فصلنامه اقیانوس شناسی
پیاپی 50 (تابستان 1401)

The birds have always been of great importance in various cycles of ecosystems. In between the number of microplastics in marine environments is increasing. In recent years, due to the entry of marine debris into the environment, all kinds of particles such as fiber, fragment, film and other particles in different sizes are accidentally ingested instead of food or accidentally by birds. Due to their indigestion, these particles block the gastrointestinal tract, reduce the useful volume of the gastrointestinal tract, suffocate and in some cases lead to the death of the animal. The present study is the first to investigate microplastic observations in the Anas crecca waterfowl of the southern Caspian Sea basin. The abundance, type, size, shape and color of microplastics in the stomach contents of this bird were examined.

Carcasses discovered from hunters in the northern provinces and lost specimens from the coast were described. SZM-LED2 Stereomicroscope with objective lens of 0.7, 0.8, 1, 1.5, 2, 3, 4, 4.5 and eye piece 10x was used to detect microplastic particles by OptikaView software version 7.

The results show that in the two provinces of Guilan and Mazandaran, a total of 316 microplastic particles including fiber, fragment and film were found in 46 of common teal (Anas crecca), which: fiber and then fragment had the highest frequency. The size range of the parts varied from the film with 0.071 mm to fiber with 13.543 mm. Also, the greatest variety of shapes was related to long linear fiber components.

The relationship between fiber density and residential areas can be considered as an indicator of urban ecosystem pressure. Continuous monitoring of the environment with the help of microplastics in the areas where bird colonies are found should be considered.

The purpose of this study is to simulate and predict the dimensions of the scour cavity downstream of the siphon overflow using the SVM model and compare it with other numerical methods. The use of the SVM algorithm as a meta-heuristic system in simulating complex processes in which the dependent variable is a function of several independent variables has been widely developed among researchers. The purpose of this study is to simulate and predict the dimensions of the scour cavity downstream of the siphon overflow using the SVM model and compare it with other numerical methods. The use of the SVM algorithm as a meta-heuristic system in simulating complex processes in which the dependent variable is a function of several independent variables has been widely developed among researchers.

The innovative aspect of this research is the prediction and numerical comparison of the geometric dimensions of the scour cavity downstream of the siphon overflow in the form of using the SVM based data model with other numerical models. The measured values ​​were collected through the collection of laboratory data performed in the laboratory.

Finally, using statistical indicators, the accuracy of each model is calculated and their function is classified.

Performance evaluation indices R, RMSE and ZDDR (max) in test and testing processes of two intelligent SVM and GEP algorithms in simulating scour hole dimensions downstream of siphon overflow for three 30, 45 and 60 degree projectiles with materials Sediment with average particle sizes of 1.4, 3.7 and 8.1 mm indicates better performance of the GEP model than the SVM model.

Many animal species are currently experiencing anthropogenic pollutions in their habitat. Noise pollution from human activities affects many species of animals. Noise pollution in terrestrial and aquatic ecosystems is prominently recognized as a source of stress and disruption of biological activities, and an important and pervasive global environmental pollutant. Recent studies have shown the effect of sound on various aquatic vertebrates, including fish and marine mammals. However, despite the diversity of invertebrates and crustacean that they are among the earliest links in the food chain in ecosystems, studies on the effect of acoustic stimuli on their behaviour are limited. Therefore, the aim of the present study was to investigate the effect of continuous sound exposure, the most common temporal patten among underwater sound sources, on the behaviour of an invertebrate, red cherry shrimp (Neocaridina davidi) under laboratory conditions.

In total, 70 red cherry shrimps were housed in a holding aquarium (48 cm × 32 cm × 28 cm; water depth: 22cm; wall thickness: 4mm) connected to a water circulation system on a 14 h light; 10 h dark cycle and with the water temperature kept at 27℃. All shrimp individuals were fed twice daily for two weeks with spirolina tablet before being transferred individually to the experimental set-up. The experiments were conducted in a rectangular glass tank aquarium (40 × 30 × 30 cm; water depth: 20 cm; wall thickness: 2cm) equipped with a custom build underwater speaker connected to a power amplifier. Behavioural experiments were performed after the shrimps had acclimated to the experimental set-up. The shrimps were divided in two treatments and individually exposed either to ambient noise as a control (96.52±1 dB ref 1µPa) or continuous sound (110.40±1 dB ref 1µPa) in a bandwidth range of 400 to 2000 Hz. Here, in this study, we investigated the effect of sound exposure on movement speed, spatial distribution and food finding behaviour of shrimps.

According to the findings, in general, once the passing gate opened, the movement speed in sound and control treatments showed a significant decrease(P<0.05), but there were no significant changes between total minutes of control and sound treatments(P>0.05). The spatial distribution of shrimps in response to the sound treatment showed significant changes (P<0.05). Moreover, the time to find the food source also increased significantly in the sound treatment (P<0.05).

The findings of this study confirm the effect of sound on the behaviour of red cherry shrimp, under laboratory conditions. Elevated sound levels caused changes in spatial distribution and to some extent movement speed of shrimps. Moreover, sound exposure negatively affected allocated time budget to find food source; shrimps spent more time to find food source. Our study highlights that invertebrate are likely to be susceptible to the impacts of anthropogenic sound. We suggest that sound has the potential to increase the risks of starvation and may have subsequently negative effects on the timing of foraging and predatory- prey activities and that may affect population of meiofauna and benthic organisms in aquatic ecosystems. Finally, our laboratory study should not be extrapolated directly to outdoor conditions, but calls for investigation of behavioural responses of invertebrates to acoustic stimuli.

Influence of water mass on sound propagation in the Gulf of Aden underwater acoustics used for communication, navigation and identification of objects by both humans and marine mammals and for investigating the detrimental effects of anthropogenic activities (e.g. pile driving, seismic survey and ships) on marine animals. The Gulf of Aden presents a unique ecosystem that deserves scientific attention. In addition to its extraordinary biotic richness, the Gulf of Aden also serves as a highway for international trade between east and west. The Gulf of Aden is an important Gulf connecting Red sea water with the Indian Ocean. Red Sea Water is the most prominent water mass in the Gulf of Aden and there is no ambiguity about its origin. It outflows into the Gulf of Aden from the Red Sea through Bab-el-Mandab strait. Sound speed in the oceans depends on temperature, salinity, and pressure and has large seasonal and spatial variations.

This paper studies patterns and seasonal variations of propagation sound in the presence of the Red sea water mass by using a coupled ocean model (MITgcm) and an acoustic model (ray method). For this purpose, first using the results of Shafiei et al. (1397), temperature and salinity output were extracted and then using the Mackenzie equation, the speed of sound was calculated.

By examining the sound speed profile horizontally and vertically, the intrusion flow of the Red Sea water to the Gulf of Aden was observed at depths of 300 to 800 meters Also in winter, the outflow area of the Red Sea is larger than in summer. Then, the influence of this strong intrusion on sound propagation are comprehensively analyzed with the parabolic equation and explained by using the ray theory. Using the ray theory, in the presence of infiltration flow of Red Sea water to the Gulf of Aden in different scenarios, including in the direction perpendicular to this flow, parallel to the movement of this flow and different depths of the sound source, how sound propagation from this phenomenon in these seasons Analyzed.

Propagation sound was studied in 2D and 3D, the results show that displacement the sound source across intrusion flow can change the propagation paths and cause the convergence zone to broaden and approach the sound source. In addition, the results of two-dimensional and three-dimensional simulations showed that the presence of these masses caused changes in the distribution of acoustic energy in both seasons. Overall, the results show that intrusion flow can change the propagation paths and cause the convergence zone to broaden and approach the sound source.

 Coral reefs are one of the world's most attractive ecosystems. They have been covering large parts of the world in the tropic areas. Coral reefs in the Iranian waters of the Persian Gulf are largely limited to the Islands. Many factors, including natural and anthropogenic activities cause stress to the reef communities affecting reef development. Coral bleaching events due to raised temperatures are increasing in both frequency and magnitude worldwide. Coral bleaching is considered a major threat to coral reefs worldwide, especially because large-scale bleaching events have been linked to global warming. The most intense global coral bleaching events reported have occurred worldwide in the last three decades. The Persian Gulf is considered the warmest coral sea in the world. Temperature conditions associated with coral bleaching in the Persian Gulf are higher than in any other area in the world. Therefore, the coral reefs in the Persian Gulf are also at assailable to temperature anomalies and their long-term effects. Sea surface temperature is one of the most important physical factors that affects the life of coral reef communities. Coral bleaching occurs in the Persian Gulf in the recent years due to the global warming and increased sea surface temperature (SST) resulting in high mortality in the coral. Thus, in this research the effects of coral bleaching and its threats in Kish Island have studied. The study area includes coral reefs in the around Kish Island in the Persian Gulf and the effects of stresses.

In this research, sea surface temperature (SST) daily values from 1985 to 2017 (in 1°×1° spatial resolution) prepared by the National Oceanic and Atmospheric Administration (NOAA). The degree heating week index (DHW) was examined to check the cumulative effect of heat stress, which indicate the severity of the whitening threshold based on a long-term period for each site. For trend analysis of sea surface temperature (SST) changes in studying regional, the Mann-Kendall non-parametric test has been used.

The results indicated that the maximum of sea surface temperature is 35.17 ˚C (August, 11th, 2017). Analysis of sea surface temperature trend indicates that SST has increased trend. The DHW threshold for the study region is 5.3 which is warning for whitening of coral communities on Kish Island. The results illustrate the ability of the DHW index to predict bleaching events in the coral reef communities of Kish Island, and can be an effective tool in managing this ecosystem.

The thermal analysis showed that there is an overlap between the recorded bleaching events in different years and the years of the El Niño occurrence. Therefore, these results help in years when there are no reports of bleaching or the data isn’t recorded properly, using overlap, the reconstructed this lack of information.

Marine organisms have a high potential in the production of bioactive compounds. Portunus segnis crab is one of the most widely distributed in the Persian Gulf and the Sea of Oman. Lateral fishing is caught on fishing nets. The aim of this study was to investigate the inhibitory effect of swimmer crab tissue extracts on gastric ulcers in mice as an animal model.

Crab was caught from the Persian Gulf - Bushehr. Hexane, ethyl acetate, butanol, and aqueous extracts of Portunus segnis crab muscle tissue were prepared. The prepared extracts were etched on ethanol-induced gastric ulcers in rats, and the number and percentage of ulcers were evaluated. Changes in superoxide dismutase, mouse serum was assayed. The most effective extract compounds were evaluated with Gas chromatography-mass spectrometry.

According to the results, consumption of all extracts in different doses of 25, 50, and 100 mg/kg significantly reduced the number and percentage of wounds. Butanol extracts at a dose of 100 mg/kg showed an anti-ulcer index of 62%. The effect of the extracts was dose-dependent and at doses much lower than omeprazole, they had a similar effect in the treatment of gastric ulcers. Superoxide dismutase levels also increased with wound healing. In butanol extract 17 compounds such as palmitoleic acid, 9-octadecenoic acid, n-hexadecanoic acid, (z) -9-octadecenamide, eicosane and hexacosane were identified.

Butanol extract of swimming crab had preventive effects on the gastric ulcer at a dose of 100 mg/g. The results of this study showed that consumption of all extracts in different doses of 25, 50, and 100 mg/kg significantly reduced the number and percentage of gastric ulcers. Therefore, it is recommended to use crab extracts to prevent this disease.

 The role of human resources in the use of technology and product production is very important. Therefore, labor productivity is recognized as one of the important factors in the comprehensive development of ports, which, despite the industrialization of communities, has not diminished its importance. Insufficient attention to the factors affecting the productivity of manpower in ports (Chabahar port), as the main gateways for the entry and exit of goods, the flow of goods and trade in the country will face serious problems. The purpose of this study is to provide a solution to improve productivity by identifying and prioritizing the factors affecting labor productivity in Chabahar port. This study, according to its objectives, is an applied research that tries to provide a suitable solution to improve personnel performance by identifying and prioritizing the factors affecting the productivity of human resources in Chabahar port.

The required data and information have been collected by library and field scientific methods. The statistical population of the study consists of port and marine experts, active in the field of Chabahar port and Makran coastal region, expert managers and experts in ports and human resources. First, the influential factors on productivity of port's manpower have been identified by reviewing the literatures and distribution of the questionnaire among the statistical sample, and then the fully influential factors have been identified. In the next step, the identified factors are prioritized using the Analytical Hierarchy Process (AHP), which is a structured technique for organizing and analyzing complex decisions.

Findings showed that, management and leadership style, the existence of proportionality between personal interests and job, staff promotion system based on competence, the existence of proportionality between individual skills and job, and having a work conscience, respectively, are the first to fifth factors in influencing performance of manpower is in Chabahar port. Also, the existence of appropriate salary systems, in-service training, having relevant education, the existence of suitable conditions for career growth and promotion, and adherence to laws and regulations, are in the sixth to tenth priority, respectively.

Attention of managers to the priority and the influence of factors affecting the performance of manpower in ports, investment, research and development in this regard, will have a significant impact on improving the performance of manpower in the port and thus prosperity and economic development.

The aim of this study was to evaluate the biodiversity of zooplankton in the Caspian Sea basin in Noshahr and Chalus.

Sampling was carried out in three transects including depths (5–10 and 20 m) in two seasons of 2013 (autumn and winter).  Totally, 8 zooplankton groups were identified during two seasons. In autumn, the highest abundance belonged to bivalve larvae (8060 ind/m3) and the least abundance belonged to polychaetes species N. diversicolor (299 ind/m3). In winter, Rotifera species Asplanchna sp. (6877 ind/m3) had the highest abundance. The least abundance belonged to one of the larval stages of Barnacle (Cypris of Balanus sp.) (372 ind/m3).

In each of the two seasons, the abundance of zooplankton groups had significant differences in most of the stations (P <0.05). Also in autumn and winter, all identified zooplankton groups had uniform distribution. Values of species diversity and richness indices were different in two seasons. In autumn, Shannon diversity and Margalev richness indices in most of the stations were higher compare to winter. However, the values of the Simpson Diversity and the Menhinick Richness indices were higher at most stations in winter. Also, the values of qualitative (Jaccard) and quantitative (Kulczynski) similarity indices were completely different in the autumn and winter.

In autumn the stations were different in terms of qualitative and quantitative similarity indices but in winter all stations were qualitatively and quantitatively similar (100%).

The Lagrangian SVP drifter, developed by Niller, has a good non-slip flow tracking capability in a variety of atmospheric conditions due to its holey-sock drogue. An important factor in the design of drifters is the surface drag coefficient. In the design of drifters, the drag area coefficient of the drogue should be about 40 times of total drag area coefficient of the surface float and tether, and also the amount of torque applied to the tether should be low to minimize the slip of the float surface in waves and strong winds.

In this research, ANSYS-FLUENT has been used to investigate the holey-sock drogue in three-dimensional turbulent environment. Flow field around the holey-sock drogue clarified the rule of them on hydrodynamic forces. Holes on the drogue cause uniform distribution of the pressure and viscous force around the drogue.

 By modeling the blade drogue, it was found that the presence of the blade on the drogue causes a significant increase in pressure force, which in turn increases the drag coefficient, but these blades cause an undesirable increase in torque on the tether.

It was found that if the blade width is about 10% of the drogue diameter, the drag coefficient is improved by 26%, while the torque on the tether changes by only 3%.

One way to predict how marine ecosystems will react to climate change is to use the time series data. Considering the various economic and ecological values ​​of marine species, and that the demographic dynamics of these species depend on two factors of climate variability and human activities, it was decided to investigate the time series of the data and conduct the present study on catfish storage considering the export value and the role of predators in the ecosystem And change in stock can affect dependent populations. The population vulnerability of these species was investigated by climate change and time series data. In this study, the relationship of fishing time series data on fishing effort unit (CPUE) of catfish from 2007 to 2018 monthly with environmental data including: sea surface temperature, chlorophyll a as well as evaporation rate, rainfall, wind speed and air temperature Using regression methods, neural network and decision tree were studied in the waters of the Persian Gulf and the Gulf of Oman. The results showed a decrease in catfish stocks in the waters of Khuzestan and Sistan-Baluchestan provinces and a steady trend in the other two provinces. In Khuzestan waters, catfish CPUE showed a significant relationship with wind speed and in Bushehr waters with chlorophyll-a, Hormozgan with evaporation and in Sistan - Baluchestan air temperature had a significant relation. Considering the resilience of the mentioned environmental factors and the continuation of the climate change process, it seems that in order to sustainably exploit the fish, environmental factors should be considered.