فصلنامه بوم شناسی آبزیان
سال دوازدهم شماره 2 (پیاپی 45، پاییز 1401)

In this study, some reproductive characteristics of the yellow gooseberry, Upeneus doriae were investigated in Bandar Abbas coastal waters for a period of 8 months from July 2018 to February 2019. 300 fish specimens were selected from the bycatch fish of shrimp trawl. The samples were then transferred to the laboratory and the biometric data and some aspects of the biology of the fish were recorded. The results showed that male fish were more prevalent (53.3%) than females in trawl catch during the study period. The male: female sex ratio was significantly different in each month and in the whole period of study. According to the results of this study, it is expected that the spawning of this species begins in January. The fork length in which 50% of females reach sexual maturity is 10.6 cm.

Four sampling sites were selected in different parts of the Anzali wetland watershed to predict the habitat preferences of the river prawn (Macrobrachium nipponens). A set of abiotic variables together with the abundance of the species were monthly measured at each sampling location during the 1- year study period (2017-2018). The results of Mann-Whitney test (given the non-normal data) showed a significant difference between the presence and absence of shrimp and the most studied variables (p< 0.01). In fact, the results of the test were based on the abiotic variables in which presence/absence of the species was observed. The prediction of the decision tree model showed that the increase of dynamic and structural variables of ecosystem such as water depth and flow velocity and the increase of water quality parameters such as salinity or the decrease of pH might lead to the absence of the species. According to the results of the generalized linear model, there was a significant difference (p< 0.01) between the presence and the absence of shrimp related to the variables (some of the variables with high collinearity were excluded) so that the probability of shrimp presence decreases if flow velocity, depth of sampling sites, electrical conductivity, chloride, salinity, sulphate and total hardness increase. On the contrary, the increase of dissolved oxygen concentration, water turbidity and acidity might increase the probability of shrimp presence in the wetland. Given the factors predicted by the applied models, it is necessary to pay more attention to these variables in future monitoring for the habitat preferences of shrimp

Coral bleaching, loss of symbiotic algae of Symbiodinium sp. or photosynthetic microalgae pigments from their coral host have become commonplace in recent decades due to the rising of sea temperatures and changes in physicochemical factors. It is essential to study the susceptibility of corals to bleaching, the physiology of its symbiotic algae, and its capacity to cope with abiotic stress. Oxidative stress is of particular importance due to the fact that it can be caused by photosynthetic dysfunction drived by temperature and other physicochemical factors. The aim of this study was to compare the effects of physicochemical factors on the photosynthetic performance of Symbiodinium sp. symbiosis with Stichodactyla haddoni in the Persian Gulf and the Gulf of Oman. To determine whether the cultured Symbiodinium sp. has different sensitivities to oxidative stress and whether winter and summer play a role in oxidative stress and coping with it, DPPH test and Freak ion reduction method (FRAP) were used and Physicochemical factors were measured through the HQ40D prototype device. Moreover, air data (wind speed) was obtained from the website www.irimo.ir. Statistical analysis was performed through one-way analysis of variance at the level of 0.05 and heatmap analysis. The results showed that the highest antioxidant capacity was assigned to Symbiodinium sp. extract in Chabahar in winter (IC50:135.768 μgr/ml) and the lowest antioxidant capacity was allocated to Chabahar in summer (IC50:349.090 μgr/ml). Ferric ion reduction of Symbiodinium sp. extracts showed the highest inhibition compared to ascorbic acid at a concentration of 2 mg/ml (0.297) and the lowest inhibition at a concentration of 0.063 mg/ml (0.015) in Chabahar in winter.

In the present study, the interaction effect of climate change accomplished by phenanthrene as a representative of contaminants was investigated on the expression of nacrein gene in the mantle tissue of Pinctada radiata. To determine the studied gene expression pattern changes, pearl oysters were exposed to isolated/ combined warming in two levels (24 and 28 °C), acidification in two levels (8.1 and 7.6) and phenanthrene concentration in two levels (0 and 8 ng/L) for 4 weeks. Experimental setup was arranged in eight exposure treatments with triplicate aquaria per treatment and each aquaria containing 15 animals in 20 L. Sampling was performed three times, i.e.,24 h 48 h and 28 days after exposure. After 28 days of exposure, although no mortalities were observed in any treatments, the studied parameters caused significant reduction of nacrein expression in isolated exposure except for temperature, double interactions except for temperature and phenanthrene combination, and triple interaction. The quadruple interaction showed no significant effect on nacrein gene expression. These results demonstrated that the decreased seawater pH and elevated temperature in presence of contaminants caused downregulation of the nacrein gene and might impact the quality of pearl and shell of pearl oyster, P. radiata.

This research was carried out to determine the concentration of heavy metals in Pacific white leg shrimp cultured in farms of Ganaveh, Deylam, Hillah, Mand, Delvar and Shif and its consumption risk. The shrimp samples were prepared based on the standard methodology. The health risk of its consumption was evaluated according evaluated according to the daily intake (DI) index. Our results showed that the shrimp reared in the Deylam site had the maximum values of toxic metals mercury, nickel, and zinc compared to other sites of Bushehr Province. The concentrations of As, Cd, Cu, Fe, Hg, Ni, Pb, and Zn in shrimp muscle were 0.021, 0.028, 11.725. 42.003, 0.095, 3.278, 0.122 and 6.748 mg/kg dry weight (DW), respectively. Based on the findings, the concentration of Cu and Ni were significantly higher than the permissible maximum recommended amounts for human consumption by the world health organization (WHO), and they were 0.38 and 10 mg/kg DW, respectively. On the other hand, the health risk evaluation of the maximum tolerable daily intake (MTDI) of heavy metals showed that daily and continuous consumption of shrimp is safe for consumers in different age groups (children, adults) and despite the high levels of nickel and copper, there is no serious risk to consumers.

In this study, the concentrations of heavy metals in water and aquatic plants Azolla filiculoides and Lemna minor in three special zones of Anzali Wetland located in the north of Iran were investigated. Sampling was performed in summer 2018 and metal concentrations in water and plant samples were measured by ICP-OES. The results showed that the sequence of the average total concentration of metals in water samples is Fe>Mn>Ba>Ni>V>As>Ag>Ti>Co>Cu>Zn>Cr>Hg>Pb>Cd. The highest bioaccumulation was obtained in both plants belonging to Mn, Fe and Ba and the lowest concentrations were obtained for Cd and Ag. BCF results obtained for both plants for all metals were more than 1000 indicating that both plants are powerful hyper accumulators for heavy metals in the region. Although the potential of these species can be used with environmental considerations to reduce pollutants for various effluents, but the presence of these species in the food chain of the wetland might be a serious threat to the species consuming these plants by creating biological magnification.

The aim of this study was to identify environmental factors affecting the abundance and biodiversity of fish communities in the Dinor River in Kermanshah province. For this purpose, six stations were selected for sampling fish along the Dinor River in June 2018. In addition, physicochemical parameters and biodiversity indices of fish were determined. Canonical Correspondence Analysis (CCA) was used to determine the environmental factors affecting biodiversity indices and fish species. Based on the results, a total of 2543 fish samples were caught from in Dinor River, which belonged to 20 species. Most fish species belonged to the Cyprinidae family. Alburnus sellal (with 1358 samples) and Capoeta trutta (with 1 sample) showed the highest and lowest abundance in Dinor River, respectively. Medium bedrock diameter with a coefficient of 0.65, water flow velocity with a coefficient of 0.60 and TDS with a coefficient of 0.52 were identified as the most effective environmental variables on fish abundance in the Dinor River. In addition, among the studied environmental variables, river width with a coefficient of 0.64, depth with a coefficient of 0.58, EC with a coefficient of 0.44 and TDS with a coefficient of 0.42 showed the most significant contribution to fish species diversity in the Dinor River.