Now showing items 1-6 of 6

    • Article

      Effect of salinity on hemolymph calcium concentration during the molt cycle of the prawn Penaeus monodon 

      FD Parado-Estepa, JM Ladja, EG de Jesus & RP Ferraris - Marine Biology, 1989 - Springer Verlag
      Prawns (Penaeus monodon) were obtained from ponds in Iloilo, Philippines, in 1984 and 1985 and maintained in salinities from 8 to 44‰. Total hemolymph calcium was largely affected by molt stage and less so by salinity. A sharp, transient increase in hemolymph calcium occurred 3 to 6 h postmolt, followed by an equally rapid decrease from 6 h postmolt to intermolt. This biphasis response was limited to prawns in 8, 20 and 32‰S; in 44‰S, hemolymph calcium remained the same throughout the sampling period. Peak concentrations of total calcium were greater in low (8 and 20‰S) than in high salinities. Salinity had no effect on the duration of molt cycle nor on time of occurrence of molt. Almost half of molting incidents occurred between 18.01 and 0.00 hrs, and one-third between 0.01 and 06.00 hrs.
    • Article

      Effect of salinity on the osmotic, chloride, total protein and calcium concentrations in the hemolymph of the prawn Peneaus monodon (Fabricius) 

      RP Ferraris, FD Parado-Estepa, JM Ladja & EG de Jesus - Comparative Biochemistry and Physiology - Part A: Physiology, 1986 - Elsevier
      1. Osmolality and chloride concentrations in the hemolymph of Penaeus monodon became stable 1 day after molting in 32 ppt, while total protein and calcium concentrations remained stable throughout the molting cycle. When intermolt (≥ 36 hr postmolt) animals were transferred from control (32 ppt) to experimental (8–40 ppt) salinities, osmolality, chloride and total protein, but not calcium, concentrations in the hemolymph achieved steady state values 24–48 hr after transfer.

      2. The hemolymph osmolality was a linear function (slope = 0.28) of medium osmolality at salinities between 8 and 40 ppt. It was isosmotic to seawater at 698 mOsm (10 g prawns) and 752 mOsm (30 g), and was hyperosmotic to the medium below isosmotic concentrations, and hypoosmotic to those above.

      3. Hemolymph chloride concentration was isoionic to seawater at 334 mM, and was hyperregulated below isoionic concentrations, and hyporegulated to those above.

      4. P. monodon maintained its hemolymph calcium concentration between 6.4 and 10 mM when medium salinities increased from 8 to 40 ppt.

      5. Total protein concentration in the hemolymph was independent of medium salinity (8–40 ppt) and hemolymph osmolality (540–850 mOsm).
    • Book chapter

      Nursery culture of high-value fish species in brackishwater ponds 

      JM Ladja & RSJ Gapasin - In Training Handbook on Rural Aquaculture, 2009 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      Osmotic and chloride regulation in the hemolymph of the tiger prawn Penaeus monodon during molting in various salinities 

      RP Ferraris, FD Parado-Estepa, EG de Jesus & JM Ladja - Marine Biology, 1987 - Springer Verlag
      The effect of molting on osmotic and chloride concentrations in the blood of the prawn Penaeus monodon Fabricius (20±3 g) at various salinities was investigated. Prawns were obtained from ponds in Iloilo, Philippines, in 1984. They were stocked in salinities of 8, 20, 32 and 44‰, and their hemolymph was sampled during molt (Time 0), and then 0.125, 0.25, 0.5, 1, 2, 4, 6, 10 and 14 d after molting. Prawns during and immediately after molt tended to conform to the environmental osmolality. Subsequent postmolt (≧0.5 d) stages displayed more divergence from external salinity. The isosmotic point was higher (940±30 mOsm kg-1) during molt than during intermolt (663±8 mOsm/kg-1), suggesting different osmotic requirements in early molt. Hyperregulation of hemolymph chloride below 20‰ S, as well as isoionic point (301±6 mM), were independent of molting stage. At 20‰ S and above, newly molted (0 to 0.25 d post-molt) individuals tended to conform to the external chloride concentration while intermolt (≧0.5 d) post-molt individuals did not. Contribution of hemolymph chloride to hemolymph osmolality was greater during intermolt than during ecdysis, suggesting an important role for other negatively charged ions during molt. When molt occurred in 20‰ S (the test salinity most similar to the isoionic salinity), there was little or no change in hemolymph osmolality or chloride concentration from 0 to 14 d postmolt. At 8, 32 and 44‰ S, the change from molt to intermolt values in hemolymph osmotic and chloride concentrations was hyperbolic. Non-linear least-squares regression showed that prawns generally achieved intermolt values within 1 d after molting. Prawns at intermolt regulated hemolymph osmolality (620 to 820 mOsm kg-1) and chloride concentration (300 to 450 mM) at a much narrower range than during molt (520 to 1 170 mOsm kg-1 and 250 to 520 mM, respectively). Hemolymph osmolality was a more sensitive indicator of physiological response than hemolymph chloride concentration. Distribution and culture of P. monodon might be limited in low salinities by its ability to maintain a hemolymph osmolality ≧500 mOsm kg-1 during molt and ≧600 mOsm kg-1 in intermolt, and in high salinities by its capacity to reduce the hemolymph osmolality from values at molt to those in intermolt. Osmotic and chloride concentrations in the blood of P. monodon clearly varied with both molt stage and salinity of the medium. Dependence on external factors, however, gradually declined in older molt stages, suggesting a reduction in integument permeability and greater development of ion absorption/secretion mechanisms as the exoskeleton hardened.
    • Article

      Responses of intermolt Penaeus indicus to large fluctuations in environmental salinity 

      FD Parado-Estepa, RP Ferraris, JM Ladja & EG de Jesus - Aquaculture, 1987 - Elsevier
      The osmotic and chloride regulation by 5- to 10-g intermolt Penaeus indicus was investigated by abruptly changing medium salinity from seawater (32 ppt) to test salinities of 8, 20, 32 (control) or 40 ppt. Hemolymph samples were taken at 0, and then at 0.25, 0.5, 1, 2, 5 and 10 days after the change in salinity, and were analyzed for osmolality and chloride concentrations. Tissue water content was also determined. Throughout the study period, daily mortality was low (1.8%), and was the same among control and experimental salinities. Hemolymph osmolality and chloride as well as tissue water content were stable within 0.25 to 0.5 days after the abrupt salinity change, except for tissue water content at 8 ppt which did not reach a steady state for 2 days. Intermolt P. indicus exhibited hyperosmotic or hyperionic regulation in salinities below isosmotic or isoionic salinities, and hypoosmotic or hypoionic regulation in those above. Hemolymph osmolality and chloride were positive linear functions of external osmolality and chloride concentrations (slope=0.24±0.02 and 0.20±0.02, respectively). Isosmotic and isoionic values were 780 mOsm/kg and 330 mM, respectively. Percentage tissue water decreased as a function of external osmolality (−0.0056% kg mOsm−1) and hemolymph osmolality (−0.0232% kg mOsm−1), indicating that tissue cells were relatively permeable to hemolymph water, and that the hemolymph acted as a barrier to buffer the cells from large fluctuations in external salinity. These results indicate that, like many penaeids, P. indicus is a good osmoregulator suitable for culture in brackishwater ponds where there are large fluctuations in salinity.
    • Article

      A survey of chemical and biological products used in intensive prawn farms in the Philippines 

      JH Primavera, CR Lavilla-Pitogo, JM Ladja & MR de la Peña - Marine Pollution Bulletin, 1993 - Elsevier
      With attractive prawn export prices and the availability of hatchery fry and commercial feeds, Philippine aquaculture has experienced a shift from milkfish to prawn Penaeus monodon and an intensification from traditional and extensive prawn culture to higher stocking densities. This paper features the results of a survey of intensive prawn farms (n = 21) in Western Visayas and Northern Mindanao conducted in 1990. Average farm size, production, feeding and water management are described. To solve the self-pollution characteristic of intensive ponds, the farms utilized some 40 chemical and biological products; at least another 35 were available in the market at the time of the study. These include therapeutants and disinfectants, soil conditioners, bacteria-enzyme preparations, algicides and piscicides, plankton growth promoters, and feed additives. The possible ecological effects of effluents drained into adjacent marine waters are discussed; some recommendations are given.