جستجوی مقالات مرتبط با کلیدواژه « polychaetes » در نشریات گروه « زیست شناسی »

The study aimed to assess temporal and spatial variations in the population of polychaetes, a significant invertebrate group in deep-sea ecosystems, across the northern waters of the Persian Gulf and the Oman Sea. Sampling occurred from fall 2018 to winter 2020, covering regions in Hormozgan, Bushehr, Sistan and Baluchestan, and Khuzestan. A total of 115 stations were surveyed, utilizing 0.1 square meters and a 500 μm sieve (repeated thrice) to collect bed sediments within the depth range of 12 to 90 meters. Within this study, 35 species/genus of polychaetes were identified in the waters of the Persian Gulf and the Oman Sea. Notably, Flabelligra sp., Manayunkia aestuarina, and Glycinde sp. exhibited the highest abundance, with Flabelligra sp. and M. aestuarina serving as indicator species in both regions. The provinces of Sistan and Baluchestan and Bushehr displayed the highest Shannon diversity and species richness, recording 3.592 and 6.998, respectively. Comparing these findings with prior reports revealed a reduction in the diversity of identified polychaete species in the Persian Gulf. This decline could stem from various factors such as habitat damage due to fishing equipment, and the incidence of contaminants. Continual research and database establishment for time series analysis could significantly aid researchers, authorities, and environmental advocates in comprehending the health status of the Persian Gulf and the Oman Sea. Such efforts would facilitate environmental monitoring and pollution prevention measures, contributing to the preservation of these ecosystems

Polychaetes are important in determining the environmental status of seabed and their role in the food chain. Sampling of sediments in three areas of Beris, Ramin and Pasabandar was performed at 10 stations in the north of the Makoran Sea by Garb van-veen during three periods of pre-monsoon, monsoon, and post-monsoon winter with recordings of chemical physical parameters from November to March 2016. In the study identified 18 families of polychaetes communities it was found that the highest density in Monson period and in Post-Monsoon with 4364.67 ± 570 ind/m2 and the lowest density in Post-Manson period in Roman region with 225.33 ± 89 ind/m2.  In the pasaBandar area, the highest percentages belonged to the families Spionidae, Maldanidae and Cirratulidae, and to the families of Nephtydae, Phyllodocidae and Cirratulidae and to the Ramin family's Orbiniidae, Maldanidae and Cirratulidae. One-way ANOVA showed significant differences between stations and time periods (P <0.05). The highest densities of the polychaetes were estimated in terms of the period of Monsoon> Pre-Monsoon> Post-Monsoon period, respectively. Results of correlation between polychaete density and environmental factors of grain size sediment and TOM in pre-monsoon period showed a positive and significant correlation. There was no positive and significant correlation with environmental factors in monsoon period (P <0.05), but there was a significant positive correlation with grain size in post-monsoon period (p<0.05). The results showed that winter monsoon causes significant changes in the populations of the studied areas and the increase in density in monsoon can be due to the change of the currents direction and consequent increase of nutrient load in the area.

Polychaetes are ecologically important in the food chain, and also vital in ecosystem monitoring and environmental stress assessment. In the current study, sequence variation in a segment of COI gene sequencing by mitochondrial DNA barcoding and comparing nucleotide divergence was employed for molecular analysis of Perinereis polychaetes (Nereididae). Analysis of 50 sequenced specimens, representing 39 new sequences, and 11 sequences with 100 percent similarity with GenBank records, which revealed 1.8 times more sequence divergence between than within species (1.96 versus 3.52%). Phylogenetic analysis data indicated that maximum divergence within barcode clusters increased by the number of specimens. The phylogeny also suggests that most of the identified Perinereis species in this research showed low genetic relationship towards similar species from other world regions. Assessment of genetic similarity rate showed that Perinereis polychaetes in Bushehr province were highly similar, while Perinereis polychaetes in Bandar Abbas were less similar to Bushehr Perinereis polychaetes, the observed divergence was mostly at subspecies level and it can be concluded that in terms of species structure, Perinereis polychaetes of Deylam, Bushehr, Dayyer and Bandar Abbas, showed low genetic divergence.

The aim of this paper was to study monsoon effects on polychaetes population structure in subtidal area based on some biodiversity indices. Sediments sampling was carried out by grab van-veen from 12 subtidal stations in three time periods (pre-monsoon, monsoon and post-monsoon). The physical and chemical parameters were also recorded. Mean density of polychaetes were recorded 1101.2 ±614.3 ind/m2 (pre-monsoon), 428.9 ±316.2 ind/m2 (monsoon) and 588.8 ±313.3 ind/m2 (post-monsoon). Shanon diversity indices were 2.08, 1.63, 1.83 respectively. The Hill indices was reversed and showed highest number in monsoon season and minimum number in pre-monsoon. These results represented non-uniform polycheates distribution during pre-monsoon. Cluster analysis of each season showed that deep stations were in separate disturbances. During the summer monsoon, variations in environmental factors and bottom distractions affected the density and diversity of polychaetes and as a stressor reduced the diversity and density during the monsoon.

The aim of this study was to identify and assess the diversity and dominance index of polychaete in the rocky intertidal area of the Bushehr province in 3 stations include Bushehr, Dayer and cape of Nayband. Sampling was carried out in four seasons during 2011-2011 along one transect perpendicular by the quadrate 0.5×0.5 square meters at low tide zone. At each station, one transect deployed perpendicular to the shore. Samples were collected on each transect from low tide level up to the high tide area. Environmental factors such as temperature, salinity and pH were measured in each station. Our results indicated the highest and lowest temperatures in the summer (33.9°C) and winter (19.26°C) and the highest and lowest salinities were recorded in the summer (43.15 ppt) and autumn (40.62 ppt). There were no significant changes in acidity in all seasons. In this study, 16 families of polychaetes were identified. Among them; species Spirobranchus kraussii had the highest frequency during the study years. The highest and lowest diversity was observed in the summer and autumn, respectively

This research was carried out to compare diversity and distribution of polychaetes in western and eastern Jask creeks protected areas in Jask Port (Gulf of Oman)، located in the East of Hormozgan province. Sampling of sediments was done seasonally from fall 2009 to summer 2010 by 0. 04m2 Van Veen Grab، in three stations including mouth، middle and end of each creek. A total of 72 sediment samples were taken from the stations. In this study، 20 species belonging to 16 families in the easten Jask area with a frequency of 9075 per m2 and 17 species belonging to 13 families in the western Jask area with a frequency of 4800 per m2 were identified. Polychaetes families were mainly consist of Nereididae، Owenidae، Capitellidae and Pilargidae. Ecological indices including Shannon - Wiener، Margalef and Simpson also were calculated. The average of Shannon index in different seasons and stations of eastern Jask (1. 02±0. 47) were higher than the western Jask (0. 898±0. 74). Correlation analysis between environmental factors and polychaetes showed that the abundance of polychaetes has a significant positive correlation with the temperature، oxygen، salinity and EC (P<0. 05). Results of ANOVA revealed no significant differences between indices in different seasons (P>0. 05). The results of Kruskal-Wallis test showed significant differences between the abundance of polychaetes in the eastern and western Jask (P<0. 05). In additon، the results of this test indicated a significant difference in the abundance of polychaetes، between summer and fall and also between summer and winter، in both of Eastern and Western Jask (P<0. 05).

The study took place to survey the changes in diversity and distribution of Polychaetes in fishing area of Bahrakan, due to the trawling. Sampling was taken before (15 May) of trawling and two weeks (5 Sep) and three months (14 Nov) after trawling in 2010, in three period in Bahrakan coast. Therefore, eighteen stations placed with the depth of 6 meters and 10 meters.The amount abundance Polychaetes had decreased significantlyin both depths two weeks after trawling (P<0.05). Also in 6m depth, no significant difference was observed between abundance Polychaetes in two weeks and three months after the trawling (p>0.05). Only in 10m depth, abundance Polychaetes after three months comparing to two weeks after trawling had increased significantly (p<0.05). Changing biomass Polychaetes was similar to Changing abundance. After the trawling, small size individuals became dominant.Abundance Species ofCossura longicirrattahad increased in both depths in two weeks after the trawling. Also in both depths, Shannon Diversity and Margalef Species Richness indices showedprocess decreasing and Simpson dominant Index showedprocess increasing. In both depths, Pielou Evenness Index two after trawling had increased. While, after three months comparing to two weeks after trawling had decreased and most effects of trawling were on 6m depth.