Marine Bacterial Community Structures of Selected Coastal Seawater and Sediment Sites in Qatar

Severe environmental conditions can have a diverse impact on marine microorganisms, including bacteria. This can have an inevitable impact on the biofouling of membrane-based desalination plants. In this work, we have utilized indicator bacteria such as total coliform, fecal coliform, and Pseudomonas aeruginosa, as well as 16S rRNA sequencing, to investigate the impact of environmental conditions and spatial variations on the diversity of bacterial communities in the coastal waters and sediments from selected sites in Qatar. The concentration levels of indicator bacteria were affected by increasing temperatures and pH, and by decreasing salinity of seawater samples. Diversity indices and the molecular phylogeny demonstrated that Proteobacteria, Bacteroidetes, and Cyanobacteria were the dominant phyla in all locations. The most abundant operational taxonomic units (OTUs) at the family level were from Flavobacteriaceae (27.07%, 4.31%) and Rhodobacteraceae (22.51%, 9.86%) in seawater and sediment, respectively. Alphaproteobacteria (33.87%, 16.82%), Flavobacteria (30.68%, 5.84%), and Gammaproteobacteria (20.35%, 12.45%) were abundant at the species level in both seawater and sediment, while Clostridia (13.72%) was abundant in sediment only. The results suggest that sediment can act as a reservoir for indicator bacteria, with higher diversity and lower abundance compared to seawater.

K. Habeebullah S, Ali AK, Al-Zakri WM. Diversity and spatiotemporal variations in bacterial and archaeal communities within Kuwaiti territorial waters of the Northwest Arabian Gulf

Kuwaiti territorial waters of the northwest Arabian Gulf represent a unique aquatic ecosystem prone to various environmental and anthropogenic stressors that pose significant constraints on the resident biota which must withstand extreme temperatures, salinity levels, and reducing conditions, among other factors to survive. Such conditions create the ideal environment for investigations into novel functional genetic adaptations of resident organisms. Firstly, however, it is essential to identify said organisms and understand the dynamic nature of their existence. Thus, this study provides the first comprehensive analysis of bacterial and archaeal community structures in the unique waters of Kuwait located in the Northwest Arabian Gulf and analyzes their variations with respect to depth, season, and location, as well as their susceptibility to changes in abundance with respect to various physicochemical parameters. Importantly, this study is the first of its kind to utilize a shotgun metagenomics approach with sequencing performed at an average depth of 15 million paired end reads per sample, which allows for species-level community profiling and sets the framework for future functional genomic investigations. Results showed an approximately even abundance of both archaeal (42.9%) and bacterial (57.1%) communities, but significantly greater diversity among the bacterial population, which predominantly consisted of members of the Proteobacteria, Cyanobacteria, and Bacteroidetes phyla in decreasing order of abundance. Little to no significant variations as assessed by various metrics including alpha and beta diversity analyses were observed in the abundance of archaeal and bacterial populations with respect to depth down the water column. Furthermore, although variations in differential abundance of key genera were detected at each of the three sampling locations, measurements of species richness and evenness revealed negligible variation (ANOVA p<0.05) and only a moderately defined community structure (ANOSIM r2 = 0.243; p>0.001) between the various locations. Interestingly, abundance of archaeal community members showed a significant increase (log2 median ratio of RA = 2.6) while the bacterial population showed a significant decrease (log2 median ratio = -1.29) in the winter season. These findings were supported by alpha and beta diversity analyses as well (ANOSIM r2 = 0.253; p>0.01). Overall, this study provides the first in-depth analysis of both bacterial and archaeal community structures developed using a shotgun metagenomic approach in the waters of the Northwest Arabian Gulf thus providing a framework for future investigations of functional genetic adaptations developed by resident biota attempting to survive in the uniquely extreme conditions to which they are exposed.

The Reproductive Capacities of the Calanoid Copepods Parvocalanus crassirostis and Acartia pacifica under Different pH and Temperature Conditions

The increasing atmospheric CO₂ concentrations and warming of marine waters have encouraged experiments on multi-stressor interactions in marine organisms. We conducted a multigenerational experiment to assess reproductive capacities regarding egg production in calanoid copepods Parvocalanus crassirostis and Acartia pacifica under different pH and temperature conditions. The experimental set-up allowed assessing the tandem effect of warming and acidification on the number of eggs produced by healthy copepod pairs under two pH conditions of 8.20 and 7.50 (hard selection) as well as with a gradual reduction of 0.05 pH units at each generation (soft selection). The results are quite interesting, with very diverse performance across temperatures. The number of eggs produced under hard selection was higher at pH 8.20 compared to pH 7.50 for both species, with the maximum number of eggs produced at 24-28 °C, whereas under soft selection, there was no significant difference in the egg production rate at 24-28 °C across generations and there was an improvement in the number of eggs produced at 8-16 °C. The results provide evidence that in a future ocean scenario of lower pH and higher temperature, the two species, and possibly the copepod population at large, might not decrease. Copepod populations might be resilient, and the transcriptomic evidence of adaptation to increased temperature and lower pH is a ray of hope. We believe further studies are needed to provide more robust datasets to underpin the hypothesis of adaptation to climate change.

Ocean Acidification-Mediated Food Chain Transfer of Polonium between Primary Producers and Consumers

Phytoplankton and zooplankton are key marine components that play an important role in metal distribution through a food web transfer. An increased phytoplankton concentration as a result of ocean acidification and warming are well-established, along with the fact that phytoplankton biomagnify 210Po by 3−4 orders of magnitude compared to the seawater concentration. This experimental study is carried out to better understand the transfer of polonium between primary producers and consumers. The experimental produced data highlight the complex interaction between the polonium concentration in zooplankton food, i.e. phytoplankton, its excretion via defecated fecal pellets, and its bioaccumulation at ambient seawater pH and a lower pH of 7.7, typical of ocean acidification scenarios in the open ocean. The mass of copepods recovered was 11% less: 7.7 pH compared to 8.2. The effects of copepod species (n = 3), microalgae species (n = 3), pH (n = 2), and time (n = 4) on the polonium activity in the fecal pellets (expressed as % of the total activity introduced through feeding) was tested using an ANOVA 4. With the exception of time (model: F20, 215 = 176.84, p < 0.001; time: F3 = 1.76, p = 0.16), all tested parameters had an impact on the polonium activity (copepod species: F2 = 169.15, p < 0.0001; algae species: F2 = 10.21, p < 0.0001; pH: F1 = 9.85, p = 0.002) with complex interactions (copepod x algae: F2 = 19.48, p < 0.0001; copepod x pH: F2 = 10.54, p < 0.0001; algae x pH: F2 = 4.87, p = 0.009). The experimental data underpin the hypothesis that metal bioavailability and bioaccumulation will be enhanced in secondary consumers such as crustacean zooplankton due to ocean acidification.

Assessment of Sargassum sp., Spirulina sp., and Gracilaria sp. as Poultry Feed Supplements: Feasibility and Environmental Implications

Eutrophication, coupled with ocean acidification and warming, results in an increased concentration of marine algae, severely impacting some regions. Several algae are a rich source of protein and minerals. Marine algae are rich in bioactive molecules with antioxidants, anti-inflammatory, anti-fungal, and antimicrobial properties. These properties make them attractive for usage in the pharmaceutical industry. This study evaluated Sargassum sp., Spirulina sp., and Gracilaria sp. for use as poultry feed. Chemical analyses show that crude protein (CP) in analyzed algae was 9.07–63.63%, with a fiber content of 0.15–17.20%, and a crude fat range of 0.152–2.11%, suggesting that algae can partially substitute imported protein sources used for poultry feed. A rapid impact assessment matrix (RIAM) was used to assess the environmental footprint of algae usage in poultry feed. The environmental assessment results show promising opportunities to help harvest the algae from the marine area. However, the feasibility of establishing outdoor algal ponds is not environmentally viable in the Middle East.

Antibiotic Resistance Genes Associated with Marine Surface Sediments: A Baseline from the Shores of Kuwait

Marine sediments are a sink for antibiotic resistance genes (ARGs) and antibiotic-resistant microbes (ARMs). Wastewater discharge into the aquatic environment is the dominant pathway for pharmaceuticals reaching aquatic organisms. Hence, the characterization of ARGs is a priority research area. This baseline study reports the presence of ARGs in 12 coastal sediment samples covering the urban coastline of Kuwait through whole-genome metagenomic sequencing. The presence of 402 antibiotic resistance genes (ARGs) were recorded in these samples; the most prevalent were patA, adeF, ErmE, ErmF, TaeA, tetX, mphD, bcrC, srmB, mtrD, baeS, Erm30, vanTE, VIM-7, AcrF, ANT4-1a, tet33, adeB, efmA, and rpsL, which showed resistance against 34 drug classes. Maximum resistance was detected against the beta-lactams (cephalosporins and penam), and 46% of genes originated from the phylum Proteobacteria. Low abundances of ESKAPEE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumanii, Pseudomonas aeruginosa, Enterobacter sps., and Escherichia coli) were also recorded. Approximately 42% of ARGs exhibited multiple drug resistance. All the ARGs exhibited spatial variations. The major mode of action was antibiotic efflux, followed by antibiotic inactivation, antibiotic target alteration, antibiotic target protection, and antibiotic target replacement. Our findings supported the occurrence of ARGs in coastal marine sediments and the possibility of their dissemination to surrounding ecosystems.

Communities of culturable yeasts and yeast-like fungi in oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar

This report is the first investigation of yeast biodiversity from the oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar. Yeasts and yeast-like fungi, were cultured from seawater sampled at 13 coastal areas surrounding Qatar over a period of 2 years (December 2013-September 2015). Eight hundred and forty-two isolates belonging to 82 species representing two phyla viz., Ascomycota (23 genera) and Basidiomycota (16 genera) were identified by molecular sequencing. The results indicated that the coastal waters of the Qatari oligotrophic marine environment harbor a diverse pool of yeast species, most of which have been reported from terrestrial, clinical and aquatic sources in various parts of the world. Five species, i.e., Candida albicans, C. parapsilosis, C. tropicalis, Pichia kudriavzevii and Meyerozyma guilliermondii (n = 252/842; 30% isolates) are known as major opportunistic human pathogens. Fifteen species belonging to nine genera (n = 498/842; 59%) and 12 species belonging to seven genera (n = 459/842; 55%) are hydrocarbon degrading yeast and pollution indicator yeast species, respectively. Ascomycetous yeasts were predominant (66.38%; 559/842) as compared to their basidiomycetous counterparts (33.6%; 283/842). The most isolated yeast genera were Candida (28%; 236/842) (e.g., C. aaseri, C. boidinii, C. glabrata, C. intermedia, C. oleophila, C. orthopsilosis, C. palmioleophila, C. parapsilosis, C. pseudointermedia, C. rugopelliculosa, C. sake, C. tropicalis and C. zeylanoides), Rhodotorula (12.7%; 107/842), Naganishia (8.4%; 71/842), Aureobasidium (7.4%; 62/842), Pichia (7.3%; 62/842), and Debaryomyces (6.4%; 54/842). A total of eleven yeast species ( n = 38) isolated in this study are reported for the first time from the marine environment. Chemical testing demonstrated that seven out of the 13 sites had levels of total petroleum hydrocarbons (TPH) ranging from 200 to 900 µg/L, whereas 6 sites showed higher TPH levels (> 1000-21000 µg/L). The results suggest that the yeast community structure and density are impacted by various physico-chemical factors, namely total organic carbon, dissolved organic carbon and sulphur.

Petroleum hydrocarbon pollution in sediments from the Gulf and Omani waters: Status and review

This review presents the spatio-temporal distribution of petroleum hydrocarbons including total petroleum hydrocarbon (TPH), total organic carbon (TOC), total aliphatics, unresolved complex mixture (UCM), polycyclic aromatic hydrocarbons (PAHs), and total aromatic hydrocarbons in marine sediments of the Gulf (Iraq, Iran, Kuwait, Saudi Arabia, Bahrain, Qatar, United Arab Emirates and Oman). The TPH ranged between 0.134 and 48,018 μg g^-1 dw where 10-15 μg g^-1 dw was considered as a background concentration. The TOC levels were between 0.04 and 14.96% with a mean concentration of 1.154 ± 0.523%. Total aliphatic hydrocarbon levels were reported between 0.1 and 76 μg g^-1, the 2005 levels that had the largest spatial coverage were between 0.1 and 4.4 μg g^-1. The unresolved complex mixture was very variable post Gulf War but by 2005 most of the Gulf War artifacts had decreased and the levels were between 1.5 and 73.5 μg g^-1. The ƩPAHs in bottom sediments by 2005 were between 0.3 and 3450 ng g^-1. The total aromatics were limited in spatial extent and varied between 1.0 and 14,000 μg g^-1. Most of the locations with elevated contamination levels were near point sources, e.g. oil facilities and ports, and these sites could be categorized as chronically contaminated by oil. This review highlights the paucity of the data both in terms of the spatial extent and temporal coverage, and with several Gulf states undergoing large-scale coastal developments and offshore oil exploration, it will be prudent to undertake regular monitoring of the petroleum hydrocarbons to ensure effective ecosystem functioning as well as seafood and drinking water safety in the Gulf region. The spatial distribution also highlights the lack of uniformity in assessments and the need to support marine pollution assessments in the Gulf countries.

Ciguatera in the Indian Ocean with Special Insights on the Arabian Sea and Adjacent Gulf and Seas: A Review

The dinoflagellates of the genus Gambierdiscus are found in almost all oceans and seas between the coordinates 35° N and 35° S. Gambierdiscus and Fukuyoa are producers of ciguatoxins (CTXs), which are known to cause foodborne disease associated with contaminated seafood. The occurrence and effects of CTXs are well described in the Pacific and the Caribbean. However, historically, their properties and presence have been poorly documented in the Indian Ocean (including the Bay of Bengal, Andaman Sea, and the Gulf). A higher occurrence of these microorganisms will proportionately increase the likelihood of CTXs entering the food chain, posing a severe threat to human seafood consumers. Therefore, comprehensive research strategies are critically important for developing effective monitoring and risk assessments of this emerging threat in the Indian Ocean. This review presents the available literature on ciguatera occurrence in the region and its adjacent marginal waters: aiming to identify the data gaps and vectors.

An assessment of microplastics threat to the marine environment: A short review in context of the Arabian/Persian Gulf

Microplastics are recognised as a (persistent) pollutant and are believed to be ubiquitous in the marine environment. The importance of this issue is evident from the large number of technical publications and research efforts within the past decade. However, the Arabian (Persian) Gulf region has few reported datasets in spite of being an area with excessive plastic use and a hefty generation rate of plastic solid waste. This communication aims at stimulating a discussion on this topic focusing on the available regional and international datasets, along with the environmental conditions that are likely to contribute to the disintegration and transport of the plastic debris rendering it as microplastic. This work also highlights some of the constraints in sampling techniques, identification methods, and the reported units of microplastics. Most studies employ neuston nets of variable dimensions that samples different thicknesses of surface water, which also posses a major constraint in standardising field sample collection. Extrapolation of a trawl to units such as particles.km^-2 without considering the fact that neuston nets collect three-dimensional samples, is also another aspect discussed in this communication. This study also intends to initiate a discussion on standardising the practices across the region to enable an intercomparison of the reported data. In addition, it calls for a comprehensive assessment using the standardized methodology for putting a mitigation plan for microplastics as a potential threat detected in environmental sinks.

Assessment of Climate Change Impacts on Sea Surface Temperatures and Sea Level Rise—The Arabian Gulf

The Arabian Gulf is one of the regions in the world experiencing major changes due to increased economic growth rates and development practices. As a shallow water body within a hot desert, the Gulf is exposed to obvious warming in the sea surface temperatures (SST). Remotely sensed SST data were utilized to estimate decadal change in SST with a focus on coral reef locations. There is a positive trend in monthly time series SSTs, with a maximum value of about 0.7 °C/decade for the western side of the Gulf. This high trend of SST is associated with significant coral reef bleaching and it coincides with major climate/ocean interactions. Most of the Arabian countries along the Gulf have coastal developments at low-land areas of high vulnerability to sea level rise. Digital elevation models showed that there are more than 3100 km2 of coastal areas that occur at 1 m level along the Arabian countries of the Gulf. Coastal protection and conservation measures are crucial to protect low-lying coasts of urban use.

Contamination and ecological risk assessment of heavy metals pollution from the Shalateen coastal sediments, Red Sea, Egypt

To assess the contamination and ecological risk assessment of the Shalateen coastal sediments, Red Sea, Egypt, 35 samples were collected to analyze Cu, Sr, Zn, Cd, Pb, Fe, Co, Ni, Mn, and total organic matter with an atomic absorption spectrophotometer. Several indices were calculated to estimate the contamination levels. The results indicated the following order of metal concentrations: Fe > Sr > Mn > Zn > Ni > Pb > Cu > Co > Cd, and revealed that the investigated sediments are highly enriched and contaminated with Sr, Cd, Pb and Zn. Statistical analyses subdivided the elements into Fe and Mn from natural sources, Sr, Cd, Pb and Zn from anthropogenic sources, and Ni, Cu and Co from combined natural and anthropogenic sources. The average Pb and Cd concentrations are considerably higher compared to the Caspian Sea, Indian Ocean, northern Red Sea, background shale, and continental crust. Possible sources of pollutants are fishing operations, antifouling paints, runoff, desalination plants, industries and dissolution of carbonate sediments.

Response of Corals Acropora pharaonis and Porites lutea to Changes in pH and Temperature in the Gulf

Coral reefs are harboring a large part of the marine biodiversity and are important ecosystems for the equilibrium of the oceans. As a consequence of anthropogenic CO2 emission, a drop in pH and an increase in seawater temperature is observed in the Gulf coastal waters that potentially threaten coral assemblages. An experimental study was conducted on two species of corals to assess the effect of ocean warming and ocean acidification on the net calcification rate. Two pH conditions 8.2 and 7.5 and three temperatures, 22.5, 27.5 and 32.5 °C, were considered. Net calcification rates were measured using 45Ca radiotracer. Both temperature and pH had a significant effect on net calcification rates following a similar pattern for both species. The highest calcification rate was observed at low temperature and high pH. Increased temperature and decreased pH led to a decrease in net calcification rates. An interactive effect was observed as the effect of pH decreased with increasing temperature. However, the two species of coral were able to calcify in all the tested combination of temperature and pH suggesting that they are adapted to short term changes in temperature and pH. Ability to calcify even at a high temperature of 32.5 °C that is identical to the summertime Gulf seawater temperature under both the ambient and low pH condition with no mortalities, raises a question: are these corals adapted to high seawater temperatures and low pH? More in-depth assessments will be required to confirm if this is an adaptation to higher temperatures in Persian Gulf corals.

Assessment of seawater pollution of the Al-Khafji coastal area, Arabian Gulf, Saudi Arabia

Twenty-seven coastal seawater samples were collected to assess seawater pollution and document the possible sources at Al-Khafji coastal area, Arabian Gulf, Saudi Arabia. Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, Hg, and Pb were analyzed using inductively coupled plasma mass spectrometer (ICP-MS). The results revealed the following order of concentration: Sr > Ni > V > Cu > As > Zn > Al > Fe > Cr > Mn > Pb > Co > Cd > Hg. Most metals exhibited a fluctuated pattern within the studied sites without obvious trend, except Sr and Ni, which showed a fluctuated pattern with increasing trend southwards. The studied sites were classified into polluted, slightly polluted, and non-polluted ones based on HCA analyses. The higher levels of metals in the seawater of the polluted sites may be attributed to atmospheric input and oil spills from underwater pipelines, off offshore oil wells, loading and handling operations, oil terminals, and oil tanker incidents in the Arabian Gulf in general and many other anthropogenic sources in Al-Khafji area in particular such as desalination plant, landfilling due to new constructions, industrial sewage, and the Khafji Joint Operations (KJO).

Microplastics contamination in molluscs from the northern part of the Persian Gulf

Microplastics (MPs) are well-known emerging contaminants in the marine environment. A key route by which MPs can directly affect marine life is through ingestion. The objective of the present study was to evaluate the occurrence of MPs in marine life and seafood for human consumption in the Persian Gulf. We conducted a whole body analysis of MP (between 10 and 5000 μm in diameter) abundance in five species of molluscs with different feeding strategies, including both gastropods and bivalves from the littoral zone of the Iranian coast of the Persian Gulf. The mean number of total encountered MPs in all species ranged from 0.2 to 21.0 particles per g of soft tissue (wet weight) and from 3.7 to 17.7 particles per individual. Overall, microfibres followed by fragments were the most common type of MP isolated in each species (respectively > 50% and ≈26%). Film (≈14%) and pellets (≈2%) were less commonly observed. The observed MPs were classified into three size groups (ca. 10-25 μm, 25-250 μm and 250-5000 μm), and 37-58% of MPs fell into the smallest size group. Fourier transform infrared (FT-IR) analysis confirmed the presence of polyethylene (PE), polyethylene terephthalate (PET), and nylon (PA). Our results indicated that molluscan shellfish from the Persian Gulf contain MPs, with higher concentrations in a predatory species, suggesting trophic transfer of MPs in the food web. The consumption of edible species may be a source of human microplastic intake. We compared our results with those previously reported for other regions of the world and identified the need for further studies in the Persian Gulf.

The changing dynamics of coral reef science in Arabia

Six percent of the world's coral reefs occur around the Arabian Peninsula, providing a valuable ecological, economic and scientific resource for the nations bordering its shores. We provide the first region-wide assessment of the current status and historical trends in coral reef research, focusing on research in the Red Sea, Arabian Sea, and Arabian Gulf. In total, 633 regional reef publications have been produced since the 1930s, covering a wide variety of themes and taxa. Our results show a great deal of commonality in regional reef research, but also highlight important differences in research among the various seas as well as knowledge gaps that represent opportunities for future research. A regionally-integrated approach to future research is essential. There is a growing need for large-scale research to guide management of reefs and their stressors, as these operate at much larger scales than the national borders within which most research currently occurs.

Baseline concentrations of strontium and 90Sr in seawater from the northern Gulf

Baseline concentration of strontium and Sr-90 in Gulf is presented. The strontium concentration is much higher than reported for other oceanic waters, while the Sr-90 concentration is low at 0.7-1.0 mBq l(-1), that represents the background level following nuclear tests and can be used as an effective tracer in case of any radioactive release in the region. The strontium concentration is primarily related to the increasing salinity off the Gulf coast.

Future seagrass beds: can increased productivity lead to increased carbon storage?

While carbon capture and storage (CCS) is increasingly recognised as technologically possible, recent evidence from deep-sea CCS activities suggests that leakage from reservoirs may result in highly CO2 impacted biological communities. In contrast, shallow marine waters have higher primary productivity which may partially mitigate this leakage. We used natural CO2 seeps in shallow marine waters to assess if increased benthic primary productivity could capture and store CO2 leakage in areas targeted for CCS. We found that the productivity of seagrass communities (in situ, using natural CO2 seeps) and two individual species (ex situ, Cymodocea serrulata and Halophila ovalis) increased with CO2 concentration, but only species with dense belowground biomass increased in abundance (e.g. C. serrulata). Importantly, the ratio of below:above ground biomass of seagrass communities increased fivefold, making seagrass good candidates to partially mitigate CO2 leakage from sub-seabed reservoirs, since they form carbon sinks that can be buried for millennia.

The growth of coral reef science in the Gulf: a historical perspective

Coral reef science has grown exponentially in recent decades in the Gulf. Analysis of literature from 1950 to 2012 identified 270 publications on coral reefs in the Gulf, half of which were published in just the past decade. This paper summarizes the growth and evolution of coral reef science in the Gulf by examining when, where and how research has been conducted on Gulf reefs, who conducted that research, and what themes and taxa have dominated scientific interest. The results demonstrate that there has been significant growth in our understanding of the valuable coral reefs of the Gulf, but also highlight the fact that we are documenting an increasingly degraded ecosystem. Reef scientists must make a concerted effort to improve dialogue with regional reef management and decision-makers if we are to stem the tide of decline in coral reefs in the Gulf.

Assessment and management of heavy metal pollution in the marine environment of the Arabian Gulf: a review

The Arabian Gulf is considered among the highest anthropogenically impacted regions in the world. Heavy metals contamination in coastal and marine environments is becoming an increasingly serious threat to both the naturally stressed marine ecosystems and humans that rely on marine resources for food, industry and recreation. Heavy metals are introduced to coastal and marine environments through a variety of sources and activities including sewage and industrial effluents, brine discharges, coastal modifications and oil pollution. The present paper reviews heavy metal contamination in a variety of marine organisms, and sediments, and suggests measures for environmental management of heavy metal pollution in the Arabian Gulf. Most of the reviewed literature confirmed that heavy metal concentrations in marine organisms were generally within allowable concentrations and pose no threat to public health. Likewise, studies suggested that levels of heavy metals in marine sediments are similar or lower compared to other regions. However, localized hotspots of chronic metal pollution in areas influenced by industrial facilities, desalination plants, and oil refineries have been reported. Holistic spatial and temporal monitoring and comprehensive national and regional strategies are critical to combat and manage heavy metal pollution in the Arabian Gulf.