Osmotic, total protein and chloride regulation in Penaeus monodon

Abstract only.The osmotic, total protein and chloride ion regulation in two size groups (10 and 30 g) of Penaeus monodon Fabricius was investigated. Preliminary experiments showed that osmolality, total protein and chloride concentrations tend to become stable 24 to 36 hours after molting.Thus,hemolymph values 36 to 240 hours after sampling were not significantly different from each other. Based on these results, only 36 hours (or more) postmolt animals were sampled after transfer from control (32 ppt) to five test salinities (8, 16, 24, 32 and 40 ppt). Hemolymph samples were then taken 1, 2, 3, 5, 7 and 10 days after transfer. Results showed that in general, osmolality, total protein and chloride concentrations in the hemolymph did not vary with time within the same salinity.Both sizes exhibited hyperosmotic and hyperionic regulation in lower salinities and hypoosmotic and hypoionic regulation in higher salinities. The isosmotic values obtained were approximately 676 to 720 mOsm (24 to 28.8 ppt) for the 10 g, and 724 to 792 mOsm (26 to 28.5 ppt) for the 30 g size group. For chloride, the isoionic values ranged from 324 to 339 mM in 10 g prawns. Slopes of the regression lines of hemolymph osmolality versus salinity in 10 g prawns were not significantly different from slopes of similar regression lines in 30 g prawns. These results suggest that the ability to regulate osmotic and total protein concentration in the hemolymph is similar in the two size groups

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

Responses of intermolt Penaeus indicus to large fluctuations in environmental salinity

SEAFDEC-AQD Contribution No. 208.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

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

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

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

SEAFDEC Contribution No. 197The 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

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

SEAFDEC Aquaculture Department Contribution No. 159.1. 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)