The present study has done to evaluating the exploitation status and estimating the reference points of the Caspian roach in the Southeast coast of the Caspian Sea in four time periods 2009-2011, 2012-2014, 2015-2017 and 2018-2020 using the LBB model.The relative biomass (B/B0) values for the species in four time periods were calculated as 0.32, 0.14, 0.04 and 0.13, respectively, which indicated that the lowest and highest depletion rate are 68 and 96%, which are related to the first and third time periods, respectively. The ratio of fishing mortality to natural mortality (F/M) varied from 1.16 in the period of 2009-2011 to 8.79 in the period of 2015-2017. The ratios of M/K, F/K and Z/K obtained from the data of the entire sampling period were estimated as 1.44, 3.94 and 5.38, respectively. In different periods of time, the values of these indices fluctuated so that the highest value of M/K and the other two indices corresponded to the first and third periods, respectively. According to indicator B/Bmsy, the Caspian roach stock in the period of 2015-2017 was in a collapsed status and in other years it was grossly exploited. Therefore, the results of the model show that the amount of harvesting is now more than the maximum sustainable yield (MSY) and the stock is severely decreasing and in a critical state. The values of F/M and B/B0 also confirmed the greatl overfished status. In general, the results of the LBB model confirm that the fishing resources of the Caspian roach in the coastal waters of the South Caspian Sea have greatly decreased and are in danger of extinction, and it is necessary to provide more effective and strict management measures to recovery/rebulding the abundance of the Caspian roach stock and save/conserve its stock.

Population dynamics and annual biomass of the Nereis diversicolor in 1, 2 and 3 meter depths of the Gorgan Bay (Bandargaz coast) was studied in the years 2004-2005. Results revealed the highest density and biomass were in 3 meter depth in Spring and Winter and in 2 meter depth in other Seasons (p<0.05). The highest and lowest average density and biomass of this worm were observed in 3 and 1 meter depths, respectively (845.37±664.06 and 658.23±622.61 ind/m2, and 2571.29±2828.56 and 2065.50±2500.26 mg/m2). Significant Seasonal differences in the population of this worm were observed (p<0.05), so that the highest density and biomass in all depths were encountered in Spring and the lowest density and biomass in all depths Were observed in Winter. Result of this reSearch showed that biomass and density of this worm have increased by on comparison with the previous studies.

In this study, Population dynamics and biomass of the invasive Polychaete, Streblospio gynobranchiata, in 1, 2 and 3 meter depths of the Gorgan Bay (Bandargaz coast) was studied in the years 2004-2005.Results indicated increased density and biomass as depths increased. The average density of this worm in 1 and 3 meter depth was 1147±796 /m2 and 2894±1137 /m2, respectively; the average biomass in the respective depths were 0.31 ± 0.15 g/m2 and 0.614±02 g/m2. The highest density and biomass in 1 and 2 meter depths were encountered in autumn; in 3 meter depth, The highest density was observed in summer while the highest biomass was observed in summer and autumn. The lowest density and biomass at all depths observed in winter.

The overview of geological condition of an area is too important for land-use planning. An engineering geological model can provide this overview. In this reSearch, based on carried out studies and investigations, a model is given that shows the general engineering geological conditions of sediments in western Caspian Sea coast. This reSearch is based on geomorphological, geological, sediment logical, hydrogeological and geotechnical studies. In this model, land units with similar behavior are defined and then the engineering geological characteristics and relevant geological hazards of these units are quantified. This model cannot be used as detail site investigation but serves as useful tool for preliminary investigation. This model helps to better design of field surveys as well as optimal selection of investigation methods for future civil engineering projects.

Wave-induced hydrodynamics within the near shore region and the subsequent sediment transport and evolution of beaches under wave attack are important elements governing the stability of coastal zone. Based on surf zone hydrodynamics several efforts have been made to estimate the sediment transport and beach profile evolution during storm conditions. Recently, it has been found that the dominant processes responsible for along-shore and cross-shore sediment transport in coastal zone can be categorized in to two major parts: long shore transport due to wave-induced current resulted from oblique wave breaking and on-offshore transport due to the combination of wave orbital velocity and mean return flow or undertow in the surf zone. One of the main steps in calculating morphological changes of a beach profile is the determination of sediment transport rate due to the main flow pattern in the surf zone. In this paper the effect of geotechnical parameters such as medium grain size of the bed, internal friction angle of sediments, density and void ratio of sediments on sediment transport rate are investigated analytically and through field measurements. Field data have been collected from different locations along Caspian Sea coast (from Astara region on the west toward the eastern coast of guilan province). Different soil mechanics tests have been performed in the laboratory on the samples and the results are plotted compared with those estimated by a numerical model. Using the Advanced Near shore Profile Model (ANPM) developed by Nairn (1990), the sensivity of the transport rate results to different parameters are considered. The results obtained from the present work indicate that the geotechnical parameters have remarkable effect on sediment transport rates in the surf zone. It has been also found that the direction of long-shore sediment transport rate is from the west toward the eastern coast due to the change in the medium grain size of the sediments. Moreover, the major behavior of Caspian Sea coast in terms of cross-shore sediment transport is erosional which results of current reSearch can be implemented in the different coastal projects along the Caspian Sea coast.

The sampling of fishes and Macrobenthic were performed in Goharbaran Mazandaran province by selecting four stations at a depth of 5 meters and four stations at a depth of 10 meters a monthly basis from May 2013 to April 2014 and fish samples of coastal blade caught were used. During the study, a total of 565902 Macrobenthic invertebrates isolates belonging to 22 species of 9 families. Oligochaeta worms were identified at the level of the class and Polychaeta worms including 5 genera and species were. Crustacea with 16 species had the highest number of species than other species. Among the 6 species of fish, Rutilus kutum and Liza aurata were 73. 05% and 24. 67% of the total catch, respectively. The present study showed that Bivalvia, especially Cerastorderma, have a high relative importance for Rutilus kutum and the importance of Gastropoda, Crabs, Fish eggs, Filamentous alge was rare for this species. Also the most feeding of Cyprinus carpio, Liza auratus, and Liza saliens species were from Detrite. After Detrite, the most important food items for Cyprinus carpio were Bivalvia, Abra ovata, Gastropoda, Oligochaeta, Nereis, Fish eggs, Filamentous alge. After Detrite, the most important food items for Liza auratus were Foraminifera, Porifera and Balanus and for Liza saliens were related to Gastropoda, Bivalvia and Porifera. Due to the combination of Macrobenthic invertebrates and the reduction of Bivalvia in the Goharbaran region, bait Food is not enough for the Rutilus kutum stocks. The present study showed that Bivalvia, especially Cerastorderma, have a high relative importance Rutilus kutum. The relative importance of Bivalvia in feeding carp was far more than other foods. In Ditritus, Mugillidae of fish in the present study was consistent with the results of other studies.

The wetlands are dynamic ecosystems, having greater biodiversity and special botanicecologica l structure. These ecosystems are always changing under the influence of natural and human factors by passing through healthy threshold and destruction. One of the approved regulations of Ramsar convention and AGENDA 21 about wise use of wetlands and immigrant birds, for member countries is the measurement of ecological characteristics and sustaining the biodiversity in order to evaluate the environmental consequences in wetlands. To understand the effects of socio-economical activities of human societies around wetlands on vegetation structure of these ecosystems, the present reSearch has been carried out in 7 indicator wetlands in northern Iran, located in southern coast of Caspian Sea during 1995-2005. The evaluation of the changes in relative density of observed plants on water surface has been done by Distance Method and the statistical analysis has been carried out by using the ANOVA with SPSS9 software. Based in the results of the reSearch, the following plant species: Azolla filiculoides, Nympha alba, Phragmites australis, Nelumbiym nuciferum, Juncus articulatus, Scirpus maritimus and Utricularia neglecta are the increasing species and the following plant species: Lemna minor, Butomus umbelatus, Sparganium erectum, Salvinia natans and Iris pseudacorus are the decreasing species in northern Iran's wetlands. Considering the growth rate, propagation and morphological characteristics of increasing species, these plants decrease the penetration of light into the water with their continuous canopy cover, interfere in the food chain, decrease the diversity of fauna and flora and finally by accumulation in the wetland bed, create the phenomenon of eutrophication and the death of these aquatic ecosystems.

Background: Knowledge about the amphistomid fauna in Iranian domestic ruminants depends on the studies conducted almost 30 years ago. The last situation in cattle is introduced here in the provinces in south coast of Caspian Sea.Methods: Amphistomid species were collected from cattle at slaughter houses of the provinces Gilan and Mazanderan in 2010. Median sagittal sections were prepared by the conventional method.Species were identified by the histomorphological pecularities of the muscular argans.Results: Five amphistomid species, Paramphistomum cevri, P. gotoi, Calicophoron calicophorum, Carmyerius spatiosus and Gastrothylax compressus, recovered. Calicophoron calicophorum is a new species for Iran. Criteria used in identification of the species were illustrated.Conclusion: Iran has a rich amphistomid fauna and mostly under the influence of oriental conditions.

Members of family Pseudocumidae, order Cumacea are among benthic crustacea that constitute a key part of food chain in the Caspian Sea. Study on identification and distribution of these creatures were conducted under the broad project of "Hydrology and Hydrobiology of the Caspian Sea". During this study which was conducted up to l00m depth (depth of 10, 20, 50 and l00m), 9 species of 4 genera were identified. The four most aboundant species were: Stenocuma diastyloides, Schizorhynchus eudorelloides, Stenocuma gracilloides and Schizorhynchus bilamellatus. Density and number of species sampled from different depths with 4 sampling periods were compared.

This study was carried out to investigate microbenthic diversity and Seasonal variation in two sampling areas including estuary and river stations during 4 Season in 2010. Sampling was done using Van Ven Grab in 3 replicates and the collected samples were fixed in 4% formaldehyde. The results showed that there are 12 benthic taxa families belonging to 9 orders in the river station, in which the most frequent family was Lumbriculidae (19. 39%), and Tubificidae has the lowest abundance (2. 07%). While the estuary station contained 12 families belonging to 10 orders. The following families had high abundance: Ampharetidae (21%), Lumbriculidae (11. 55%), Naididae (11. 32%) and Gammaridae (9. 98%). The highest and lowest abundance of macrobenthoses in the river station were observed in fall and in winter respectively, while in the estuary station the maximum and minimum were observed in spring and in winter. The maximum Shannon-Wiener index in the river were observed in the spring (2. 36) and in the estuary was in the summer (2. 13). The highest value of Simpson index in the river area was in the summer (0. 19) and in the estuary area in the spring. Results of Richness index showed that the highest amount in the river was observed in the spring, while the highest amount in the estuary was obtained in the autumn. It can be concluded that river station had higher density and diversity than estuary, indicating better ecological conditions.