فصلنامه بوم شناسی آبزیان
سال پنجم شماره 4 (پیاپی 504، بهار 1395)

In the present study, we investigated the effects of a sub-acute concentration of cypermethrin on some hematological parameters of Capoeta damascina. The specimens had an average weight of 150 ± 10 g and average length of 21 ± 1 cm (mean ± SD). The fish were exposed to 0, 0.25, 0.5, and 0.75 µg/L (each with 3 replicates) for 10 days. Blood samples were collected on days 1, 5 and 9. Hemoglobin (Hb) and hematocrit (Hct), red blood cell count (RBC), white blood cell count (WBC), mean cell volume of red blood cells (MCV), and mean corpuscular hemoglobin concentration (MCHC) were measured. There was a significant decrease in RBC, Hct, MCV and Hb of the specimens exposed to cypermethrin compared with those of the control group. Therefore, this study has indicated that environmental pollutants cause negative effects on hematological parameters of Capoeta damascina and impairment of these parameters may initiate other biological complications.

In this study, we divided 300 goldfish (average weight: 12.30 ± 2.11 g) into 4 groups. Fish were fed diets that contained 4 levels of thyme extract: 0 (control), 200, 400 and 800 mg/kg (Thyame, LN23IN, France) for a period of 2 weeks. At the end of 2 weeks, each group of the mentioned treatments was divided into 2 groups: nanosilver-exposed group and control. In the aquarium of the nanosilver-exposed group, we prepared 0.04 mg/L of nanosilver until the end of the experiment. At the end of the experiment, body weight (BW), condition factor (CF), specific growth rate (SGR), feed conversion ratio (FCR), survival rate and serum biochemical parameters of glucose (mg/dl), triglycerides (mg/dl) and uric acid (mg/dl) were measured. The results showed that the nanosilver-exposed group that consumed the diet with 800 mg/kg of thyme extract had the highest percentage of weight gain (21.46 ± 0.15) and specific growth rate (0.46 ± 0.01). All nanosilver-exposed groups had lower survival rate than non-exposed groups. The condition factor (CF) in treatments that contained thyme extract in the diet was significantly higher compared with the control group (P

The aim of this study was to assess the effect of different light intensities and photoperiods on growth, survival, and the yolk sac absorb of the Persian sturgeon, Acipenser persicus, larvae. Larvae were reared from hatching to yolk sac absorb (eight days) at four light intensities (0, 50, 150 and 300 lux) and three photoperiods (00L:24D, 12L:12D and 24L:00D) which consisted of seven treatments and a control group. Growth factors, including the length, weight, weight gain, specific growth rate condition factor, the percentage of body weight gain and survival rate were calculated in the larvae. The larvae showed significant growth and better yolk sac absorption at the high light intensity (300 lx) and 24L:00D photoperiod compared to the low light intensity (0 lux), continuous darkness photoperiod, and the control group. There were significantly higher survival rates for larval Persian sturgeon in the 50 lx and 12 h photoperiod and 0 lux and 24 h photoperiod (73.1±0.04 & 72.41±0.12% respectively) were compared to larvae reared in the 300 lux light intensity and 24 h photoperiod (47.06%) treatment until 8dph. There was no significant difference observed in the condition factor among different treatments. This study revealed that photoperiod and light intensity were important factors on growth - parameters, survival rate and yolk-sac absorption of the Persian sturgeon in the larval stage.

Nitrate and phosphate are abundant in urban wastewater. We evaluated the efficiency of nitrate and phosphate removal from wastewater by Scenedesmus obliquus and its use as a medium for Scenedesmus obliquus. Samples were collected from the effluent of central wastewater treatment in Gorgan. This experiment was done by 3 treatments and 6 replications that effluent with 100%, 50% and 0% were diluted. The results showed that Scenedesmus obliquus could be grown in wastewater and 100% phosphate (group S100) and 100% nitrate (all of group) was removed. The highest biomass production (0.6 g/L), chlorophyll a (4.87 mg/L), the number of cells (106 cells/ml) was observed in the S0 group. Statistical analysis of the data with analysis of variance (one-way ANOVA) and the Duncan test at a 5% level of significance (SAS software version 9.2) indicated that the algae could be used to remove phosphates, nitrate and algal biomass in municipal wastewater filtration systems before they enter the environment. The municipal wastewater can be used as culture medium for mass production of algae.

This study investigated seasonal changes in density and diversity of phytoplankton, chlorophyll a content, and some environmental characteristics in the Sistan region during 2014. Totally, we detected 28 genera that belonged to five groups of Chlorophyta (12 genera), Bacilloriophyta (7 genera), Cyanophyta (5 genera), Dinophyta (3 genera), and Euglenophyta (1 genus). We observed that Chlorophyta contributed to the maximum density and diversity followed by Bacilloriophyta, Cyanophyta and Dinophyta. The mean Shannon index varied from 1.7 to 2.3 during the study period. Maximum (3.6×104 cells 1p1) and minimum (1.1×104 cells 1p3) densities were recorded. The present study revealed that Phytoplankton groups have different relationships to environmental factors of pH, temperature and nutrients that have a greater role in the changes of phytoplankton in the reservoirs. In this study the annual average chlorophyll a was 2.36 µg/l, which reservoirs of Chahnime grouped into oligotrophic regions. These types of studies are prerequisites for evolving fish culture programs and management of water resources.

In recent years, monitoring the amount of pollutants in aquatic ecosystems by quantity measures in water, sediment and fish tissue has shifted to the quality measures of pollutant effects on aquatic animals and assessment of aquatic animal health and, ultimately, the ecosystem. This research performed on three replicates has examined the histopathological response of hepatopancreas and gill in Metopograpsus messor crab exposed to cadmium pollutants. We prepared an aquarium that contained a 5 μg/L concentration of cadmium as well as a control group. After the start of the experiment, we sampled the crabs in 2 steps short-time (72 h) and long-time (14 days). After the routine histological procedures, we performed H & E staining. Oserved complications in the gills included: disruption of the pillar cells and collapsed lamellae, hyperplasia, necrosis, detached cuticle, club-shaped distal tips of gill lamellae, vacuolisation, malformation at the tip of the gills, slight lamellae distortion. In the hepatopancreas we observed formation of abnormal lumen, necrosis, thickened basal laminae, increased numbers of B-cells, presence of reserve inclusion, and dilation of the hemal sinuses. A comparison of the two groups showed a direct correlation between the duration and severity of damage.

We conducted this study during the Summer, 2013 to evaluate morphological features of the species of the genus Paracobitis in Sistan basin. For this purpose, 60 specimens randomly were caught by a gill-net from different parts of Lake Chah Nime (Zabol, Sistan and Baluchistan), fixed in formalin solution and transferred to a laboratory for further examination. We measured 37 absolute morphological characteristics by a digital caliper and 6 meristic analyses using a stereomicroscope. We calculated 34 relative morphological characteristics with a division of absolute morphological characteristics by standard length and head length. In order to compare the morphological samples, the obtained morphological characteristics (absolute and relative) and meristic analyses were analyzed by principal component analysis and canonical variables. According to the results, we confirmed the existence of two species, P. vignai and P. rhadinaea, in the studied areas and appropriate geomorphic features were provided for their separation - barbel length, presence or absence of scales, mouth width and number of pectoral fin rays as morphological characteristics to distinguish the two species. In addition to the two species, different morphological forms were present in the sample. We proposed the use of molecular markers for better, more accurate results.

In the present study, we evaluated the pathogenicity of Yersinia ruckeri on Persian sturgeon (Acipenser persicus) fingerlings. We divided the sturgeon into one treatment group, one positive control group and one negative control group (with three replicates for each group). The treatment group juvenile Persian sturgeon received 0.1 ml of bacterial suspension (2.8 × 106 cells/fish) via an intraperitoneal injection. Positive control fish received 0.1 ml intraperitoneal injection of sterile normal saline. The negative control group received no injection. According to the results, first mortality was observed 48 h post-challenge in the treatment group. Mortality rates in the treatment group post-challenge were 6.7% (48 h), 26.6% (72 h), 60% (96 h), and 70% (7 days). Haemorrhage in terminal part of intestine and accumulation of bloody fluid in the intestinal lumen were observed in the majority of sick fish. Intestinal histopathology was characterized by spread necrosis in the epithelium of the villi and lymphocytic infiltration to the connective tissues. In the haematological study, we observed significant differences in RBC, WBC, MCH, MCHC, hemoglobin, and hematocrit counts between fish from the treatment and control groups.

Salinity adaptation and sea water tolerance are vital, challenging phenomena in the life history of anadromous species such as kuttum fish. Evaluation on feed deprivation in gill chloride cell development of kuttum fish is the aim of this study. Kuttum juveniles that weighed an average weight of 0.5 grams were divided into two groups. One group (control) was fed ad libitum during the experiment. Fish in the other group were feed deprived. Both groups were exposed to the salinity challenge for 7 days. Gill sampling was performed on the second, third, fourth, and seventh days after salinity challenge initiation. Consequently, we evaluated Na K ATPase activity, gill chloride cell numbers and size. Results showed a significant decrease in gill Na K ATPase activity, chloride cell diameter, perimeter and area due tofasting. Based on the obtained results we concluded that feed deprivation might have a disruptive effect on chloride cell development during seawater adaptation.

We conducted this study to determine the chronic effects of Azadirachtin on growth parameters, survival and gill morphology of grass carp [Ctenopharyngodon idella (C. idella)] with an average weight of 11.09±2.3g. We equally distributed 120 fish between three treatments and a control group, with three replicates each. Sublethal concentrations of poison, 0.073 (10% LC50), 0.15 (20% LC50), 0.22 ppm (30% LC50) were selected. Fish were exposed to these doses for 28 days. Increasing doses of Azadirachtin did not affect growth parameters and survival (P>0.05). During the test, we observed fish behavior patterns of irregular swimming, rotation, reaction increased response versus stimulus exterior, solitary and imbalance, histology, epithelial uplifting (swelling), hyperplasia, fusion of gill lamellae and necrosis of gill epithelial cells. The results showed that although the sublethal dose of Azadirachtin over a short time did not affect growth and survival of C. idella but brought about abnormal behavior in fish. There was increased gill tissue destruction with increased poison levels which showed that it could be effective on long duration of exposure.

The potential entry of nanomaterials into the water ecosystems increased following their increasing use. In addition to the direct effects of nanomaterials on aquatic organisms, they also affect the toxicity of other pollutants on aquatic organisms. This study assessed the presence of titanium dioxide nanoparticles (nTiO2) in water on acute toxicity of silver nanoparticles (AgNPs) on zebra fish (Danio rerio). After preliminary tests, we simultaneously exposed the fish for 96 h to different concentrations of each of these nanoparticles so that, in each of the treatments, the concentrations of nTiO2 were ten times the concentration of AgNPs. The results showed that the presence of nTiO2 in water decreased the acute toxicity of AgNPs to more than three times in the zebra fish. The median lethal concentrations of AgNPs increased from 0.014 (in the absence of nTiO2) to 0.044 (in the presence of nTiO2). The reduction in toxicity of AgNps in the presence of TiO2 nanoparticles in this study possibly happened due to decreased bioavailability of AgNPs by binding to the nTiO2 and its deposition in water media.

Despite the variety of marine organisms recorded from the Persian Gulf, acidians located along the Persian Gulf have not received much attention. We collected Ascidian samples from four sites along Larak Island (Persian Gulf) using Scuba diving and snorkeling at a depth that ranged from 5-15 m. Taxonomic identification was carried out by authoritative keys and texts. We found 4 species that belonged to 4 genus, which included 2 solitary ascidians (Phallusia nigra and Pyura gangelion) and 2 colonial (Didemnum sp. and Distaplia sp.).

We used 50 specimens of Alosa braschnikowi (A. brschnikowi) to study the growth effect on Gill raker morphology. Gill rakers counted as 26-47 which increased in relation to increase in TL (P

Artemia, as live food, is of vital importance in aquaculture. In this study, we have studied the helium-neon (He-Ne) laser beam with 10 mw on the hatching and life span of Artemia cysts. He-Ne laser irradiation was performed with a 10 mw power at 3, 4 and 5 h irradiation periods. Cysts were hatched by standard method. Hatching percentage after 4 h of irradiation was more than other treatments after 18 and 24 h of hatching. We compared the lifespan of this treatment which showed that this treatment was more than the control in females (12 days) and males (10 days; P

We conducted this study to investigate the effect of culture depth of red algae Gracilaropsis persica on the growth and biomass production of this species. Three culture depth of 5, 6, and 7 m were used to cultivate algae in the Persian Gulf (Bandar Abbas) for 45 days. Algae was collected from its natural environment and cultivated on polyethylene rope in the sea. We measured relative growth rate (RGR) and total biomass every two weeks. Temperature, salinity, pH, and nutrients (nitrate, nitrite and phosphate) were measured during the trial. The results showed significant differences in growth rate between different treatments (P