جستجوی مقالات مرتبط با کلیدواژه "environmental parameters" در نشریات گروه "شیلات"

The presence- absent and frequency of any species in a riverian habitat is hnfluenced by numerous factors, and the particular domains prefer the changes of each habitat factor. The purpose of this study was to investigate the habitat suitability index of Alburnoides eichwaldii in the Lavij River in Mazandaran province. A sampling of fish was carried out at 22 stations in Junuary 2017 by electrofishing, frome the top of the river to the Chamestan city (Kashpel forest park) in downstream of the river. At each station, 11 environmental factors were measured. The results showed that, station 21 is the most suitable station for A. eichwaldii and at this station, parameters such as altitude (until 150 m), width (6-9 m), depth (19-25 cm), substrate (3-7 cm) and water flow velocity (0.6-1 m/s) played the highest role in the high habitat suitability index. According to the obtained chart of the CANOCO software, temperature and ammonium the importance and impact of these variables on the frequency of species, especially A. eichwaldii in the Lavij River. The results showed that areas like station 21, which have been less destroyed in terms of human activities, had the highest level of suitability.

In order to evaluate the quality of effluent pollutants from the rainbow trout breeding farms in the selected farms of Kohgiluyeh and Boyer Ahmad Province, water samples were taken from five individual farms during the years 2021-2022. The physical and chemical indicators of water including acidity, biological oxygen demand, dissolved oxygen, electrical conductivity, nitrite, nitrate, phosphate, total suspended solids, total dissolved solids, total hardness, alkalinity, iron, oxygen saturation were measured once in each season from the inlet and outlet water (each treatment with 3 replicates). Based on the results, the range of pH changes (5.93-7.29), biological oxygen demand (6.41-7.56 mg/l), ammonium (0-0.319 mg/l), nitrite (0-0.181 mg/l), nitrate (2.19-19.2 mg/l), phosphate (0. 1-0.18 mg/l), total alkalinity (132-238), dissolved oxygen (3.35-8.11 mg/l), electrical conductivity (311-899 microsiemens/cm), TDS (203.7-607.9), and total hardness (312-157.77 mg/l) were obtained. The results showed that the concentrations of ammonium, nitrite, nitrate, phosphate, EC, and total dissolved solids parameters in the effluent compared to the input from the different farms has increased due to the increase of metabolism, fish density, concentration of nutrients, drugs and disinfectants, intensity and speed of water and the oxygen concentration in the effluent of the farms has decreased due to more metabolic activities than the input from the rearing ponds. Also, the amount of biochemical oxygen demand (BOD) and environmental chemical oxygen demand (COD) were increased and the dissolved oxygen was consumed and its amount decreased due to the increase of organic substances, nitrate, and the provision of oxidation conditions.

The threats to the rivers caused by human activities and stress factors that have endangered the biodiversity of the inhabitants in these ecosystems, especially fish. Therefore, it is necessary to understand the habitat needs and assess the suitability of the habitat for organisms living in rivers to protect biodiversity. This study aimed to investigate the Habitat Suitability Index (HIS) of Barbus karunensis in Bashar River using the kernel smoothing method in summer and autumn seasons 2021. In this study, 16 stations were selected and sampled with 3 repetitions. At the same time, environmental factors, including temperature, geographical slope, water velocity, river width, water depth, elevation, pH, electrical conductivity (EC), and total dissolved solids (TDS) were recorded and measured. Based on the results, the habitat preference of this species in the summer season was river sections with high elevation, high temperature, low average water velocity, high slope and width of the river, middle depth with high pH, average TDS values, and higher EC. In the autumn, the most preferred habitat of fish was high elevation, low temperature, low water velocity, high slope, medium width, low depth TDS, and pH. It can be concluded that the habitat of B. karunensis was different in the summer and autumn seasons and this species prefers different ranges of environmental parameters in the summer and autumn seasons.

The aim of the study was to determine the quality of the inlet and outlet water of five selected rainbow trout breeding farms in Mazandaran Province (Haraz, Chalous, Tonekabon, and Sari) based on environmental parameters during four seasons in 2021-2022. Forty samples were collected and measured based on standard methods. According to the results, the range of water temperature (3.0-24.0°C), air temperature (2.0-25.0°C), DO (6.16-12.24 mg/l), BOD5 (0.24-2.76 mg/l), COD (2.40-93.70 mg/l), EC (284-783 µs/cm), turbidity (1.12-220-0 NTU), TSS (2-288 mg/l), pH (7.44-8.62), total phosphorus (0.2-2.12 mg/l), phosphate (0.01-0.206 mg/l), ammonium (0.012-0.538 mg/l), ammonia (0.001-0.018 mg/l), nitrite (0.001-0.426 mg/l), nitrate (0.52-6.10 mg/l), fecal coliform count (6-1000 CFU/100ml) and water quality index (WQIIR) (62.0-91.0) were registered. The water quality of this river was placed in class III (low pollution) based on the average parameters of organic pollution (BOD5 and COD) and human activities were not one of the main factors in the increase of organic matter in the river. The concentration of ammonium and nitrite was within the threshold limit, but the concentration of phosphate in all the inlet and outlet stations and in different seasons was more than the maximum limit of unpolluted rivers. The results showed that the WQIIR was in the range of 62-91. 7.5% of the total data and the mean of this index indicated the relatively good quality of the inlet and outlet water of the rainbow trout breeding farms. The highest quality of water, i.e. very good quality, is recorded in 12.5% of all data, which is observed at the inlet water of rainbow trout breeding farms. The outlet quality index of the farms was lower than its inlet, but it was categorized as good quality. The overall WQIIR (77.4±6.6) in all inlet and outlet stations indicates that the water of this farm is suitable for fish and wildlife and also suitable for rainbow trout breeding.

The Maximum Entropy Model (MaxEnt) is a high-performance machine learning algorithm that is used to investigate the presence of species and to forecast the possible distribution of a target species according to its maximum entropy under different conditions and to determine the habitat suitability of species. In the present study, habitat suitability modeling for Nemipterus japonicus in the Makoran region (northern shores of the Makran Sea) was performed using the Maximum Entropy Model (MaxEnt). For this purpose, the data obtained from the fishing of Nemipterus japonicus during the period of 2015 to 2019 recorded by the Chabahar Offshore Fisheries Research Center in five areas were used to find points of presence. Based on the results obtained from the model, the variables of sea surface temperature at night and day and chlorophyll a concentration were recognized as the most important parameters in identifying the suitable areas, including the Gowatr bay area. Also, the area under the curve index (AUC) was equal to 0.998, which indicates the high accuracy and efficiency of the model in identifying the most suitable areas of Nemipterus japonicus distribution. The obtained results can be used as an effective tool for effective evaluation of conservation strategies for sustainable yield of Nemipterus japonicus fish stocks.

This study was conducted to determine the temporal and spatial distribution of Opusia indica in the Hara Biosphere Reserve in the Persian Gulf. Seasonal sampling (four seasons) was performed from winter 2019 to autumn 2019. Sampling was done in five regions and three habitats within each region using metal quadrats with dimensions of 25 × 25 cm. In each habitat, environmental parameters including temperature, salinity, dissolved oxygen, pH along with organic matter and grain size were measured. The results showed that the abundance and biomass of Opusia indica have decreasing trend with increasing habitat complexity. Seasonally, the highest abundance and biomass were observed in winter and autumn, respectively, and the lowest abundance and biomass were observed in spring. There was a significant difference between habitats and seasons (p <0.05). Salinity showed a significant difference between habitats but didnchr('39')t have seasonal changes. While temperature didnchr('39')t show a significant difference between habitats, but it had seasonal changes. There was a significant difference between dissolved oxygen levels and pH between habitats and seasons. Significant changes were observed between habitat and seasons in sediment grain size, while the amount of organic matter showed only differences between habitats. Also, analysis of Kendall correlation between environmental factors (temperature, salinity, dissolved oxygen and pH) with abundance and biomass showed that there was a significant correlation between these environmental factors but no significant correlation was observed between abundance and biomass with the amount of organic matter. The results help to better understand the situation of this species in the mangroves ecosystem.

Presence-absence and abundance of each fish species in a river habitat depends on several factors and they prefer a specific range of each habitat factor. The present study was carried out to investigate habitat suitability index of Capoeta capoeta and the effect of habitat factors on its distribution and abundance in Roodbabol branch of the River Babolrood (Mazandaran Province). To do, fish sampling was performed at 20 sampling stations during December 2017 and January 2018 and 11 habitat factors were measured at each sampling station. Then, habitat suitability curves for each parameter and suitability index of each station were obtained using HABSEL software. Also, determination of distribution pattern of C. capoeta and its relation with the best habitat factors were surveyed using dbRDA analysis according to its abundance at each station in Primer+Permanova (Ver. 6).Based on the HABSEL results, C. capoeta inhabiting in Roodbabol prefers wide locations with low water flow speed, temperature between 14 to 18°C, average depth (22 to 30 cm), average altitude (140-180 m), average EC (260-300 μS/cm), small grain size of substrate rocks (100-125 mm), high level of dissolved oxygen (12 to 13 mg/l), and average salinity (1.5-1.7 mg/l) which are covered by bush and shrubs and shadow level is 41-70%. Also, dbRDA graph based on DistLm model indicated that factors of depth and width in the first order and water flow with EC in the second order affected the abundances differences of C. capoeta among various stations.

Every year the trend of catches and the maximum harvestable water from the water resources are studied and studied. Extensive studies of catch data have been conducted to estimate reserves. The main objective of this study was to predict Caspian mullet catch by decision tree algorithm (C&R tree) presented using Clementine 18 data mining software. Decision tree structure in machine learning is a predictive model that contributes to the observed facts about a phenomenon with inferences about the objective value of that phenomenon. For this purpose, 10-year catch data as a dependent variable (year of catch, month of catch, latitude and longitude of catch point, depth of catch, rate of catch) derived from bony fish stock assessment projects and environmental information (temperature, chlorophyll-a) From the NASA site and the factors of pH, transparency, salinity, oxygen, benthic organisms from northern seas hydrology projects) were considered as independent variables that besides specifying the effective factor on fishing, prediction of fish mullet in water The Caspian Sea also occurs. Among the investigated factors, water surface temperature and salinity were identified as the two main factors affecting fish mullet catchment and the prediction value for 1400, 862/484 tons of mullet with an accuracy of 98/42%.

Primary production is an important component in the biological cycle in terms of carbon storage and a key indicator for evaluating of ecosystem function. In this study, net primary production and its components were investigated in the coastal zone of Iranian basin of Caspian Sea during four seasons from 2018 to 2019. In addition, the effective environmental factors on spatial-temporal distributions of net primary production have been studied. As a results, mean (±SD) of Chl-a, euphotic depth (Zeu), active photosynthetic radiation (PAR), maximum primary production per unit of Chl-a (PBopt) and daily net primary production (DNPP) were obtained 2.54±3.23 mg/m3, 28.9±6.8m, 40.42±16.84 Einstein/m2.day, 5.05±1.11 mgC/mgChl-a.h and 2.04±0.73 gC/m2.day. The value of DNPP in the central region was more than the western and eastern regions. It probably is due to effects of wind and waves turbulent on re-suspension of sediment and decrease of light penetration in water column in the western and eastern regions. The seasonal variation of net primary production was in order: autumn>summer>spring> winter. The significant higher NPP in autumn than other seasons (p< 0.05, ANOVA-test), primarily caused by Chl-a and PBoptic. Based on regression and PCA tests, temporal-spatial changes of DNPP has been significantly affected by the two variables of Chl-a and PBoptic.  In general, the classification of trophic state based on net primary production showed that 52% of the data had trophic states in the range of oligo-mesotroph  and mesotroph (49%) to eutroph (3%) and 48% of the data were in the oligotroph group (mainly in the eastern region).

The establishment of aquaculture cages in the right place will be associated with the least adverse effects on the ecosystem, so the quality of sediment is very important in monitoring fish cages farming. The aim of this study was to investigate the sediments chemistry parameters around fish cage culture in the southern of Caspian Sea (Nowshahr region). Sampling was conducted in four stages of the breeding period during 2017 and 2018, underneath the cages and at 200m and 1000 m longitudinal distance in four geographical directions from the cages. Based on the results the variations in different forms of phosphorus such as Loosely-P, Fe-P, Al-P, Bioava.-P, Ca-P, TIP, Res.-P and TP were 1.2-13.8, 22-114, 12-121, 37-211, 61-2170, 150-2223, 0-937 and 203-2283 µg/g. dw, respectively. The order of different forms of phosphorous were registered as Ca-P>Res.-P >Fe-P>Al-P>Loosely-P. The variation range of pH, Eh and TOC% were 8.05-8.60, (-63)-(-83) and 1.36-7.87, respectively. The results revealed that temperature, Eh and pH had the main role in the adsorption and release of loosely-P, Fe-P and Al-P. Comparison of 25-75th percentiles of total organic carbon (1.97-2.60%) with permissible threshold showed that the sediments of Nowshahr region can be classified as moderately polluted.

This study was conducted to determine the effects of some environmental parameters (sea surface temperature SST, sea level SL and Volga river water volume VRWV) on biomass of golden grey mullet Chelon aurata in Iranian coastlines of the Caspian Sea. In the study, the catch and population parameters of golden grey mullet during the years 1991-2017 used as input data. In these years, the catch of golden grey mullet ranged from 1425 to 6600 mt. The total biomass increased from 10870 mt in 1991-92 to 20950 mt in 2000-01 and then declined to less than 8800 mt in 2017-18. Also, the biomass of 2 years (as recruitment R) increased from 1757 mt 1991-92 to 2617 mt in 2001-02, then declined to 387 mt in 2016-17. There is a significant negative relationship between R-SST (p<0.017), and a positive relationship between R-VRWN (p<0.024) and R-SL (p<0.002). By using stepwise regression, among three environmental parameters, only SL had significant effects on R biomass (R2 = 0.339). It seems that the SL has the main role in the biomass of golden grey mullet in the Caspian Sea. Therefore, an ecosystem-based approach to Management is required to sustainably exploit of golden grey mullet stocks in the Caspian Sea.

This study was carried out to determine the water environmental parameters as risk factors for rainbow trout breeding and rearing farms in the Haraz River. 84 water samples were collected at 6 stations during seven months in 2017-2018. Water samples were analyzed by standard titration and spectrophotometry. Results showed that the range of water  temperature (4.0-17.0◦C), weather temperature (5.0-28.0◦C), dissolved oxygen (7.36-14.24 mg/l), BOD5 (0.20-20.80 mg/l), COD (3.50-41.40 mg/l), electro-conductivity (345-650 µS/cm), turbidity (2-81 NTU), TSS (0.01-0.72 g/l), pH (6.98-8.15), TP/P (0.01-0.15 mg/l), PO43- (0.01-0.20 mg/l), NH4+ (0.02-0.31 mg/l), NH3 (0.14-4.36 µg/l), NO2- (0.01-0.21 mg/l), fecal coliform (9-30000 CFU/100ml) and water quality index (48.5-98.5) were changed. The results of the stepwise regression analysis indicated that the risk factors of water quality in the Haraz River were fecal coliform, phosphate, turbidity, and BOD5 parameters, and fecal coliform had a higher coefficient factor (beta coefficient) than other parameters (p<0.05). As a result, according to the average water index of stations (less than 55), water of the Haraz River is contaminated and critical to breeding and rearing trout, but it has acceptable microbial count for fish farming and wildlife. In addition to seasonal conditions such as environmental conditions and rainfall, the way of pound managing has been effective in maintaining water quality.

Appendicularians are the most important group among zooplankton communities, widely distributed in all the oceans and they are considered as one of the most important sources of productivity and food supplies for secondary consumers. So this study aimed to identify, introduce and assess the temporal and spatial variations of the Appendicularians in the Persian Gulf, restricted to coastal waters of northern part of Bushehr. Appendicularians were collected during seven sampling programs, from Frake river-estuary, three sites of large creek-estuary of the Shif, one site in the sea, and one site in the Lashkari creek-estuary, at middle and last day of each season, midsummer of 2016 to spring of 2017. During all surveys, depth of the sampling location, Secchi depth, water temperature, pH, and salinity were measured. Finally, 4 species were identified, Oikopleura dioica, Oikopleura longicauda Appendicularia sicula and Fritillaria sp. The highest total density was observed in the sea station at March, with dominance of O. dioica and a relative abundance of 80%, relative abundance of O. longicauda, A. sicula and Fritillaria sp. were calculated 18.9%, 1.06% and 0.04% respectively, so Fritillaria sp were introduced as rare species. Two species of O. dioica and O. longicauda demonstrated completely different spatial and temporal distribution pattern, and based on dbRDA (distance based Redundancy Analysis), transparency explains effectively the distribution pattern of O. longicauda, and also depth and salinity are the most important factors which explain the distribution pattern of O. dioica and temperature was correlated factor with abundances of A. sicula, in our study area.

Phycocyanin is a blue pigment of Spirulina algae that has antioxidant, anticancer and anti-inflammatory properties. In this study, primary culture of Spirulina was performed in the modified Zarrouk medium. Phycocyanin was extracted enzymatically using lysozyme and was purified by the use of ammonium sulfate 40% solution. The stability of phycocyanin was evaluated by the split factorial experiment in a completely randomized design based on three factors including temperature (-18, 4 and 10°C), pH (4.5, 5.5 and 7) and time (15, 30 and 45 days). The concentration and purity of phycocyanin in the crude extract were 1.815 mg/ml and 0.825, respectively whereas the concentration and purity of phycocyanin in the purified extract were 3.751 mg/ml and 1.135, respectively. The results showed that the stability of phycocyanin was relatively decreased by increasing the storage time at various temperatures. However, the highest stability of phycocyanin was observed at -18°C followed by 4°C with the same trend in the range of pH. By increasing the storage temperature to 10°C, the stability of phycocyanin drastically reduced especially in a pH of 5.5 and the absorbance of light was reached to zero in 30 days. The best conditions for the minimum concentration loss of phycocyanin were in a pH of 4.5 at -18 °C and storage duration of 30 days. According to the results, it is possible to use phycocyanin in the food products that are stored in cold or freezing temperatures such as dairy products and ice cream.

Selecting suitable sites for the establishment of cage based aquaculture has a very important role in aquaculture development and investment success. In Iran, there is a growing tendency for seawater aquaculture development due to the limited resources of freshwater. In the present study, the effective biotic and abiotic factors in cage culture that were collected through the hydrological and hydrobiological studies from 1387 to 1389 were analyzed. Iranian waters of the Caspian Sea from shoreline to the depth of 100 meters were investigated with the use of Geographic Information Systems (GIS). Analysis was carried out based on the site selection criteria including the minimum depth of 20 m, short distance from the beach, no interference with other maritime activities, being at least 5 km far from the river mouth and the most suitable environmental parameters. Results indicated that Iranian waters of the Caspian Sea were appropriate for cage culture in which, central region between the cities of Kheshtsar to Kiashahr with an approximate length of 245 km was the first priority and the western and eastern regions were the second and the third priorities for aquaculture development, respectively. In central region, the match compliance criteria for the establishment of floating cages were 80 to 97.5 percent and the suitability of the environmental conditions were increased from the east to the west. Fourteen sites out of the fifteen suitable sites, which had the most appropriate conditions for the establishment of floating cages, were in a region between Chaboksar and the western part of Sepidroud River and the remaining site was in Tonekabon region.

The Shahid Rajaei Reservoir constructed for various purposes such as drinking water supply. In this context, and also because of the importance of the bloom events and eutrophication process in dams, this paper is to survey the relations between some of physicochemical parameters and phytoplankton composition and density, chlorophyll-a and some water quality indices (Trophic, Saproby, Shannon) using mono and multivariate statistical analysis. Water samples collected from 4 stations during May, June, July, August, September, November and February in 2012-2013. According to the results, the maximum concentration of dissolved inorganic nitrogen, chlorophyll-a, phytoplankton abundance, trophic and saproby indices observed in a month of summer which it was accompanied to the minimum value of species diversity index (Shannon). Pearson analysis revealed direct correlation between abundance of Goniaulax polyedra, Goniaulax digitale and trophic index. In the other words, higher abundance of the two species decreased the water quality. Also based on the PCA analysis, the significant correlation observed between abundance of Cyclotella meneghiniana with Shannon and saproby indices which were negative and positive, respectively. This result indicates to the relation of degradation of water quality with increasing the abundance of Cyclotella meneghiniana. Meanwhile, the presence of the three parameters (abundance of Cyclotella meneghiniana, Shannon and saproby indices) in first component of PCA indicated the important role of Cyclotella meneghiniana and two biological indices in determining of water quality in Shahid Rajaei Reservoir.

This study was done (in summer 2010 to summer 2011) to investigate the diversity, richness, dominance of Xanthoid crabs in intertidal rocky 2010 Shores of Hormoz Island. Samples of crabs were collected from intertidal zones during the low-tide at 3 stations) environmental parameters determinated such as salinity, PH , Solvable O2, temprature and bed gradint and using Correlation`s test of spirman indicated significant differences (p <0.05) with their relation in the xanthoid crab abundance . Also PAST tool using for Computation ecological indices (Margalef, Shannon - Wiener and Simpson). Cluster analysis of the stations led to the recognition of three abundance clusters with the highest Semblance being in spring and autumn. Correlation between ecological indices (Margalef, Shannon - Wiener and Simpson) and the environmental parameters showed significant correlation between salinity and Simpson index. margalef index has studied in three station and season that showed mohitzist statian and winter had higher Species Richness