Now showing items 1-10 of 10

    • Article

      Acute toxicity of nitrite to mud crab Scylla serrata (Forsskål) larvae 

      ML Seneriches-Abiera, F Parado-Estepa & GA Gonzales - Aquaculture Research, 2007 - Blackwell Publishing
      Early larval stages of mud crab Scylla serrata were exposed to different concentrations of nitrite (40, 80 and 160 mg L−1 and a control, without added nitrite) and three salinity levels (25, 30 and 35 g L−1) using a static renewal method. No interactive effect of nitrite and salinity was detected. Estimated LT50 in 96-h toxicity tests decreased in all stages with increasing nitrite concentrations in all salinity levels. The 96-h LC50 values of nitrite-N were 41.58, 63.04, 25.54, 29.98 and 69.93 mg L−1 for zoea 1, 2, 3, 4 and 5 respectively. As the larvae grew, they showed a progressive increase in tolerance to nitrite. The toxicity of nitrite to larvae increased with exposure time. The median lethal concentration was not affected by salinity. The chloride component of salinity within 25–35 g L−1 did not seem to be as effective in alleviating toxicity as has been reported in other crustacean species. Based on 96-h LC50 and an application factor of 0.1, the ‘safe level’ of rearing mud crab larvae was calculated to be 4.16, 6.30, 2.55, 2.99 and 6.99 mg L−1 nitrite-N for zoea 1, 2, 3, 4 and 5 respectively.
    • Oral presentation

      Cause of musty flavor in pond-cultured penaeid shrimp. 

      RT Lovell & EJ Livant - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      In 1983, penaeid shrimp shipped into the United States from culture ponds in Ecuador were found to have an intense earthy-musty flavor which made them unmarketable. High concentrations of geosmin (trans, 1-10-dimethyl-1-9 decalol), a musty odorous compound, were found in the tail muscle of the shrimp. The level of geosmin, 78 mg/kg muscle, was much higher than levels usually found in pond-cultured freshwater catfish of 13±3 mg/kg muscle. Cause of the rare occurrence of off-flavor in the shrimp is hypothesized to be severe reduction in salinity in the coastal culture ponds which allowed growth of odor-producing blue-green algae.
    • Oral presentation

      Description of the embryonic stages of Penaeus notialis and the influence of some abiotic factors on the species. 

      I Fernandez & M Oliva - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The embryonic development of the shrimp Penaeus notialis Farfante, 1967 is studied. The duration from spawning to hatching of the nauplii was 14-16 hr. As soon as spawning occurs, a sequence of transformations is observed in the characteristic cell mitosis up to the formation of the embryo which breaks the membrane and emerges as the first naupliar stage. The process of development is very similar to other penaeids and the duration of each stage is characteristic of the species. The influence of salinity and pH on spawning, hatching rate and survival, and the optimal values for each factor were determined.
    • Conference poster

      Effect of temperature and salinity on the hatching of eggs and larval development of sugpo, Penaeus monodon. 

      EP Reyes - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Incubation of Penaeus monodon eggs and rearing of different larval stages were undertaken at nine temperature-salinity combinations. The eggs, nauplii, zoea and mysis from one spawner kept as stock culture at ambient temperatures of 26-30°C and salinity of 32-33 ppt were exposed to temperature levels of 23, 28 and 33°C and salinity levels of 23, 28 and 33 ppt.

      Eggs and nauplii survived the sudden change of temperature and salinity (from ambient to experimental) but the zoea and mysis did not. However, salinities of 23 and 28 ppt in combination with any of the temperature levels produced weak larvae. Highest mean hatching rate was obtained at the temperature-salinity combination of 23°C-33 ppt, followed by 28°C-33 ppt and 33°C-33 ppt. Incubation periods for these treatments were 22, 16 and 14 hr, respectively. Survival rate of nauplius (taken from stock cultures) to first zoeal stage was highest at 28°C-33 ppt, followed by 33°C-33 ppt and 23°C-33 ppt with molting time of 50, 45 and 75 hr, respectively.

      The nauplii exposed to 33°C-33 ppt molted to zoea stage within 38 to 40 hr but later died. Those exposed to 23°C-33 ppt and 28°C-33 ppt reached zoea stage within 57 to 60 hr and 48 to 50 hr, respectively. Similarly, the nauplii taken from the stock cultures and reared until postlarval stage (P1) under experimental conditions completed the zoea and mysis stages in 9 to 11 days at 28°C C-33 ppt, 7 to 9 days at 33°C-33 ppt, and 13 to 15 days at 23°C-33 ppt.

      Statistical analysis showed that salinity had highly significant effect on rates of hatching of eggs and survival from nauplius to first zoeal stage but not temperature although the latter had an apparent effect. However, both factors affected time of hatching of eggs and time of molting from nauplius to zoea. Interaction effect was significant only on rate and time of hatching. Different sources (spawners) of eggs and nauplii did not have significant effect on time of hatching and molting from nauplius to zoea, but significantly affected the hatching rate of eggs and survival rate of nauplii to zoea stage.
    • Article

      Effect of various salinity levels and stock manipulation methods on the survival of milkfish fry (Chanos chanos) during storage. 

      GF Quinitio & JV Juario - Fisheries Research Journal of the Philippines, 1980 - Fisheries Research Society of the Philippines
      The survival and growth of milkfish (Chanos chanos ) fry stored in plastic basins at different salinity levels and stock manipulation methods without aeration and fed with hard-boiled chicken egg yolk over a period of 14 days were determined. Results showed that survival rate and increase in body weight did not differ significantly (P > .05) at different salinity levels nor with different stock manipulation methods. Moreover, there was no evidence of a significant interaction between salinity and stock manipulation method. The highest survival rate was 97.8% with stock manipulation 1 and 8 ppt salinity, while the lowest was 95.% with stock manipulation 1 at 32 ppt salinity.

      Results indicated that there was no need to reduce the salintiy of water used in storing fry in order to obtain higher survival rates as commonly believed. Sufficient food and maintenance of good water quality appeared to be more important than salinity for higher survival of fry during storage.
    • Article

      Effects of salinity on egg development and hatching of Siganus guttatus 

      MN Duray, VM Duray & JME Almendras - The Philippine Scientist, 1986 - University of San Carlos
      Experiments were conducted to determine the tolerance of Siganus guttatus eggs to salinity changes. In the first run, the female was induced to spawn spontaneously by using human chorionic gonadotropin. The fertilized eggs were transferred to seawater of salinities ranging from 8 to 40‰ either at the blastomere or at the gastrula stage. In the second run, the eggs were stripped from the female and artificially fertilized following the dry method.

      Results indicated that eggs transferred at gastrula stage were more tolerant to salinity changes than those transferred at the blastomere stage. Hatching occurred at all salinities but was highest at 24‰. Percentage of viable larvae was highest at 24‰ and lowest at 8‰. The larvae that hatched at low salinities were relatively longer than those that hatched at ambient and higher salinities.
    • Conference poster

      The influence of temperature and salinity on oxygen consumption of Penaeus monodon postlarvae. 

      S Licop - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effect of salinity and temperature on oxygen consumption at different developmental ages of Penaeus monodon postlarvae (P5 to P60) was studied. The design was a 2 × 5 factorial, using two levels of temperature (15 and 30°C) and 4 levels of salinity (10, 15, 20 and 30 ppt). One-day old postlarvae (P1) were acclimated to various salinities prior to the start of the experiments. Oxygen consumption was determined after three hours using a YSI dissolved oxygen meter vis-a-vis Winkler titration method.

      Respiratory activity as affected by temperature and salinity varies, dependent on the postlarval stage tested. Statistical analyses showed that temperature did not significantly influence oxygen uptake at early stages (P5-P8) until P25-P28. Its effect started to become apparent when the postlarvae were P35-P38 and was most pronounced at P49-P52. general, the postlarvae consumed more oxygen at higher temperature and the variation in the oxygen consumption of the postlarvae under the two temperatures become less obvious as the postlarvae were older. Salinity seemed to affect the oxygen consumption of the young postlarvae, P5-P8 and P25-P28, more than temperature. Differences in rate of oxygen consumption at various salinities were greater in younger postlarvae (P5-P38) than in older postlarvae (P42_P60). The relationship between rate of oxygen consumption and body weight is nearly linear in the various salinity-temperature treatments. In all cases, the regression was significant at 1% level. P. monodon postlarvae behaved as respiratory con-formers in all the salinities tested at ambient temperatures.

      The least oxygen consumption rate was noted at salinities of 20 and 30 ppt at low temperature (15°C) and 20 ppt at high temperature (30°C). The importance of these findings is discussed and related to improvement of postlarvae transport methodology.
    • Conference paper

      Osmoregulation in Penaeus monodon: effects of molting and external salinity. 

      The effect of molting on osmotic, chloride, calcium and total protein concentrations in the hemolymph of the shrimp Penaeus monodon was investigated. Regardless of medium salinity, tissue water as well as osmotic and chloride concentrations in the hemolymph became stable within one day after molting. In general, total protein concentrations remained stable throughout the molting cycle. Large fluctuations in hemolymph calcium were observed 0-6 hours after molt. In low salinities, hemolymph calcium peaked at 3 hours postmolt to values 30% higher than those during molt. These values subsequently decreased rapidly one after molting, when hemolymph concentrations achieved intermolt values. At 44 ppt, calcium concentrations were highest during molt, then gradually declined by about 15% to intermolt values.
    • Conference paper

      Survival of newly-hatched larvae of Epinephelus malabaricus at different salinity levels. 

      FD Parado-Estepa - In P Lavens, P Sorgeloos, E Jaspers & F Ollevier (Eds.), Larvi '91. Short Communications and Abstracts of Contributions Presented at the International Symposium on Fish and Crustacean Larviculture, 27-30 August 1991, Gent, Belgium, 1991 - European Aquaculture Society. EAS Special Publication No. 15
      The development of an appropriate hatchery culture-technique for grouper Epinephelus malabaricus requires knowledge on the biology of this species. The environmental requirements, a critical aspect of biology, have, however, not yet been investigated. This study specifically deals with the influence of salinity on the survival of newly-hatched larvae.
    • Article

      Survival of young rabbitfish (Siganus guttatus Bloch) under simulated transport conditions 

      FG Ayson, MM Parazo & DM Reyes Jr. - Journal of Applied Ichthyology, 1990 - Blackwell Publishing
      The effect of loading density, transport duration, water temperature, and salinity on survival of young rabbitfish (Siganus guttatus Bloch) under simulated transport conditions was investigated. The rocking motion of transport was simulated by an electric shaker. At ambient temperature and salinity (28°C/32‰S) increasing loadin density and transport duration resulted in decreasin fish survival rates. When both temperature ant salinity (20°C/20‰S) were lowered survival improved sinificantly. Dissolved oxygen, water temperature, and salinity were critical factors affecting survivaf of young rabbitfish during simulated transport. Based on the results, a density of 100 fish/L can be packed for 8 hours of transport and 300 fish/L for 2 hours at 28°C and 32‰, and about 200 fish/L for 4 hours at 20°C and 20‰S.