In this research, the ability of Cyanobacteria "Nostoc sp"; in relation to adaptation with flactuations of salinity levels were investigated. Specimens were collected from paddy fields of Gorgan, and after purification were treated with 0;0.5; and 1% NaCl salinities; pH 5, 7, 9 and air CO2 condition, (with and without vanadate). Results showed that this species can grow successfuly in 0.5%; and 1.0% salinites. The effect of 0.5% salinity on heterocyst frequency were noticable. There were not seen a recovery stage in 0.5% salinity. The causes of the excretion of phycobilliproteins were discussed. Growth and heterocyst prodnction completely blocked in pH5. Growth curve in pH 9 and also results of treating vanadate in air CO2 condition; show possible function of bicarbonate concentrating mechanism in this species.

In this research, the ability of growth, changes in heterocyst frequencies, and pigmentation of Nostoc sp. in response to low light energy (20,30,40,50 and 60 mmol quanta m-2s-1), light dark duration (12/12), and complete darkness (with galactose; sucrose or fructose) were studied. Results showed that, in 40 mmol quanta m-2s-1), a considerable lag phase in growth curve exists. Phycoerythrin was more efficient in light adaptation than phycocyanin light / dark durations caused a noticable decrease in heterocyst frequency. The ability of growth and heterocyst production completely blocked in dark in the presence of galactose and sucrose but in the presence of fructose this ability was slightly observed.Heterocyst frequency was reduced efficiently and significantly: even after 5-minute exposure of UV-C. The ability of recovery was not seen in this species. The content of phycoerythrin reduced considerably in relation to exposure time.

Due to the importance of benthic cyanobacteria in nitrogen fixation in paddy fields, the physiological responses of Fischerella ambigua FS 18 to salinity (NaCl 0, 0.5 & 1%) were investigated. Results indicated that growth rate was higher in control and that NaCl did not inhibit growth of other treatments. Similar responses were seen in the case of other physiological processes. Chlorophyll was declined with increasing salinity.Phycobiliproteins (PBP), phycocyanin (PC) and allophycocyanin (APC) were at least in 0.5% but the differences were not significant. The light-saturated photosynthetic rate was higher in control and decreased with increasing in salinity. With respect to nitrogenase activity, the highest rate was in control and the cultures with higher growth rates reached to the maximum level at a shorter time. There was no significant difference between 0.5 and 1% in relation to nitrogenase activity.

Biological soil crusts occur as assemblage of lichens, mosses, liverworts, and cyanobacteria. Lichens and mosses are the two important components of biological soil crusts, especially in arid and semiarid rangeland environments, where vascular plants vegetation is poor. Available information indicates that biological soil crusts contribute to a variety of ecological functions such as soil stabilization and vascular plants establishment, but their role in infiltration is not well understood and results of reported researches have been conflicting.Current study was conducted to show possible effects of biological crusts on soil infiltaration rate and moisture condition on Qara Qir rangelands, with an area of 8560 ha, in Turkmen steppe. For this, double ring, core and tensionmeter were used to determine infiltration rate, moisture condition (weight and volume percentage) and matric potential, respectively. Since research was performed at one site with the same climate, topography, vascular plants, and soil texture, the difference of the study points in soil – hydrologic properties, was related to the absence or presence of cryptogamic crust. Comparing means using t- test showed a significant difference between above-mentioned factors in crusted and uncrusted soils. Crusted soil had better condition in view point of infiltration and moisture. Therefore, one can conclude that presence of lichens and mosses in Qara Qir rangelands is important for soil-water relations.

Cyanobacteria are a big groups of monera kingdom, that high potential for product some natural product, such as nutritional, pharmacologic material and etc. Oscillatoria is a kind of filamentous cyanobacteria. This microorganism observed in Tyab - bay in all of seasons. Seawater medium (SWM) is the best media for isolation of Oscillatoria from natural environment. Enriched SWM with B12 and semi-solid Z8 medium (0.7% agarose) is too suitable for purification of condense culture. Maximum coefficient (m) was in valance medium. Purification of Oscillatoria has down at during nine months.Oscillatoria was exposed to five treatments of light/ dark periods and six different temperatures. Results obtained revealed that among the employed 30oC treatment has had the best effect on increase maximum coefficient (m=0.602) and also another treatment among the employed 14.10 (light/ dark) hours (m=0.506). In this treatment temperature was 25 oC.

Tubiphtes morronensis has been regarded as a community consisting of foraminifera (miliolid) and an overgrowth of some kind of algae or cyanobacteria. Although occurring in a wide variety of different facies, Tubiphtes morronensis represents a valuable marker fossil for environmental conditions. This is due to the ability of these foraminifera to adapt to different conditions by developing different growth forms. Important feature is the thickness of the outer test, apparently depending on the amount of light available for the algal symbiont. Shallow-water tests may show diameters of more than I mm, whereas the diameter of the outer test of deeper water forms strongly tends towards zero. In the Esfandiar Limestone Formation, the diameter of Tubiphtes morronensis is 0.7mm to I mm and shows adaptations to shallow water environments.