Aquatic Ecology
Year:2020 | Volume:10 | Issue:2|Papers Count:9

This study was carried out to determine growth and mortality parameters of mud crab R. harrisii during a period of 12 months from May 2017 to April 2018 in northeast parts of Gorgan Bay-southeast Caspian Sea. A total of 307 crabs were collected using small beach scene and snail traps, including 120 females and 187 males. The total length of the male crab ranged from 7. 01 to 18. 36 mm with a mean of 13. 07± 0. 16 mm, while that of females ranged between 5. 56 and 8. 92 mm with a mean of 11. 02± 0. 02 mm. The largest mean value of observed lengths, which is 20. 52± 0. 50 mm, was in November and the lowest was recorded in May with the value of 12. 84 ± 0. 81 mm. Based on von Bertalanffy growth model, L-infinity and K parameters were 23. 5cm and 1. 63 years-1 for females and 22 cm and 1. 1 year-1 for males. Using carapace width, the parameter of Lm50 was 12mm. The index ofɸ-Munro was 2. 97 and 2. 95 for males and females respectively. The results on growth and reproduction of the species provided in this were the first one and could be useful in conservation plans of the species and Miankaleh wildlife refugee area as well.

This study was conducted to investigate the morphologic and morphometric characteristics of sagittal otolith of Psettodes erumei in the north of the Persian Gulf and Oman Sea (Hormozgan Province). For this purpose, 119 specimens were collected from October 2016 to November 2017. After biometry of the specimens, sagittal otolith pairs were extracted and their morphometric parameters (length, width, perimeter, diameter, area, and weight) were measured and recorded. Then, the otolith size index (OSI), the otolith thickness index (OTI), and the otolith longitude index (OLI) were calculated. The calculated values of OSI (0. 05), OTI (0. 13), and OLI (2-2. 6) showed that sagittal otoliths of P. erumei are large, thin, and have a medium longitude. According to the results, the otolith location side had been identified as a factor affecting the otolith morphometric characteristics. Moreover, the results showed a directional asymmetry between otoliths. Regression models between fish total length and otolith morphometric parameters showed a strong correlation between fish length and otolith length, area, and weight (R2>0. 75). The results of this study provide fundamental information for stock identification of P. erumei, a commercially valuable flatfish species, in the north of the Persian Gulf and Oman Sea based on the otolith shape and chemistry analysis and through this provide key information for fishery management and sustainable exploitation of P. erumei in the area.

The aim of this study was to determine the lethal concentration of zinc oxide nanoparticles in freshwater angelfish. Accordingly, 126 specimens of angelfish were prepared with a mean standard length of 3 ± 0. 51 mm and an average weight of 3. 5 ± 0. 3 g and after adaptation to new conditions, a toxicity test was performed in a completely randomized design with three replications for 96 hours. In addition to the control group, 6 treatments were prepared with concentrations of 0, 40, 80, 120, 160, and 200 mg/l zinc oxide nanoparticles. After the end of the experiment, the data were analyzed by probit analysis with a 95% confidence level and lethal concentrations ranging from 5 to 95 percent values ​ ​ were calculated from the probit table. Then, the lethal concentration of 50 percent at 24, 48, 72 and 96 hours was 188. 04, 119. 93, 83. 75, and 74. 99 mg/L, respectively, by probit analysis. The results of this study show that zinc oxide nanoparticles are slightly toxic in terms of toxicity to freshwater angelfish.

Due to using of nanoplastics in a wide range of applications such as biosensors, photonics, nanocomposites and etc., and highly enhancement of plastic debris in aqueous environments have raised concerns about the potential effects of these substances on microalgae that are primary producers. The aim of this study was, to investigate the effects of different concentrations (0. 25, 2. 5, 25, and 250 mg/L) nanopolystyrene particles (PS-NH2+) after 96 hours on the growth, chlorophyll a content, and amount of antioxidant production of microalgae chlorella vulgaris. The growth rate (counting of cells) and chlorophyll a content and amount of antioxidant (measuring optical density/absorbance) were evaluated. The growth and chlorophyll a content showed a decreasing trend than the control group, with increasing concentration of nanoplastic and exposure time (12 days). Also, the results demonstrated that the amounts of antioxidant production in the exposed samples to nano-polystyrene were higher than the control samples. Finally, it`s suggested that this nanoparticle causes acute impacts on this microalgae in a long time and has the ability to affect cellular mechanisms.

Climate change and human intervention have led to an increased occurrence of harmful cyanobacterial blooms in mangrove ecosystems, which can be considered a threat to the life of plant and animal species in this ecosystem. The aim of this study was to evaluate the biodiversity pattern of cyanobacterial populations living in mangrove forests and to investigate the toxicity of cyanotoxins extracted from shrimp larvae. The results of bacterial isolation from 3 water and sediment sampling stations using culture-based methods led to the isolation of 150 isolates. The biodiversity pattern of cyanobacteria based on morphological identification confirmed the presence of 5 distinct dominant genera including Phormidium, Spirulina, Oscillatoria, Microcystis, and Anabaena. The extracted cyanotoxins from the biomass of strains 2A, 7A, and 14C showed toxicity with LC50 of 173. 2, 283. 1, and 209 μ g /ml against Artemia, respectively. The LC50 of these cyanotoxins against shrimp larvae was 310. 3, 293. 3, and 234. 1 μ g /ml, respectively. The presented results showed a high diversity of cyanobacteria and the presence of toxicogenic strains in the study area. Therefore, continuous monitoring programs in mangrove habitats, especially protected estuarine ecosystems, are recommended.

The experiment was conducted to evaluate the effect of different commercial prebiotic (Mannan Oligosaccharide) on the growth performance, survival, and resistance to salinity in Cyprinus carpio fry. 180 fish were supplied for experiments. 20 fish with an average weight of 13/2± 0. 5 gr were held in 300 l treatments for 60 days. A group of fishes (feed without MOS) was as control. Fishes were fed with 1 and 2% Mannan Oligosaccharide (MOS) as treatment. The results revealed, There were significant differences in the survival rate of fish in different groups (p<0. 05). The results showed, There were significant differences in the percent of Bodyweight increase, mean of daily growth, and specific growth rate in fishes in different groups (p<0. 05). The results revealed, There were no significant differences in protein efficiency ratio and resistance to salinity in different groups (p>0. 05). However, the results showed that the use of 2% prebiotics of Mannan Oligosaccharide (MOS) as supplementary of dietary had positive effects more.

Urban sewage contain high amounts of nutrients such as nitrogen and phosphorus compounds. Microalgae can be utilized in removal and treatment of excessive nutrients from the sewage. The present study investigated the effect of different concentrations of urban sewage entering Gursuzan embayment in Bandar Abbas on the growth and chemical components of microalgae Tetraselmis chuii during a 14 days rearing period. The growth of T. chuii in 6 treatments (with 3 replicates) had an increasing trend and the maximum growth (Optical density: 1. 4), was observed on day 14 in treatment 5 (consisting %60 F2 culture medium + %40 urban sewage). Moreover the maximum amounts of nitrate and phosphate (0. 013± 0. 0007 and 0. 003± 0. 00001 µ g/l), chlorophyll a and b (0. 19± 0. 002 and 0. 16± 0. 003 mg/g), protein (1. 3± 0. 04 mg/g) and fatty acids EPA and DHA (3. 36± 0. 09% and 3. 76± 0. 12%) were also observed in treatment 5. The results indicated that microalgae T. chuii is capable of efficiently removing organic compounds from urban sewage, and due to the more effective role of treatment 5 culture medium (%60 F2 culture medium + %40 urban sewage), in rapid propagation and production of more algal biomass rich in unsaturated fatty acids, it can be recommended to be utiulized as a proper alternative, for the secondary treatment and rehabilitation of urban sewage.

The present study aimed to determine the sensitive habitats and reproductive status of hawksbill turtles in Shidvar international wetland in Hormozgan province from March to June 2019. During the study 61 turtles were biometry. According to the beaches monitoring, the northern and eastern parts of Shidvar Island were identified as sensitive nesting habitats with a total of about 1, 700 meters were determined. Most nesting turtles were observed from 15 April to the end of May. The results showed that mean CCL and CCW were 72. 757± 4. 7 cm, and 66. 303± 2. 6 cm, respectively, and the mean total number of eggs were 86. 2± 19. 2, mean of normal and abnormal eggs were 72. 2 ± 19. 2 and 14. 2± 13. 2, mean of normal egg diameter and weight were 36. 92± 2. 2 mm and 31. 2± 3. 2gr, and mean of abnormal egg diameter and weight were 22. 2± 11. 2 mm and 8. 2± 7. 2gr. The mean of hatchling length, width, and weight were 37. 17 ± 0. 49, 29. 77± 2. 52 mm, and 13. 5± 0. 51gr. The incubation period and hatching percentages were 64. 3 days and 53. 2%. Comparing biological factors in the Shidvar area with other laying areas all over the world showed that the hawksbill turtle in the study area is smaller than others in the world. But the diameter and weight of eggs are no different from others in the world.

The technology of deploying and designing micro and nanostructures using silica is expensive and has technical and practical complexities, so the use of natural nanostructures can be cheaper and more environment-friendly. Presentation of this green capacity can be the starting point for further study developments by interested engineers and nanotechnologists. A group of these structures that are abundantly found in water and soil is diatoms. Diatoms are a group of algae with silicate frustules and have symmetrical and periodic structures, however, they have an acceptable abundance in coral shores such as the Persian Gulf in all seasons. Thus, they have a high potential to use in chemical and physical sensors or optical circuit components. In this article, we introduce some of the most commonly used diatoms in nano-Optics and review their optical characteristics of them. We also identified some species present in the local waters of Dez River, and we tested their light waveguiding