Assessing the optimum temperature for survival, growth and reproduction of adult Caspian Sea Pontogammarus maeoticus

This study was conducted to assess the effect of different levels of temperature on survival, growth and reproduction of adult Caspian Sea Pontogammarus rnaeoticus. Temperature effects were studied in 5 thermal levels (15, 20, 25, 30 and 35°C) where salinity was constant (7.1±0.2ppt). The sampling was made from Hassan-nrud coastal area in Guilan province. The results showed that survival was maximum at 20CC (95.56%) with higher temperatures showing a significant descending trend in survival (P<0.05) in which all samples perished on I 8th day at 35°C treatment. The number of produced brood followed a significant ascending , trend from 15°C to 25°C treatments and reached its climax at 25°C (117.3+12.2 broods). The minimum value for produced brood was reported at 15°C treatment (21.3±2.4 broods). A significant persistent increment of growth rate was observed throughout all treatments (P<0.05) where the maximum and minimum values were observed for the final (5.76±0.1mm) and the first (1.77±0.06mm) treatments, respectively. We suggest 25°C, 20°C and 30°C temperature treatments for producing the maximum brood per unit of time, the highest survival rate and the maximum growth, respectively. The temperature 25°C is defined as the best for aquaculture of pontogammarus as livefood of aquatic organisms

Structure and arrangement of photoreceptors in the retina of big eye kilka, Clupeonella grimmi (Kessler 1877)

The big eye kilka, Clupeonella grimmi, is a marine fish living in depth of 20 to 200 meter of the Caspian Sea. Its eye and retina were processed for histological and SEM studies. Paraffin embedded retina was cut radially and tangentially in 5 µm thickness and stained with hematoxylin and eosin method. The unstained sections were manipulated for SEM image observations. Tangential retinal sections showed irregular arrangement of cones. Five morphologically different types of photoreceptors were distinguished as rods, short single cones, long single cones, twin cones and double cones. The cones were counted in each quadrant of the retina and cone density was determined. The cones showed increment in diameter but reduction in number at anti-clockwise direction without any specific arrangement. Presence of four types of cone cells and their pattern of distribution revealed assistance in near surface color vision and more light capture in dim light of deeper waters as an adaptation to planktivorous feeding habit and deep water living habitat

Histomorphological investigation of Liza aurata (Risso, 1810) (Mugilidae) ovary in the late oogenesis in the Caspian Sea

In the present study, various developmental stages of Liza aurata oocyte, especially IV and V stages have been described. On the basis of histological investigations, oocyte development in L. aurata comprises immature (I), the early maturing (II), the late maturing (III), mature (IV), ripe (V), and spent (VI) stages. In the stages I and II, nucleus occupied a large volume of oocyte. Vacuolization and vitellogenesis appearance started at stage III. Vitellogenesis increased by further growth of oocyte at stage IV and also vacuolization occurred. Zona radiata and follicular cells were more conspicuous at this stage. In the late stage IV, the number of vacuoles decreased due to the fusing of small vacuoles and nucleoli located on different places of the nucleus at this stage. At stage V, oocyte normally possessed one or two oil droplets; nucleus disappeared after migration to animal pole. Recently spawned oocytes were fluid, lemon in color and 779.2µm in diameter. The maximum gonadosomatic index (GSI) value was found at stage V

Effect of dietary digestible energy level on growth indices of kutum (Rutilus frisii kutum Kamenskii, 1901)

A 60-days feeding trial was conducted to evaluate the effects of dietary digestible energy levels (DE) on kutum, Rutilus frisii kutum. Four isonitrogenous (35% protein) diets with digestible energy levels of 2500, 2600, 2700 and 2800kcal kg-1 were tested. Two hundred and forty advanced fry (2±0.4g) were randomly distributed in 12 fiberglass tanks of 400L capacity. Nutritional responses in terms of WG, FCR and PER as well as survival rate (SR) significantly improved (P<0.05) with increase in DE level from 2500 to 2800 kcal kg-1 diet, but no difference between 2600 and 2700kcal kg-1 diet was found. Body crude protein and fat significant were increased (p<0.05) when the dietary energy was raised up from 2500 to 2600kcal DE kg-1 diet, but a further increase on energy did not improve the fish crude protein and fat content

Histopathological changes of gill, liver and kidney in Caspian kutum exposed to Linear Alkylbenzene Sulfonate

The histopathological effects of Linear Alkylbenzene Sulfonate on the gill, liver and kidney tissues of the Caspian kutum, Rutilus frisii kutum were studied. The fish were exposed to three sublethal concentrations of anionic detergent, Linear Alkylbenzene Sulfonate (LAS) for short term intervals (192 h). Gill, liver and kidney samples were collected after 192 h of exposure to LAS and lesions were analyzed by light microscopy. The histological changes to gills were edema, fusion of lamellae and lamellar aneurism. Some alterations like reduction of the interstitial haematopoietic tissue, tubular shrinkage, degeneration in the epithelial cells of renal tubule and necrosis were observed in the kidney. In the liver tissue, hepatocyte degeneration, congestion and dilation of sinusoid and vacuolar degeneration were seen. It seems that sublethal concentration of LAS may affect severe changes to gill, kidney and liver of R. frisii kutum specimens that leads to malfunction of these organs which cause damage to health of the fish

The study of reproductive behavior and growth of Caspian Sea Amphipod: (Pontogammarus maeoticus)

Amphipods collected from the southern coasts of Caspian Sea (Jefrood beach) were transferred to laboratory along with sediment from the same area. Samples were maintained in controlled laboratory condition at temperature of 2510oC, salinity of 9± 0.5 ppt and a 12 hrs. light - dark regime. The average period spent in precopula stage was about 2.6±0.91 days and embryonic development took about 8.5 ±1.05 days. The fecundity was estimated as the number of fertilized eggs existing in brood pouch of each female (14.125). First precopula was observed after about 40 days of birth. To study the effect of feed composition on growth, Gammarus of similar size were fed by composite food of (fish-potato), (fish-bread) , (fish-leaf), (leaf-potato), (leaf-bread) and (breadpotato). At the end of 6th week the head of all specimens were measured. The result of statistical analysis showed significant difference between the treatments (p0.05). The combination of potato-bread was found to be the most suitable food for Gammarus

First record of Limnodrilus claparedeianus ratzel, 1868 (Annelida: Oligochaeta: tubificidae) from Anzali wetland, Guilan Province, Iran

Oligochaeta worms are important organisms in aquatic ecosystem. Their omnipresence makes them as an indicator of environmental changes and health of aquatic ecosystem. The members of the family Tubificidae and in particular, genus Limnodrilus are considered as the most tolerant oligochaets to aquatic pollution. Therefore identification and biological characteristics of this taxon are of great help to evaluate the ecosystem of water bodies. Limnodrilus claparedeianus were collected from Anzali Wetland with a grab of 0.04 m2 capacity at 13 stations from August 2012 through June 2013. Penis sheath was one of the main characteristics to identify them. Results showed their maximum and the minimum density in spring (601.27 ± 466.8346 Ind.m-2) and in autumn (156.12 ± 136.3 Ind.m-2) respectively which was significantly different (P<0.05). Comparative spatial distribution of L. claparedeianus among 13 stations revealed significant differences in the west stations (P<0.05). According to the results, correlation analysis did not exhibit any relation between abundance of L. claparedeianus and total organic matter, abundance of the species and percentage of silt in substrate sediment

Optomotor response in zebrafish (Danio rerio) to black –white, gray-green and gray-red stimuli

The optomotor response is one of the methods used for measuring zebrafish behavior towards moving objects. The present research has been carried out on zebrafish reaction to moving objects. In the experiment, newly fish matured of both sexes were used. To study the optical power of zebrafish an appropriate apparatus was designed. Experiments were performed with different widths of stripes in black , white (1, 2 , 7 cm), with width stripes of 1 cm in red - gray , green - gray at different velocities of 2, 3, 4, 7, 10 , 15 rpm. Results of 2-way ANOVA showed significant differences between the various widths, velocities (P0.05). Nevertheless, the fish demonstrated the most optomotor response to green-gray color (0.10±0.13), a velocity of 10 rpm (0.41±0.13)

Morphometric variation among four populations of Shemaya (Alburnus chalcoides) in the south of Caspian Sea using truss network

To analyze the morphometric differentiation among four groups of Shemaya, Alburnus chalcoides (Guldenstadf, 1772), sited in four habitats i.e.: Lisar, Shiroud, Babolroud rivers and Anzali region (southern part of the Caspian Sea), truss network analysis was employed to take multivariate analysis. Truss characters between fourteen selected landmarks on 357 specimens were measured, then allometric method was used to obtain size-adjustment shape data. Multi and univariate analysis of variance revealed significant differences between means of four populations and sexes (P < 0.01). In principal component analysis of the shape variations among the populations, the first two components accounted for 50% and 56.6%, of males and females, respectively. The loadings of the first and the second principal components and discriminant functions showed that the differences were located mainly on abdominal, caudal regions and length of fins, indicating to be important in description of the population characteristics. Results indicated that samples of Anzali region were clearly distinct and diverged from other three populations probably because of difference in the habitat condition. Generally female samples showed more morphometric differences than male samples did, but their influence on this issue remained unknown