Ppt Seawater Research Articles

Variations in renal morphology during adaptation to salinities in tilapias

Fifteen days oldOreochromis niloticus andO. mossambicus juveniles were gradually adapted to 10, 20, 30 and 35 ppt sea water. Kidney morphology was observed after transfer to higher salinities and compared with freshwater controls. Despite differences in salinity tolerance, both species have similar transformations when transferred at high salinity, particularly reduction of the glomerular area after 2 months adaptation to sea water, and change in tubule morphology.

Effect of desiccation, pH, heat, and ultraviolet irradiation on viability of Baculovirus penaei

Tolerance of Baculovirus penaei virus to desiccation, pH, heat, and ultraviolet irradiation (uv), as well as its survival in 32 ppt sea water, was investigated using larval Penaeus vannamei in a bioassay. Test shrimp were sampled from 36 to 264 hr after food-borne exposure to treated B. penaei and examined for patent infections (polyhedral inclusion bodies detectable in fresh preparations of hepatopancreas) with light microscopy. B. penaei was completely inactivated within 30 min after exposure to pH 3, whereas exposure to pH 11 extended the prepatency period (period before infection is apparent) but did not inactivate the virus. B. penaei was inactivated by 10-min exposures to temperatures of 60–90°C. Ultraviolet irradiation for 40 min at a wavelength of 254 nm when B. penaei was 5 cm from the light source inactivated the virus (measured as a cumulative uv dosage of 7.08 × 10 6 μW · sec/cm 2). Desiccation for 48 hr also inactivated the virus, and that method is the most practical to halt or prevent infections in some aquaculture facilities. B. penaei free from its host survived 32 ppt sea water at 22°C for 7 days and at 5°C for at least 14 days.

Lethal Effect of Nitrite on Metapenaeus ensis Larvae

Abstract Metupenaeus ensis larvae at different stages were exposed to a series of nitrite‐N (nitrite as nitrogen) concentrations in static renewal toxicity tests. Larvae at zoea stage were the most susceptible, and postlarvae were the most tolerant to nitrite among the larvae tested. The 24 h LC50s were 31.29, 16.05, 47.60 and 70.06 mg/L nitrite‐N for third nauplius substage (N3). second zoea substage (Z2), second mysis stage (M2), and first postlarva substage (PL1), respectively, in 33 ppt seawater at a pH of 8.20 and a water temperature of 30 C. The 48 h LC50 for M2 and PL1 were 20.67 and 27.10 mg/L nitrite‐N, respectively. The “threshold time” was 108 h, and the “incipient LC50” for M. ensis PL1 was 7.06 mg/L nitrite‐N. A “safe level” for rearing M. ensis larvae was estimated to be 0.71 mg/L nitrite‐N in the hatchery.

Lethal effects of ammonia and nitrite on Penaeus penicillatus juveniles at two salinity levels

1. The 24,48,96, 144-hr lc 50 (median lethal concentration) of ammonia on Penaeus penicillatus juveniles were 59.49, 38.72, 29.77, 25.03 mg/l and 50.28, 31.26, 24.88, 20.66 mg/l for ammonia- N (un-ionized plus ionized ammonia as nitrogen); and 2.22, 1.44, 1.11, 0.93 mg/l and 2.00, 1.25, 0.99, 0.82 mg/l for NH 3- N (un-ionized ammonia as nitrogen) in 34 and 25 ppt seawater, respectively. 2. The 24, 48, 96, 144-hr lc 50 of nitrite- N on P. penicillatus juveniles were 92.88, 79.45, 40.86, 26.29 mg/l and 83.34, 52.93, 38.52, 25.55 mg/l in 34 and 25 ppt seawater, respectively. 3. A decrease of salinity from 34 to 25 ppt increased by more than 20% toxicities of ammonia and nitrite to P. penicillatus juveniles. 4. The “threshold” was found at 156 and 144 hr for ammonia, and 192 and 168 hr for nitrite in 34 and 25 ppt, respectively. 5. The “safety level” for P. penicillatus juveniles was 2.37 and 1.97 mg/l for ammonia- N; 0.09 and 0.08 mg/l for NH 3- N and 2.04 and 2.28 mg/l for nitrite- N in 34 and 25 ppt, respectively.

Variability in Agonistic Behaviour and Salinity Tolerance between and within Two Populations of Juvenile Chinook Salmon,Oncorhynchus tshawytscha, with Contrasting Life Histories

Agonistic behaviour and salinity tolerance were investigated in eight families of chinook salmon, Oncorhynchus tshawytscha, from two populations in the Nanaimo River, British Columbia. From emergence to 3 mo, there were small differences in agonistic behaviour among families within populations, but "First Lake" chinook had strikingly higher levels of agonistic behaviour than salmon from the "lower Nanaimo" population. Lower Nanaimo chinook were larger, lost less weight, and had higher survival after 24 h in 20 ppt and 30 ppt seawater than First Lake salmon. Within populations, families of larger than average size tended to perform better in seawater than families of smaller size. At a common body size, salinity tolerance was similar in salmon from the two populations, but significant differences among families within populations suggest that families may differ in factors other than size that influence salinity tolerance. It was concluded that the greater agonistic behaviour of First Lake chinook has a genetic basic and is related to their longer period of territorial stream residence before seaward migration. By contrast, the two populations exhibited only small differences in salinity tolerance, but significant interfamily variation illustrates the importance of considering family effects in studies of interpopulation differentiation.

Effects of thyroxine, growth hormone and cortisol on salinity preference of juvenile coho salmon(Oncorhynchus kisutch)

Freshwater yearling smolts of coho salmon (Oncorhynchus kisutch) weighing 25–70 g showed no preference for 33 ppt seawater from March to July; instead, seawater aversion was detected in June and July after the migratory period. In April during the migratory period, the fish showed restless behavior (swimming actively between compartments), which resulted in a high standard error of the mean. Effects of hormone administration on preference for 14 ppt seawater were examined using underyearling coho weighing 0.8–8.8 g. Fish treated with thyroxine (T4) or with ovine growth hormone (oGH) showed a significantly greater preference for 14 ppt salinity than the controls. The combination of T4 + oGH further increased this preference. Cortisol administration resulted in a less but still significant increase in preference. The finding that thyroid hormone, growth hormone and Cortisol all stimulate salinity preference of young coho, suggests the importance of these hormones in preparing smolts for downstream migration...

Toxicities of ammonia and nitrite to Penaeus monodon adolescents

Penaeus monodon adolescents (91.0±8.0 mm) were exposed to various concentrations of ammonia (NH 3+NH 4 +) and nitrite in 20 ppt seawater at a pH of 7.57 and a water temperature of 24.5°C using the static renewal method. The LC50 values of ammonia-N (un-ionized plus ionized ammonia as nitrogen), NH 3-N (un-ionized ammonia-N) and nitrite-N decreased with longer exposures. The 24-, 48-, 96- and 144-h LC50 values were 97.9, 88.0, 53.4 and 42.6 mg/l of ammonia-N (1.76, 1.59, 0.96 and 0.77 mg/l of NH 3-N), respectively. The 24-, 48-, 96-, 144-, 192- and 240-h LC50 values of nitrite-N were 218, 193, 171, 140, 128 and 106 mg/l nitrite-N, respectively. The “thresholds” of ammonia and nitrite toxicity were found at 144 and 240 h, respectively, on a toxicity curve approaching an asymptote. Based on the incipient LC50 value and an application factor of 0.1, safe values for rearing adolescent P. monodon (20 ppt, 7.57 pH, 24.5°C) were calculated to be 4.26 mg/l ammonia-N, 0.08 mg/l NH 3-N and 10.60 mg/l nitrite-N.

Saltwater-induced decreases in weight and length relative to seasonal gill Na +K + ATPase changes in coho salmon ( Oncorhynchus kisutch): a test for saltwater adaptability

Juvenile coho salmon challenged for 24 h in 31 ppt seawater experienced decreases in weight and length. These decreases became significantly less pronounced during the period of rise in gill Na +K + ATPase activity induced during parr-smolt transformation. It is suggested that these saltwater-induced changes in weight and length could be used as simple tests of seawater readiness.

Salinity tolerance and osmoregulation of the arctic marine amphipods Onisimus litoralis (Kroyer) and Anonyx nugax (Phipps)

The gammarid amphipod Onisimus litoralis, which inhabits arctic and subarctic intertidal and under-ice habitats, is a euryhaline hyperosmotic regulator. It survives 10 d exposures to salinities from 5 to 55 ppt. It hyperregulates its hemolymph osmolality during 3 h exposures to dilutions of 33 ppt seawater and remains hyperosmotic for at least 2 w. The hemolymph is isosmotic to the medium after 12 h exposures to salinities higher than ≈33 ppt. The gammarid amphipod Anonyx nugax, which inhabits arctic and subarctic subtidal areas, tolerates salinities from 23 to 45 ppt with little mortality. Unlike Onisimus, however, it is an osmoconformer and its hemolymph becomes isosmotic to all dilute salinities within its tolerance range after 12 h and to concentrated media after 3 h. The salinity tolerances and osmoregulatory abilities of both species are reflected in their distributions in the field.

Effects of food containing betaine/amino acid additive on the osmotic adaptation of young Atlantic salmon, Salmo salar L.

One-year-old salmon ( Salmo salar L.) were reared in freshwater (FW) and fed with either control feed or an experimental feed containing 1.5% of betaine/amino acid additive. After 1 month of rearing in freshwater, some of the fish in each group were gradually acclimated to 39 ppt seawater (SW) over a week, then reared in it for 4 weeks. The rest of the fish were maintained in FW. Physiological samples were taken at the start of the experiment, after 4 weeks' rearing in FW and five successive times during the SW stage. In addition, a group of the FW fish were challenged with SW three times during the experiment using an abrupt change from FW to SW and a further stay of 48 h in SW. The surviving fish were sampled for physiological analyses. The betaine/amino acid additive induced some physiological changes in FW fish. The most marked were a lowered muscle water content and delayed desmoltification of the experimental fish. The additive somewhat improved the capacity to maintain the ionic and osmotic balance in SW but, due to the low number of experimental animals, the difference in SW survival was insignificant. The seawater challenge tests indicated that betaine may also help the fish to maintain the ionic and osmotic balance after abrupt transfer to SW. There seem to be several mechanisms of action: the gill ion extrusion is somewhat enhanced as expressed by elevated gill Na,K-ATPase activity, but the effects on the water and magnesium balance are more pronounced, indicating changes in the intestinal and renal ion and water transport.

Influence of salinity on the energetics of gill and kidney of Atlantic salmon (Salmo salar)

The effect of seawater acclimation and adaptation to various salinities on the energetics of gill and kidney of Atlantic salmon (Salmo salar) was examined. Smolts and non-smolts previously reared in fresh water were exposed to a rapid increase in salinity to 30 ppt. Plasma osmolarity, [Na(+)], [Cl(-)], [K(+)] and [Mg(++)] increased in both groups but were significantly lower in smolts than non-smolts. Gill Na(+), K(+)-ATPase specific activity, initially higher in smolts, increased in both groups after 18 days in seawater. Kidney Na(+), K(+)-ATPase specific activity was not affected by salinity in either group. Gill and kidney citrate synthase specific activity was not affected by seawater exposure in smolts but decreased in non-smolts. In a second experiment, Atlantic salmon smolts reared in fresh water were acclimated to 0, 10 or 30 ppt seawater for 3 months at a temperature of 13-14°C. Gill Na(+), K(+)-ATPase was positively correlated with salinity, displaying 2.5- and 5-fold higher specific activity at 10 and 30 ppt, respectively, than at 0 ppt. Kidney Na(+), K(+)-ATPase specific activity was not significantly affected by environmental salinity. Citrate synthase and cytochrome c oxidase specific activities in gill were slightly (6-13%) lower at 10 ppt than at 0 and 30 ppt, whereas kidney activities were lowest at 30 ppt. Oxygen consumption of isolated gill filaments was significantly higher when incubated in isosmotic saline and at 30 ppt than at 0 ppt, but was not affected by the prior acclimation salinity. The results indicate that although high salinity induces increased gill Na(+), K(+)-ATPase activity, it does not induce substantial increases in metabolic capacity of gill or kidney.

Changes in plasma osmolality and chloride concentration during abrupt transfer of milkfish ( Chanos chanos) from seawater to different test salinities

Milkfish juveniles (40, 120 or 260 g) were acclimated to 32 ppt seawater, then abruptly transferred to water with salinities of 0, 16, 32 (control) or 48 ppt. Blood samples were taken 0, 1, 2, 3, 5, 7 or 14 days after transfer. Survival rate was 95% or greater in all salinities. Plasma osmolality in fish exposed to salinities other than 16 or 32 ppt deviated from control values immediately after transfer but were subsequently regulated to near normal levels after several days. Although these deviations were significant, they were relatively small (≤20% of initial) as plasma osmolality changed by less than 0.07 mOsm/kg per unit change environmental salinity. Plasma chloride values generally followed the same pattern of changes as plasma osmolality. When these deviations were integrated across time, summed deviations (mOsm·day kg −1 or mEq·day l −1) were proportional to the osmotic or ionic gradient but were inversely proportional to size. For 40-g fish, summed deviations were larger in 48 than in 0 ppt; for 120- or 260-g fish, these deviations were larger in 0 than in 48 ppt. These results indicate that small milkfish tend to adapt better to fresh than to hypersaline water while larger milkfish are more likely to find hypersaline water less stressful than freshwater. Like other organ systems previously studied in milkfish, these size-dependent adaptations in osmoregulatory mechanisms reflect natural habitat shifts during development.

Plasma cortisol and secondary stress responses of cultured red drum ( Sciaenops ocellatus) to several transportation procedures

Transportation procedures induced rapid elevations in plasma cortisol and glucose concentrations (100–160 ng/ml and 60–140 mg/100 ml, respectively) within 15–30 min of capture and loading in cultured juvenile red drum. The elevations were transient and plasma levels of cortisol returned to baseline levels during the 5.5 h transport, suggesting that capture and loading are the most traumatic procedures. Plasma glucose concentrations had returned to baseline values within 1–2 days of transport. Plasma osmolality increased during transportation in 32 ppt seawater and decreased during transport in 4 ppt seawater. Survival ranged from 96 to 100%, indicating that despite the trauma associated with initial transport procedures, juvenile red drum can be transported successfully in seawater or low salinity seawater. Anesthesia with MS-222 (80 mg/l) prior to capture, coupled with the use of sedating doses (5 and 25 mg/l MS-222) in the transport tanks, did not decrease the magnitude of the stress responses. On the contrary, the corticosteroid stress response was augmented in fish transported in 25 mg/l MS-222. Laboratory tests showed that long-term (30–90 min) exposure to sedating doses of the anesthetic caused a dose-dependent increase in plasma cortisol levels, whereas anesthetization of red drum with MS-222 prior to capture and transport in anesthetic-free seawater markedly reduced the plasma corticosteroid response after capture/loading and at the end of transport. Plasma glucose levels and osmolality were also lower in those fish anesthetized prior to capture. These results suggest that acute exposure to immobilizing doses of an anesthetic, MS-222, is an effective method of reducing endocrine and metabolic disturbances during transportation of red drum.

Toxic effects of mercuric chloride on sperm and egg viability of two populations of mummichog, Fundulus heteroclitus

Exposure of mummichog ( Fundulus heteroclitus) sperm from polluted Piles Creek (PC) to 0·01 ppm mercuric chloride (Hg) for 2 min caused a significant reduction in fertilization success. However, comparable exposure of sperm of mummichog from a relatively clean area in Long Island (LI) did not effect the fertilization success. Exposure of PC mummichog sperm to 0·05 ppm Hg for 2 min caused significant reduction in sperm motility. On the other hand, comparable exposure of LI mummichog sperm did not have any effect on motility. These data indicate that Hg is more toxic for PC mummichog sperm than LI mummichog sperm. Exposure of both PC and LI sperm either to 15 ppt sea water or to 0·05 ppm Hg for 15 min did not affect the morphology of the sperm, as seen by scanning electron microscopy. Exposure of PC and LI mummichog eggs to 0·05 ppm Hg up to 25 min had no effect on fertilization success, indicating that eggs are more tolerant to Hg than sperm.

The uptake and in vivo metabolism of the organophosphate insecticide fenitrothion by the blue crab, Callinectes sapidus

Callinectes were exposed to [ 14C]fenitrothion at a level of 5.2 μg/liter in either 22°C, 34 ppt; 22°C, 17 ppt; or 17°C, 34 ppt seawater. Uptake from the water, as measured by a decrease in fenitrothion, and the distribution of radioactivity throughout the Callinectes were determined. The nature of radiolabeled metabolites in the water and hepatopancreas was also determined. Fenitrothion was absorbed more rapidly from the water at the higher salinity and temperature. Radioactivity was detected in all the organs assayed by 24 hr postexposure, though the levels increased in most tissues throughout the experiment. The highest concentrations of radioactivity were found in the hepatopancreas and stomach. The metabolites which were detected in the water and liver indicate that Callinectes metabolize fenitrothion by oxidation of the phosphorothioate to a phosphate to yield fenitrooxon. The presence of aminofenitrothion and 3-methyl-4-aminophenol shows that reduction of the nitro group to an amino group also occurs. The isolation of desmethyl forms of fenitrooxon and fenitrothion as well as 3-methyl-4-nitrophenol indicates that hydrolysis of both the P-O-aryl and P-O-alkyl bonds occurred. Glycoside and sulfate conjugates of both phenols were inferred in the hepatopancreas. Higher levels of fenitrooxon and lower levels of desmethyl fenitrothion were detected in the 34 ppt seawater than in the 17 ppt seawater. The 5°C differential had no significant effect on the nature and concentrations of metabolites detected in the seawater.

Importance of river migration to the development of seawater tolerance in Columbia River anadromous salmonids

Gradually increasing levels of gill Na +K + ATPase activity were observed in juvenile chinook, Oncorhynchus tshawytscha, and coho, Oncorhynchus kisutch, salmon and steelhead trout, Salmo gairdneri, undergoing parr-smolt transformation in artificial rearing facilities on the Columbia River. Portions of the same populations released to migrate seaward, however, generally showed much greater increases in enzyme activity with time and distance from the release point. After migrating 714 km to the Columbia River estuary, spring chinook salmon had a mean gill Na +K + ATPase activity 2.5 times greater than fish retained at the hatchery and 1.9 times greater than fish adapted to 28 ppt seawater for 208 days. Similar observations were made on coho salmon.

Biomass and Pigment Production in Three Isolates of Azolla I. Response to Water Stress

Two isolates of Azolla Lam. from Colombia, South America, and one from the USA (Florida) were selected for characterization of their growth potentials in certain defined stress environments. These isolates were Amazonian (RAR) and Atlantic coastal (M-3) specimens of Azolla caroliniana Willd and a Floridian variety (LA) of Azolla filiculoides Lam. Osmotic stress (from polyethylene glycol-amended media) and osmotic/salt stress (from sea water-amended media) were the chosen determinants in these trials. Their effects on growth responses were monitored. Initial growth rates of LA and M-3 were stimulated at 1 and 5 ppt seawater salts, relative to growth under control conditions. RAR, however, was generally the most stable isolate in the experiments with seawater-induced ionic stress. LA was most stable in its biomass growth in experiments with polyethylene glycol 6000, but chlorophyll accumulation data were again least affected in RAR. LA survived the longest of the three isolates at a water potential of approximately -10 bars with either seawater (13 ppt salts) or polyethylene glycol (26 per cent). The latter amendment was usually more inhibitory to acetylene reduction rates in RAR and consistently more inhibitory in LA. RAR was tentatively judged by its reactions to water stress to be the superior isolate of the three.

GROWTH. FEED DIGESTIBILITY, AND PROXIMATE BODY COMPOSITION OF JUVENILE Penaeus vannamei AND Penaeus monodon GROWN AT DIFFERENT DISSOLVED OXYGEN LEVELS

ABSTRACTGrowth, feed digestibility (apparent total dry‐matter digestibility), and proximate body composition of juvenile Penaeus vannamei and Penaeus monodon were evaluated at dissolved oxygen (DO) levels of 1, 2, 3, and 4 ppm at a mean temperature of 28°C. The four different W levels were obtained by aerating different rates of nitrogen gas countercurrent to a constant flow of seawater. A standard formulated diet containing the marker material Cr2O3, and a mean 280% exchange of 30 to 32 ppt seawater per day were used. Initial wet weights of shrimp were 60.2 and 55.5 mg for P. vannamei and P. monodon, respectively. Final mean wet weights for shrimp maintained at 1, 2, 3, and 4 ppm DO level after a 16‐day growth trial were 0.24, 0.40, 0.42, 0.46 g, and 0.16, 0.26, 0.29, 0.29 g for P. vannamei and P. monodon, respectively. For both species, a significant reduction in growth and in the instantaneous growth rate (k) was obtained at the lowest Do level. No significant differences were observed for apparent feed digestibility in either shrimp. Laboratory analysis revealed no differences in moisture and lipid content for both species, while protein content was found to differ only in P. monodon grown at different DO levels. A description of the experimental system and a discussion of the significance of the data to the production of shrimp in ponds is presented.

Adaptations of Crocodylus acutus and Alligator for life in saline water

1. 1. American crocodiles ( C. acutus) weighing less than 200 g are unable to grow when kept in 35 ppt sea water in the laboratory. Yet paradoxically there are some highly saline areas in south Florida where rapid growth occurs. It is possible that these conflicting observations can be reconciled by behavioral osmoregulation of young crocodiles. 2. 2. Hatching occurs during the rainy season and small crocodiles may drink from the brackish “lens” available during and after rainfall. 3. 3. Using a weekly regime of alternating exposure to 35 ppt (6 days) and 4 ppt (12–24 hr), it has been demonstrated that growth of small crocodiles occurs. Feeding takes place primarily when brackish water is available. Salinities as high as 18 ppt were drunk when crocodiles were dehydrated by 15–20% of initial mass. 4. 4. C. acutus and Alligator have a rather low rate of water efflux in sea water (0.2ml/100g-hr). 5. 5. Sodium influx in sea water of C. acutus is low, but higher than efflux. Thus there is no evidence yet for a significant role of the lingual salt glands in sodium excretion. 6. 6. The major adaptations to saline water of hatchling C. acutus are a low intake of sodium, an ability to selectively drink water of lower salinities, and to grow very rapidly (within 3–4 months) to a size much more tolerant of immersion in 35 ppt sea water.

Osmoregulation in the brook trout, Salvelinus fontinalis—II. Effects of size, age and photoperiod on seawater survival and ionic regulation

1. 1. Brook trout ( Salvelinus fontinalis) of a single genetic stock, and hatched at the same time, were raised under two photoperiod and two feeding regimes to obtain fish of the same age but with different sizes and photoperiod experiences. In 11 experiments over 1.5 firs, fish were gradually exposed to 32 ppt seawater for 20 days to investigate the ontogeny of salinity tolerance. 2. 2. Daily changes in plasma osmolarity, [Na +], [Cl −], [K +], [Mg 2+], thyroxine, hematocrit and gill Na +,K +-ATPase during adaptation to 10, 20 and 32 ppt were examined in one experiment. 3. 3. Size was the primary determinant of seawater survival ( r 2 = 0.77) the effect of size on seawater survival slowed after fish reached a fork length of 14 cm. The effect of age on seawater survival ( r 2 = 0.65) was through its covariance with size. 4. 4. Photoperiod affected seawater survival only through its influence on the timing of male maturation, which decreased salinity tolerance. 5. 5. Regulation of plasma osmolarity, [Na +], [Cl −], [K 2+], [Mg 2+] and hematocrit in sea water increased linearly with size over the entire range of sizes (6–32 em). 6. 6. Gill Na +,K +-ATPase activity after 20 days in seawater decreased with increasing size of brook trout, possibly reflecting decreased demand for active ion transport in larger fish. 7. 7. Plasma thyroxine concentrations declined in seawater, but no definitive role of this hormone in seawater adaptation was found. 8. 8. Size dependent survival and osmoregulatory ability of brook trout is compared to other salmonids and a conceptual model is developed.