This research was conducted with the aim of determining the biodiversity of Pertaran communities in three areas with mangrove cover and in 9 stations including one station in Gowatr Bay and 4 stations in each of Gowatr bay and Bahu Kalat on the eastern coast of Chabahar port. From each station, from the winter of 2019 to the fall of 2014, three sediment samples were collected seasonally for the separation and identification of sediments and one sample for the analysis of grain size and total organic matter of the sediments by Grab van Veen with a cross-sectional area of 0.028 square meters. In total, 12 genera belonging to 10 families were identified. Among the groups of the detected families of spionidae, the highest percentage of the average frequency with 13.70% was related to the Spionidae family. The survey of the density of the birds in total is 17800 ± 180 in the mentioned seasons, the average density of the birds in winter is 8720 ± 42 and the average density of the birds in the autumn is 9080 ± 181.63 in the mentioned seasons, the lowest average in winter is related to the Nereidae family: 0.5 600±67 and the most number was for Spionidae family: 1280±31.47 individuals in one square meter. The lowest average in autumn was related to the Nereidae family: 560 ± 32.65 and the highest to the Spionidae family: 1160 ± 62.94 individuals per square meter.

The present study was conducted for identification and assessment biodiversity of Polychaeta of Mongoft Artificial Reef structures in Bushehr Province.At first, 3 stations were selected. Seasonal samples were collected in spring and summer 2009, with 3 replication by diving operations, using Quadrates from each station was done. In total 7 species of Polychaeta were identified.Maximum frequency of Polychaeta, 644.64 n/m2, in the spring and the minimum number of 204 was recorded in summer.Results showed that Nereis sp. with 277.44 n/m2 (32.69 %) in the seasons and sampling stations was the most abundant.ANOVA results identified significant differences between the number of Polychaeta of the two seasons (P<0.05).In review of the biological indices, greatest Shannon diversity index was in station 1 in the spring with the amount of 1.83 and smallest Shannon diversity index in to the station 1 was in the summer with the amount of 0.50 has been. Indices were compared to determine that spring was diversity more diverse than summer. Considering the values obtained, biological indices it can be concluded that the region is exposed to stress, and it can affect the diversity of benthic fauna.

Polychaeta are the most important benthic .animal sand consist of many species with a vital role in food web. We conducted a survey froin, summer 2005 to spring 2006 to complete the ecological studies of macro benthos in rocky shotes of the intertidal zone of the Hormouz Island. Three main regions were studied in the west, south and south-eastern parts and three transects were sampled in each region to test variation in Polychaeta distribution and abundance along the entire intertidal zone. At each one of the nine transects the shore was levelled and a general qualitative description was made, which also aided in the stratification of subsequent quantitative sampling. Samples were fixed in %4 formalin and transported to lab for analysis. Results showed presence of 10 genera of Polychaeta among which Nereis was the most abundant in the intertidal rocky shores. Our study also revealed seasonal and zonal distribution of Polychaeta in rocky shores of the area. Abundance of Polychaeta was markedly higher in summer compared to winter and in the upper zone compared with the mid littoral zone. Results of Shannon and Simpson diversity indexes affirmed above conclusion.

Family Spionidae is one of the largest families of the class Polychaeta (Williams, 2000). This is the first report of existence of this family in the southern reach of the Caspian Sea (Noor City). Sampling of bentic community in Noor coast during autumn 2004 revealed polychaetes that is differed from the ones reported earlier. The new samples were found to belong to spionidae family, not reported earlier from the Caspian Sea. This was approved by the concerned scientists at Zoological Museum Universitesparken of Denmark and South Australian Museum by observing the samples and pictures send to them.

The study is Considering the importance of the role of benthic communities in evaluating the ecological status of aquatic ecosystems and part of a research project in the southern coasts of the Caspian Sea (depths less of 30 meters) was conducted in 2019. The aim of this study was investigation of the distribution, density and biomass of macrobenthos organisms in the water at a depths of 5, 10 and 30 meters south Caspian Sea. Sampling was seasonaly at eight with using Van Veen Grab. Overall 34443 organisms of Polychaeta including 3 families, 4 genuses and 4 species. The results showed that the highest density at Sefidrood station with mean of 327±27.71 N/m2 and lowest was at Bandartoraman station with mean 77±5.33 N/m2. The highest of Polychaeta was in summer and depth 30 meters with mean 285±26.18 N/m2 and lowest density in spring and depth 10 meters with mean 38±10.81 N/m2. The highest biomass was in spring and depth 30 meters with mean 0.23±0.02 g/m2. The highest species was assigned to S. gynobranchiata with mean 352±19.74 N/m2 and frequency 80%. In general, the results showed that in most seasons of the year, S. gynobranchiata was the dominant Polychaeta species.

Sampling for determine of density and composition marcrobentos in shrimp farming ponds in Tiab area, was done from July to Nov 1999 in 9 pondat every month. Samples were calculated by Grab with %2 m2 area. Results showed 4 group macrobentos in ponds that including: Polychaeta, copepoda, nematoda and shrimp larvae. Maximum frequency was belong to polychaeta with %49 and minimum frequency was belong to shrimp larvae with %1. Macrobentos density in unit per area was low and farm 1 was lowest in among other farms. Studies showed decreased density and composition of macrobentos in during farming term and some of the groups reached to zero.

Desalination technology is growing due to population growth and water shortage. These kinds of activites can have environmental impacts where brine discharges into the sea. This study examined the effects of brine discharge from desalination plant Chabahar Konarak on the sea environment were used to study polychata assemblage. Sediment samples were sampled from 7 stations in pre monsoon and post monsoon in year 2011 using by van veen grab (0.025m2) samplers that 5 stations were around the discharge point and 2 station as controls. The results of the statistical analysis showed that the abundance and richness significances differences (P<0.05) between stations. The most abundance of polychaetes was occurred in station 6 with 3666.62 and 2079.92 individuals per m2 in pre and post monsoon respectively. While the lowest values observed in station1 in pre and post monsoon periods with 306.97 and 0 numbers in m2.The richness, diversity and evenness results indicated that the highest and the lowest values is observed in control stations 0.94, 1.07 and 0.67 in pre monsoon and station 1, zero in post monsoon. According to results, we observed different sensitivity of polychaete to brine discharges because abundance and ecological indices were decreased in stations near the discharges area comparing to control stations far from the brine discharges zone. Results of the CCA indicated that salinity and temperature effects on polychaete structure. The most frequancy family in this study was spionidae that it showed tolerance of this family to brine discharges. With monsoon occurrence of stress added to the study area where that the lowest abundance (0) in one station in post monsoon.