سیده لیلی محبی نوذر

Chlorophyll-a, as an important indicator of algal blooms and water quality, holds significant importance in marine studies. This research aims to compare linear and nonlinear regression models based on machine learning algorithms for estimating the chlorophyll-a levels in the coastal waters of Bandar Abbas, Hormuz, and Qeshm Island. The study utilizes data from the TERRA sensor’s MODIS satellite and field measurements from various points within the study area. The examined models include linear regression, generalized linear model with Poisson distribution, random forest, and support vector machine. The performance of these models is evaluated using metrics such as root mean square error (RMSE), mean percentage error (MPE), mean absolute error (MAE), and coefficient of determination (R-squared). The results demonstrate that linear regression and generalized linear models perform poorly, while random forest and support vector machine exhibit better performance. Particularly, the random forest model shows the highest performance with an RMSE of 0.5725 and R-squared of 0.6632. This model has the capability to detect nonlinear and complex patterns and can effectively handle large datasets by employing a large number of decision trees. Overall, this research highlights the effectiveness of machine learning models, especially random forests, in accurately predicting chlorophyll-a levels as a crucial factor in managing marine ecosystems in the study area.

In this study, a comprehensive assessment of the occurrence and spatial distribution of heavy metals including Nickel, Lead, Zinc, Copper, Cadmium and Chromium, as well as, TPHs in the surface sediments of the coastal areas and far from the coast of the Persian Gulf in Bushehr and Khuzestan provinces were performed to identify the possible sources of sediment contamination and determining the degree of pollution. Eight pollution indices were used to evaluate the quality of sediments in terms of heavy metal and TPH pollution. The investigated areas could be distinguished by a significant degree of heavy metal pollution of Nickel, Cadmium and Zinc. High concentrations of Nickel and Zinc were observed in stations around Nakhiloo, Bushehr. The comparison of average pollution indices between regions showed that both Bushehr and Khuzestan provinces, respectively, with the average of contamination degree (CD) (20.25 and 22.11), modified contamination degree (MCD) (3.38 and 3.69), pollution load index (PLI) (31.17 and 57.57), potential ecological risk index (PERI) (353.54 and 349.39) have a significant degree and risk of Nickel and Cadmium pollution, especially in Nakhiloo area, Bushehr. Investigating the spatial fluctuations of the concentration of TPHs in two provinces showed an increasing trend from Bushehr to Khuzestan. However, areas were located in no pollution or low pollution zonation and were safe from the adverse biological effects of TPHs. Comprehensive and impressive strategies to control and reduce these pollutions, especially in polluted areas, should be considered, so that the sources of these pollutions be managed.

In the current work, a comprehensive assessment of the spatial distribution of heavy metals including Cd, Pb, Ni, Cu, Zn, and Cr was performed in the sediments of mangrove and coral areas from 32 stations located in Tiab, Azini, Lark,  Hengam and Qeshm, Island, Bandar e pol and Bandar Khamir during the 2021 to 2022. The concentration of heavy metals showed significant spatial variations between the areas. The highest concentration of Cd 1.64±0.01 μg/g was observed at the station "Near Tabl village, South of the mangrove trees". The station "Tiab, end of the estuary" had the highest concentration of Pb 17.87±2.17 μg/g. The highest concentration of Ni 135.22±1.85 µg/g was seen in "North Tiab station, irrigation branch". The maximum concentration of metal Cr 18.41±0.41 μg/g was observed at the "Center of mangrove reservoir" station. There was the highest concentration of Zn 94.61±30.74 μg/g in "Azini Station 2" and finally, the highest concentration of Cu 40.5±0.28 μg/g was observed in the station "Khamir port, sandy bed of mangrove trees". The stations located in Tiab and the mangrove reserve had a higher intensity of pollution than other places and showed considerable risks of pollution, especially in terms of Ni and Cd. Cadmium was considered as the most dangerous metal in the studied areas which is probably caused by industrial activities. It is necessary to consider comprehensive and impressive strategies to control and reduce these heavy metal pollutions, especially in Tiab habitats and mangrove reserves where show high intensity of Cd and Ni contamination to identify, and manage the sources of these pollutions and minimize the impact of human activities on mangrove and coral ecosystems.

In this study, the possible impact Asian sea bass fish (Lates calcarifer) cages culture on the population structure of phytoplankton in the coastal waters of Qeshm Island.Water sampling was done monthly for a period of six months in three stations from October 2018 to March 2019.The results showed that the mean Variations of total abundance of phytoplankton at the location of fish cages culture compared to the Reference station had a significant increase (P <0.05). At the location of cages culture, the Trophic status level was high (<5), the risk of eutrophication status (<4) and the value of trophic efficiency coefficient were high. According to the analysis of Simper test, Among the Forty-one genera identified, Noctiluca sp. with a relative abundance of % 82.37, contribution rate of 21.8% with high algal bloom at the location of cages in autumn season and then the genera Chaetoceros sp., Nitzschia sp. and Coclodinium sp. with a relative abundance of less than 10 percent in differentiating the population structure of phytoplankton have played a significant role in the dissimilarity of the population structure of phytoplankton between stations In general, in this study, the effects of fish farming activities on the population structure of phytoplankton are ineffective, but it causes the abundance of some species, available nutrients, increases the trophic level, and the probability of harmful algal blooms in the location of the cages culture.

The possibility of algal blooms at the location of the cages and the surrounding water is one of the major risks associated with the management of fish farming in cages. In the present study, the risk of eutrophication (risk of algal blooms), the rate of nutrient enrichment (eutrophication) and the availability of nutrients (for phytoplankton consumption) due to fish farming in the waters adjacent to the cages with Farther from the location of the cages during a six-month rearing period in Qeshm region was compared. In the study, the range of changes related to scale and non-scale trophic indices and trophy efficiency coefficients were equal to 3.75-5.23, 3-4-78 and 3.78-4, respectively. Based on the studied indicators, the trophy status in the waters adjacent to the cages is high (at the mesotrophic level) and the risk of blooming is high, as well as the availability of nutrients by primary producers (phytoplankton) based on the trophy efficiency coefficient was high. However, in the waters farther from the location of the shelves (control station), the trophy status was moderate (at the mesotrophic level) and the risk of blooming and the availability of nutrients were low. The use of superior technologies and proper, principled and scientific management of water and food quality, in addition to reducing the environmental effects of such activities can play an important role in increasing production, exports and further valuation by this industry.

With the arrival of large amounts of effluent during the one period from aquaculture into coastal ecosystems, it can introduce large amounts of pollutants into coastal waters during each breeding period. A review of recent studies in the region shows that the changes in phosphate levels, total suspended solids and BOD levels in the effluents were beyond the scope of the environmental standard. The results of the organic load estimate showed that, during a breeding period, with a minimum of 5% water replacement, approximately 500 tons of soluble Dissolved inorganic nitrogen and 25,000 tons of soluble phosphate entered the Enter the waters of the Tiab estuary through effluents. Therefore, it is suggested that by creating sedimentation ponds (to reduce suspended solids), build a biological treatment system (to reduce nutrients), define environmental standards permissible limited necessary for effluents to enter coastal waters and revision the management of Shrimp farms, from any Effects and environmental risks associated with aquaculture activities in coastal ecosystems be avoided.

The aim of the present study was to identify the phytoplankton species which producing domoic acid and okadaic acid toxins in coastal waters of Banar Abbas city, and to determine the concentration of domoic acid and okadaic acid toxins in water and shellfish samples.Water sampling was performed in winter 2015 and summer 2016 from coastal areas overlooking the discharge of municipal and industrial effluents. Shellfish were collected from the coasts of Bandar Abbas and Bandar-e- Lengeh. Phytoplankton toxins were measured by kit method and instrumental analysis based on ELIZA method.Pseudonitzschia delicatissima, Pseudo-nitzschia pungens and Pseudo-nitzschia seriata were identified in the production of domoic acid, while Dinophysis caudate and Prorocentrum Lima were recorded as okadaic acid producers in the coastal waters of Bandar Abbas. Water-soluble okadaic acid showed significantly higher concentrations than domoic acid. Instudied shellfish samples (Circenita callipyga, Barbatia candida, Telescopium telescopiumandThalessa savignyi), the measured concentrations of okadaic acid ranged from 59.8 ± 2.38 to 121.96 ± 28.25 μg / kg. This value for domoic acid was from 0.85 to 83.59 ± 38.72 μg / kg.Compared to the guideline values, the observed concentrations of okadaic acid and domoic acid toxins in the studied shellfish were lower than the allowable level.  But this value was recorded for the water-soluble domoic acid above the allowable value, which requires continuous monitoring to achieve the quantitative and qualitative pattern of phytoplankton toxins in order to support the safety of the marine ecosystem users in Hormozgan province.

In this study, Given the importance of water quality management of shrimp farms, three farms (three pond per farm) in the northern Tiab area of Minab city of Hormozgan province were studied to evaluate the Environmental conditions of shrimp ponds (Litopenaeus vannamei) during a six-month period (June to December, 2014).The results showed that the ranged water temperature were (15.50C-37.40C), pH (7.1 - 8.97), salinity (41 p.p.t -59.5 p.p.t), dissolved oxygen (0.7 mg.l - 9.5 mg.l), nitrite (0.3 μm.l - 54.5 μm.l), Ammonia (0.01mg.l - 0.13mg.l) and Transparency (10 cm - 95cm) . The results of cluster analysis showed that the water quality has varied between shrimp farms together. The high water temperature and salinity of shrimp farms acts as a negative and limiting factor for shrimp production. Also the water temperature, dissolved oxygen, salinity, Transparency and chlorophyll-a were out of range (permissible limits) in shrimp farms for Litopenaeus vannamei.Avoid increasing shrimp density at surface if poor water quality management is not implemented. On the other hand, increasing the concentration of pollutants in waste water shrimp ponds can cause problems in the future for the coastal environment.

Shrimp is one of the most important food items in the southern parts of the country, especially Hormozgan province. Therefore, harvest management of shrimp stocks was an issue that has always been taken into consideration for sustainable catches. In this study, the relationship between meteorological factors (wind speed average, temperature and rainfall) was evaluated with catch rate at shrimp catch season (7 Oct. - 6 Dec.) in the period of 1985-2015. The Principal Components Analysis (PCA) was used in order to investigate the selected climatic parameters with shrimp catching. The results of the KMO index in this test were 0.71 and Bartlett's test was significant. The results of special values, variances and cumulative variables and factor loads related to the components showed that the first component((Shrimp catch(0.03), wind speed average(0.06), temperature(0.82) and rainfall(0.33)) with 33.58% and the second component(( Shrimp catch(0.76), wind speed average(-0.84), temperature(0.28) and rainfall(0.79))with 28.67% of the total variances (62.25%), can be used to verify the identification the most important parameters affecting on shrimp changes in the province during the last thirty years .In addition, evaluation of factors related to factor loading obtained from PCA showed that rainfall (0.79) and wind speed average(-0.84), in the second component, had the most positive and negative effect on shrimp catching changes (0.76) respectively. The effect of wind on the reduction of commercial shrimp catch may be related to the lower efficiency of trawl gear due to not placing the otter board trawl on the sea bed. It is probable that the annual rainfall will not be effect on the catch in catching area, and their effect may be on the stock of young shrimp in nursery grounds last year.