Jiann-Chu Chen

Toxicity of copper sulfate for survival, growth, molting and feeding of juveniles of the tiger shrimp, Penaeus monodon

Abstract The aim of this study was to determine the acute and chronic toxicity of copper sulfate for juveniles of Penaeus monodon . The 96-h LC50s (median lethal concentrations) of copper on juvenile P. monodon (0.63±0.13 g) were 3.13 and 7.73 mg/l in seawater of 15‰ and 25‰, respectively. The mortality rates of P. monodon juveniles (0.19±0.02 g) following exposure to 0 (control), 0.45, 0.90, 1.80 and 4.50 mg/l copper after 30 days was 0%, 0%, 5.6%, 22.2% and 55.6%, respectively. After 30 days of exposure, the body weight and total length of shrimps exposed to copper at 0.90 mg/l and higher was significantly lower ( P P P. monodon shortened the time to the first molt, and decreased its growth and molting frequency. Following exposure to copper as low as 5.0 mg/l, P. monodon juveniles (6.25±0.09 g) decreased their feeding. The MATC (maximum acceptable toxicant concentration) was 0.45 mg/l copper based on the growth and molting of shrimps weighing 0.18–1.03 g, and was 1.0 mg/l copper based on the feeding of shrimps weighing 6.25 g.

Lethal effects of ammonia and nitrite onPenaeus chinensis juveniles

Juveniles of the prawnPenaeus chinensis (3.96 ±0.18 cm, 0.36±0.06 g) reared in Taiwan in 1989 were exposed to different concentrations of ammonia and nitrite, by a static renewal method in 33‰ seawater at pH 7.94 and at 26 °C. The 24, 48, 96 and 120 h LC50 (median lethal concentration) of ammonia were 3.29, 2.10, 1.53 and 1.44 mg l−1 for NH3-N (un-ionized ammonia as nitrogen) and 79.97, 51.14, 37.00 and 35.09 mg l−1 for ammonia-N (un-ionized plus ionized ammonia as nitrogen). The 24, 96, 120, 144 and 192 h LC50 of nitrite-N were 339, 37.71, 29.18, 26.98 and 22.95 mg l−1. The LC50 decreased with increasing exposure time. During the first 96 h,P. chinesis juveniles were more susceptible to ammonia than nitrite. However, prawns were less tolerant to nitrite than ammonia when exposed for more than 96 h. The “threshold” was found at 120 and 192 h for ammonia and nitrite, respectively, on the toxicity curves. “Incipient LC50” was 1.44 mg l−1 for NH3-N, 35.09 mg l−1 for ammonia-N and 22.95 mg l−1 for nitrite-N. The “safe value” forP. chinensis juveniles was 0.14, 3.51 and 2.30 mg l−1, respectively.

SURVIVAL, HAEMOLYMPH OSMOLALITY AND TISSUE WATER OF PENAEUS CHINENSIS JUVENILES ACCLIMATED TO DIFFERENT SALINITY AND TEMPERATURE LEVELS

Abstract Survival, growth, haemolymph osmolality and tissue water of Penaeus chinensis (Osbeck) juveniles (0.11 ± 0.04 g) were investigated, after they were acclimated to 10, 20, 30 and 40 ppt from 33 ppt for 14 days at 24°C, and then acclimated to 12, 18, 24 and 30°C at each salinity for 14 days. The survival of shrimp was the lowest at 10 ppt and 12°C. Growth of shrimp increased with increased temperature in the range 12–24°C, with no significant difference among four salinity levels at 18, 24 and 30°C. Haemolymph osmolality increased with increased salinity, and decreased with increased temperature. The isosmotic point computed from the linear relationship between haemolymph osmolality and medium osmolality was 664, 632, 629 and 602 mOsm/kg which is equivalent to 25.2, 24.1, 24.0 and 23.1 ppt at 12, 18, 24 and 30°C, respectively. Tissue water decreased with increased medium osmolality and haemolymph osmolality. The slope obtained from the relationship between haemolymph osmolality and medium osmolality indicated that there is an impairment of osmoregulatory ability for the P. chinensis juveniles at 12°C.

RESPONSES OF OXYGEN CONSUMPTION, AMMONIA-N EXCRETION AND UREA-N EXCRETION OF PENAEUS CHINENSIS EXPOSED TO AMBIENT AMMONIA AT DIFFERENT SALINITY AND PH LEVELS

Abstract Oxygen consumption (O 2 mg g −1 h −1 ) of Penaeus chinensis juveniles (0.76 ± 0.05 g) increased with increased concentration of ambient ammonia-N in the range of 0–10 mg 1 −1 , but decreased with increased salinity level in the range of 10–30 p.s.u. (practical salinity units) and pH level in the range of 7.0–8.5. Urea-N excretion and nitrite-N excretion of shrimp increased with increased salinity, pH and ambient ammonia-N levels. Whereas, ammonia-N excretion of shrimp decreased with increased salinity, pH and ambient ammonia-N levels. Ammonia-N uptake occurred when shrimp were exposed to ambient ammonia-N at 5 mg 1 −1 or greater at every salinity and pH level tested. Shrimp at an increased salinity level, and at an increased concentration of ambient ammonia-N enhanced their urea-N excretion, an effect that was more pronounced at high pH than at low pH.

Hemolymph oxygen content, oxyhemocyanin, protein levels and ammonia excretion in the shrimp Penaeus monodon exposed to ambient nitrite

Subadult Penaeus monodon (21.03±3.19 g) were exposed individually in sea water (30 mg·ml-1) to 0.02 (control), 1.04, 5.02, 10.11 and 20.06 mg·l-1 nitrite-N for 24h. Hemolymph pH, partial pressures of oxygen and carbon dioxide, bicarbonate concentration, oxyhemocyanin and protein levels, and whole animal ammonia-N excretion and nitrite-N uptake were determined. Ammonia-N excretion and hemolymph oxygen partial pressure increased, whereas hemolymph pH, HCO3-, oxyhemocyanin, protein and the ratio of oxyhemocyanin/protein levels decreased with increasing ambient nitrite-N. It is suggested that accumulated nitrite of P. monodon following exposure to ambient nitrite causes reduction of oxyhemocyanin, protein and the ratio of oxyhemocyanin/protein in the hemolymph, and affects nitrogen metabolism and acid-base balance at low hemolymph pH.

Salinity tolerance of Haliotis diversicolor supertexta at different salinity and temperature levels

Abstract Juvenile abalones, Haliotis diversicolor supertexta Lischke maintained in different environmental regimes (25, 30 and 35‰ combined with 20, 25 and 30°C) were examined for salinity tolerance by increasing and decreasing salinity at a rate of 2‰/h. They were also examined for the LS50 (median lethal salinity) when transferred directly into a series of higher salinity (32–48‰) and lower salinity (9–25‰) water baths. The 50% CSMax (critical salinity maximum), USTL (upper salinity tolerance limit), 50% CSMin (critical salinity minimum) and LSTL (lower salinity tolerance limit) increased directly with salinity, but were inversely related to temperature. The juveniles maintained in 25°C and 25, 30 and 35‰ had 50% CSMin–50% CSMax of 11.2–41.8‰, 12.5–43.9‰ and 13.5–49.8‰, respectively. The juveniles maintained in 25‰ and 30°C survived salinity of 14–33‰, and those maintained in 35‰ and 20°C survived salinity of 20–45‰, when salinity was decreased or increased gradually. It is suggested that H. diversicolor supertexta juveniles maintained in 35‰ or higher at 20°C or lower survive salinity higher than 45‰ when salinity is increased. It is also suggested that the juveniles maintained in 25‰ or a lower salinity at 30°C or a higher temperature survive salinities lower than 14‰ when salinity is decreased.

Effects of temperature on oxygen consumption and nitrogenous excretion of juvenile Macrobrachium rosenbergii

Abstract Oxygen consumption (O 2 mg g −1 h −1 ) and ammonia-N, urea-N, organic-N and total nitrogen excretion (N μg g −1 h −1 ) of juvenile Macrobrachium rosenbergii increased directly with temperature in the range of 17–32 °C. No urea-N excretion was found at 17 °C. The proportion of ammonia-N excretion to total nitrogen excreted by prawns was inversely related to temperature, whereas the proportion of urea-N excretion to total nitrogen excreted increased directly with temperature. At 32 °C, the amount of ammonia-N, urea-N and organic-N excreted by prawns accounted for 70.2%, 4.2% and 25.6%, respectively of total nitrogen. Relationships between cumulative amount of oxygen consumed, ammonia-N excreted, organic-N excreted, and total nitrogen excreted, temperature and time are given.

Survival, growth and intermolt period of juvenile Penaeus chinensis (Osbeck) reared at different combinations of salinity and temperature

Penaeus chinensis (Osbeck) juveniles (0.23–0.36 g) were reared at 16 combinations of salinity (10, 20, 30 and 40 ppt) and temperature (12 °, 18 °, 24 ° and 30 °C) for 50 days. All shrimp survived at 20 ppt and 18 °C, whereas no shrimp survived at 10 ppt and 12 °C after 30 days. Animals at 20 and 30 ppt and at 30 °C grew significantly faster (P < 0.05) than those at 30 and 40 ppt at 24 °C, and at 40 ppt and 30 °C. The intermolt period of shrimp was 21.5–28.5 days, 10.8–14.4 days, 8.0–8.9 days and 7.4–8.5 days at 12 °, 18 °, 24 ° and 30 °C, respectively. Best growth of juvenile P. chinensis was achieved over the range 20–30 ppt at 30 °C.

Changes of haemocyanin, protein and free amino acid levels in the haemolymph of Penaeus japonicus exposed to ambient ammonia

Abstract Haemolymph ammonia-N of Penaeus japonicus (15.6 ± 2.17 g) increased with increased ambient ammonia-N, as they were exposed individually in 30 ppt seawater to 0.003 (control), 0.367, 0.731, 1.439 and 3.665 mmol/1 ammonia-N after 24 hr. Ammonia-N excretion was inhibited and net ammonia-N uptake occurred, as shrimps were exposed to 0.367 mmol/1 ammonia-N or greater. Haemocyanin and protein levels in the haemolymph of shrimp decreased, whereas free amino acid levels increased with increased ambient ammonia-N in the range of 0.003–1.439 mmol/1 ammonia-N. Exposure of shrimp to ambient ammonia-N at 1.439 mmol/1 caused accumulation of haemolymph ammonia and urea, and caused catabolism of haemocyanin and protein to free amino acids. Urea, taurine and glutamine are the major organic constituents in the haemolymph of shrimp under ammonia stress.

Effects of saponin on survival, growth, molting and feeding of Penaeus japonicus juveniles

Abstract The median lethal concentration (LC50) of saponin on juvenile Penaeus japonicus was 20.82 mg l−1 and 18.14 mg l−1 at 48 h and 96 h, respectively, in sea water of 34 practical salinity units. The mortality rate of juvenile P. japonicus exposed to 0 (control), 0.1, 0.5, 1 and 2 mg l−1 saponin after 60 days was 3.3%, 6.6%, 10%, 33.3% and 43.3%, respectively. After 36 days of exposure, the weight of shrimps exposed to 1 and 2 mg l−1 saponin was significantly lower than for those exposed to 0.1 and 0.5 mg l−1 saponin. The growth factor of shrimps exposed to 0.5 mg l−1 saponin was significantly lower than those exposed to 0.1 mg l−1 saponin and the control solution. Following exposure to saponin as low as 0.5 mg l−1, P. japonicus shortened the time to the first molt, and decreased its feeding, growth and molting frequency. The maximum acceptable toxicant concentration was 0.1 mg l−1 saponin.