Daphnia pulex through physical and chemical factors

Regarding the key role and importance of Daphnia in aquaculture, particularly for survival and adaptation of fishes in larval stages, a comprehensive study on hatching rate of Daphnia ephippial eggs was implemented to obtain an optimum technique. The effects of abiotic factors was investigated on the hatching response of Daphnia pulex diapausing eggs collected from live food ponds in Cultivation and Breeding Centre of Gorgan. After isolation, the eggs were kept in dry and wet conditions at 4°C for 2 months in darkness. Following the preincubation period, the eggs in each group were subdivided into 2 parts and treated with 1% NaOCl and distilled water. The effect of temperature levels (15 C, 20 C, 25 C) and photoperiod levels (12L: 12D, 24L: 0D) were identified on the hatching of eggs in AdaM medium during 15 days. Results indicated that the exposure of wet-kept eggs to 12-hour photoperiod and 25 C without soaking in 1% NaOCl, caused the maximum rate and speed of hatching

Survey of effects of different concentrations of electrolytes and pH on characterization of sperm motility in wild carp (Cyprinus carpio)

Effects of pH, Na, K, Ca^+ Mg^2+ ions on characterization of sperm motility (duration of motility and percentage of motility) of wild carp (C. carpio) were investigated. After determination of optimum pH, its interaction effect with Na, K, Ca^2+ and Mg^2+ was studied. Maximum motility (duration of motility and percentage of motility) was observed at pH=8.5. Effects of different treatments of NaCl on sperm motility was significantly different (P<0.05) while that of the MgCl _(2) was significantly different (P<0.05). In general, it is concluded that movement of spermatozoa of wild carp is influenced by high concentration of ions

Seasonal changes of fatty acids in Nerita textilis on intertidal area of Chabahar Bay (Oman Sea)

The aim of this research was to identify and isolate the fatty acids composition of Nerita textiles in intertidal area of Chabahar Bay, and also to explore the seasonal changes of fatty acid content in Nerita textiles. GC/MS resulted thirteen fatty acids, that saturated fatty acids (SFA) of palmitic acid (16:0) was the most abundant category of fatty acid obtained in total lipids. There were no significant differences in total saturated fatty acids between different seasons. No significant differences were also observed in total unsaturated fatty acids between different seasons. The majority of unsaturated fatty acid reached their maximum levels during winter, while saturated acids reached their maximum levels in summer. Saturated acids were more than unsaturated fatty acids. Statistical analysis showed the positive significant correlation between temperature and saturated fatty acids and a negative significant correlation between temperature and unsaturated fatty acids. Biomarker fatty acids revealed that diet of Nerita textiles probably includes phytoplankton, zooplankton, detritus, bacteria, diatoms, red and brown algae. The results showed that meat quality indicated n-6/n-3 ratio in the range of 1.9 to 4.3

Effects of different levels of Daphnia and Artemia extracts on food acceptability and growth factor rates of beluga (Huso huso Linnaeus, 1758)

In a 30 day feeding trial, Daphnia and Artemia extracts were added to diets of juvenile Beluga (Huso huso) at different levels to evaluate its effects on growth and survival rate of the fish. The trial was carried out in aquaculture research center of the Gorgan University, during which three different dietary levels of extracts (1:25, 1: 50 and 1:100) were used in 250 liter PVC tanks filled with about 125 liters of water. A total of 20 juvenile Beluga with an average weight of 5 plus or minus 0.2g each was stocked in tanks and were fed 4 meals a day. Growth and survival factors were analyzed at the end of the trial period. The results showed that the addition of extracts in diets led to improvement of body weight increase, weight increase percentage, specific growth rate (SGR), daily growth rate (DGR), daily growth index (DGI), condition factor (CF), price index (PI) and decrease of food conversion ratio (FCR) compared to the control treatment. The best improvement of growth index was achieved at the dietary level 1:50 Artemia extracts. There was no significant difference (P>0.05) in survival among treatments

Evaluation of metallothionein protein as a biomarker of Mercury pollution in Scat (Scatophagus argus)

Total Metallothionein (MT) biosynthesis and Mercury bioaccumulation under control & acute Mercury exposure were investigated in Scat (Scatophagus argus). Tissues from liver and gill of samples Scats were exposed to different Mercury concentrations (10, 20, 30μ g/l) for 24, 48, 72 hours. Mercury contents were determined through Cold Vapour Atomic Absorption Spectrometry (CVAAS). Total MT levels were determined by Enzyme-linked Immunosorbent Assay (ELISA) method. Induction of MT during exposure was tissue specific, displaying different response patterns in gill and liver. Mercury accumulated in liver much stronger than gill and the latter also showed lower MT level. Although after exposure to different mercury concentration during different periods, MT biosynthesis in liver showed a significant increase (P<0.05) but in gill did not significantly modify total MT except for 72h exposure at 30 g/l. Nonetheless, the relationship between MT biosynthesis and Mercury bioaccumulation in both tissues was significant. The results suggest that this form of MT presence in S. argus was Hg-inducible and could be extended as a biomarker of Mercury pollution in marine ecosystems and especially in Persian Gulf

The effects of prebiotic oligofructose on hematological, serum biochemical parameters and liver enzymes of juvenile beluga (Huso huso)

The aim of the present study was to investigate the effects of dietary oligofructose (1, 2 and 3%) on blood profiles of beluga Huso huso juveniles (18.77±0.76g). After 7 weeks feeding on experimental diets hematological parameters, metabolic products (cholesterol, glucose and total protein) and serum enzymes (lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase) were measured. Compared to the control group (0% oligfructose), oligofructose had no effects on red blood cell counts (RBC), mean corposcular volume (MCV), mean cellular hemoglobin concentration (MCH) or mean cell hemoglobin concentration (MCHC) (P>0.05). However, hematocrit (Hct), hemoglobin concentration (Hb) and leucocyte counts (WBC) were significantly higher in fish fed 2% oligofructose (P0.05). These results indicate an immunomodulatory effect and the potential to reduce serum cholesterol levels in beluga sturgeon

The probiotic effects of dietary inactive yeast Saccharomyces cerevisiae var. ellipsoideus on growth factors, survival, body composition and intestinal microbiota of Beluga juvenile (Huso huso)

The probiotic effects of inactive yeast, Saccharomyces cerevisiae var. ellipsoideus was studied on growth performance, survival and intestinal microbiota of beluga juveniles (Huso huso). The study was done in complete randomize design that included feeding of beluga juveniles with diets supplemented with 0 (control), 1, 2 and 5% yeast (4 treatments with 3 replicates). Beluga juveniles (11.40±0.56g) were randomly allocated in 12 oval tanks at a density of 35 fish per tank and triplicate group were fed with experimental diets. At the end of the trial, growth factors (final weight, weight gain, SGR, CF) as well as feed conversion ratio (FCR), body composition (protein, lipid, ash, moisture) and intestinal microbiota (total viable bacteria and Lactobacillus spp. levels) were determined. Our results confirmed that juveniles fed on diet supplemented with 5% S. cerevisiae var. ellipsoideus had significantly higher final weight, weight gain, specific growth rate (SGR) and lower food conversion ratio compared to control and 1% treatment (P0.05). The study of body composition showed no significant difference between treatments (P>0.05). Total viable bacteria and Lactobacillus spp. count were significantly higher in 5% treatment compared to control (P0.05)

Reproduction and feeding biology of madagascar meager (Argyrosomus hololepidotus) from Khuzestan coastal waters

Biological attributes of Madagascar Meager (Argyrosomus hololepidotus) was studied from October 2008 to September 2009 in coastal waters of Khuzestan province. Average maximum length was 128.4±7.50 in October and average minimum length was 104.86±12.47 in May. The maximum weight was 27500g, the minimum weight was 5700g and mean weight for males and females were 15.222±4.40 and 16.942±5.09, respectively. Reproductive studies showed that peak maturity season occurred in July. The length­ weight relationship were calculated as W=0.042L 2 70 for males and W=0.06L2 61for females. The male-female sex ratio was calculated as 1:1.07 and chi-square analysis showed no significant difference (P>0.05) between the two sexes. The average absolute and relative fecundity were estimated to be 4054045±37265 and 179.19±50.41, respectively Madagascar Meager is carnivore and we found the diet of the species consisted of fish (75%), crustaceans (20%) and mollusks (5%). Analysis of monthly variation in the condition factor (CF) indicated a fluctuation throughout the year, with a high level during May. Vacuity index indicated a higher feeding rate in males compared to females. We also found that the species continues feeding in the spawning season