جستجوی مقالات مرتبط با کلیدواژه « بقاء » در نشریات گروه « زیست شناسی »

Iran has different populations of Artemia that live in different climates and ecological conditions. Physicochemical conditions of lakes and lagoons have intensified the allopatric Artemia speciation. The aim of this study was to investigate the effect of one of the ions in these climates so that Artemia can be cultivated semi-naturally in some wetlands of Golestan province.

To do this, the effect of four treatments (10, 16, 33, and 50%) of magnesium sulfate instead of other salts on cyst and growth parameters of Artemia franciscana was studied.

There was a significant difference between the experimental groups in the Artemia growth index (P <0.05). Maximum and minimum body lengths were observed in the control and 50% magnesium sulfate groups, respectively. Also, 33 % magnesium sulfate treatment showed a significant decrease in growth rate compared to the control treatment (p <0.05) but did not show a significant difference with 50% magnesium sulfate treatment (P <0.05). At low concentrations of magnesium sulfate growth rate insignificantly decreased in Artemia compared to control treatment. The highest and the lowest survival percentage were observed in control and 50% magnesium sulfate, respectively. On the 15th day, the maximum and minimum survival rate was 83 % and 46% in control and 50% magnesium sulfate treatment, respectively. The highest hatching percentage was observed in the control treatment and the lowest was observed in the 50% magnesium sulfate treatment. Increasing magnesium sulfate concentration significantly decreased the number of nauplii but increased the number of non-hatched cysts (P <0.05). Moreover, the highest number of umbrella stages of Artemia was observed in the treatment with 50% magnesium sulfate. Maximum and minimum hatch efficiency were insignificantly observed in control and 50% magnesium sulfate treatments, respectively. The highest mortality of nauplii was significantly observed in the treatment with maximum magnesium sulfate.

The results of this study showed that magnesium sulfate in high-level amounts limits the hatching and growth of Artemia which should not be introduced to such climates.

Water Hyacinth, Eichhornia crassipes is one of the world’s worst weeds. It originates from Amazonia and be invader to other areas in the worldwide. It has recently been detected in several natural areas of northern part of Iran such as Anzali Wetland. Here, distribution of Water Hyacinth was studied in Anzali Wetland during 2015-2018. Also some biological characteristic including; evapotranspirative water losses, surveillance against salinity gradients and nutrient effect on biomass production of root and green parts were investigated. Water Hyacinth infestation was observed from 7 to 84 points of Anzali Wetland with 100 to 1000 m2 in different years. The distribution of Water Hyacinth was limited in summer of 2017 because of a prolonged temperatures below freezing winter. The seed was germinated in study area after two years. The water losses were estimated up to 2.5 times more from Water Hyacinth compared to open water. While the mortality of Water Hyacinth was observed in salinities more than 5.2 g.l-1, the leaves was increased in salinities lower than 1 g.l-1. The biomass of root was more than biomass of green part in areas with lower nutrient while it was versus in regions with high nitrogen level. Water Hyacinth has a high risk threat in the most water bodies in northern Iran because of the favorite climate situation and high eutriphication level. A multidisciplinary approach should be designed in the fight against Water Hyacinth in Anzali Wetland that awareness raising among local communities and the stakeholders is the most important.

In this study, the effect of methanol extract of Tribulus terrestris (MET) in different treatments containing control group (without using plant extract), 0.5, 1 and 1.5 g MET /kg diet on growth performance, body chemical composition and activity of oxidant enzymes of grey mullet Mugil cephalus were investigated in triplicate for 60 days. In each 60 litre 20 water tank, 20 fish with initial average weight of 8.42±0.43g were stored. At the end of the experiment, the results showed that there was no significant difference in growth parameters (FW, BWG, PER, SGR and CF), between all treatments and control group (P>0.05). Increasing of survival rate were observed in 3 and 4 compared with control treatment. The crude protein and moisture of  treatment 4 significantly increased compared to other treatments (P<0.05). The crude fat significantly decreased in 3 and 4 treatments compared to control and treatment 2 (P<0.05).The activity of superoxidedismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) enzymes have been increased more significantly in treatment 4 compared with the control treatment (P<0.05). Also, the value of malondialdehyde (MDA) was lower in all treatments compared to the control treatment (P<0.05). MDA value has been the most lowest in 3 and 4 treatments compared with the control treatment (P<0.05).So, based on the results, in order to reduce lipid oxidation and improve the carcass duality and survival status of fish, it is recommended to use 15 g methanol extract of Tribulus terrestris /kg diet of grey mullet fish.

In regarding to study the effect of biological parameters of female rainbow trout (Oncorhynchus mykiss</em>) brood stocks on girt, 30 specimen of rainbow trout brood stocks were selected from 3 different age class (3, 4, 5 years). The results showed, maximum of girt 36.35± 0.35cm , ovary weight 600±11.25 gr, hatching 90±4 % and larvae weight after hatching 0.15±0.01 were in 5 and 3 years old brood stocks, respectively. The results  showed significant  differences between 3,4 and 5 years old  brood stocks for this instances (P</em><0.05). Maximum of number of eggs in each gram 15±0. 26 Registered in 3 and 5 years old brood stocks, respectively. Maximum absolute fecundity, relative fecundity, and working fecundity were recorded in 4 and 3 years old brood stocks, respectively. The study pointed significant difference between investigated brood stocks (p<0.05). Maximum of larvae survival percentage were observed in 4 and 3 years old brood stocks, respectively. The results showed no significant difference between 5 and 3 years old brood stocks, but for 4 and 5 years old brood stocks was saw significant difference (P</em><0.05). Maximum of gonadosomatic index were observed in 5 and 3 years old brood stocks, respectively. Although gonadosomatic index between 4 and 5 years old fish showed no significant difference, but the study showed significant difference for 3 years old brood stocks (P</em><0.05).

In recent years, extension of Artemia applications in aquaculture and decreasing of natural resource, lead many of related studies to the distribution of Artemia population and new resource assessment studies. Urmia Lake as one the biggest habitat for Artemia because of ecological variations in the regions in which of its differentiations in cyst biometry and Artemia, moreover some genetic variations suggested to have some several Artemia populations in the Lake. In this project Artemia cyst samples were collected from 5 ecological stations of the Lake Urmia. The cyst hatching and the nauplii breeding up to adult Artemia stage were done according to optimum conditions in laboratory. Growth rate and survival of larva in days of 3, 5, 7, 11, 15, 20 of rearing period were measured in feeding with a complex of Dunaliella tertiolecta and Lanzy PZ for a period of 20 days in 75 and 150 ppt. Data and its statistical analysis revealed that according to previously records the growth rate of the Artemia was influenced by increasing the salinity from 75 to 150 ppt survival and growth rate of Artemia have been influenced by water salinity (P<0.05) but increasing the salinity only in two population of Bari and Eslami led decreasing of survival. The produced cysts in two salinity showed that Artemia population can produce the cysts with different diameter and there were not any statistic correlations between the salinity and populations. The Dandrogarm of population statistic analysis emphasized that according to growth rate and survival parameters and among populations under this test there were 4 different populations of Artemia urmiana in which had interesting differentiations in growth rate and survival.

Artemia mainly due to its nutrition value and also its merits has been considerate very in research biology and aquaculture. L-carnitine as a food supplement which stimulates the fatty acids oxidation and its affect on increasing of the nitrogen retention and stimulation of resistance against the environmental stresses is used lately in modern aquaculture. In order to study of the effect of dietary L-carnitine supplementationon the growth performance, survival rate and early maturation of Artemia franciscana, treatments were done by 1, 10, 100, 1000mg/l of L-carnitine supplement. The cysts of A. franciscana were hatched in optimal conditions. Acquired larvae were fed as long as 15 days with a compound of enriched yeast with HUFA and the alga Dunaliella tertiolecain salinity of 80g/l. L-carnitine supplement was added directly in culture medium and indirectly added by enrichment the algae were fed by specimens. Results revealed that this supplement can stimulate early sexual maturation and aggravates masculinization in all of the experimental groups in comparison with the control group. The best result, in this regard was recorded for 1000 mg concentration of L-carnitine in which at 15th days the best percentage of sexual maturation, 13.03%, was seen. These results showed that L-carnitine has significant effect on growth performance when it exposes in 100 mg concentration of L-carnitine

Remediation of petroleum polluted soil and water is very important. One of the pathways of oil remediation is usage of microalgae and cyanobacteria. In this research the effects of oiled based drilling mud waste (including 70% gasoline) on survival, growth and pigments of three cyanobacteria (Oscillatoria+Calothrix, Nostoc, Calothrix) in mix and unialgal forms were investigated. These cyanobacteria were isolated from soil of Arvand-rood in Abadan city. Results indicated that biomass of first sample was three fold of other samples. Growth rate in first sample was increasingly. In second and third samples, growths were decreased and reach to stationary phase after one week. All samples survived in treated experiments and oil compound did not have any toxic effects of them. Chlorophyll contents were similar to biomass and in first sample were three fold of others. Totally, results showed the resistance and potential of these species to degradation of oil pollution. Also these results are the first report from oil polluted fields of Iran.