ1 larvae were successfully cultured until PL1 stage within 11 days with 68% survival on a feeding regime of Tetraselmis chuii Kylin (Butcher) (20 cells mu L-1), Chaetoceros calcitrans Paulsen (50 cells mu L-1), Isochrysis galbana Parke (30 cells muL(-1)) and five newly hatched Artemia nauplii mL(-1) from M1 onwards at 28 degreesC.Öğe Off-season maturation and spawning of Penaeus semisulcatus by eyestalk ablation and/or temperature-photoperiod regimes(Elsevier, 2003) Aktas, M; Kumlu, M; Eroldogan, OTIn this study, nine different treatments were tested on off-season reproductive performance of Penaeus semisulcatus for 60 days in a recirculating system, in round tanks (1.2-m diameter) situated in a greenhouse. A combination of raised temperature (28 degreesC) and shortened (10 h) or increased day length (14 h) was not sufficient to induce maturation in unablated females of P. semisulcatus. Unablated females showed no sign of ovarian development at a constant low temperature of 20 degreesC. Cyclic fluctuation (period of 10 days) of water temperature (20-28 degreesC) at local winter photoperiod regime (10-h illumination) induced successful maturation and even multiple spawnings within the same moulting period. Natural daylight supplementation (14-h illumination) did not produce any advantage over natural illumination (10 h). Unilateral eyestalk ablation had the most profound effect on the induction of ovarian development and spawning in this species. Even at a temperature of 20 degreesC, eyestalk-ablated females developed their ovaries up to the 4th stage but with still no spawning. It appears that P. semisulcatus requires not only optimal environmental conditions but also a certain stimulus such as ablation or temperature fluctuation for successful maturation and spawning in captivity during the winter season. Small tank size (1.2 m in diameter) did not inversely affect mating success of P semisulcatus at the sex ratio of 1:2 male/female and 10 shrimp/m(2) stocking density. The present results have demonstrated that eyestalk ablation or cyclic temperature fluctuation techniques can successfully be applied to obtain off-season spawning from P. semisulcatus broodstock in the subtropics. (C) 2003 Elsevier Science B.V. All rights reserved.Öğe Optimum feeding rates for European sea bass Dicentrarchus labrax L. reared in seawater and freshwater(Elsevier, 2004) Eroldogan, OT; Kumlu, M; Aktas, AGrowth, feed conversion efficiency, fillet composition and morphological indices of European sea bass (initial weight of 2.6 +/- 0.3 g) were investigated in a 6 x 2 factorial designed experiment employing two salinities [seawater (SW, 40 ppt) and freshwater (FW, 0.4 ppt)] and six different feeding rates (2.0%, 2.5%, 3.0%, 3.5%, 4.0% of their body weight (bw) day(-1) and to satiation) for 60 days. Twenty fish were stocked into 155-1 round tanks and each treatment had three replicate tanks. Throughout the experiment, weight gain and specific growth rate (SGR) were highest at ration 4.0 bw day(-1) and to satiation in SW group. Regardless of feeding rate, sea bass fingerlings grew about 20-30% more in SW than those reared in FW. There was a significant (P<0.05) interactive effect of feeding rates and culture media (SW and FW) on weight gain and feed conversion efficiency (FCE). FCE was found to be lower in fish fed to satiation (65-66%) compared to the feeding rate of 3.5% bw day(-1) which was best in both SW (89.1%) and FW (86.5%). There were no significant differences in either protein or ash contents of the fish cultured in SW or FW although lipid and moisture contents changed with increasing feeding rate. Condition factor, fillet yield and carcass/body weight were significantly increased, whereas hepatosomatic index, viscera somatic index decreased when the feeding rate was increased above 2.0% bw day(-1). Feeding rate proved to be the main differentiating factor in all growth, FCE and fillet composition parameters. Values of SGR plotted against feeding rates allowed the maintenance, optimum and maximum feeding levels to be determined. Based on the calculations, the optimum feeding rate for sea bass fingerlings (3 g) reared in SW and FW is 3.0% and 3.5% bw day(-1), respectively. In addition, the optimum feeding rate for FCE was calculated as 2.7% bw day(-1) in SW and 3.8% bw day(-1) in FW It is concluded that growth and FCE of European sea bass can be improved by feeding them at about 3.0-3.5% bw day(-1) in SW or FW. (C) 2004 Elsevier B.V. All rights reserved.
