The present study investigated the biodiversity of Nayband beach by using molecular and morphological studies. For this purpose, samples were taken from dominant bivalvia in sandy shores of Bushehr, Nayband in April 2016. To record morphological features such as shell shape, decorating on the shells, umbo shape, position, numbers and shape of valve teeth was photographed. For molecular studies, DNA was extracted by using CTAB method and mitochondrial Cytochrome oxidase subunit gene segment (COI) was PCR and sequenced. results of morphological identification showed that all the samples are most likely belong to Callista genus, C.umbonella Species and from the Veneridae families. But sample NI9, the blast of sequences from sample present study showed the highest percentage of similarity with Turtonia minuta (DQ184850) from Veneridae family. however, the sample NI9 is most closely resembles with Costacallista impar species (DQ184808) species showed that this species is also belongs to Veneridae family. phylogenetic trees and alignment of these sequences in the gene bank was only able to prove their belonging to the veneridae family. results evolutionary tree topology for all three analyzes (Maximum parsimony, Maximum likelihood,) per 17 sequences showed that the nucleotide sequence of the COI gene, in all samples that presented as one species, are not the same. although, there were very similar morphology in the samples, the genetic differences among trees drawn between these samples revealed that it should be considered the possibility of creating new species and further studies and more detailed studies of morphology and molecular markers presented more decisive idea.

Population ecology of commercial marine Bivalves is the subject of many studies; conversely, information on the fresh water Bivalves is very scarce because the exploitation of these mollusks has never been important, except in limited areas and at certain periods. For example, in Northern America, pre-Columbian societies used freshwater mussels mainly for food. In the Tennessee Valley the shell of ten species are used in the button industry and exported to Japan for cultured pearl industry. In Rumania, the shells of freshwater Bivalves, nominally those of the genus Unio, are exploited for button industry and their soft tissues are used as fodder in poultry farming. According to Negus, her studies on Unio and Anodonta were the first on the growth rate and production of freshwater Bivalves. Magnin & Stanczykowska compared the results of their research on the production of fresh water Bivalves in Canadian lakes with those done by European authors due to lack of American studies on this subject. Most researches started from the 1960’s, when these mollusks were used as indicators of radioactive and stable pollutants. Even if the commercial value of the freshwater Bivalves is negligible, their role in the trophic ecology of certain environments is important.Freshwater Bivalves of south Caspian Sea lands are dispersed in major parts of this area. The swan mussel (Anodonta cygnea) is one of the most famous fresh water suspension feeders in comparison with other few fresh water mussels in Caspian Sea lands. It seems to be an active agent in natural water cleaning from suspended particles down to bacteria.

Bivalvia is one of the least studied classes of the Persian Gulf. A survey and molecular analysis was conducted to determine Bivalve species diversity in the Persian Gulf. To the best of our knowledge, this is the first report of barcoding data on Bivalves of the Persian Gulf. We examined 40 individuals representing 8 species, 6 genera and 5 families. We collected samples from Hengam, Larak and Qeshm Islands and Bandar Lengeh in Persian Gulf, Iran. After DNA extraction, mitochondrial 16S ribosomal DNA (16SrDNA) and Cytochrome Oxidase subunit I were amplified by polymerase chain reaction (PCR). Based on obtained 16SrDNA and COI gene sequences and maximum parsimony, neighbor joining and maximum likelihood trees of these genes there was no overlap between maximum Kimura 2-parameter distance among conspecifics. Most species formed agglutinate sequence units with a small amount of changes. Eventually, comparison of the 8 selected studied species with metadata from India, Brazil, Japan, China, and America exposed that these species in Persian Gulf are classified in sister clades with high bootstraps except Pinctada. Since there is not much work on Bivalves identification in the Persian Gulf, larger sampling and more research is needed to investigate mollusc diversity in this area.

The main purpose of this study was to find the absorption of Pb as heavy metal and cyclic aromatic hydrocarbons (PAHs) by Dreissena polymorpha under oil pollution. Totally, 130 samples with an average length range of 3. 5± 0. 7 cm and average weight range of 25. 5± 3 g were collected from the Tajan River estuary in Mazandaran province and transferred to the laboratory. Three stations were considered (Station 1: Oil Company Wastewater (OCW), Station 2: Car Oil Change Wastewater (COCW), Station 3: Agricultural Pumping Canal (APC)). The amounts of PAHs and lead metal uptake by Bivalves were measured during warm and cold water seasons. Tissue mass was isolated to measure PAHs at each station. In the cold season, the maximum concentration of lead was in the OCW station (0. 762± 0. 01 mg/L) and the lowest concentration was observed in APC station (0. 367± 0. 06 mg/L) (p<0. 05). In the warm season, the highest concentration of Pb was observed in COCW station (0. 558± 0. 02 mg/L) and the lowest was in APC station (0. 376± 0. 01 mg/L). There was no significant difference between OCW and COCW stations in the cold season (p>0. 05). Also, in the warm season, the highest concentration of Pb was observed in COCW station and the lowest concentration was in APC station (p<0. 05). During the experiment period, the highest absorbed concentration of Bivalves was recorded at OCW station (328. 39 ± 1. 33 ng/dw) and the lowest concentration was in APC station (62. 85± 8. 9 ng/dw). Moreover, there was a significant difference between PAHs concentration of OCW station with other stations (p<0. 05). The concentration of the compounds measured in February was higher than in August due to the precipitation and flooding of the route to the Bivalve stations. Heavy compounds were also more concentrated than lighter compounds. Finally, it can be concluded that this Bivalve can be used as an appropriate biomarker for monitoring oil compounds in the environment.

Microplastics are small pieces of plastic waste (less than 5 mm), which are found along the coast, the sea level and the bedding. The present study examines the frequency, distribution, and forms of microplastics in Bivalve tissues and sediments sampled on the coast of Bandar Lengeh. Microplastic separation was performed by spectral density and spectrophotometric (FT-IR) and (SEM-ED) methods for polymer detection. The microplastics found were varied colors including black, white, transparent, red, pink and green. Using the obtained data, at the Lengeh port stations, the average total number of extracted microplasms per shell was 3. 93 and the number of microplastics in Bandar-Lengeh sediments was 34. 5 ± 0. 17. The most commonly found polymers were polyethylene (PE), polyethylene terephthalate (PET) and nylon. The most abundant type of micro-plastics isolated from Pinctada radiata, microfibers and fragments were extracted from fiber and film sediments. The present study can provide useful information for further research as well as forensic monitoring and monitoring of this contaminant in the Persian Gulf marine environment.

Polychlorinated biphenyls (PCBs) are known amongst the most dangerous toxicants entering the coastal marine waters from various polluting sources. Even the smallest PCBs doses are capable to change physiological and biochemical processes exerting toxic, mutagenic and carcinogenic effects. So, the aim of this study was to analyze the impact of PCBs at 1, 100, 1000 µg/L on oxidative stress parameters (level of oxidized proteins (neutral aldehydes and ketones, basic aldehydes and ketones) and lipid peroxidation), antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT)) and cholinesterase (ChE) activity in the hepatopancreas of mussel Mytilus galloprovincialis during 5 days’ of the toxicological experiment. Level of all forms of the oxidized proteins was found significantly increased at 100 µg/L and 1000 µg/L (+50-78% and +150-282%, respectively) compared to the control (p<0.05). Level of lipid peroxidation was considerably higher at 1, 100, 1000 µg/L (+59%, +134%, +269%, respectively) compared to the control (p<0.05). SOD activity significantly raised at 1, 100, 1000 µg/L (+63%, +200%, +118%, respectively) compared to the control (p<0.05), while CAT activity reduced at 1000 µg/L compared to the control, 1 µg/L and 100 µg/L (-29%, -66%, -40%, respectively) (p<0.05). ChE activity was found lower at 1, 100, 1000 µg/L (-60%, -93%, -30%, respectively) compared to the control (p<0.05). Possible mechanisms of M. galloprovincialis biochemical response to PCBs are discussed. Studied biochemical parameters can be suitable biomarkers for evaluating the toxicity of PCBs and M. galloprovincialis can be used as a bioindicator in the monitoring of marine ecosystems contaminated with these pollutants.

Pteriomorpha, Heterodonta, Paleoheterodonta and Anomalodesmata Bivalves from the Kazhdumi Formation of the Geno and Gerash sections in the southeast of Zagros Mountains are studied here. In order to this research, Bivalve speies are identified and described as follow: Arctica angulata, Birostrina concentrica, Ceratostreon flabellatum, Crassatella manzourensis, Flaventia belviderensis, Granocardium productum, Gyrostrea delettrei, Illymatogyra africana, Mytiloides concentricus, Neithea dutrugei, Neithea sp. 1, Neithea sp. 2, Paraesa faba, Pinna cfcretacea, Pholadomya fabrina, Pholadomya vignesi, Protocardia hillana, Pterotrigonia scabra, Rhynchostreon suborbiculatum, Tenea delettrei, Venericardia deserti. Many of these species excluding Ceratostreon flabellatum, Illymatogyra africana, Neithea dutrugei and Pterotrigonia scabraare reported for the first time from Iran. Kazhdumi Formation disconformably overlies the top of the Dariyan Formation and underlies the Gurpi Formation.

As a RAMSAR site (no.1204), Ashtamudi Lake has very productive and significant ecosystem services. Currently, the lake is being threatened by severe pollution stress, especially with heavy metals. Heavy metal pollution is a great concern of matter as it enters in the bioaccumulation and  bio-magnification processes of the aquatic food chain. The present study seasonally investigated the bioaccumulation   of seven heavy metals (Pb, Zn, Fe, Cu, Cr, Cd and Co) in the body tissues of an edible Bivalve, Marcia recens, from three sampling stations (viz. Neendakara, Kureepuzha and Asramam) of the lake during the study period in 2019. The results showed that, as per the standard permissible limits (FAO/USEPA, 1989), some of the metal accumulations  were extremely high in the Bivalve tissues. Highest Metal Pollution Index was observed in station Ⅱ. There were significant spatial and temporal variations in the accumulation of heavy metals in the the examined Bivalve. Two way ANOVA analysis also reveals a statistically significant differences (p<0.5), in the heavy metal accumulation in the Bivalve,  among the stations as well as seasons. The continual exposure to even a relatively low levels of these metals by regular consumption of contaminated Bivalves, may entail adverse health issues. Implementation of appropriate scientific and sustainable conservation strategies will ensure the health of the estuaries and the sustainability of bio-resources.

Crude oil is comprised of four groups: Saturates Aromatics, Resins and Asphaltenes. Oil pollution has irreversible effects on marine ecosystems. Therefore paying attention to oil pollution and the management of the ports is very important. Biodegradation of oil derivatives is more effective, more powerful and more economically efficient method for remediation in polluted sites rather than physicochemical methods. In this study, for isolation of crude oil degrading bacteria, seawater and mussels were collected from Persian Gulf. Enumeration of bacteria were done in collected samples. Isolated bacteria were identified by biochemical and molecular tests. Crude oil biodegradation for each strain was assessed by spectrophotometer and Gas Chromatography (GC). The results of this study show that the quantity and biodiversity of heterotrophic and crude oil degrading bacteria in Crassostrea gigas mussels was higher than surrounding environment (seawater). Eleven crude oil degrading bacteria were isolated from Persian Gulf, 7 strains were identified biochemically and 2 strains were selected on the basis of higher degradation. These isolated strains were identified as Shewanella and Alcanivorax. The half percentage of oil was removed by these strains in 15 days of incubation. These bacteria could be used for cleanup oil-polluted marine areas after more research and field observation.