Zoantharians of the Persian Gulf (PG) experience periods of anomalous high temperature, irradiance and desiccation. Their survival largely relies on the symbiotic relationship with single celled dinoflagellates of the genus Symbiodinium. However, the phylogeny of symbionts of zoantharians has not been investigated in the region. In this study, the second internal transcribed spacer region of ribosomal DNA (ITS2) was used to recognize in hospite populations of Symbiodinium in Palythoa aff. mutuki, Palythoa tuberculosa and Zoanthus sansibaricus colonies from Hengam, Kish, Larak, and Qeshm Islands, in the PG. The results showed subclade D1–4 and a variant of A1, were the most prevalent subclades of Symbiodinium. Predominance of stress tolerant subclade D1–4 and putatively radiation tolerant variant of A1 of Symbiodinium in zoantharian species might suggest an adaptation strategy to the extreme physical environment of the PG.

The concentrations of polybrominated diphenyl ethers (PBDEs) were determined in the surficial sediments of Bushehr coasts, the Persian Gulf. Eighteen samples were collected from 6 sites at distances of 500, 1000 and 1500m from the coast. PBDEs were detected in all the samples, indicating their widespread occurrence in marine sediments of the studied area. BDE-209 and ∑7PBDEs were in the range of n.d. (not detected) to 6.29ngg−1 and n.d. to 0.62ngg−1 dw, respectively. The studied area can be classified as the region with the minimal contamination values reported globally as yet. The concentrations of PBDEs were lower than the Canadian benchmarks, and risk quotient assessments demonstrated low ecological risk. BDE-183 and then BDE-153 were the congeners with the highest detection frequencies in the stations, confirming extensive occurrence of Octa-mix in the studied area.

The present study aimed to geochemical speciation of metals in the surface sediments of the northern Persian Gulf. Metal contents in the sediment were observed in the order: Al>Fe>Cr>Ni>V>Zn>Cu>Co>As>Pb>Cd. The results of sequential extraction procedure revealed that all metals were predominantly associated with the residual fraction. Among the metals, Cu and As exhibited higher bioavailability. The risk assessment code (RAC) indicated that Cu, As and Cd had medium environmental risk at some sampling sites. Based on enrichment factor (EF), Cd and As had moderate to significant enrichment.

Coral reefs of the United Arab Emirates were once extensive, but have declined dramatically in recent decades. Marine management and policy have been hampered by outdated and inaccurate habitat maps and habitat quality information. We combined existing recent datasets with our newly mapped coral habitats to provide a current assessment of nation-wide extent, and performed quantitative surveys of communities at 23 sites to assess coral cover and composition. Over 132km2 of coral habitat was mapped, averaging 28.6±3.8% live coral cover at surveyed sites. In the Arabian Gulf low cover, low richness Porites dominated communities characterized western Abu Dhabi, while reefs northeast of Abu Dhabi city generally contained higher richness and cover, and were dominated by merulinids (formerly faviids). Distinct communities occur in the Sea of Oman, where cover and richness were low. We provide management recommendations to enhance conservation of vulnerable coral reefs in the UAE.

Determining how coral ecosystems are structured within extreme environments may provide insights into how coral reefs are impacted by future climate change. Benthic community structure was examined within the Persian Gulf, and adjacent Musandam and northern Oman regions across a 3-year period (2008–2011) in which all regions were exposed to major disturbances. Although there was evidence of temporal switching in coral composition within regions, communities predominantly reflected local environmental conditions and the disturbance history of each region. Gulf reefs showed little change in coral composition, being dominated by stress-tolerant Faviidae and Poritidae across the 3years. In comparison, Musandam and Oman coral communities were comprised of stress-sensitive Acroporidae and Pocilloporidae; Oman communities showed substantial declines in such taxa and increased cover of stress-tolerant communities. Our results suggest that coral communities may persist within an increasingly disturbed future environment, albeit in a much more structurally simple configuration.

Numerical simulation of oil slick movement with respect to tidal factors and wind effects was performed in order to counteract oil pollution in the Persian Gulf. First, a flow model was invoked with respect to water level fluctuations. The main tidal constituents were applied to the model using the initial conditions of water level variations in the Hormuz Strait near the Hangam Island. The movement of oil pollution was determined due to wind, tide and temperature effects and confirmed by applying a verified field results. Simulations were focused near an important terminal in the Persian Gulf, Assaluyeh Port. The results were led to preparing a risk-taking map in a parallel research for the Persian Gulf.

A severe bleaching event affected coral communities off the coast of Abu Dhabi, UAE in August/September, 2012. In Saadiyat and Ras Ghanada reefs ~40% of the corals showed signs of bleaching. In contrast, only 15% of the corals were affected on Delma reef. Bleaching threshold temperatures for these sites were established using remotely sensed sea surface temperature (SST) data recorded by MODIS-Aqua. The calculated threshold temperatures varied between locations (34.48°C, 34.55°C, 35.05°C), resulting in site-specific deviations in the numbers of days during which these thresholds were exceeded. Hence, the less severe bleaching of Delma reef might be explained by the lower relative heat stress experienced by this coral community. However, the dominance of Porites spp. that is associated with the long-term exposure of Delma reef to elevated temperatures, as well as the more pristine setting may have additionally contributed to the higher coral bleaching threshold for this site.

Symbiotic associations are complex partnerships that can lead to new metabolic capabilities and the establishment of novel organisms. The diversity of these associations is very broad and there are still many mysteries about the origin and the exact relationship between the organisms that are involved in a symbiosis. The aim of the present study is to find symbiotic crude-oil degrading bacteria in the mussels that collected from the Persian Gulf. Fifteen crude-oil degrading bacteria were isolated from Mactra stultorum mussel that collected from oil contaminated area at Persian Gulf. According to high growth rate on crude oil five strains were selected from 15 isolated strains for more study. Determination of the nucleotide sequence of the gene encoding 16S rRNA show that these isolated strains belong to: Alcanivorax dieselolei strain BHA25, Idiomarina baltica strain BHA28, A. dieselolei strain BHA30, Alcanivorax sp. strain BHA32 and Vibrio azureus strain BHA36. Analysis of remaining of crude oil by Gas Chromatography (GC) confirmed that these strains can degrade: 64%, 63%, 71%, 58% and 75% of crude oil respectively.

Internal macrobioeroders and their erosion rate in three live and dead coral genera (Favia, Platygyra and Porites) from the intertidal zone of the Hormuz Island were studied by collecting five live and five dead colonies from each genus, from which 4mm cross-sections were cut and photographed. Photos were analyzed using the Coral Point Count with Excel extensions. Totally, 9 taxa were identified: four bivalve species, one sponge, three polychaetes, and one barnacle. Bioerosion rate did not significantly differ among the three live corals, but among the dead ones only Porites was significantly more eroded than Favia. Sponge had the highest role in the erosion of the dead Platygyra, while barnacles were the most effective eroding organism in the live Platygyra. Polychaetes, followed by bivalves, were the most destructive bioeroders on the dead and live Porites. Further, none of the bioeroding organisms had selectively chosen either the dead or live Favia.

Coral populations in the Persian Gulf have a reputation for being some of the toughest in the world yet little is known about the energetic constraints of living under temperature and salinity extremes. Energy allocation for sexual reproduction in Gulf corals was evaluated relative to conspecifics living under milder environmental conditions in the Oman Sea. Fecundity was depressed at Gulf sites in two Indo-Pacific merulinid species (Cyphastrea microphthalma and Platygyra daedalea) but not in a regionally endemic acroporid (Acropora downingi). Gulf populations of each species experienced high temperature bleaching at the onset of gametogenesis in the study but fecundity was only negatively impacted in P. daedalea and A. downingi. Large population sizes of C. microphthalma and P. daedalea in the Gulf are expected to buffer reductions on colony-level fecundity. However, depleted population sizes of A. downingi at some Gulf sites equate to low reef-wide fecundity and likely impede outcrossing success.