Combined Effects Of Temperature And Salinity On Egg Hatching Rate And Incubation Time Of Penaeus Semisulcatus (Decapoda: Penaeidae)

This 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-l round bottom glass flasks and received one of nine temperature (24, 28 and 32°C) 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 24°C. In terms of hatching rate, the best combinations in descending order were 24°C at 40 ppt, 32°C at 40 ppt and 28°C at 40 ppt. However, the incubation time was longer at 24°C (17.5 h) than at 28°C (14.5 h) or 32°C (11.5 h)

Combined effects of cycled starvation and feeding frequency on growth and oxygen consumption of gilthead sea bream, sparus aurata

Triplicate groups of gilthead sea bream, Sparus aurata (10.4 g), were distributed among 27 tanks (12 fish per tank) and reared in flow-through seawater. A factorial experiment (3 × 3) was designed to include a continuously fed control group and two cycled starvation groups: 1 + 3 (starved 1 d, fed 3 d), 1 + 5 (starved 1 d, fed 5 d). Each of the feeding groups was subjected to one of three feeding frequencies (2, 4, and 6 times per day) over the 60-d experiment duration. The average final weight of fish in 1 + 3 and 1 + 5 groups were significantly lower than that of the control group. Partial compensation was observed in the starved groups subjected to any of the three feeding frequencies. Regardless of the feeding frequency, control fish consumed less feed than the starved groups. The highest body protein content was found in the control group. The rate of oxygen consumption significantly increased 30 min after the feeding and the magnitude of the effect increased with the feeding frequency. These results suggest that the present cycling starvation schedules did not invoke a full compensation in gilthead sea bream. © by the World Aquaculture Society 2011

Off-season maturation and spawning of Penaeus semisulcatus by eyestalk ablation and/or temperature-photoperiod regimes

In 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°C) 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°. Cyclic fluctuation (period of 10 days) of water temperature (20-28°C) 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°C, 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/m2 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. © 2003 Elsevier Science B.V. All rights reserved

The effect of salinity on larval growth, survival and development of Penaeus semisulcatus (Decapoda: Penaeidae)

This study determined the optimal salinity for larval growth, survival and development of Penaeus semisulcatus. Protozoea 1 (PZ1) larvae were stocked 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 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 ppt until PL1/2 stages within only 6-7 days with a feeding regime of Tetraselmis chuii (20 cells/µl), Chaetoceros calcitrans (50 cells/µl) and Isochrysis galbana (30 cells/µl), plus 5 newly hatched Artemia nauplii/ml from M1 onwards, at 28°C

Combined effects of temperature and salinity on egg hatching rate and incubation time of penaeus semisulcatus (Decapoda: Penaeidae)

This 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 32°C) 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 24°C. In terms of hatching rate, the best combinations in descending order were 24°C at 40 ppt, 32°C at 40 ppt and 28°C at 40 ppt. However, the incubation time was longer at 24°C (17.5 h) than at 28°C (14.5 h or 32°C (11.5 h)

Effects of restricted feeding regimes on growth and feed utilization of juvenile gilthead sea bream, Sparus aurata

The effect of restricted feeding on growth, feed efficiency, and body composition was studied in juveniles of gilthead sea bream, Sparus aurata. Juveniles (6.4g) were stocked into 12 tanks at a density of 16 fish per tank. Four different feeding schedules were tested on triplicate groups of juvenile fish: (1) control fed for 48d without deprivation, (2) starvation for 1d and then refed for 2d (S1), (3) 50% satiation for 2d and then refed to apparent satiation for 2d (R2), and (4) 50% satiation for 6d and then refed to apparent satiation for another 6d (R6). Results indicated that all fish subjected to cycled restricted feeding regimes were unable to achieve catching up with control group. The specific growth rate of fish in the control was significantly higher than those in S1, R2, and R6, which were not significantly different from each other. Protein efficiency and protein productive value were significantly higher in R2 compared to control, S1, and R6. Fish in R2 had lowest feed conversion ratio (1.12) compared to the control (1.17). Body protein composition in R6 was less than that of the control, S1, and R2, while moisture, lipid, and ash content were not significantly different compared to the control. © Copyright by the World Aquaculture Society 2008

Effects of temperature and salinity on larval growth, survival and development of Penaeus semisulcatus

Four temperatures (22°C, 26°C, 30°C and 34°C), and the combined effects of three salinity (25, 30 and 35 ppt) and three temperature (26°C, 30°C and 34°C) levels from protozoea I (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°C showed the highest survival (69%) to PL1 compared to 61% at 26°C, 44% at 30°C and 12% at 34°C. However, 22°C slowed the growth and delayed the larval development by about 2-4 days. Growth rate at 30°C (0.44-0.48 mm day-1) was double of that (0.22-0.25 mm day-1) at 22°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°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°C as compared to 36°C (44-73%) and 34°C (14-21%). However, daily growth rate at 30°C and 34°C was about 60% higher than at 26°C. Larval development was also 3-4 days faster at 30°C and 34°C. Based on the survival and growth results, the best salinity and temperature combination for the culture of P. semisulcatus was 30 ppt and 30°C. (C) 2000 Elsevier Science B.V.We thank Dr. Oya Isik and Research Assistant Vildan Uyarlar for their support during the culture of micro-algae. This study was financed by Research Fund of University of Cukurova with project no. SUF 98.3

The effects of salinity and added substrates on growth and survival of Metapenaeus monoceros (Decapoda: Penaeidae) post-larvae

This study was carried out to determine the optimal culture salinity and to investigate the effects of added substrate on growth and survival of Metapenaeus monoceros during its nursery culture in two separate experiments. In Experiment 1, at the end of a 50-day culture period, post-larvae (PLs) reared at 5, 10, 20, 30, 35, 40 and 50 ppt displayed 8, 11, 48, 49, 52, 59 and 36% survivals, respectively. Daily growth rates at salinities above 30 ppt (0.266-0.320 mm day-1) were about 5-fold higher than those obtained at salinities below 10 ppt (0.035-0.056 mm day-1) (P < 0.05). Total lengths (TL) at 30, 35, 40 and 50 ppt were 19.09, 18.97, 19.09 and 18.89 mm, respectively (P > 0.05). Mean wet weights acquired at 30-40 ppt (63-71 mg) were 7-8 times higher than those at 5 and 10 ppt (8.12-9 mg) (P < 0.05). A rise in salinity resulted in a drastic increase in biomass (over 50-fold) from 0.018 g at 5 ppt to 0.927 g at 40 ppt. Hence, optimum salinity for the nursery culture of M. monoceros PLs appeared to be between 30 and 40 ppt at 28°C. In experiment 2, Group A received no additional substrate while the other two groups had added substrates consisting of wooden frame with vertical (Group B) or horizontal (Group C) plastic mesh. Additional substrate increased habitable surface area approximately 330%. Percentage survivals in Group A, B and C were 71, 70 and 63%, respectively. TL was significantly lower in Group C (15.65 mm) than in either Group A (17.71 mm) or Group B (17.23 mm) (P < 0.05). The PLs in Group A attained a significantly greater mean final weight (62 mg) than those (40-55.14 mg) in both treatments containing artificial substrates. The PLs in Group B and C had 12% and 40% lower biomass than that in Group A. The current results demonstrated that the use of either vertically and horizontally placed substrates do not provide any advantage during the nursery culture of M. monoceros. © 2001 Elsevier Science B.V.SUF 99.4We thank Dr. O. Isik for her support during the culture of micro-algae. This study was financed by the Research Fund (SUF 99.4) of the University of Çukurova, Turkey