International Journal of Aquatic Biology
Volume:1 Issue: 1, Feb 2013

Early body shape changes of beluga sturgeon (Huso huso) were studied using landmark-based geometric morphometric approach to recognize its allometric growth pattern. Sampling was done from hatching up to 50 days post hatching (DPH). Left side of specimens were photographed using digital camera and nine landmark points were digitized on two-dimensional images. Total length (TI) was measured using the software ImageJ. To study of the body shape changes during early development, the mean procrustes distance between all specimens of same age, for all age groups, was calculated. The scores of relative warp analysis (RW) were used as descriptors for the variation in shape. RW analysis revealed a sharp body shape change during early ontogeny on 18 DPH. Growth trajectory was computed by plotting RW against TL. The inflection point of body shape corresponds to a TL of 23.3 mm (18 DPH). Results showed that ontogenetic shape changes encompassed a pre-inflection shape changes, which included the elongation of the head and tail regions i.e. positive allometric growth pattern and post-inflection shape changes, with a nearly isometric growth pattern.

Common carp, Cyprinus carpio (L.) were blood-sampled after 0, 2, 6, 12, 24, 48 and 72 h fasting to find serum baseline levels. There was a significant difference in serum glucose, lactate, triglyceride and total protein but not cholesterol, albumin and calcium levels among the treatments. Glucose levels increased with fasting tine and reached to a peak after 6 h. Then, the glucose level decreased to the lowest level after 12 h. Changes of glucose and lactate had reverse trends, as lactate levels decreased with fasting time and reached to the dip point at 6 h and, thereafter, the levels increased to peak point at 12 h. Serum glucose and lactate levels showed stable values during 24-72 h of fasting, compared with the values measured at 0 h. Triglyceride levels showed an increasing trend parallel to that of the fasting period and reached to a peak point after 6 h. The levels reached 0 h values at 24 h and showed further decrement at 48 and 72h. Total protein showed elevation while fasting progressed and reached the peak point at 6 h and remained stable during 24-48 h fasting; However, it decreased after 72 h fasting. According to the results, cholesterol, calcium and albumin baseline levels were not affected by 0-72 h fasting. Glucose and lactate baseline could be determined after 24-72 h fasting. Total protein baseline could be determined after 24-48 h fasting. Triglyceride levels are significantly affected by fasting period which should be taken into account when it is measured. Possible mechanisms involving in common carp serum fluctuation over 0-72 h fasting period are discussed.

Goldfish (Carassius auratus) were subjected to either formalin (250 ppm) or NaCl (10 ppt), over a 0.5-h period followed by 24-h freshwater exposure. Serum biochemistry was monitored before exposure (0), immediately after (0.5) plus 3 and 24 h after exposure. Results showed that both formalin and NaCl treatments caused rapid increase in cortisol with a peak at 3 h, which did not recover until 24 h. Likewise, glucose showed similar patterns, however, returned to initial levels at 24 h after exposure. Formalin caused significant decrease in sodium and chloride levels which returned to initial levels at 24 h after exposure. Both formalin and NaCl caused calcium and total protein elevation at 3 and 24 h after exposure. Albumin and globulin levels were significantly affected by formalin and NaCl at 3 and 24 h after exposure. It is suggested that formalin and NaCl at the therapeutic concentrations cause rapid stress in goldfish which is eliminated after 24 h in freshwater. In addition, formalin causes slightly osmotic disturbance which is eliminated after 24 h recovery in freshwater. Both formalin and NaCl cause serum calcium and protein alteration after a while, which lasts until, at least, 24 h. More studies are needed to explain underlying mechanisms. Formalin and NaCl treatment, although advantageous in ecto-parasite removal, are stressful in goldfish, which should be considered if they are going to be used. Since formalin causes osmotic disturbance and more stress response, NaCl treatment is suggested as an alternative.

Common carp (Cyprinus carpio) population has been declined in the Caspian Sea in the recent years, mainly due to human manipulation. This valuable species needs to be protected in the Caspian Sea. Considering the commercial value of common carp, its rehabilitation program has been established. In the present study, 8 microsatellite loci were used to assess genetic variation and population structure of common carp in Gomishan bay (GB) and Gorganroud River (GR). These two regions are the most important habitat of common carp. Mean actual (Na) and expected (Ne) alleles numbers were 15.12 and 11.35 for GB and GR, respectively. Mean observed (Ho) and expected (He) heterozygocity were 0.99 and 0.90 for GB and GR, respectively. Results, also, showed that all investigated loci were polymorphic. Twelve out of 16 tested locus×region combinations showed significant deviation from Hardy-Weinberg equilibrium (HWE) which could be mainly due to increase in He. FST index was found to be 0.011. Hence, AMOVA showed that observed variation was related to within population (99%) as well as between populations (1%). According to the results, it is suggested that studied populations have a great allelic richness and gene flow.

In the present study, sulfuric acid was used for Artemia cysts decapsulation. Cysts of Artemia franciscana were hatched out in regular manner or following hypochlorite or acid decapsulation. Two acid concentrations (1 and 5%), three acid immersion times (10, 30 and 50 min) were used and hatching rates were recorded after 15, 18 and 24 h incubation. Hatching rates increased but hatching time decreased in line with acid concentration and acid immersion time increment. Hypochlorite-treated cysts had significantly higher hatching rate (97%) compared to other groups. However, among the acid- treated cysts, the best hatching rate (92.4%) was achieved in cysts treated with 1% acid over 50 min. Acid treatment could be used as a decapsulation method which saves cost and labor because of increasing the hatching rate and speed.

Concentration of heavy metals in aquatic ecosystems is considered as an important environmental issue. In this study, the Namrood River located in Firoozkooh (Tehran province, Iran) was assessed for the existence of heavy metals. The Namrood River is situated by the main road being by pollutants from tourism and recreational centers, gas stations, sewage of villages, agricultural wastewater and fish culture effluent. The water is extremely contaminated in some parts and possibly contains heavy metals. In the present study, two stations up- and downstream were determined to sample the sediments and Chironomidae and Gammarus pluex in both cold and warm seasons of the year (middle of March and middle of August). The copper and zinc were measured in sediment and benthos. The results showed that copper and zinc concentrations ranged 0.170-0.966 and 0.187-3.846 ppm, respectively. Sediments of the upstream station had the highest copper concentration among the samples in both cold and warm seasons of the year.

Effect of different photoperiodic regimes was evaluated on growth performance and survival rate of the Beluga (Huso huso) prelarvae and larvae. Newly hatched prelarvae were stored in 5 round fiberglass 500 L tank with different photoperiod (24L:00D, 18L:06D, 12L:12D, 06L:18 D, 00L:24D) till 50 days post hatch with three replicates. Light intensity was 200 lux during the experiment. Feeding was started from 8 days post hatch using live artemia nauplii. Higher total length, survival rates and lower body area, yolk area for beluga prelarvae obtained in long light photoperiods (24L:00D, 18L:06D). Also, higher growth parameters of the beluga larvae observed in long light photoperiods while different photoperiods had no effect on survival rate. The present study indicated that growth performance and survival rates of larvae are significantly influenced by photoperiod. The photoperiod 18L:06D resulted in the best growth performance and survival rate during early development of the beluga.