Urmia Lake is one of the hyper saline Lake on world which has been faced with drought crisis recently. Increasing salinity up to saturation, the sharp reduction in the density of unicellular and multi-cellular algae as well as Artemia are effects of the crisis. Despite this critical situation on the lake, in summer of 2012 a very strong Algal Bloom was seen at northwest Urmia Lake (Bari station). Analysis of the chemical compositions of the water and study of the algae species were provided on the obtained samples from that area. Molecular analyses were provided by study of 18srDNA gene and sequencing of ITS region. The results of this study revealed the dominant species of the algae as Dunaliella tertiolecta which was found in concentration of 1.2´106 cells/ml in salinity above of optimum. Also high levels of certain minerals such as phosphate, ammonia, nitrate, as well as salinity stress in the area was proposed as possible causes of Algal Bloom.

Red tide is an Algal Bloom phenomenon which causes a lack of oxygen in the deeper water layers and with consumption of oxygen in the water, conditions for growth and aquatic life will be very hard and also can cause fish death. Algal Bloom is a very complex phenomenon. In some cases, it has quite natural origin and sometimes it is occurred due to anthropogenic activities. In the absence of anthropogenic cause of this phenomenon, there are varieties of factors such as wastewater, agricultural and industrial wastewaters which contains Nitrate and Phosphate and in large quantities used in agricultural fertilizers,important factors affecting the aquatic environment are exacerbated in low-oxygen conditions. Also increase in greenhouse gases, Iron-rich dust, hydrological factors and massive changes in global climate, handling and transport of non-indigenous species through ballast water of ships and many unknown factors are affecting on occurrence of the red tide. Algal Bloom could affect the fishes, aquatic organisms, and also could have negative effects on economy and health of the local peoples in the affected region.

Due to the importance of this red tide phenomenon and its effect on the habitats of marine life, the study of this phenomenon in the Persian Gulf and the Sea of Oman is necessary. This research is written only with a physical view and the study of other aspects is the responsibility of experts in the relevant fields. There are various methods to study this phenomenon, including field studies, satellite studies and numerical modeling. In this research, one-dimensional PROBE software has been used for different stations in the Oman Sea, the Strait of Hormuz and the Persian Gulf. The input data of the model include meteorological synoptic data: air temperature, u and v components of wind speed, cloudiness and relative humidity of Qeshm station in February 2008. Studies show that the modeling results of temperature, salinity, phosphate and nitrate are almost consistent with the measurement data. In stations located in the Persian Gulf and the Sea of Oman, in places where the amount of temperature, salinity and nutrients is maximum, the concentration of plankton, which depends on these parameters, also reaches its maximum. As predicted, the amount of green-blue plankton concentration is higher than (only) nitrate and phosphate dependent plankton concentration.

Algal Blooms in Iran's southern waterways, particularly in the Strait of Hormuz, have caused substantial economic and environmental damage during the previous two decades. Identifying acceptable remote sensing and numerical models for monitoring Algal Bloom, effective environmental factors, and analyzing the spatial-temporal pattern of Algal Bloom from 2003 to 2009 was the goal of this study. Chlorophyll concentration at high levels was considered as the major characteristic to indicate Algal Bloom, and its interaction with environmental factors such as sea surface temperature, salinity, aerosol optical thickness, and wind speed was explored for this purpose. Temperature and salinity were seen to be the most critical factors, with 22-27 ° C and 37. 5 ps psu being the optimal temperature and salinity ranges for Algal growth in the region, respectively. Between November and February, Algal Blooms are most likely to develop. Algal Blooms are also more prevalent in the northern and central parts of the Strait of Hormuz than in other part. The results of this study can play an important role in preventing and controlling the damage caused by algae Blooms in the region by developing early warning models.

Aim and Background: Given the importance of the intertidal benthic communities as well as increasing urban and industrial facilities on the coast, this study was carried out to obtain basic information required in the control of the coast, environmental.Material and Methods: Sampling was conducted in Bandar e Abbas, Bandar e Jask and Bandar e Lengeh by a powerboat in 2011 seasonally.Conclusion: In this study Polycheata, Oligocheata, Crastacea, Mollusca, Nematoda, Nemerteana, Foraminiferida, Ophiuroidea and others were carried out. Results showed that Crustacea had the maximum density with amount of 333950 indm-2.Discussion: Any changes to coastal ecosystems and intertidal zone will result in a change in the factors that govern the benthic communities as indicators of environmental changes as well as the dynamics of the visible world, evaluating and calculating.Results: Due to Macrobenthos density and biodiversity indicators, it seems that a significant change in the density and biodiversity after Algal Bloom did not exist therefore; it had been before on the coast of Hormozgan.

Cyanobacterial Blooms cause huge and irreparable financial losses to fish farmers every year. One of the most effective methods for managing water cyanobacterial Bloom is biological control by adding pathogenic agents to break down cyanobacterial cells. Therefore, this study investigated the possibility of using Pseudomonas putida bacteria to control the Bloom of cyanobacteria Chroococcus sp., Oscillatoria sp., Microcystis sp. and Gloeocapsa sp., isolated from fish Culture ponds was done in the laboratory. The results of this study showed that Pseudomonas putida bacteria have a significant effect on controlling all 4 cyanobacterial species. So, for the cyanobacterium Chroococcus sp. In the experimental group containing 106 CFU/ml of Pseudomonas putida bacteria, there was a moderate 80.7% reduction and also in the group containing 104 CFU/ml of this bacterium, there was 63.1% reduction compared to the control group models on the 10th day. Also, for the cyanobacterium Oscillatoria sp. at the 10th day, 78.9% reduction occurred in 104 CFU/ml and 87.7% in 106 CFU/ml. Next, for the cyanobacterium Microcystis sp. On the tenth day, there was 61.7 percent decrease in the group containing 104 CFU/ml and 70.5 percent decrease in the group containing 106 CFU/ml of Pseudomonas putida bacteria. Finally for the cyanobacterium Gloeocapsa sp. A decrease of 72.3% was observed in the experimental group containing 104 CFU/ml and an 83% decrease in the group containing 106 CFU/ml. Although the control group show an increase of 37-78 percent (P˂0.05). The results of this research showed that the bacterium Pseudomonas putida has a high efficiency in controlling the Bloom of cyanobacteria.

Cochlodinium polykrikoides was Bloomed in the Persian Gulf for the first time in September 2008, started from the Strait of Hormuz and then spread out towards the northern parts covering most of the areas of the Gulf and lasted 8 months. In order to find out environmental conditions during the Bloom, a monthly sampling program was carried out in seven surface stations in 2008-2009. At each station, three samples (triplicates) were collected for phytoplankton analysis and also one sample for environmental analyses, including salinity, chlorophyll a and nutrients. Blooms of C. polykrikoides were observed with a seawater temperature of 20.1 to 31.0°C, salinity 37.0-40.1 ppt and nutrient concentration ranges during the Bloom and red tide were 0.064-0.707 mg/l nitrate+nitrite and 0.001-1.66 mg/l phosphate, respectively. Maximum of C. polykrikoides abundance was measured 26´106 cells L-1 in October 2008. Kruscal wallis test demonstrated a significant difference in densities and chlorophyll-a in different months and seasons not in different stations. This study showed increase of temperature (>31.0°C) stopped Bloom and red tide due to C. polykrikoides in both the eastern and middle sampling stations but in the western stations was determined decrease in nutrient amounts as the major factor therefore increased nutrient of coastal waters, and environmental conditions could have efficacy the occurrence of this din oflagellate.

In recent years, there have been some reports of seawater discoloration in the coastal part of the Persian Gulf. Red tide is a natural phenomenon that occurs due to the proliferation, growth and accumulation of phytoplankton and their dense aggregation in water and as a result, the color of the water turns red. Red tides are not necessarily always red, and this term is more closely related to the nature of the Blooms phenomenon. In recent decades, the Harmful Algal Blooms (HABs) has increased in the coastal waters of the world, endangering human health and marine ecosystems. Approximately 75% of HABs species are “ dinoflagellates” and many of their toxic species produce resistant cysts. The transport of dinoflagellate cysts in the ballast water of ships is the main method of its transport and the global increase of HABs. Also, strong winds, coastal upwelling currents, heavy rains, fertilizer application and some physical and chemical factors such as changes in salinity, temperature and pollution are effective in the occurrence of this phenomenon. So far, no specific method has been identified to prevent the red tides phenomenon. Also, the duration of its occurrence, the time of its disappearance and the new place of its occurrence are not predictable. The effect of red tide on aquatic and human life is important and can be studied. HABs cause toxins and poisoning in humans, fish and other aquatic animals. The health of scuba divers is threatened and the food basket of the people on the shores is destroyed. The socio-economic consequences of the red tide on the breeding, fishing and tourism industry and wildlife are significant.

Background and Objectives: Noctiluca scintillans is a dinoflagellate without armor that has extensive winter Blooms in the northern Indian Ocean. Green layers from dense Algal masses of N. scintillans were observed in all the studied stations in the winter, PGE 1801 cruise of the Institute of Oceanography and Atmospheric Sciences in the Strait of Hormuz. The aim of this study was to an assessment of the distribution of the Bloom in the winter of 2017 in the Strait of Hormuz using field data and remote sensing. Methods: The density of N. scintillans species in the upper layer of water was calculated using closing net samples. The density of other phytoplankton was obtained by direct sampling of water by Niskin sampler. In all stations, the profiles of salinity, water temperature, and chlorophyll A parameters were measured from surface to layer close to the substrate using CTD. MODIS satellite data were used to investigate the distribution and extent of the Bloom. Findings: The results of correlation analysis (Pearson) showed a significant relationship between chlorophyll A (values ​​obtained from remote sensing) and the number of N. scintillans cells per liter (R = 0. 74, P <0. 05). Conclusion: It seems that the intensity of N. scintillans Bloom is higher in the western part of the Strait of Hormuz and the waters near the coast. Also, satellite remote sensing data show that there is a strong correlation between the distribution of N. scintillans Bloom and mid-scale eddies in the Strait of Hormuz.