Metabolic and NH4 excretion rate of fresh water species, Chondrostoma regium in response to environmental stressors, different scenarios for temperature and pH.

Changes in water temperature and pH levels have substantial adverse effects on aquatic organisms, hence causing physiological constraint on their well-being. To understand the physiological responses of Chondrostoma regium to temperature or pH changes, standard metabolic rate (SMR), maximum metabolic rate (MMR), absolute and factorial aerobic scope (AS&FAS) as well as the specific rate of ammonia excretion (Jamm) were measured at following temperatures: acute low (3.5-4.5 °C), 24 h low (5.5-6.5 °C), 7 d low (5.5-6.5 °C), acute high (30-31 °C), 24 h high (29-30 °C), 7 d high (28-29 °C), and different pH treatments: acute low (4.3-4.4), 24 h low (4.3-4.4), 7 d low (6.3-6.4), acute high (9.8-9.9), 24 h high (9.8-9.9), 7 d high (8.8-8.9). A control group was also assigned to optimum temperature = 22-23 °C and pH = 7.8-7.9. These experimental ranges for each treatment were obtained based on critical thermal and pH thresholds, i.e., 1.9 to 31.7 °C and 2.7 to 11.1, respectively. SMR was enhanced significantly (P < 0.05) following pH treatments, except for 24 h low pH treatment. Results showed significant (P < 0.05) changes in both SMR and MMR at low and high temperature treatments. The AS was elevated following pH treatments except for acute low pH treatment in which AS significantly was declined (P < 0.05). Low temperature treatments resulted in lower AS while no significant changes in AS were observed in high temperatures. In all treatments, FAS value did not differ significantly from control, except for acute and 24 h low treatments of both temperature and pH. All high pH and temperature treatments showed a significant increase (P < 0.05) in Jamm. Histopathological results of gills indicated hyperplasia and fusion of secondary lamella and kidneys histopathology revealed necrosis and loss of tubular lumen in the most treatments. Results indicated that increases in water temperature or pH are more stressful than the lower ranges of them, suggesting higher capability of fish to adjust to the low levels of temperature or pH.

Effects of water-borne copper and lead on metabolic and excretion rate of bahaii loach (Turcinoemacheilus bahaii).

Beyond the role of anthropogenic activities, natural sources of metal contaminations are still controversial, together counting, however, as a major threat to inland and coastal waters, becoming an even more prominent stressor for aquatic life. To address the effects of metals on the physiological response of fish, standard metabolic rate (SMR), maximum metabolic rate (MMR), aerobic scope (AS) and factorial aerobic scope (FAS) as well as specific rate of ammonia excretion (Jamm) of Turcinoemacheilus bahaii were determined following different water-borne Cu2+ and Pb2+ treatments. Following LC50-96 h determination, 72 fish (BW = 1.153 ±â€¯0.56 g and TL = 6.155 ±â€¯0.97 cm) were exposed to different amounts of Cu2+ and Pb2+ in 9 different treatments (eight fish/treatment), including 0.910 mg l-1 Cu2+ for 24 h, 0.455 mg l-1 Cu2+ for 7d, 0.182 mg l-1 Cu2+ for 14d and 0.091 mg l-1 Cu2+ for 30 d as well as 124.430 mg l-1 Pb2+ for 24 h, 62.215 mg l-1 Pb2+ for 7d,12.443 mg l-1 Pb2+ for 14d, 6.221 mg l-1 Pb2+ for 30d and control. The SMR of fish was reduced following exposures to all Cu2+ and Pb2+ treatments (P < 0.05), except for 30d exposure as compared with the control. The MMR remained steady following all Cu2+ treatments while it was raised significantly (P < 0.05) following Pb2+ treatments at 7, 14 and 30d exposure. Although the AS showed a similar pattern to MMR, the FAS was elevated (P < 0.05) following all the treatments when compared with control. Lower Jamm were observed following all metals-treated fish in comparison with control (P < 0.05). In addition, higher (P < 0.05) levels of injuries were observed following all Cu2+ and Pb2+ treatments in gills and kidneys. The results suggest that Cu2+ and Pb2+ over the experimental period could impair the metabolic and excretory capacities, hence affecting the possible physiological performance of fish.

Combined effects of dietary low molecular weight sodium alginate and Pediococcus acidilactici MA18/5M on growth performance, haematological and innate immune responses of Asian sea bass (Lates calcalifer) juveniles.

Six weeks feeding trial was conducted to examine the effects of dietary administration of low molecular weight sodium alginate (LMWSA) and Pediococcus acidilactici MA 18/5M (PA) on humoral and mucosal immune responses, haematological parameters and growth performance, of Lates calcarifer juveniles. Fish (12.0 ±â€¯0.2 g) were fed experimental diets as follows: Control (diet 1, basal diet), 5 g kg-1 LMWSA (diet 2), 10 g kg-1 LMWSA (diet 3), 0.9 × 107 CFU g-1 PA (diet 4), 5 g kg-1 LMWSA + 0.9 × 107 CFU g-1 PA (Diet 5), and 10 g kg-1 LMWSA + 0.9 × 107 CFU g-1 PA (Diet 6). Results indicated a significant (P < 0.05) increase in innate immune parameters including serum lysozyme, bactericidal, hemolytic and respiratory burst activities as well as mucosal immune responses including lysozyme and bactericidal activities, when diet was supplemented with immunostimulants. Moreover, the combined effects of LMWSA with PA resulted in more pronounced immunological responses compared to the control and singular administration. Red and white blood cell counts significantly increased with either singular or combined administration of LMWSA and PA compared with the control group (P < 0.05). The singular administration of PA and combined supplementation of 5 g kg-1 LMWSA with PA significantly increased growth performance and feed intake compared with other experimental groups (P < 0.05). These results indicated that combined administration of LMWSA and PA can be considered as beneficial feed additive and immunostimulant in L. calcarifer juveniles.

Metabolic capacities of common carp (Cyprinus carpio) following combined exposures to copper and environmental hypoxia.

In aquatic ecosystems, a decline in water O2 level is the main factor that can release heavy metal ions from top sediment layer. Therefore, hypoxia in turn, and in association with heavy metals might provide undesirable environment and impairs physiological functions of aquatic animals. To address this, metabolic capacities, including standard metabolic rate (SMR), maximum metabolic rate (MMR), aerobic scope (AS) and factorial aerobic scope (FAS) of common carp were determined following exposures to different levels of water-borne Cu(2+) as well as hypoxia. Treatments for Cu(2+) were included: 100% (acute), 50% (sub-lethal) and 10% (chronic) of LC50-96h for immediately, 24h and 7 days exposures respectively. Hypoxia treatments were assigned as acute for immediately, sub-lethal for 24h and chronic for 7 days. Combined effects of treatments were also considered as acute Cu(2+)+hypoxia, sub-lethal Cu(2+)+hypoxia and chronic Cu(2+)+hypoxia. While SMR of carp was reduced by chronic hypoxia, significant (P<0.05) increase was observed during acute hypoxia, as compared with control. The MMR and AS were significantly reduced (P<0.05) following all hypoxia treatments. The acute and chronic Cu(2+) treatments showed significant (P<0.05) increases in SMR and MMR values. All acute and sub-lethal combined treatments showed significant (P<0.05) reductions in SMR, MMR and AS values, whilst chronic combined treatments showed generally increasing trends for MMR and AS. PCrit was relatively reduced following all treatments except for acute and sub-lethal Cu(2+)-treated fish that showed higher value (P<0.05) and no change respectively. Although all Cu(2+) treatments increased the number of mucus cell, hypoxia treatments did not show any remarkable differences when compared with control group. In general, the results of present study reveal that hypoxia acts as limiting stressor whilst Cu(2+) do act as loading stressors in the case of common carp metabolism. The interactive exposures mostly showing a synergist effect in all metabolic capacities with an exception for chronic treatments.

Effect of dietary flaxseed oil level on the growth performance and fatty acid composition of fingerlings of rainbow trout, Oncorhynchus mykiss.

This study evaluated the suitability of flaxseed oil as a source of supplemental dietary lipid for fingerlings of rainbow trout (Oncorhynchus mykiss). Triplicate groups of the 30 fingerlings held under identical culture conditions were fed twice daily by iso-nitrogenous, iso-calorific and iso-lipidic diets for 8 weeks. Experimental diets consisted of 30.2% protein, 18.6 kJ g(-1) energy and 16.5% lipid from fish oil (FO), flaxseed oil (FxO) and 1:1 blends of the oils (FFxO). Moisture, ash, protein, final body weight, specific growth rate, weight gain, feed conversion ratio, survival and hepatosomatic index were not affected by treatments but the percent of lipids was significantly highest in fish fed the flaxseed oil diet (FxOD). The condition factors of fingerlings reared on FxOD and fish and flaxseed oils diet (FFxOD) were significantly lower than those fed the fish oil diet (FOD). Protein efficiency ratio (PER) was significantly higher than those fed the FOD and FFxOD. Whole body fatty acid compositions mirrored those of diet treatments. The highest amounts of highly unsaturated fatty acids (HUFAs) were detected in fish fed 100% FO, which was significantly different from other treatments. In all treatments polyunsaturated fatty acids/saturated fatty acids (PUFAs/SFAs) and n-6/n-3 ratios were higher than 0.45 and lower than 4, respectively. Present results indicate the fingerlings can be reared on diets in which FO has been replaced with FxO, with no significant effects on fish performance.

Long-term effects of propolis on serum biochemical parameters of rainbow trout (Oncorhynchus mykiss).

Long-term effects of propolis administration on serum biochemical parameters of rainbow trout (Oncorhynchus mykiss) were investigated. To determine the possible toxicity and side effects of propolis, fish were fed on diets containing 0, 0.5, 1.5, 4.5 and 9 g propolis/kg diet for 8 weeks. At the end of the experiment, various seric biochemical parameters were determined. Our results showed that all dosages induced no significant alterations in growth parameters and the seric levels of total protein, albumin, globulin, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides and activities of glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, alkaline phosphatase and lactate dehydrogenase, when compared to the control group. On the basis of our findings, propolis is a non-toxic substance for rainbow trout and its long-term administration might not have any side effects.