e. ramezanifard

Reproduction and spawning patterns of the Yellowtail scad (Atule mate) were studied in the Persian Gulf and Oman Sea (Hormozgan coastal waters) from December 2016 to November 2017. A total of 447 fish were collected from Bandar Lengeh, Qeshm Island, Bandar Abbas, and Bandar Jask landing sites. Minimum and maximum fork lengths of this species were 10 and 33 cm, with average 20.63±1.73 cm. The total weight ranged from 12.9 to 363.2 g, with average 113.08±31.69g. The relationship between length and weight was obtained as W=0.017L 2.89(R2=0.92) which showed that the fish has an isometric growth. Monthly analysis of the reproductive stages and gonadosomatic index showed that reproductive cycle beginning in January and continued with a sharp decreasing trend from March. The mean length at first maturity (Lm50%) for female was 19.8 cm. The sex ratio )F:M) was 1.5:1.

Investigating the relations and mechanisms of coexistence among sympatric species is essential to comprehend their ecological roles in the food webs. In the present study, the diet and trophic interactions of 5 abundant teleost species coexisting in the northern Oman Sea were examined using stomach contents analyses. The cumulative prey curves showed that the sample size of each studied species was large enough to clarify the general dietary preferences. The vacuity indices of Netuma thalassina, Plicofollis dussumieri and Otolithes ruber were less than 50%, indicating the comparatively gluttonous behavior of these species, while the estimated vacuity indices of Lutjanus johnii and Carangoides malabaricus were more than 50%. Assessment of %IRI (index of relative importance) revealed that diets of N. thalassina, O. ruber and C. malabaricus were similar and consisted mostly of teleost fishes followed by crustaceans. Conversely, P dussumieri and L. johnii mostly fed on crustaceans followed by teleost fishes. Results showed that P. dussumieri and L. johnii occupied an intermediate trophic level, whereas N. thalassina, O. ruber and C. malabaricus occupied high trophic levels, placing them as top predators in the food web. In total, analyses indicated that there were no significant differences in diets between these 5 teleost species.

Shark cartilage is considered as a natural dietary supplement consisting of anti-angiogenic, immunostimulatory, and anti-inflammatory characteristics. Therefore, this study was designed to inspect the possibility that whitecheek shark (Carcharhinus dussumieri) cartilage proteins motivate expression of NKG2D, CXCR3, NKP46, and NKP44 receptors on natural killer cells and their activities against SW742 cell line. To this end, cartilaginous areas of whitecheek shark were caught, minced, stored at −20°C and then lyophilized and kept in refrigerator. Peripheral blood samples were collected from healthy people and a number of 106 cells were considered for cell viability using trypan blue method. Activation of NK cells was determined using 106 cells stimulated following exposure to 0.2 and 3 mg mL-1 extracted shark cartilage proteins in 4, 8, and 18 h incubation. The results showed that cytotoxicity of NK cells increased significantly by elevating the concentration of extracted proteins at incubation period of 24 h (p˂0.05). The findings demonstrated that NK activity elevated markedly by increasing the concentration and volume of protein suspension and the exposure time (p˂0.05). Interestingly, the expression of NKG2D, CXCR3, NKP44, and NKP46 receptors was not significant in any transcription level by exposing to 0, 25, and 75 µg mL-1 in 4, 8, and 18 h incubation period (p˃0.05). Together, extracted shark cartilage protein could motivate the immune system capabilities through using NK cells against cancer tissues but specific receptors on T cells cannot be activated by these bioactive materials.

The present study was conducted to determine the appropriate weight to release the hatchery produced fingerling of stellate sturgeon, Acipenser stellatus, into its natural habitat. For this purpose, prolactin and cortisol hormones, plasma electrolytes and osmolality as well as histological changes in the gill and kidney of stellate sturgeon transferred from fresh to brackish water at different weight (0.5, 1, 2, and 3 g) were assessed during a one-week time course. A total of 2400 fingerlings with different weights (0.5, 1, 2, and 3 g) were equally assigned into 24 aquariums, each one containing 200 L of freshwater or brackish water. After 24 hours, prolactin showed the highest concentration in 0.5 and 3 g fish groups kept in both experimental waters. Cortisol exhibited a time-dependent increase in the 0.5 g group in both experimental waters as well as the 2 g larvae kept in the brackish water. Generally, lower levels of Mg2+, Ca+2; K+, Na+, and Cl- were measured in the fish kept in freshwater aquariums. The lowest levels of osmolarity were found in the 0.5 g fingerling, especially those kept in the freshwater aquariums, whereas the highest levels were observed in 3 g groups in both experimental waters. Histological assessments illustrated that the volume of chloride cells in freshwater increased with increasing fish weight, whereas the cell count decreased. The same held true for glomerular capillary network size. Taken together, the evidence from this study suggests that stellate sturgeon fingerling less than 2 g are almost incapable to be transferred to brackish and saline environment, due to lack of kidney and gill development.

In the present study, a trophic structure model for some fish species of the northern Oman Sea is developed through using mass balance modeling software, Ecopath with Ecosim (EwE). In this model, we simulated 16 functional groups spread across an area of 3998.20 km2 from 2017 to 2018. Mean trophic level in the area of the present study was 3.49. Values calculated for system omnivory and connectance indices were 0.42 and 0.44, respectively. However, the values of ecotrophic efficiency in the model were high (>0.5) for most consumers of high trophic levels except for sharks and rays because of their high fishing mortality. Accordingly, mixed trophic impact showed that phytoplankton and detritus positively impacted almost all ecological groups. Also bentho-pelagics, the medium demersals, benthos, and crustaceans had a very negative impact on themselves due to cannibalism. Furthermore, the highest realized trophic level was 4.34 for sharks. The maximum omnivory index is calculated as 0.99 for medium demersals for feeding on a wide variety of preys. Also, the average catch per net primary production, i.e., the gross efficiency of the system was around 0.000198 (lower than the global average) indicating that the fishery is harvesting fishes high in the food chain. The primary production/respiration (PP/R) ratio is found to be 3.57 and the values of ascendancy (45.40%) and overhead (54.60%) showed stability of the ecosystem. Thus northern Oman Sea can be classified as an immature ecosystem (in the developmental stage), although it has some kind of system maturity. Accordingly, the food web of northern Oman Sea is consisted mostly of detritivorous, planktivorous, and carnivorous fish species. Besides, Ecopath with Ecosim (EwE) software can be an excellent option to examine interactions among ecological groups, and the impact of fishing in northern Oman Sea which is unquestionably helpful to develop concrete management strategies. The proper ecosystem-based fisheries management practice can improve the efficiency of this overexploited ecosystem.

The application and development of nanotechnology is increasingly expanded in many areas. However, considering this expansion, several concerns regarding their potential toxicity in marine biology have been addressed. Indeed, the overuse of these materials can adversely influence marine ecosystems and living organisms. Herein, the potential impact of copper-based nanoparticles on the expression level of three genes, i.e. prophenoloxidase, serine protein and glutathione peroxidase genes functioning in shrimp immune response, were assessed. For this end, the shrimps were exposed to three semi-acute toxicity treatments, including 0.25, 0.5 and 1 mg/L of CuNPs. The qRT-PCR results indicated negative effect of supplied nanoparticle on the expression level of these genes. Additionally, histopathological alterations in the hepatopancreas and lymphoid organs were observed in the shrimps after exposure in different concentrations of CuNPs. Overall, we showed that toxic concentration of CuNPs can damage shrimp immune system as well as some internal organs. These results open up novel insights into innate immunity of shrimps subjected to copper-based nanoparticles.

The growth of the gastrointestinal tract of the larvae and juvenile of Alburnus chalcoides was studied after histological analysis using light microscopy, haematoxylin-eosin staining and the mouth development was scanned via electron microscopy. This study focuses on the morphology and histology of the mouth growth and digestive tract of A. chalcoides larvae to test the best weaning time for providing practical diet for fry based on the grade of their morphological aspects. It was observed that on the fifth day after hatching, the larvae mouth was opened. On the eighth day, the yolk sac was absorbed by two-thirds. On the same day, food is fed manually. Yolk sac was completely absorbed in 10th day. The histological base of the esophagus was formed by day 3. At day 3, the formation of enterocytes started. Also, the larvae hepatopancreas was formed on 5th day. According to the results, it was observed that after 8 days onwards, larvae of these fish can have a proper diet. At this day, the size of the mouth was 84 µm. when the lips were formed within 20 days and for the mouth angles 45ºand 90º, the food size for mouth, was 168 and 307 μm, respectively.